Building 27' Plywood Boat With No Epoxy?

[raymacke]

Looking for some opinions!

I have built and heavily used an 18' stitch & glue Glen-L Cabin Skiff (17000+ miles - Building A Cabin Skiff (http://egyptian.net/~raymacke/index.html) ). I now am entertaining the idea of building a 27' plywood over frames boat (Hankinson Coastal Cruiser) that will be trailered and used in fresh water. The problem is during the Skiff project I became very allergic to epoxy resin - can't get near the stuff anymore! But still I love to work in wood and really crave a bigger boat project. So here is what I am considering -

Using XL Plywood as my main planking material. I am leaning towards it because it is treated with Chromated Copper Arsenate which should alleviate any rotting problem since I can't encapsulate with epoxy. Inside will be either left bare, painted or varnished - depending on what I find to be the best. Boat will be outboard powered so bilge should be able to be kept free of all oil, fuel and water.

The outside of the hull will be covered with glass cloth and vinylester resin. A barrier coat of epoxy might be used below the waterline if I have someone else apply it over the vinylester. The superstructure will be covered the same or possibly with polyester resin.

The most controversal material will be the structual adhesive. I plan to use PL Polyurethane Construction Adhesive instead of thickened epoxy. I had read several reports of builders using this with good results. In fact, last year I built and 8' dingy just as a proof of concept project (Sabotina). The adhesive worked well and I honestly feel the joints are every bit as strong as epoxy ones. It is waterproof (100% Polyurethane like 5200), fills gaps well (up to 3/8") and is a delight to use when compared to the mixing and mess of epoxy.

So there it is. I feel for a trailered boat this process will work fine. But I want to make sure I haven't just "talked myself into it" so I am looking for opinions. I know epoxy is better BUT it won't work for me. I NEED alternatives!

Thanks,
Ray Macke

[RonW]

Hello Ray, glad to see you found the wooden boat board. I enjoy your articles and really like the pictures, always neat to see river pictures.

Believe it or not, you are not the only one to have caught the dreaded epoxy poisoning, commonly referred to as googe. But there are those that do not appreciate the word GOOGE.

Here is some suggestions, and I am sure others will ring in loud and clear.
#1- Have you gave any thought to planking the boat in the traditional strip planked fashion, instead of some form of sheet planking. Very solid and sound, simple to do, easy to get materials. You can use the P.L.Premium and ring shank boat nails either in bronze or 316 stainless.On the outside, sand it and give it a good coat of cuprinol, a few days to dry good and followed by several thin coats of a good oil based paint, like maybe kirby's. No epoxy and no fiberglass cloth.On the inside, clean it up and coat with cuprinol, thats it, install drain plugs and floor and sides, no need to do more.
#2- If you want to use sheet material, you will have problems with fiberglass cloth or paint if you are talking about using treated plywood.
Actually the best plywood you can get in my opinion is douglas fir marine plywood, for strength and rot resistance. Plenty of plain fir marine ply boats around that are over 50 years old with out any glass. But it does have the problem of checking. One of the ways I have heard to prevent this is coating it liberally with raw linseed oil and letting it soak for several days, then wiping off excess and painting again with many thin coats of oil based paint. The other way is a product to stop fir checking, don't know where to get it.
#3- Use M.D.O. or H.D.O. plywood, it has a resin overlay and is used for exterior sign material. It will paint as pretty as a glass boat.

Personally I think you will enjoy the traditional strip planked method, and have a much better boat with a good resale. You can strip plank even hard chime vee hulls, on the Atkin site, William Atkin speaks highly of doing vee and hard chime boats in strip planking.
On a opinion of fiberglass, I think it is grossly over exaggerated as to it's benefits.On the elco site they right now have a used elco in excellent condition for sale for $77,000. it was built in 1897, and the family still owns and use a original that was built in 1893. So wooden boats don't deteariate without glass as we have been told.Most rotten wooden boats rot on the trailers in the backyard with no covers, and they fill up with rain water and leaves, well they would have rotted just the same if they had fiberglass and googe. A little food for thought, good luck....RonW..

[generic]

The only experience I've had with boatbuilding and polyurethane glues is with Balcotan (http://www.holdich.demon.co.uk/chemical/balcotan.html).
It's been used in Yoorp for decades without, as far as I can tell, any major problems.It glues green Oak poorly as it reacts with the tanins, I don't know how it would do with CCA.
It will fill gaps for sure, but not structurally.

Are all poly. glues the same? someone with a bigger brain than mine will have to answer that.

If you used West on your previous boat, try getting close to some MAS. It seem to me (and others) that it's quite a lot more benign.

[ 03-25-2005, 07:16 AM: Message edited by: generic ]

[jboat]

I agree, there are plenty of plywood boats around that never saw a drop of epoxy. Good fir marine ply is a perfectly acceptable building material and if treated properly and maintained it will last as long as real wood.
Personally I would stay away from PL adhesives and lean heavily towards weldwood or another waterproof resorcinol but thats just me.
Pick your materials carefully, build carefully and your plywood boat will be around as long as you will. Epoxy is overated and overutilized.

[Bruce Hooke]

I am not familiar with XL Plywood but one thing I would consider when looking at any potential plywood for use in a boat's hull is does the plywood have any internal voids. As a general rule it seems like most softwood, non-marine plywoods will. This creates two problems 1) the voids, if they are at all large, can make it hard to get a fair curve in the plywood and 2) more importantly, there are widespread reports that condensation can build up in the voids and start rot from within the plywood.

In your situation I would certainly at least consider whether "traditional" plywood construction would work for what you have in mind. As previously noted, plenty of plywood boats were built before the days of googe (epoxy and poly) and if maintained they can survive just fine. In some ways I think the likely lifespan of a pure plywood boat might be better than a plywood boat that is only partially encapsulated in googe because partial encapsulation can create places where moisture can accumulate and not be able to escape.

[Bruce Hooke]

Be careful about using Resorcinal...it is pretty nasty from a toxicity perspective and it calls for very tight fitting joints and high clamping pressures. The latter could be pretty hard to achieve when applying plywood to the side of a boat. How critical those high clamping pressures are to success is a question I've never seen a really good answer to, so I err on the side of caution...

[Bob Smalser]

You live in hardwood heaven.

Why plywood at all? Betcha solid would be cheaper.

[Jack C]

John Guzzwell has the same problem, and used a epoxy-like derivative when he built Endangered Species. Check it out, there's bound to be some more information about it somewhere.

Jack

[Tom Lathrop]

Hello Ray,

Welcome aboard. Good questions.

First, there were a lot of ply on frame boats built before glass & epoxy. True, most of these died long ago from rot and neglect but that does not need to happen. The fact that you intend to keep the boat on a trailer is a plus and if you keep it under cover as suggested, its life can be very great. I recently completed a permanent boathouse for "Liz" and expect my heirs will inherit a boat that is still in good condition.

