epoxy vs screws

[chuckm]

I saw no need to use # 8 1 inch silicon-brass screws at the end planks of my GS project. The clamping arrangement and healthy amount of expoxy and cabosil meet the stem and stern quite nicely. The designer does call for them in plans, but in his book (Oughtred boat building manual) he say's that he uses less and less screws. Any thought's? On one frame I did use a screw where it was difficult to clamp. Is that not an appropriate use?

[Dan McCosh]

Neither screws or epoxy create a well-understood joint. The epoxy depends on a thin bonding layer, which is either extremely strong, or susceptible to various sheer forces which invite catestrophic failure with little warning. Screws point-load the joint, but will survive sheer forces until the metal snaps or the wood splits. Elminating one or the other without some study seems a bit chancy.

[JimD]

Personally on anything heavier than a kayak I like to both glue and screw (for the reasons Dan has just mentioned). But others will tell you there are plenty of quite large, heavy boats that are glued only. I suspect that as faith in epoxy grows there are fewer designers calling for a generous fastening schedule but if you have plans for an older design even though if meant to be glued it will still call for plenty of screws and nails.

[paladin]

Tana Mari, at 44 feet, had no mechanical metal fasteners in the hull and deck, except to hold chainplates or other hardware....Amihan, at 38 feet, used epoxy, but also had monel staples used in place of other metal fasteners, and Nepar, at 31 feet was built the same way, but with steel staples that were removed after 48 hours waiting for the epoxy to set...

[chuckm]

So use the screws at end plank stem and stern and move on. OK

[Rick Starr]

My boats have essentially no metal fasteners in them. No problems yet.

[chuckm]

Now that expoxy has dried, Is it appropriate to screw down now? Maybe its better to set the screw in even though the epoxy is set and overkill this lap. To tell you the truth I just forgot to use the screws. You get going gluing and have all the clamps line up. I forgot.

[pipefitter]

Personally on anything heavier than a kayak I like to both glue and screw (for the reasons Dan has just mentioned). But others will tell you there are plenty of quite large, heavy boats that are glued only. I suspect that as faith in epoxy grows there are fewer designers calling for a generous fastening schedule but if you have plans for an older design even though if meant to be glued it will still call for plenty of screws and nails.

I agree with this. Beyond the necessity,it brings peace of mind when you're out in the snot.It's something you don't have to question or think of again.

Yes you can put the screws in after. Just fill the screw holes with epoxy before driving them home.

[mcdenny]

I've got a 24' 50 mph plywood runabout five years old with zero metal fastenings, all epoxy. Zero cracks or any signs of failure.

[Bob Perkins]

I had the same questions when building my runabout. I called the designer, etc.. In the end - I decided that w/o screws a failure would more likely be large in scope. With screws - a weakening should be more visible over a longer period of time.

I used screws after epoxy was dry.

Good luck,
Bob

[kc8pql]

I like the belt and suspenders idea.

[Tom Robb]

If building a one-race-only boat where winning is everything, overbuilding is a poor choice.
If you're at sea and you and/or your loved ones lives are at stake, the belt and suspenders may seem better to you.
"You have to ask yourself, do you feel lucky today...?"

[Mike Vogdes]

If the plans call for screws and epoxy then thats what you should do. Following the plans is best, in the event of a failure and someone gets hurt or killed, you only make matters worse by not building as designed.

[Bruce Hooke]

Just to present the counter-argument to the belt and suspenders approach...I believe the Gougeon Brothers argue that in some cases screws can create concentrated load points that can actually reduce the overall strength of a joint by providing the starting point for a failure. It is sort of like why you round the edge of openings so that the corner of an opening does not create a load point where a crack can get started.

[gert]

I am building the same boat as Chuckm; he's about a month ahead of me; I plan on screwing at the plank ends as per designers notes. However, the stems on this boat are a 2 piece, the outer one applied after planking, this protects and would hold (somewhat) the plank ends in place should there be a shear failure in the epoxy at the plank/innerstep glueline.

[Gary E]

Seems to me that waiting for the glue to dry so you can start on the next joint is a expensive waste of time...

Glue it AND Screw it and you can keeep on working.

But maybe your rich wood boat owners who dont care about time or money.

[cluvrs]

i need a copy of wb # 180. will pay top dollar. thanks.

[Don Maurer]

Think of it this way. If the epoxy were to fail, would you rather have a small crack or a sprung plank? A few screws is cheap insurance.

[Bruce Hooke]

But maybe your rich wood boat owners who dont care about time or money.

I think most people here are amateurs, so their time is their own to price as they see fit...

[Bruce Hooke]

i need a copy of wb # 180. will pay top dollar. thanks.

http://www.woodenboatstore.com/prodinfo.asp?number=205-180

[boylesboats]

I saw no need to use # 8 1 inch silicon-brass screws at the end planks of my GS project. The clamping arrangement and healthy amount of expoxy and cabosil meet the stem and stern quite nicely. The designer does call for them in plans, but in his book (Oughtred boat building manual) he say's that he uses less and less screws. Any thought's? On one frame I did use a screw where it was difficult to clamp. Is that not an appropriate use?

Why not both? I leave screws in places to give additional holding power..