I had a boat built with ply on frame and Resorcinol that was very solid when sold after 30 years. Clamping pressure was provided with ring shank nails which appeared very adequate. I'm not familiar with toxicity problems with Resorcinol.

I have used PL and like it but just don't know how it would be long-term in a structural situation. One thing to consider is, how much 5200 or Sika would be needed for the main joints like the chine, keel, sheer and deck-cabin joints? The stuff is expensive but I don't think the total cost of 5200 would be overly significant in the whole boat. I'd have no qualms about using PL for other, less critical, areas.

Your question will draw responses from those who have hangups with epoxy but you already know that it is great stuff when used properly but is just not possible for you.

I would not use treated fir though. I believe the mfg process weakens the wood and promotes more checking than in the normal stuff. Some say that it does not glue or paint as well but I have no experience with that. I have used MDO and know that it gives a very smooth and long lasting exterior surface that will not check. With MDO, you could avoid the sheathing issue altogether.

I have had experience with the powder glues like Weldwood and know that they are not weatherproof enough to use on any boat for me. I recently busted up some beams laminated with Weldwood that had been left outside for years. The glue was all deteriorated.

I could not identify the Coastal Cruiser on the Glen-L site. Which one is it?

[JimD]

Ray, do you already have the plans for Ken's design? It looks like last week he decided to call it a day, closed the website, and retired.

[bainbridgeisland]

My motorboat is medium density overlay (MDO) on Cedar with 3M 5200 adhesive. I built it in the winter, outside, under a tarp in the Pacific Northwest. I have no glass at all on the boat. I did use 3-coats of epoxy inside the anchor well due to possible rot due to poor ventilation. The boat is painted with Brightsides enamel and looks very good.

The only complaint I have about the building system is a consequence of using 3M 5200. The adhesive moves slightly as temperature changes making the joints show sometimes. Another thing about the adhesive is that it is harder to clean up than epoxy. This is because it continues to squeeze out of a joint many hours after the joint has been made up.

When using MDO, you don't want to sand it much before painting. Just smoothing the surface with scuff sanding seemed to be about right. This means you need to make up your joints accurately though. Using putty for fairing defeats the purpose of using MDO. The surface is ready for paint as delivered from the factory.

Longevity wise it is hard to beat MDO on Cedar as long as the edges of the plywood are sealed. I just ran a router down the chines (and other joints), glued in a strip of cedar and planed it flush. The boat is now 3-years old. I notice slight imperfections in the paint and will add a coat of paint this summer. The plywood grain does not show at all through the painted MDO surface.

I used Western Red Cedar for most of the framing and a little Alaska Yellow Cedar for high load areas. Scantlings need to be a little larger for WRC because it is not as strong as most woods used for framing.

I very much enjoyed building a boat this way. Though very proficient with epoxy and fiberglass, I prefer not to use them. Besides, I couldn't have used those materials outside in the winter here.

[raymacke]

I really appreciate the input. It is nice to know help is as close as the keyboard. BUT the replies have produced MORE questions but a little clarification first.

The boat will be trailered and kept under cover. I used Glen-L's epoxy on the first project have no problems with using epoxy again if I could get away with it. The boat I have in mind is a design by Ken Hankinson. It has a semi-displacement hull with hard chines. I already have the plans. I talked with them about 2 or 3 weeks ago and there was no mention of closing shop but it has happened. Pulled down their web site and have an answer machine telling you to "write them" if you have any questions.

Now the questions! The plans call for 1/2" ply on the bottom and sides. Can I just use the same frame set-up and attach planks? What wood would you use and how thick? How about weight? This will be a trailered boat and weight can be critical.

I like the idea of plywood planking, but perhaps that is just because I am familiar with this type of construction (also it is the easiest for me to obtain). DF ply by itself will check but a light weight cover of FG cloth & resin seems to solve this. (On my Skiff I have had no covered ply checks but some white oak that was only painted has - need to glass it.) If DF ply is covered on the exterior what is the best practice for the interior?

Although I have used it before I am not a fan of Weldwood Plastic type glues. I agree with Tom as I have seen it revert back to powder when left exposed. Resorcinal is good bt no gap filling ability. Plus getting harder to find. Anyone know a good source?

Tom, 5200 probably would be a good choice for critical areas. I have read builders even using it to laminate ply planking. They spread it with a notched trowel. It is more costly but as you stated not a huge factor in the overall project this size.

I will also make a confession & statement that will probably really irk some. When building my Skiff the majority of the structure attached to the hull (not the hull itself) was glued with Titebond II. There I said it - let the ranting begin!! Would have never done this with a boat that sits on the water all the time or not undercover. But to date with over 1000 hours I have not had a single glue line failure. And the new Titebond III is classed "waterproof" as opposed to the II's "water resistant". It passes the 4 hour boil test (ANSI/P\HPVA Type 1). Dare I suggest using it above the waterline???

I have been searching for info about the adhesive that John Guzzwell used. It was Wonderbond by Borden Chemical. Haven't found much yet. Anyone have a link?

About MDO - I have only used it once a few years ago for an outsoor sign. The face seemed to have a paper cover that was smooth. Didn't know if resin & cloth would stick well. Sounds like it would. Am I correct?

Sorry this is so long but I have a lot of decisions to make.

Ray

[Tom Lathrop]

Ray,

I would not be one to rant against using Titebond II on a boat since I have use it quite a bit. Not in the most critical areas but have not seen any failures where it has been used. I've used gallons of it in cabinetry and furniture work. I would not risk it as the only thing holding my boat together but, when protected, as in a covered and trailer kept boat, I just don't see a big problem. It needs the addition of mechanical fasteners in stress situations because of a tendency to creep, but you do that anyway, don't you?

I don't think its necessary or even useful to glass over MDO although I am a fan of glass tape over chine and keel seams to seal them. Get a friend to do that with epoxy.

This is a good time to search out the alternative adhesives that have low sensitisization potential. Wonderbond may be a good one since Guzzwell would likely have already done the research.

Is the Coastal Cruiser a planing hull? Will really change your cruising habits if it isn't.

Best of luck.

Tom

[RonW]

Here is a little more info, the basics on strip planking, and you can use the search at the top right to research years of discussion about everything on this board.
http://www.sredmond.com/strip_plank.htm

M.D.O. & H.D.O.- A little explanation of this product, mdo is medium density overlay and hdo is high density overlay. Both of these come in quite a few grades and varieties.Some only have one side finished, and the other side a c grade plywood, forget this one, you want all grade b or better for the inner plies.(and finished on both sides) The overlays are graded by density and the better quality will be a higher price. Look up olympic and simpson panel for more tech info. The softer mdo is used for signs and the better mdo is used for better quality signs and concrete panels. The hdo is a better quality and is used for concrete panels more then the mdo is. They also grade these overlays as to how many pours, or times they could be reused as concrete panels for forming. Your boat could never see the abuse that a panel used for 50 concrete pours has seen.This is a totally finished product that all you need to do is add paint. There is a wooden boat shop in cincy that uses a lot of hdo panels as planking.It is a very nice looking product and a 1/2inch sheet 4ft. by 8ft. would cost around $80. or $90. but hey they charge that much for 3/8 occumme plywood.This should be available or able to be ordered through any major lumber yard.

All you would have to do is glue and nail or screw it to your frames and or stringers and paint. I put the sides on first and then lap the bottom over the sides leaving the bottom raw edge on the side, where I cover it with a external chine for abrasion. If you like the plywood construction, hdo is the way to fly.

Personally I am a fan of P.L.Premium and ring shank boat nails, 316 stainless on my next boat.
Yellow pine framing, hdo planking, pl premium glue, ring shank nails and oil based porch and deck paint. You might amaze yourself at what high quality and rough and tough construction you can use to build a great looking boat at a much more reasonable price once you get away from occumme plywood and epoxy and fiberglass. Not to mention the durability and longevity.Easy to get materials that are much more pleasurable to work with. No space suits and respirators.

[Tom Lathrop]

I agree with Ron except for a couple things.

HDO has a very smooth phenolic impregnated overlay and is used mainly for concrete forms. The overlay is formulated so that nothing sticks to it, including paint. I have not used HDO and would avoid it if that claim is correct.

There are always pros and cons about stainless vs bronze fasteners. If the nail or screw is to be encapsulated so that no water gets to it, either will be fine. Stainless is fine in cases where water moves freely but death if the water and stainless fastener is in a closed system that oxygenated water can not get to. Either may work but bronze is safer. In a trailered and protected boat, it is probably not an issue.

[bainbridgeisland]

We built strip planked boats one place I worked. Used a pneumatic nail gun with Aluminum nails. Since the strips were glued with epoxy and the boat was sealed inside and out with epoxy, the nails were encapsulated.

The strips were made from 5/8" thick x 3/4" Port Orford cedar. The grain occasionally redirected a nail out the side. We just pulled them out when this happened (they didn't really have heads on them. They may have been called 'brads' or something other than 'nails').

One nice thing about using Aluminum nails is that most woodworking tools can cut through them with minimal difficulty. I wouldn't use my best edge tools on them though.

This boat was built almost 30-years ago. Saw it for sale last year. Appears to be in great shape. The Aluminum fasteners caused no problems that I know of.

[RonW]

Hey Tom Lathrop - A little friendly conversation feedback. I have made the decision on my next boat to use 316 stainless ( the grade recommended for saltwater)due to a couple of things. For those of us who have read this board for a few years, we all know there is a controversy concerning the quality of bronze. Look at some of the pictures these guys have posted where the same batch of bronze from the same supplier is all different colors, and one guy a year or so ago wanted to know where to have metal tested. His bronze screws where deteariating after only 6 years. Even some of the distributors have different grades and prices on bronze. Unfortunately america has pretty well closed down a lot of our foundry's and now most of this stuff is coming from asia. The quality is a big question.Stainless seems to be controlled and not mixed in a pot in some chinaman's back yard.The last batch of bronze bolts I got, the threads where only a inch long, with a note from the supplier, sorry but this is what they sent and you can return, I ran a tap on them and exstended the thread.
Besides quality there is also price, In looking at a box of 100 bolts from jamwestown, galvanized was $48. stainless was $148, and then bronze was $560. Now this is getting serious.
All stainless is not created equal either. That is why I said 316. I have seen stainless 10 and 15 years after it was installed in commercial construction -where it can be dated- under the most severe conditions, like meat packing plants, be the same as new, and actually reuse it.
These meat packing plants are washed down twice a day, in a 24 hour period by people in space suits, with very harsh chemicals, and if anything will eat away a metal it is defintely blood.
The only thing more caustic then blood is acid, if it is a strong acid.(generalization intended)
Here looks like a good source for 316, they will be getting a order from me soon.
http://www.manasquanfasteners.com/

H.D.O. Paint adhesion, hey if we can paint a aluminum boat, surely we can paint a hdo panel.
But some of these guys want to slap 2 coats of porter water based latex house paint on it and cry paint adhesion problem. Well that doesn't surprise me at all.I would say that you would have to sand it lightly by hand, in a circular motion to scratch the surface and maybe spray the primer coat, possible look at what paint you use for primer coat.But forget house paints.

3m5200-epoxy-P.L.Premium- I have used and tested all 3 side by side, I like 3m5200 but it takes 7 days to fully cure and is pricy. I have even used it to laminated stems and knees, it is strong and tuff.In testing the 3 above and I used glen-l's epoxy grip,because west system bothers me bad, I found the p.l. to be the strongest. But I used all 3 as glues with fasteners, not as bridge filling gap joining glues, there only epoxy will work. My answer is learn how to fit your wood together and use metal fasteners.

In my opinion (I think) I have finally learned how to build a high quality plywood boat, without falling into the trap of overpriced occumme plywood that has no rot resistance and then you have to buy all this exspensive and caustic epoxy to encapsulate it with to try and make it last 10 years before repairs.Plus all the additional work and cost. Why would anyone use a nondurable wood in boatbuilding?? I think it is a scam by the people that are selling the epoxy.

But from here on out my boats, other then maybe a river scow, will be traditional strip planked. Real wooden boats. Why, if you go to sell a plywood boat, the resale value is bad and a hard sell, just because the public looks at it as a very cheap alternative. Right or wrong, fair or not, that is just the way it is.

[Greg Stoll]

First, the epoxy.

I have never heard anyone mention taking Benadryl (Diphenhydramine) for the allergic reaction. I am a Paramedic, and we carry it for mild allergic reactions as well as life threatening ones (along with epinephrine, if you start to have an allergic reaction with trouble breathing, don't hesitate; CALL 911 IMMEDIATELY!) The allergic reaction is caused by antibodies "overreacting" to the foreign protein in the epoxy. This is mostly regulated by histamine, and benadryl is potent anti-histamine. Main side-effects are drowsiness, which can be a problem if you mix epoxy use with power tools.

Secondly, I just looked at your cabin skiff site. I would have to say that yours is the best boatbuilding website I've seen. Every detail is well documented, both with pictures and written discussion and justification. All changes are thoroughly explained and justified. It's a beautiful boat!

Keep up the good work.