[JimD]

I generally prefit everything with screws out of necessity anyway. I find half the time it's the only way to hold things in place and keep things from shifting while the slippery epoxy cures.

[Gary E]

I think most people here are amateurs, so their time is their own to price as they see fit...

I shoould of added SAFETY....
their idiots if they dont use screws...

[Woxbox]

If done right, the epoxy is stronger than what all holds the wood fibers together. Isn't that strong enough? Any time I've stress-tested an epoxy joint, whether old or new, the break comes through the wood, not the joint.

[pipefitter]

Well,I feel the epoxy is strong enough but if it is holding to a veneer of a ply plank,what happens if the plank were to delam? I dont' have control of the plywood factory's quality control in the event that I was the lucky bastid that got the piece of ply when the glue machine was clogged or who knows what? Again,as JimD brings up another point of the dry fit and how much screws aid us lone builders holding things in place for the dry fit.Putting the screws in was one of the more satisfactory part of the job anyways.

[Thorne]

Gary -

I disagree. Particularly with ply boatbuilding, screws might well cause more problems (safety and otherwise) than they solve. Poking holes through the plies may provide more rot and failure than a smooth unbroken coating of epoxy.

Working with solid wood is different to a degree, particularly if the screws are coated with red lead or other sealants/fungicides.

I nearly always use screws on either solid wood or ply (possibly from habit?), but that doesn't mean that those building using Ian Oughtred's methods (epoxy w/ no screws) are stupid or careless -- just using a different method, that's all.

[JimD]

Gary -

...Particularly with ply boatbuilding, screws might well cause more problems (safety and otherwise) than they solve. Poking holes through the plies may provide more rot and failure than a smooth unbroken coating of epoxy.

Naw.

[Bruce Hooke]

Gary's just on one his wingers...

Clearly plenty of good boats have been built with just epoxy to hold much of the structure together...

[LLaver]

I'm with JimD, screws make lovely clamps and you can dry fit everything, get it sitting right, pull it off and then deal with the slippery stuff.

[Gary E]

Gary's just on one his wingers...

Clearly plenty of good boats have been built with just epoxy to hold much of the structure together...

And thousands more were built long before that so called miricle crap was ever invented... and whutz more Bruceee poxy STINKS...screws are a mechanical fastener that have been around for centuries and are still holding. Your welcome to use glue of any type on furniture, model airplanes, or on little tinker toy boats that dont go far from your near purrfickt weather world and never venture into rough seas, but if you want strength do not depend on glue of any kind alone.

Rant off.... you just aint worth the agravation...

[Dan McCosh]

If done right, the epoxy is stronger than what all holds the wood fibers together. Isn't that strong enough? Any time I've stress-tested an epoxy joint, whether old or new, the break comes through the wood, not the joint.

This is a common observation about glued joints. Virtually any glued joint will cause the wood fibers to fail before the glued joint. The glue is less elastic than the fibers, and the point where they transition causes a fatigue failure. This is exactly why screws can be superior, as they transmit the load deep into the wood and reduce or eliminate this kind of fatigue. Generally, a broad surface area, such as most long scarfs, laminations, or joints that have generous gluing surfaces, works fine with epoxy. Small surface area joints can be a problem. A plank end into a stem rabbit is one place where I would be careful, depending on the design of the stem and gluing surface.

[peter osberg]

I am surprised that no one has mentioned 'epoxy creep' under continuous loading (which affects some brands more than others) which can result in a failure at the glue line. Retaining mechanical fasteners will remove this worry (belt and suspenders approach) and any second thoughts about your glue line. peter

[Robmill0605]

I initally used only epoxy and stainless staples in the construction of my runabout project. Probably strong enough BUT, I'm now going back and using traditional bronze floor bolts, I drilled the stem and installed bronze bolts for that glue up, and I'm now taking the time to install dronze screws into the frames and chines.
Now it ain't coming apart.
Over kill? yeah...
I'm not crossing any oceans ,but my peace of mind is worth it.

[Boatmik]

Howdy All,

I find it quite surprising that there is any doubt about epoxy working without screws or nails.

I've been involved with a boatbuilding and kit supply business in Australia for close to 30 years on and off and we have only ever used screws where there is a chance of a piece of timber splitting along the grain - the common ones are gunwales and rubbing strakes toerails and the like which are only glued on one surface.

Any timber that is glued to plywood on two faces or is glassed cannot split - the ply and glass will prevent it.

Anyway here is a partial list of boats that have been built using no screws or nails except as above.

Derek kelsall 55ft cat
Derek Kelsall 45ft cat,
ditto 32 ft cat
ditto 35 ft cat x 2
ditto 25 ft cat x 3
ditto 22ft cat x 5
Wharram 31 cat
Wharram 26 x 2
Approximately 120 Oughtred boats of different sizes from Wee Robs, granny prams, Whilly boats, Acorns of different sizes through to Wee Seals and Caledonia Yawls.
Norwalk Island Sharpies 31x2 26x5 23x10(approx), 18 x 2, 29 x 2
Bolger - Micro x 3, Long Micro x 2, Folding Schooner, Martha Jane x 2, AS29 x 1, Gypsy x 4, Instant Catboat x 3, Nymph x 25, diablo x 4, Tennessee x 10, Idaho x 1.

And many more that ppl here may not be so familiar with.