Greg

[Tom Lathrop]

Ron, I really can't quibble with many of your thoughts. One thing is that there are times when light weight is a bigger factor in plywood than any of the other considerations that we have talked about. Who, in their right mind would think of building a kayak or small racing sailboat of MDO, HDO, or meranti? This same thing can carry on to much bigger boat too. I have inquiries about using meranti instead of occoume in building one of my boats. I explain that this would be the equivalent of having the weight of 2 1/2 extra adult crew aboard that you could never get rid of. The loss in performance and capacity is real. It's another decision. Just be aware of the consequences. This wonder wood kerrung (sp) is not even worthy of consideration because of weight.

I do plan to make a weight study of MDO, where applicable, instead of occoume to see where the cost, weight and performance equations go for this boat.

The simple specs on MDO/HDO that I saw says the MDO can be had in the same quality wood panel as HDO and the only difference is the slick finish of the HDO. That is why I would choose the MDO which would take a finish better.

Won't argue the stainless issue either. I use mostly stainless and very little bronze. I have had stainless to develop SERIOUS corrosion in anerobic situations like swaged fittings on mast stays.

I think I am immune to any scam that epoxy suppliers might use to get me to use non durable wood. I just accept the negatives and work around them when I think occoume is what I need.

A friend has built local traditionl skiffs with planking joined with PL Premium (window & door sealant). Looks good and tests strong. Hasn't been in the water for 10 years yet though.

Ray gets my salute for the way he built and documented his Cabin Skiff and even more for the way he uses it. We have corresponded since before the boat was first launched and I'm a bit in awe of how much cruising he has done.

I do think your methods will produce a good boat but do have a question about strip building. Would you sheath the hull with fabric? If so, what kind of resin?

[ 03-26-2005, 05:50 PM: Message edited by: Tom Lathrop ]

[bainbridgeisland]

You might not want to use stainless steel below the waterline. Sometimes it works but sometimes it doesn't. Here is an excerpt from an article I wrote for 'The Ballast' which is the newsletter for ‘The Society of Boat and Yacht Designers’ that explains why:

....What is the most distinctive property of corrosion resistant steel, stainless steel, when immersed in saltwater? The surprising answer was: corrosion. As Jim pointed out; “If it hasn’t corroded yet, wait awhile, it will.” Even by itself, without dissimilar metals affecting it, stainless steel will eventually have corrosion problems. And worst of all the rate of corrosion is difficult to predict. Stainless steel can be stable, with no corrosion, for months and then within a few weeks be severely damaged.

You can see, when looking at a galvanic table, that stainless steel has two at rest potentials, passive and active. As long as plenty of oxygen is present, stainless steel tends to be passive. This is because air passivates stainless steel. The “passivation process” only removes surface contaminates so air can passivate the metal. Conversely, excluding oxygen from stainless steel puts it at risk of eventually becoming active. The passivation film is only tens of molecules thick, making it fragile to chemical or abrasive attack.

As long as stainless steel is all active or all passive, it has a predictable corrosion rate that can be controlled like any other metal. Unfortunately, it is very difficult to keep stainless steel all passive or all active when immersed in seawater for a significant time. Abrasion of the surface of the metal or differences in the flow rate of seawater can alter the potential. The consequence of having areas of both active and passive potential is that the metal becomes its own corrosion cell, its own battery. Galvanic corrosion causes the electrons in the active area to be given up to the passive area. In stainless steel, a byproduct of this reaction is that an acid is formed on the active material as electrons are given up. Often this acid is trapped beneath the passivation layer creating a highly conductive electrolyte that accelerates the rate of corrosion.

The actual cathodic reaction is responsible for damage to the passivation layer as well. Hydrogen destroys the passivity of stainless steel and Hydrogen is a byproduct of a cathodic reaction. Further, the cathodic reaction takes place in the metal, so this hydrogen has to pass through the passivation layer to be released.

The areas that are usually most at risk of becoming active are the portion of stainless steel that fays to a surface or any pit or crevice. All of these features tend to exclude oxygen. So, for example, the mounting surface of a stainless steel fitting will tend to have an active potential due to little oxygen. The portion of the fitting exposed to flowing, oxygenated, seawater would retain passive potential longer. The two potentials in the same component create a corrosion cell, a battery, causing loss of material under the base of the fitting.

Why does stainless steel sometimes work so well and yet sometimes fail so quickly?

Stainless steel without pits or cracks, that tend to exclude Oxygen, lasts longer than material with these flaws. This is one reason stainless steel fittings are often polished.

Faying surfaces that are sealed from seawater are not exposed to the seawater electrolyte and therefore tend to have a long corrosion life. Conversely, poorly sealed stainless steel faying surfaces are exposed to seawater electrolyte but tend to be excluded from the Oxygen from flowing seawater, thus encouraging the area to become active and generating a corrosion cell that greatly shortens the corrosion life.

Stainless steel that is hauled out of the seawater, rinsed with freshwater to remove the Chloride residue, and then allowed to dry, re-passivates itself. This practice essentially resets the corrosion clock to zero. Until significant difference in potential can develop again, electrolytic corrosion due to a stainless steel corrosion cell is minimal.

Remember that electrolytic corrosion is driven by area as well as driven by electrolytic potential. Therefore, a small area of passive potential coupled to a large area of active potential could have a reasonable corrosion life. This is why stainless steel bolts and screws can work. Conversely, large areas of passive potential coupled with small areas of active potential tend to experience short corrosion life.

Sacrificial protection from less noble metals can protect the stainless steel active surface. For example, a stainless steel fitting bolted to an aluminum hull will probably be protected.

Choose the right stainless steel material. As pointed out above, all stainless steels have corrosion problems but some materials are less susceptible than others. When possible, I always specify 316L followed by 316. Stainless steel corrosion cells develop in about 6-months for this metal. Type 304 is of only marginal use for submerged service and must be very carefully controlled. Stainless steel corrosion cells develop in about 2 to 3 months for this metal. Type 304 works fine for on-deck or intermittent submerged service if it is rinsed with fresh water and dried. Some other types are useful but require extensive maintenance and installation methods to insure reasonable corrosion life. Type 303 is not suitable for use either on-deck or submerged applications. Stainless steel corrosion cells develop immediately upon immersion in saltwater for this metal.....

[Jay Greer]

Yipe! I know what it is to become sensitve to epoxy! One of our guys came down with it when we did some special boats for Disneyland. Certain hidden components of his anotomy suffered from an embarasing swelling and rash. Having seen what epoxy sensitivity can do, I try to stay away from it!

I am now more prone to enjoy traditional building methods, I now shy away from plywood and other synthetic materials more and more. I personaly would build a boat to be trailered by using soild wood and lapstrake or dory lap construction.

[maa. melee]

RonW, care to elaborate on your routing techinque for sealing plywood endges? I remember seeing old plans for a plyboat boat without epoxy using an external chine made from angle-line wood molding set in roofing cemenet.

[L.W. Baxter]

Lots of plywood boats were built before the invention of epoxy.

And there's plenty of "traditional" woodworking to be done on a 27' plywood-on-frame boat. No reason not to do it, if you've found the boat you want to build.