Some of those boats are now close to 30 years old now.

So we think that epoxy without screws and nails works fine.

There are a couple of advantages to this sort of construction that haven't been emphasised.
1/ the ease of repairs - whole panels can be removed with a router set to the skin thickness without interfering with any frames to any extent
2/ generally we have found that screws and nails where we have fitted them have had the tendency to crack the epoxy and paint (different thermal expansion?) used to finish the boat resulting on water getting into the structure.

Best Wishes
Michael Storer

[Rick Starr]

Thanks Michael.

What I don't get is the profusion of people who get their panties in a twist about trusting glue.....in a plywood boat, for the love of almighty christ. Further, I cannot understand the so called "belt and suspenders" argument invoked in favor of drilling scads of holes in an otherwise sound, watertight, proven hull. Lastly I don't get what drives people to infect their hull with hard spots and burried surprises that are prone to deterioration and which compromise the continuity of the wood around them by their very nature.

Of all the hundreds or thousands of failures we read about at sea, not ONCE have we heard about the failure of a properly executed glue-lap ply joint.

*shaking head*

[peter osberg]

For those with confidence in epoxy only scarfs, I would suggest doing your own stress test. Get a couple of 10 ft pieces with a 10:1 scarf in the middle, that has cured, and hang a weight on one end with only one end fixed. Wait a few weeks....with some epoxy brands the scarf joint opened up for me! peter

[pipefitter]

It's not that big a deal. It hurts nothing to use screws or fasteners. How many ameteurs are guaranteed to assemble ideal epoxy joints?How many one off builders should go out and buy 30 deep throated clamps for one boat or even 5? Sure you can use the clothespin clamps but they just get you close. Screws adequately hold the plank in place and can be tightened in micro pressure increments as to watch the size of your glue joint.Especially with some of the plywoods and other materials that are marked as acceptable for builds on this very forum. What about putting tapered frames in a glued lap hull after the fact? Like to see the clamp schedule that gets that done faster and easier than screws do,while holding it as intended until the glue sets. Then what,remove all the screws and fill the holes? Most of these threads that advocate doing away with hardware or adhesives or quality marine ply seems to be more about squeezing that nickel than just good building sense. When I started building my boat,the consensus here was epoxy sux or epoxy is great but not any sign of a collective middle grounds. I went by the plans and some common sense and after years in the trades,it wasn't hard to decide what needed or "might" benefit from the use of a few fasteners here and there. The screws made not having the use of extra set of patient,knowledgeable hands when and where I needed them a non issue.So now I have plywood,shiney paint,epoxy,fibreglass and screws and a stinky outboard. What have I done? Went against every purist ideal that could possibly be affixed to these hoit-toit notions instead of just trying to have a somewhat fashionable,reliable, machine to catch some stinky fish with. I've been airborne in this Simmons a few times and I am kind of glad the screws are there.Alot of these do or don't topics in the name of tradition or purity,are setting up new builders to have a hard time with their projects.

[erster]

Three zillion designs and three hundred gazillion builders fill the waters with boats. Three zillion experts or lack of experts fill the waters with boats. Epoxy ain't crap with too big of a joint or hard points that continue to be part of boats built as oneoffs by the average Joe in too many cases.

. A backyard builder, especially the builder of his first boat, has no business depending on a glue simply because its a glue that has big expensive promos and press releases in shiny color ads. If a person buys a set of plans, go by the dang plans and building instructions.


But that alone will not be enough if the builder has never experienced those stupid twists and turns in tortured plywoods or funky grain patterns of off the street planks. If you don't fit the parts together with a fair shape and proper angles, without a fastener, its still going to release when put in a bind om a heavy sea or when moisture intrudes into any wood. At least a fastener with mosture surrounding it for whatever reason, will show some problem and many times a person will catch it with blisters under the paint over the heads.

Oh yea, sheetrock screws are the best.;)

Boatnik, just curious, how many of your listed hulls were built by backyard one off builders with no help or assistance from experienced people?

[George Roberts]

chuckm ---

The engineering for most boats is so inaccurate that any questions of sufficiency can be answered that the boat is "overbuilt."

Screws can be left out from most if not all properly designed epoxy connections.

On the otherhand most connections are not designed at all. So they are suspect.

[Clinton B Chase]

We learned to build cruising boats without a single fastener...these are cold molded 27 foot power yachts, the Arundel 27 (http://www.thelandingschool.org/ls_arundel27.html). Steve Dalzell, the designer, and one crew took this boat through 8+ foot bone jarring chop down Buzzards Bay in a Smoley So'Wester. They came out of that experience with even more belief in the strength of epoxy, when used properly to glue joints without screws. We used screws in the stem and keelson simply for convenience...many of these were removed and filled by syringe later. Now in my own boats, I keep the screws in if I find I need to use them for convenience. That's all...they are very nice for dry fitting and clamping as others have said. So, any BEGINNERS READING THIS....don't be fooled...if you want to not use the screws and you can do a good clamp job and get your squeeze out...don't bother worrying....if you find it is nice to dry fit with screws and have the convenience then use them. Later, when the epoxy is cured just leave them in and fill the holes with epoxy. You'll figure out how you like to do it as the project moves on...don't get worked up about people's opinions here. Following the plans is the best way as a beginner and once a boat or two is under the belt, then it's OK to say, "you know what I am going to omit the screws here", etc.