Just my humble opinion.

[L.W. Baxter]

Ray, I just spent a solid hour reading your cabin skiff site. Fantastic! Your exposition of the entire process is superb.

Amongst other things, your method for marking the curvature of the cabin top on the windshield frame is a real keeper.

And you've really struck some fear in me about epoxy sensitivity. I need to be alot more careful. Thanks for the war stories.

--Lee

[RonW]

Looks like this thread is getting down and that is GOOD, that is why we are here, to trade ideas and secrets and to become either better, or at least confused boatbuilders.At least it makes us think and question different techniques.

Tom- of course occoume is great for canoes, kayaks and light work, but personally I can't see using it in a boat big enough to have floor boards.Most of the rot issues are in the bilge around the frames and nook and cranies where it holds water and has poor air circulation.
Totally agree with your assumption of keruing.

M.D.O. is going to be slightly heavier then douglas fir marine, basically the same stuff with the addition of the protective coating. Fir is already 1/3 again heavier then occoume. But don't forget to add the weight of the epoxy and cloth, and if you saturate the inside that weight as well. You may only end up with 1&1/2 adult weight instead of 2&1/2.
On the other side of the weight issue, what if you could build your boat in some kind of space age material and it only weighed 500 lbs. You could go faster, or use a smaller outboard, but every time the wind blows your boat would bounce around, and a good wave would feel like someone slapping you upside the head. It would get to the point you would hate to see a wave rolling your way.I find that weight in a boat is not a bad thing,but all things are a compromise and particularly in boats.( As Martha would say-it is a good thing)

The stainless issue, brainbridge has me thinking hard about this one. I listen when brainbridge talks and that is not nearly enough, thanks for the input or more confusion, dang it. Although I have heard guys saying that they pulled galvanized trim nails from the planking on a traditional strip planked boat, where the nail is totally encased in wood, and 35 to 50 years later they are as good as new. So..

P.L. window and door caulk, I have a tube of this and it is neat, as some say very similar to 3m5200.But I warn against using it below waterline, it might be fine but. On the side of the tube under limitations, the pl company says -not recommended for underwater applications.-
These pl or actually OSI products, unfortunately named all their products with the starting of pl, I know this has lead to confusion, just as you stated pl premium window and door caulk, actually the premium is a specific type of polyurethane glue.

As to strip planking, I am going the traditional route, regular framing and just do the strip planking instead of carvel with caulking. A old and tried and true method. I am not a fan of the modern method of leaving most of the frames out (for weight) and glassing the inside and out to help create a panel for strength. You save weight here and then add it back there, in a lot more work and exspensive method. We know that a properly built and maintained wooden boat can last a 100 years, we do not know that about wooden boats covered in polyester and or epoxy. We do know that polyester resin will absorb water and hold it in next to the wood, epoxy does too, but at only about 1/3 the rate that polyester resin does. This may not be a big issue in a trailer boat though, or is it? How do these guys have rot in their plywood boats if the boat is totally encapsulated? How did water get in? It passed through the resin. Plain wood will dry out and if it is of a good rot resistant species be fine. Thats my thoughts..

Maa Melee - I was referring to a external bump rail at the chine to cover the edge of the bottom plywood. You could use a strip and inlet it in if you wanted, but sounds like a lot of work for a work skiff. If you put it on the outside, bed it and screw it so in the future when it is all banged up, you can replace it. Workboat fashion.

[ssor]

raymacke, I didn't read through all of the posts so if I am redundant please forgive me, it is Saturday night. Plywood has been used for a hellofalot longer than epoxy has been around. If you give consideration to the area of the adhesive joints I believe that you will find that PL Premium polyurethane adhesive will be more than adaquate. I think that you have a reasonable handle on the problems involved and shouldn't encounter any unanticipated problems. Good luck with your new building project, please keep us informed.
Ross in Bel Air

[ 03-26-2005, 09:55 PM: Message edited by: ssor ]

[Tom Lathrop]

Originally posted by RonW:

Tom- of course occoume is great for canoes, kayaks and light work, but personally I can't see using it in a boat big enough to have floor boards.Most of the rot issues are in the bilge around the frames and nook and cranies where it holds water and has poor air circulation.
Totally agree with your assumption of keruing.
-----------
On the other side of the weight issue, what if you could build your boat in some kind of space age material and it only weighed 500 lbs. You could go faster, or use a smaller outboard, but every time the wind blows your boat would bounce around, and a good wave would feel like someone slapping you upside the head. It would get to the point you would hate to see a wave rolling your way.I find that weight in a boat is not a bad thing,but all things are a compromise and particularly in boats.( As Martha would say-it is a good thing).Great thread with good input by all.

We often draw different conclusions because we start with different assumptions. For instance, I never think in terms of frames or floors in plywood boats. I'm a believer in the monocoque school where every piece of structure contributes to the hull strength as well as whatever other purpose it serves. Therefore berths, bulkheads, shelves, cabinetry as well as soles are bonded parts of the hull. Full ventilation of all spaces is required along with drainage channels which eliminate any possibility of isolated pockets of water.

On the weight issue, I come from racing one design sailboats where all weight beyond that absolutely required by rules is bad. For instance, adding weight to correct a trim issue is a no-no. Correct the trim with proper design or relocation of necessary weights. True, lighter boats do tend to blow around more than heavy ones but that is not a good reason to make a boat heavy. With good design, that is only a problem around docks and tracking underway can be good, even in very light boats. Considering the benefits of light weight in trailering, planing performance and economy of operation, I'm solidly in the light weight camp but I'm not going to complain if others want their boats to be heavier.

Some will be willing to accept that occume is not a very durable material as long as they can make the whole system durable with a method of construction that counters the durability issue. From experience, I know that I can do this. I have also see some horror cases where serious rot occured because of failure to deal with durability issues properly. This holds for all kinds of construction, not just plywood.

In Ray's case, I think he will go elsewere for the best solution for him. The MDO without fabric sheathing looks like it may be the best option among those mentioned. Bainbridge's excellent posts notwithstanding, I also think stainless fastenings will be fine for Ray's intended use.

Happy Easter

[ 03-26-2005, 10:45 PM: Message edited by: Tom Lathrop ]

[raymacke]

Thanks for the kind remarks about the web site. As you can tell I really enjoyed the project AND using the end product. Wow, where do I begin. So many good questions, suggestions and opinions. I think I will start with a few answers and comments.

TOM - I plan to operate this boat at near displacement speed or a little +. It will be a change but I'll still have the skiff when I want to go long and hard. I am needing to add a little more "comfort" to entice my wife along. That way I won't feel so guilty about leaving her at work while I play and as a result reduce the need to get there and back in a short period.