Cheers,
Clint
Come to think of it, that McGuigen (sp?) Clamp might allow me to do w/o the screws in the hood ends!

[Bruce Hooke]

Well said, Clint!

[Rick Starr]

Well said, Clint!

Agreed!

To clarify my modest rant: If you want to trust glue, then fine, trust it. (I do.) If you DON'T want to trust glue, then DON'T! But it seems foolish to build a boat out of plywood (lots of thin veneers glued glued together, no screws ;) ), relying on glue in some places (as in the plies) and not in others (as in the laps).

If, by the way, you choose not to trust epoxy, then consistency demands that you avoid commercial air travel.

[erster]

Agreed!

To clarify my modest rant: If you want to trust glue, then fine, trust it. (I do.) If you DON'T want to trust glue, then DON'T! But it seems foolish to build a boat out of plywood (lots of thin veneers glued glued together, no screws ;) ), relying on glue in some places (as in the plies) and not in others (as in the laps).

If, by the way, you choose not to trust epoxy, then consistency demands that you avoid commercial air travel.

Planes are built using very strick oversight and rarely built in backyards and carry large numbers of passengers.;) Plywood is not built in backyards without some form of fasteners [even vacumn bag presses] to hold the pieces in place till cured that is not glued properly, with strick compression guidlines and with uniform spreading across the pieces with glues.

We can also conclude that a cold moulded boat is a funny shape of plywoods which has had fasteners put in place until the glue sets. Metal staples used to be used and depending on the type metals have also been left in place after the glues cured doing more than just being an annoyance or with little problem at all. Now plastic staples are used and left in still doing little if improper building technigues and fits to the components.

We also know what happens to crappy plywoods bought at your local big box stores of poor quality oversight and with inferior pieces even with rescorcinal glues. This again is caused by poor and inferior methods and materials.

I do trust epoxy in plywood laps in the Simmons, forgoing the call for rivets and the likes as was promoted by some folks, which is one of the lightest built hulls for a power boat. Many others feel the same and continue to build but would never consider forgoing fasteners to secure the structual parts to the plywoods even using epoxy to glue the plywood to the framing. Just being old fashioned I guess even though there are 50 foot boats running in most extreme sea conditions, still using fasteners only at the minimul points of contact such as rails and keels contacts. Later

[Rick Starr]

Well, sure, and my "fastener free" boats have screws where hardware is attached, obviously, and for convenience sake there are screws holding the cb bed logs and skeg to the hull.

[oakman]

All this epoxy joining may be fine for the initial build. . . but several many years down the road when the next poor sod wants to repair how nice would it be to remove a few screws, scrape off some old bedding compound and get to work with some new wood? Rather than grind through layers of toxic and itchy junk to get to more glued stuff. Give me solid wood, screws,bedding compound and linseed oil.

[pipefitter]

All this epoxy joining may be fine for the initial build. . . but several many years down the road when the next poor sod wants to repair how nice would it be to remove a few screws, scrape off some old bedding compound and get to work with some new wood? Rather than grind through layers of toxic and itchy junk to get to more glued stuff. Give me solid wood, screws,bedding compound and linseed oil.

Most of these composite boats are trailered and kept dry. If some poor sod gets my boat,it will look much like it does today.If it isn't maintained the way I do,they deserve to get some itchy on them.I'm also not real hopeful about the quality of available solid wood several many years from now.Some of us are having to make the sacrifice of utilizing lesser methods/materials, just so that you may get the solid wood you need tomorrow.

[Rick Starr]

Oakman, I think everyone here will agree that there certainly are benefits to traditional construction. I would love to build a plank-on-frame boat in the near future. But surely you must realize that all boat design is about compromise--as much in the construction technique as in the intended use. Glued lap ply boats, for example, are incredibly quick to build, strong and simple. The techniques are easy to learn for the novice, etc etc. It is these qualities that appeal to many people, for a variety of reasons. People make a mistake when they embrace the appealing qualities of this technique, then halfway through get cold feet and mix in some attribute of another established technique--screws in the case of this discussion. To do so shows a lack of understanding of the process they've undertaken.

[Boatmik]

It's not that big a deal. It hurts nothing to use screws or fasteners. How many ameteurs are guaranteed to assemble ideal epoxy joints?
I've been involved with perhaps the biggest company supplying boatbuilding companies selling boatbuilding materials, plans etc in Australia for 25 years.

We (when I worked directly with them) and since (where I have been working on a regular subcontract basis have generally been suggesting that fastenings be left out.

After all it doesn't hurt fibreglass boats not to have screws - and whatever people think about pure fibreglass construction - no-one criticises that it doesn't have screws.


How many one off builders should go out and buy 30 deep throated clamps for one boat or even 5? Sure you can use the clothespin clamps but they just get you close. Screws adequately hold the plank in place and can be tightened in micro pressure increments as to watch the size of your glue joint.

Like to see the clamp schedule that gets that done faster and easier than screws do,while holding it as intended until the glue sets. Then what,remove all the screws and fill the holes?