Greg - Epoxy Sensitivity - It's sure for real for me. It is very interesting that you mentioned Benadryl as just this week my wife shamed me into trying it (I'm one of those stubborn types that refuses to take anything stronger than an occasional aspirin). What I have found is even though it has been almost 5 years since any epoxy has been used in my shop it is still contaminated! We have cleaned and even used a leaf blower and large fan to try to exhaust the dust left from sanding but it still causes me problems. If I spend the day working in there OR go digging around in my scrap lumber supply I find that my left eye turns blood red and feels like there is sand in it. It last a day or two and makes me look like hell at the office. But this week I tried the Benadryl and have spent 2 days working in there cleaning up and so far no Evil Eye! Let's hope it's not a fluke.

PL Adhesive - They have a number of different products but the one I have been working with is the "Polyurethane Premium Construction Adhesive". There are several reasons I favor it over the "Door & Window Sealant" (and they are just my opinion, not gospel!) First, it is advertised as 100% polyurethane while the Window Door (W/D) sealant isn't. Also, the W/D sealant states it is "permanently flexible". This is a good quality in a sealant/caulk but I,m not sure about and adhesive. Naturally some "flex" is desireable. That's one of the reasons that epoxy is is a good glue and polyester a poor one. But I was concerend it would allow too much movement. I have made some test beads and globs with the Premium and allowed them to cure. It is firm but still some flex. Maybe just a little more than epoxy. Next, the W/D Sealant does state not for underwater use but the Premium does not (does that mean it can be? - good question!) And the least scientific of all, they call the D/W a "sealant" while the Premium is an "adhesive". Anyone have any thoughts on my logic (or or lack of it). If interested here are a couple of links to people experimenting with the stuff PL-1 (http://htthttp://www.simplicityboats.com/pl_premium.htmp://) - PL-2 (http://www.simplicityboats.com/jointtest.html) .

About XL Marine DF Plywood - I ran on to this at Glen-L site. Look towards the bottom at the heading Laminating Fiberglass to Plywood (http://www.glen-l.com/wood-plywood/boatbuilding-plywood.html)

Weight - Looks like DF Ply will cost me about 200 to 220 pounds weight penalty :( but without epoxy I have little choice. I guess it won't hurt as much at displacement speeds but I am sure there is still some reduction in performance.

You have me interested in the MDO. I checked a local lumber yard and the stock one they called DuraPly (said they have a local sign painter that buys a lot of it). They have it in various thickness and with one or two sides covered. Price was reasonable. A couple of questions - How is the bond when attaching over the paper side. Like gluing another piece of ply when laminating? An what do you do about the nail/screw heads? Are they counter sunk and filled? If so, does sanding them smooth damage the paper where it will show in the final paint?

[RonW]

http://www.simpson-plywood.com/sign_making/index.php

Here is some info on mdo & hdo, you should call and talk to these guys. Look at the highway hdo, it is paintable, they tell you so at the bottom of the page. It is designed for state and county road signs,and is made up of solid veneers.
If this duraply is what I think it is, which is one solid core with the face veneers and resin added, you do not want this, it is basically a high quality masonite type deal, glued and pressed sawdust. You want the panels to be made up of veneers just like marine ply is, and all solid no void in the veneers.Basically a marine ply with the resin added so as to not telegraph the grain pattern through the paint.

I talked to the pl techs a couple of years ago and asked about using the premium in a boat below the waterline. There answer was no problem, just like the tube says, the only limitations are to not use it below 40degrees, other then that have fun.

To plug nails or screws I use famowood, glen-l sells it, $4 a pint and one can might do you. Works great. You want to very slightly indent your nail or screw just the same as you would a drywall nail, use the famowood just like you would spackling, let dry a couple of hours and lightly sand. Let dry overnight to get all the shrinkage out and hit it again. You are done and ready for paint.

Remember last spring, the doctor that was building a glen-l mohagony gentlemans cruiser, He had the boat planked (veneered with epoxy) and sold it on e-bay for $1,000 due to epoxy poisoning.He probably lost 4 grand.

Keep it simple and solid and with materials that you can enjoy working with. Good luck on your next adventure.

[RonW]

Mike says.

If you have ever used 5200 in underwater applications, you will also know that it give away from saturated parts. The advantage has been, in it early stages of life, is the adhesion and stretch, but WILL FAIL against saturated wood parts This is good info, A couple of years ago, again I called the techs at 3m and asked, WAHT IS THE LIFESPAN OF 3M5200- simple question, You know what the technicians did? They played dumb and stuttered and stammered,beat around the bush. I pushed them for a answer, and finally they told me -no one has ever called and asked that- At which I promptly replied in my construction voice- you are full of sh*t..(it slipped out before I could catch myself).So I have used and do like 3m5200, but always used fasteners as well, not just depending on the adhesive alone.
But due to their tech answer I no longer use 3m5200. Plus the price is ridiculuos.Here is another reason not to use it.

[JimD]

Gentlemen, I have been reading this post with great interest, and the possibility of a strip planked boat glued with construction adhesive. Really? You think this can be done on say a 20 to 22 foot sailboat such as a Glen-l Amigo or a Selway Fisher Rathlin 20? I would still sheath the hull in epoxy set in fiberglass, dynel, or xynole. Its the thought of epoxy gluing hundreds of strips that creeps me out.

[raymacke]

I have been giving the MDO a lot of thought. I like the idea on minimal work/sanding to prepare for paint but do have one reservation. I run rivers and rivers often have floating and semi-floating debris of all shapes and sizes. And a boat hull is like a magnet to this junk. Often you don't see it just hear it "thump" off the bottom. Using the MDO as described only places a couple coats of paint and resin paper between the water and raw wood. It seems a good scrape will expose it. If true, this concerns me.

So how about a compromise. What if I use MDO for the sides and then Marine Fir or MDO for the bottom planking (which every one will best hold FG/resin) but cover the bottom up to the waterline with FG cloth and resin. That way I can get the abrasion protection I need but won't need to sand for days to get a smooth surface. The glassed surface it will be covered with bottom paint and out of sight anyway. This makes a lot of sense to me. An opinions?

Again, in my case the resin can't be epoxy so my thought is to use vinylester or polyester. I know many will shutter at the thought of using any "ester" on wood but I don't have a lot of choice. Plus most everything bad I have read about it usually involved boats that sit on the water most of the time. This one won't.

Also, if it really seems to be a concern, once built and out of the shop I could probably survive applying an epoxy barrier coat over the ester (or have someone do it for me - although thats not my nature!). Shouldn't that seal the polyester? Isn't it water intrusion through the thin glass layer that causes the problem? That's what they use on fiberglass boats to accomplish the same. But really not sure if this would be necessary.

So what the opinions on this course of action with the covered bottom and MDO painted sides?

[Hal Forsen]

Ray, found your site a couple years ago and it's inspiring; thanks for taking the time.
I've been running some tests with Titebond III and PL window and door sealant and I'm impressed. I left two pieces of marine ply sloppily glued together with the PLw&d and left it in a bucket of H20 for 6 months and then left out to weather during our wet winter and when I tried to bust it apart the ply failed.
I just finished a test on the titebond and PL;
with the PL gluing small pieces of marine ply and the titebond using DF 2 by 4.
I left them both only overnight to set, then boiled for 6 hours, then frozen over nite and while still cold rinsed off and try to break.
The titebond would not budge when struck but the big chisel and mallet broke it cleanly at the joint with only a bit of real adhesion . The PL would not budge at all and the chisel test ended up with the ply failing and not the glue.
I'm no scientist but I can say for certain the PL adhesive is STRONG stuff.

HF

[Tom Lathrop]

Ray,

Question for you. In all those miles, you have certainly hit some of this flotsom and jetsom. What speed were you running when you hit? Where on the boat did it hit? What has been the result?

I have only had one such collision with a submerged object that made a significant impression on me with the noise. Speed was about 17 or 18mph and the result was two small patches of missing paint on the boot top. The reason for that was that the Awlgrip paint of the boot top has poor adhesion to the Copperpoxy on the bottom. No physical damage at all. I have Xynole heavily saturated with epoxy and epoxy fairing on the exterior.

I actually think the MDO coating is pretty tough although a Xynole sheath would certainly add a lot of abrasion and puncture resistance. Much better than glass from my experiments.

According to some things I've read, vinlyester is very good on moisture resistance. I suspect it would do well as sheathing resin but think you should check with someone who has actually used it. I believe that high end FG boat MFGs are using it instead of polyester resin for its superior resistance to blistering.

Can you email me a plan, profile &/or sections of the Coastal Cruiser. A digital photo maybe. I can't find it anywhere.

[ 03-28-2005, 07:14 PM: Message edited by: Tom Lathrop ]

[raymacke]

Tom, I hate to think about the stuff I have hit! Most small but a few that really made my heart stop. I can't tell you how many times I have trimmed up the outboard seriousily expecting sever damage or pulled the aft deck plates to see if I was taking on water..... (We wont even talk about the 14" steel channel marker I clipped in the dark at 23 MPH - see the Nashville story on my site!!!) Most of it is at my 23 to 24 MPH cruise speed but some slower. It has hit a little bit of everywhere on the bottom. Even managed to run it up on a submereged stump once. I was going very slow but it lifted the hull on the port side up about 5 inches. Had to back off. Just knew it scraped off the paint but when I checked later could barely tell where it was.

I have to say I am truely amazed at the durability of the boat. The hull is 3/8 plywood with FG and epoxy cover. Everytime I crawl under the boat for a look I can't believe the bottom looks so good. There are a few rubs in the PolyPoxy paint but the only place the paint is missing is where the wind blew it up on a rock while at anchor.

I am extremely pleased with this paint as far as abrasion resistance and would use it again. I do have a minor problem with it getting very small blisters where it sets on the carpet covered bunks of the trailer. These stay wet for a long time and tend to work on the paint. I watched it close at first but nothing has happened so I honestly don't worry about it now.

I know the new boat I am considering will be moving much slower but still I like the idea of the extra layer of protection. Between the river and me it does get somewhat abused!

Before Hankinson pulled down their web site I had downloaded the whole thing. I don't think he would appreciate me posting it here but I am going to use a few pieces of it so you can take a look. If he yells about it I will yank it but I don't think it will be a problem. The last image is MY conception of the boat. I will build it as a 27' sedan rather than the pilothouse. Modified floor plan suits my needs. Here is the link - Coastal Cruiser (http://egyptian.net/~raymacke/CC/coascruz.htm)

[raymacke]

Hal, Thanks for the info on the adhesives. Sounds like you have done the homework that will benefit many of us. I have to agree, from what I have experienced both of these perform very well. Unless I can find a better alternative I plan to us them extensively. I love epoxy but it hates me.

By the way, the benadryl has been work well. Although I would still not tackle a large epoxy project fearing I would be pushing my luck. Hate to get in the middle and have to give. I might try using it here and there for critical joints.

[RonW]

I remember that boat, a slightly larger version of glen-l's Hercules. I shouldn't say this, but the truth of the matter is, if I was going to build that boat, I would find a way to have the hull, just the hull fabricated out of heavy welded aluminum. And then the problems are solved. Decks, cabins and everything finished in wood. It would dramatically increase the resale value also.
Some of the guys in canada are turning out reasonably priced welded aluminum hulls. You might be able to get a deal for the hull and trailer, just go and pick it up and finish it at home.

If you decide to go the mdo route, do your homework, some of the lower grades aren't worth buying for a boat hull.

[Norske3]

And the vapors and internal organs......like the brain!...there is no intermediate organ between the nose and the brain...SO, breathing in without a mask those vapors settle directly on the surface of the lower brain! :eek: ....may be the reason we get brain canser when breathing in to many diesel fumes.

[ 03-29-2005, 07:17 AM: Message edited by: Norske3 ]

[Tom Lathrop]

Ray,

I like it. There will be tons of issues to work out, some of which will cause changes, but this looks like a good place to start. The aluminum hull sounds like a possible solution to some of your problems too. I've no first hand experience with building in aluminum so it may not be the best answer. If Ken does not bless it, I'd be wary.

[John Bell]

FWIW, I built my AF4 with MDO, 5200, and bronze ringnails. Only the bottom was glassed (with epoxy). After my experience with that boat, I personally don't think its necessary to sheath an MDO boat at all. The topsides and decks were only painted and they held up well to a lot of abuse.

MDO is wonderful stuff. There's a piece that's been sitting outdoors unpainted and unprotected as the tailgate on my utility trailer for about four years now that shows no signs of deterioration or delamination. It's good stuff.

Allergic reactions aside, I think I'd still plan to suit up with respirator and barrier cream to epoxy glue any scarf joints in ply panels and long pieces of wood.

[RonW]

Again- If I recall correctly hankinson offered that boat in 3 hull types, plywood, aluminum and steel.Don't laugh. If you can't already weld aluminum, then forget it, it is too specialized to learn just to build a boat.That is why I suggested the package deal on hull and trailer.

But a steel hull might surprise you as to how cheap and readily available the materials are and welders or the equipment and a little practice.
Hankinson had a lot of hulls for steel, and practiced a stress skin technique, where the frames where set up, and lenght wise -fore and aft- stringers where in let into the frames but not welded,(he floated them) then the skin was applied to the stringers by just tack welds, and the stringers where then adjusted in and out and tack welded.
Then all the finish welds, the results where a beutifully smooth skin that needed no fairing and with a lot of wood trim could be mistaken for a wooden hull.You could also do all the hull work outside, no need to be under roof.
Hankinson had a lot of steel hull pictures on his site, and bragged on his little steel tugs, in fact he relates the story where one steel tug won first place at a wooden boat show, and the judges let it stand because of all the wood trim.
They actually thought it was a wooden hull.
He also showed pictures of 2 guys rolling over a fairly large steel hull with only the aid of a come along, so this is not a ridiculuos weight issue as one might think. It would probably only add about 60% weight to the hull over plywood, which isn't that much considering the total weight of the finished boat.