The screws made not having the use of extra set of patient,knowledgeable hands when and where I needed them a non issue.
Yep - agreed - using a cordless drill with clutch makes driving in and removing screws and drywall screws so fast that it is mindblowing to people who haven't tried it. The screws are self tapping.

You can see more about it here if not familiar with the methods
http://www.storerboatplans.com/Faq/faqindex.html


When I started building my boat,the consensus here was epoxy sux or epoxy is great but not any sign of a collective middle grounds.

I've been airborne in this Simmons a few times and I am kind of glad the screws are there.

Alot of these do or don't topics in the name of tradition or purity,are setting up new builders to have a hard time with their projects.
I agree completely with you here.

The only comments I argue with is are when some others in this thread say
that in some way "you CAN'T build boats without screws and nails!"

It is a simple failure in knowledge.

But in the end we all build the boats we are comfortable with.

So if someone wants to use screws (like you) we can have a sensible discussion about our different opinions - which is good - we can learn a bit from each other as you point out.

And we have a middle ground.

But for those who say it can't be done ... it is an ignorant position - there is just toooo much evidence to the contrary there.

Note that I am not telling anyone that you shouldn't use screws. Just that you needn't if you don't want to and go on to iterate the methods that can be used.

[oakman]

No, No please don't misunderstand me. Build what you want, with what you want. I would rather have more people enjoying the water than not, for sure! And to be sure there are many more people on this forum who are better educated and have more experience than I do with all aspects of boat building, who I respect for doing what they do. just stating my personal opinion.

[Boatmik]

But that alone will not be enough if the builder has never experienced those stupid twists and turns in tortured plywoods or funky grain patterns of off the street planks.

If you don't fit the parts together with a fair shape and proper angles, without a fastener, its still going to release when put in a bind om a heavy sea or when moisture intrudes into any wood.

At least a fastener with mosture surrounding it for whatever reason, will show some problem and many times a person will catch it with blisters under the paint over the heads.

Boatnik, just curious, how many of your listed hulls were built by backyard one off builders with no help or assistance from experienced people?
I think you are overstating the problems.

I don't see boats of ANY well regarded building method breaking or failing in any sort of consistent way.

As far as your doubts about whether epoxy boatbuilding without screwsit can be done by amateurs.

- in that comprehensive list of boats I gave that I have been involved in directly...

We have shipped materials and plans for probably 50 or 100 times that number over the last 25 years - most of those people we have told that you don't need fastenings and the simple rules for doing it that way.

Most haven't used fasteners, some have, and all has been well.

Repeat - 25 year period.

There are a lot of other companies and many designers that also now suggest that you don't need fasteners either.

It's not a problem

Best wishes
Michael Storer

[erster]

After all it doesn't hurt fibreglass boats not to have screws - and whatever people think about pure fibreglass construction - no-one criticises that it doesn't have screws


I would certainly hope that no one is coating plywood hulls, and even worse planked hulls with as much fiberglass that yields a fiberglass boat built on the outside of its "form" speced out in plans sold to the average guy.;) The use of hardware comes with some form of context in this discussion, something that is being overlooked by some but have repeatedly been addressed. Tangents.........




I did use a screw where it was difficult to clamp. Is that not an appropriate use?



Most haven't used them, some have, and all has been well.

Correct and I think many have also stated this in their replies. Small boats being built in garages and 50 footers being built with direct imput from designers and more professional people have its own value.

[Boatmik]

All this epoxy joining may be fine for the initial build. . . but several many years down the road when the next poor sod wants to repair how nice would it be to remove a few screws, scrape off some old bedding compound and get to work with some new wood?
Howdy Oakman,

How I wish repairing traditionally built boats was as sylvian as you suggest. :-)

I've had too many bloodied knuckles and done too much swearing so know it can be otherwise.

That is often the nature of repairing boats anyhow - whatever the method the boat was built with

BUT ...

Fasteningless epoxy construction is GREAT to repair.

Just grab the router - set it to the depth of the plywood and you can remove great sections of boat in minutes and glue new ones in place.

I've replace bottoms, sides, transoms and decks on boats up to quite big sizes overnight or in one day in the course of regattas. Gunwales, skegs and the like are perhaps easier still.

You can have the boat in the water with an epoxy sealed but not painted replacement section the next day if really necessary.

The trick is that a lot of people don't understand yet is how quick epoxy is when you apply it wet on wet - rather than going through the endless processes of sanding.

Coat the ply replacement panel on the inside with the normal three coats, put mixed glue mix on all the framing of the boat, then whack the new bit in place. Clean up epoxy ooze on the inside.

If it is summer the screws can probably be pulled out within 8 hours, the holes filled and the outside of the ply replacement part be given three coats wet on wet as well. In winter they would be able to be pulled out the next day.

Glasstape can be integrated with that process too - or alternatively the whole panel can be glassed.

Sand the worst of the glass edges and overlaps off the next day and drop it in the water.

So two simple unbroken wet on wet processes - one on the inside and one on the outside.

It's the fasteners that hold you up!

(but I wouldn't claim that it is always a swearing free zone!)

Best Regards
Michael Storer

[erster]

think you are overstating the problems.

I don't see boats of ANY well regarded building method breaking or failing in any sort of consistent way.