20 or 30 years down the road the resale value would probably be 3 times that of a plywood hull. And you might really appreciate it when you are too old to cruise and your main concern is just making it to the restroom on time.
Thomas Colvin is a leading expert on smaller steel hulls for backyard builders. Hankinson recommended his book highly and Colvin is still alive and selling his book.
http://www.thomasecolvin.com/

Wood boats are neat, but sometimes certain hulls are better in other materials for different reasons. There deinitely is a place for welded aluminum and steel. Don't mean you can't put the decks, cabins and trim out of wood, to make it warm and pretty. But there is room for other hull types as well. Can't think of a good reason for a fibergalss hull though. Maybe someone else can come up with a valid reason.

There's nothing like muddying up the waters is there, just stirring the pot, don't want the epoxy to solidify.

[Tar Devil]

Hi, Ray!

I'll add my opinion that your site is the best documented homebuilding presentation. Lots of interesting stuff.

Being very inexperienced I can't offer any suggestions 'cept this one... I'll never use poly resin on a boat. The transom on my factory-built boat was poly fiberglass over solid wood. When I tore it apart, the wood that wasn't mush didn't even pretend to stick to the glass. It lifted right out without so much as a grunt. I think I agree with John Bell... better off with nuttin'!

Plywood... any thoughts on using Superply? (http://www.rfpco.com/fact_sheets/SuperPly.htm)

Later,

Phil

Edited to ask... Ray, what happened to the Cabin Cruiser you bought for your wife... wasn't it a Bayliner?

[ 03-29-2005, 12:10 PM: Message edited by: Tar Devil ]

[raymacke]

In fact, aluminum was my first choice since I couldn't use epoxy. I purchased a set of plans for Hankinson's "True Grit" which is exact same hull with a sedan layout. The plans were available in either wood or aluminum/steel and I have both. I personally have a "little" experience with aluminum as I welded (TIG) up the two 12 gallon replacement gas tanks for the skiff. I also have a good friend that operates a large machine & fabrication shop and can buy the metal through him.

But after a lot of thought I hesitated. I had to ask, "Why do I want to build a boat?" The answer boils down to two reasons - #1. I can't not find a suitable factory built boat that meets my objectives. #2. I love the process! Watching it grow from a empty space in the shop to a graceful craft that I can run my hands over and smile knowing I have created it. For me there is just nothing else like it!

But I have worked in wood all my life. My father taught me how to use his ShopSmith 40 years ago and I was hooked. Aluminum sounded interesting. An my bet is the boat would probably have at least a 30% to 40% higher resale value over a plywood. But the more I thought about dragging the heavy and akward sheets around, the hot chips flying, the ear piercing scream while cutting and the endless hours welding and grinding I hesitated. Is this what I want to do? I decided the answer was NO. I just don't think I would have the same level of pleasure.

As to steel Hankinson stated it would add 2000 LB !! to the hull and would need about 1/3 more HP to get the same performance. It would be too heavy for me to tow.

And I just Won't even consider epoxy - no matter what drugs or protection used. Here is a photo of me working on my skiff. I don't want to build like this again. PHOTO (http://egyptian.net/~raymacke/CC/suit.jpg) It took 3 years before I could sleep over night in the berth with the hatch closed without breaking out. It is the dust AND fumes that get me.

As to SuperPly - its nice stuff. With the exception of two sheets of marine fir the entire Cabin Skiff was built with it.

RONW - I never considered having a hull built in aluminum - interesting! I live in the Midwest and I know of no one around here that does this type of fabrication work. Do you have any leads on the builders in Canada? I would certainly consider this. There would still be lots of woodworking to do to finish out.

Have to go now. It is the first 70 degree day we have had this year and I'm going to get the skiff wet!

[bainbridgeisland]

This will be quick since I am in Mazatlan.

Vinylester resin has an epoxy backbone. Now most folks have problems with the hardener not the resin. This is because most hardeners are far more hazardous. (There are exceptions though, look for polyamide hardeners without any solvents at all.) If you are truly allergic to the resin then you shouldn't use vinylester. It will make you sick.

MDO holds paint better than anything I know of. You only need glass for impact or abrasion resistance. Non-toxic products are available to help you here. For example; see if you can find Airbal by Borden and apply it on polyester fabric. It has good abrasion resistance.

Adios

[maa. melee]

I've seen a lil clamming skiff made of crap plywood and iron nails sitting on the same beach for 5 years now. One sunny day I took a close look and came to the conclusion that her bottom had to be coated in tar (it glistened and reaked like tar and gave way alittle under my thumbnail). Probably oil roofing tar. It was beautiful from afar and I'll be damned if she didn't leak a bit. Am I wrong to think that stuff not only waterproofs the bottom but creates a contintuous skin on the plywood? Should I consider that for a non epoxy plyboat in the future instead of latex primer under 100% acylic latex paint?

[RonW]

http://www.metalboatsociety.com/phpBB2/index.php?sid=3ac5dc70bf8d3a5853e9495faee40777

Ray talk to these people and see what they have to say. Most of my bookmarked aluminum builders seem to be out of, maine, washington state, or british colimbia. I would think you should be able to find someone around the great lakes, the internet is going to be the way to search. Might even send some e-mails to builders around the great lakes to see if they know of someone to recommend for aluminum hull.

[botebum]

Ray, First I'd like to add my attaboys for a well done site. I took the time to read it end to end and thoroughly enjoyed all of it. Second- Your only problem with the epoxy seems to be your allergic reaction which, quite correctly you surmised began from not taking enough care at first to protect yourself from. An odd aspect of that allergy is that continued exposure leads to becoming increasingly sensitive. I've seen guys that couldn't get anywhere near it(50-100ft in a closed building) after a short period(2-3 10hr days) of overexposure. However, those same guys, dressed in Tyvek suits, taped at ankle and cuff over several latex glove layers, with a painter's cloth spray hood and a full face respirator have worked side by side with me(in similar garb) with no problems. If you were to build a plastic room inside your(enviable) shop with an exhaust system to the outside and dust collection to your sander, and wear the "space suit", your exposure and contamination to the rest of your shop/office would be all but eliminated. Before removing the tent or rolling out the boat, whichever works best for you, be sure to vacuum both boat and room completely. The dust from sanded epoxy is as bad, if not worse, than the fumes. Hope my suggestion helps.