To clarify:

Hard points create problems. Newcomers do not understand compound angles, one of the basic principles of boat building, unlike doing a honeydo project like building a storage shed or something. Wood after it becomes wet moves. Trailer boats comes with additional issues of drying and expanding. Boats that get only epoxy coating in the interiors will move and have moved and created seam cracks. Two part poly paints on woods also come with this "unigue" feature. Am I pushing hardware? I am addressing more of the skill level of someone thats new in the lusting business and learning curve that needs to be experienced and the distorted hype that comes with "lets just fill the crack with epoxy". This is a typical reply that comes from some of the sellers of plans throughout the industry. Another famous quote that seems to be quite frequent in lieu of proper fits is


Epoxy works better in loosely clamped and loosely fitted seams and joints

something that has some merit but comes with some other trade offs.

One big trade off and a very common reply by people buying plans is that they


used more epoxy that was originally noted on their website and package of instructions that comes with their plans

Ever heard such a line?;) :D

[don't know why I get involved in these hardware threads.:eek: I build using junk anyway.] Later

[Joe ( Cold Spring on Hudson )]

To clarify:

Hard points create problems. Newcomers do not understand compound angles, one of the basic principles of boat building, unlike doing a honeydo project like building a storage shed or something. Wood after it becomes wet moves. Trailer boats comes with additional issues of drying and expanding. Boats that get only epoxy coating in the interiors will move and have moved and created seam cracks. Two part poly paints on woods also come with this "unigue" feature. Am I pushing hardware? I am addressing more of the skill level of someone thats new in the lusting business and learning curve that needs to be experienced and the distorted hype that comes with "lets just fill the crack with epoxy". This is a typical reply that comes from some of the sellers of plans throughout the industry. Another famous quote that seems to be quite frequent in lieu of proper fits is



Hmmmm :rolleyes:


If many novice waits till he can afford and locate 60 buck a sheet plywoods for their first project and then find out after cutting the sheets that he has made a royal mess while learning about boats, and his wife says enough, many will never get on the water. People learn from the low end and epoxy does come with some measure of forgiveness. Almost all plan sellers incorporate some use of epoxy in them nowadays.

[erster]

There is a difference in seam caulking and an epoxy glued joint of two components and 1/2" seam caulking and 1/2" epoxy glued joint especially when it comes to your wallet and long term quality of your boat, even built with junk. Fact not fiction.

[Boatmik]

Howdy Erster,

I think you make some good points

1/ That good fits are better than sloppy fits

2/ That boats with glued joins that are not also sealed with epoxy to minimise water takeup are likely to start cracking joins

3/ That often epoxy quantities are underquoted in plans.

I would reply:

1/ I agree, but epoxy can fill gaps that would be just too big in other types of boatbuilding - so can be quite forgiving for first time builders where something is slightly miscut or mishaped.

Remember too that epoxy fillets without any wood in the join are quite structural if appropriately sized - so if there is a (say) quarter inch gap between two ply panels and say the stem - then the gap can be filled providing that the contact area with the ply is 2.5 to 3 times the ply thickness.

Experience of over 25 years with hundreds (thousands - possibly) of amateur built boats show that failures from this cause are rare - so they understand the methods and materials adequately. And there are lots of others with similar sized experience - so probably talking about tens of thousands of boats worldwide.

2/ This is a really important point that hasn't been mentioned much in this thread.

So here it is again in bold

Eliminating fastenings in epoxy glued boats assumes that the timber structure is sealed with a minimum of three coats of high solids epoxy for the best results (or to the manufacturer's directions)

It prevents the timber from taking up moisture and swelling and then drying out and shrinking - which will break epoxy joins and pull out fastening no problems at all.

Here is some data to show epoxy coating is effective and also explain "high solids"
http://www.storerboatplans/Faq/Saltpreservative2.html

And again in the case of hundreds of amateur built boats in my direct experience there have been next to no problems showing that amateurs have a reasonable enough grasp of the methods.

3/ Underquoting on materials is pretty endemic in the plans business. There are some designers that are spot on, but plenty that will underquote the amount of plywood, lumber, fibreglass, fastenings.

The only plans that don't get any complaints of this type are those that don't specify quantities and leave it up to the builder :-)

So you can hardly suggest that it is the fault of epoxy boatbuilding.

Thanks for the important input about the coating!!!

Michael

[erster]

I gottta run as I have my own issues with epoxy right now. But to address the issue of epoxy and its fail safe idea about waterproofing, thats not quite right, [spoken gingerly] Its a bit diffferent than polyesters or any of the ester resins. ;) See ya.....:cool:

[Boatmik]

I'll be interested to see what you have to say.

MIK

[Pericles]

Metal fasteners expand and contract at different rates and volumes from epoxy/wood, thus in time the metal can work its way out and water penetration can occur. However this is likely to be only a cosmetic issue as the epoxy joint will maintain the boat's integrity.

This subject is really about facts and belief. Having used epoxy resins over a number of years to repair all manner of objects and never having had a failure, naturally I shall withdraw all temporary metal fasteners when building my boat, as I don't want print through nor water penetration.

On t'other hand there are some who cannot believe the reality of epoxy resins and place their faith (and lives) in lesser adhesives. To them I woud say " When polyester boats blister from hydrolysis, which resin is used to complete the repair?":confused:
http://www.yachtsurveys.co.uk/faq_osmosis.htm

Differences of opinion abound in any subject. As in all matters, progress seem to be 3 steps forward and 2 back. I am sure the first chap to try setting a sail on his dugout was subjected to cries of derision from the landlubbers on the riverbank. He probably had the last laugh, as he sailed away up the river, because he settled in a better environment, founded a larger village, built a navy of sailing dugouts and returned to slaughter all those who had mocked him.

It's what I would have done.:D:D:D:D

Pericles

(Pericles also made Athens ruler of the sea by building a huge navy. He ruled from 461 to 429 B.C.):eek: http://www.hyperhistory.net/apwh/essays/comp/cw04AthensSparta32120902.htm

[pipefitter]

I also agree that epoxy is strong enough to hold wood together. My point was more geared towards when fastening plywood to solid members such as a solid wood stem.Alot of folks are using white oak and oily woods for these parts. Resinous LL pine in my case per plan instructions where I had kind of split the difference and made a lam,not a batten or veneer lam but an opposed grain slab lam. I know many have probably used the single piece stem. Not such an issue in the case of the Simmons being that the stem will rarely,if ever, see any water. That section in my boat from the 2nd floor foreward to stem has yet to get wet. I did epoxy coat all the wood. Not to encapsulate it as much as a good base coat primer or a more homogenous primer if you will.It's obvious that it repels water better than more traditional,porous primers included with most one part paint schedules.Another proof was during the busy hurricane seasons of recent pasts,where water had gotten past the tarp(along with a mocking bird that had found shelter via the motorwell) and several inches had sat in the bilge for several days with nothing between it and the wood but epoxy. No discoloration or water stain of the ply. This was unsanded epoxy. I also agree that we are not seeing epidemic failures of most methods described here in this forum or otherwise. There is enough red flag scenarios(even if generally theoretical) that I feel most builders at the very least, are going to keep their mindset geared towards preventive maintenence which all constructions can benefit from. If nothing else,I think these discussions end up driving that (just incase) point home. This wasn't my first wood boat. It was my first wood boat built from plans and without someone else standing over me telling me what or what not to do.I had spent a fair amount of time "helping" to repair carvel planked and plywood/chop boats. It all pretty much sux.16 and 20d, SS ring shanks are NO fun to work around when taking off old extra thick planks. Screws didn't seem so bad in comparison,even on a smaller scale. Good points from both sides.

[erster]

The blisters in gelcoat is not actually water as much as its a combination of several factors that has taken place in the hulls. The result that you see under the popped blisters is snot, you know what is generated by a combination of factors in an infection of cold in your own body. The chemical makeup of polyester enjoys moisture or dampness of water.

Polyester resins have a different cure time, or basically an ongoing process of shrinking greater than the epoxies until it reaches the point that it stresses , cracks or even craters allowing moisture into the "pores" generated by the resin that has just seperated or broke apart. In fiberglass hulls, polyester resins actually wraps the strands of fabric and the epoxy satuates the glass when used in conjunction with glass.

The post cure of the epoxies is shorter unlike the polyesters and is used as its been found that it does not continue to shrink. Therefore the sealing factor for redos favors the epoxies. This was something that took some time to figure out after the fiberglass industry watched a nightmare unfold.


Without getting into a p&$%$#ing match of it being waterproof versus water resistant there are reasons that epoxy is considered to be waterproof and not just water resistant simply because we do not see the affects of the total emersion underwater as we have done with the polyester as the moisture reacts differently with the chemical in the esters.

If epoxy was the cure all you would never worry about it being exposed to the elements, never worry about overcoating it with a secondary product to actually seal the epoxy formulated with microplates of a blend of sealants and hardeners in the 2000E series of bottom products now for the hulls especially for the redos on the bottom jobs after recoating them with the epoxy on the polyester boats.

Its a water resistant product that has its limitations no difference than many other products on the market. If you think epoxy seals water out when applied on woods, try coating a piece of plywood and submerging it, leaving it for several months and then remove it. The plys may not seperate, but the end grains will be a different color, like really dark, which shows anyone that its not much better than many other products. Yes you can drown the woods with zillions of coats.

But I dare you to subject the epoxies or even the thickened epoxies to the same ongoing process of aging, side by side as the epoxy will fail, maybe not as fast, but yes epoxy fails. The two part paints fails at a slower rate but all of it fails.


Epoxies have its place and works in conjunction to many other products and will not stand alone in the same elements as your boat experiences each day while in the water. Miz it with wood, which itself deteriates over time, and changing shapes, unless super sealed and protected, or proper maintainance, it all fails, period. Done.:)

[Pericles]

Erster

Epoxy resins require protection from UV rays by coating with paints or clear seals containing UV filters. However epoxies are far better adhesives than polyesters for bonding wooden boats. All in all, wooden boats are making a comeback because of epoxies and 2 part LPU paints. The Gougeons are campaigning a 36 year old trimaran they built and http://www.vicemyacht.com/distributors.php
http://www.dolvik.com/boats.htm http://www.sculleyboatbuilders.com/const_coldmold.html
http://www.powerandmotoryacht.com/features/0903jarrettbay/ are all doing very nicely it would appear

Polyester boats with foam cores, weight for weight, are not as tough as cold moulded composite hulls, in my opinion. All vessels require preventative maintenance, some more than others and I'd take a Vicem over a Hinckley any time, Hamiliton waterjets not withstanding.:D:D
http://www.yachtworld.com/vicemusa/images/e320665.jpg

[Scott Rosen]

I saw no need to use # 8 1 inch silicon-brass screws at the end planks of my GS project. The clamping arrangement and healthy amount of expoxy and cabosil meet the stem and stern quite nicely. The designer does call for them in plans, but in his book (Oughtred boat building manual) he say's that he uses less and less screws. Any thought's? On one frame I did use a screw where it was difficult to clamp. Is that not an appropriate use?Some folks are missing a point.

Gluing plank ends to a transom can involve endgrain, depending on the construction. Plywood boats that I've seen often have frameless transoms, so in any joint between the transom and plank, one of the faying surfaces be endgrain.

Screws don't have nearly the same strength in end grain. As for glue--endgrain is notorious for glue joint failures.

It seems totally appropriate to call for screws and glue in such a joint.

Comparisons of this type of joint to a cold-molded hull are inapposite.

[pipefitter]

Some folks are missing a point.

Gluing plank ends to a transom can involve endgrain, depending on the construction. Plywood boats that I've seen often have frameless transoms, so in any joint between the transom and plank, one of the faying surfaces be endgrain.

Screws don't have nearly the same strength in end grain. As for glue--endgrain is notorious for glue joint failures.

It seems totally appropriate to call for screws and glue in such a joint.

Comparisons of this type of joint to a cold-molded hull are inapposite.

Same could be said for gluing plywood to a solid member as well.Solid wood moves more than plywood does. It just feels right to put a fastener there and to deal with that over just wondering about it from there on out. Sure,some don't give it a second thought and maybe rightfully so but I can't imagine why fasteners or non fasteners really make such room for debate. I like using them. I don't think I hurt my boat in doing so. I also thought about any issues come repair time as I was building it,what tools/methods I would use to do so. It wasn't the fasteners I was concerned with,it was the blend fairing and painting that seemed like the real work of that scenario.

[Pericles]

Hello Pipefitter,

"It wasn't the fasteners I was concerned with, it was the blend fairing and painting that seemed like the real work of that scenario."

Sam Devlin advocates the total removal of all fasteners from his boats, because they expand and contract more than the wood and so, will eventually work themselves to the surface damaging the beautiful finish you worked so hard to achieve. Thus it would be sensible to be concerned with the fasteners, sitting within the hull like termites waiting to spring their nasty surprise.:eek:

Pericles

[erster]

Erster

Epoxy resins require protection from UV rays by coating with paints or clear seals containing UV filters. However epoxies are far better adhesives than polyesters for bonding wooden boats. All in all, wooden boats are making a comeback because of epoxies and 2 part LPU paints. The Gougeons are campaigning a 36 year old trimaran they built and http://www.vicemyacht.com/distributors.php
http://www.dolvik.com/boats.htm http://www.sculleyboatbuilders.com/const_coldmold.html
http://www.powerandmotoryacht.com/features/0903jarrettbay/ are all doing very nicely it would appear

Polyester boats with foam cores, weight for weight, are not as tough as cold moulded composite hulls, in my opinion. All vessels require preventative maintenance, some more than others and I'd take a Vicem over a Hinckley any time, Hamiliton waterjets not withstanding.:D:D
http://www.yachtworld.com/vicemusa/images/e320665.jpg

You have addressed me so I will respond only to request your point in this post and would love to learn more about it. :confused: I don't see anywhere I have EVER suggested polyester for glues.:eek:

[pipefitter]

Hello Pipefitter,

"It wasn't the fasteners I was concerned with, it was the blend fairing and painting that seemed like the real work of that scenario."

Sam Devlin advocates the total removal of all fasteners from his boats, because they expand and contract more than the wood and so, will eventually work themselves to the surface damaging the beautiful finish you worked so hard to achieve. Thus it would be sensible to be concerned with the fasteners, sitting within the hull like termites waiting to spring their nasty surprise.:eek:

Pericles

That may be so but I can't imagine metal fasteners expanding more than wood. As a weldor,it takes quite a bit of heat to expand metal and I am thinking more than the paint or epoxy could stand to expand more than wood does or maybe you just meant different than wood does?
I live where it gets quite warm and given all the talk about the effect of heat on epoxy,even that caused from using colors on a boat other than white,wouldn't there be a concern of a glue only construction possibly giving way to such? Especially figuring the wood is to move with changing temps? As it is,I have yet to see documentation of these fastener issues other than heresay. Not to say that it hasn't happened but I wonder what other factors were at work. What type of plywood for one. I imagine that maybe some of the more open grained ply such as D-Fir may expand more than others of the cedar/mahogany types possibly. I could possibly believe that the wood moving and the fasteners not might be an issue more than the metal expanding.Maybe this is more an issue with boats left to the weather and full sun where as mine is not,I don't know but sofar,there has been no fastener creep in my boat to date. Maybe setting the fasteners in epoxy has helped. I would like to see some pictures of screw pops and such. I had seen them in traditionally built carvel boats where they were only covered by paint but the movement in that solid wood was extreme. Why then, doesn't the epidemic pop bungs from their holes on traditionally built boats or how come we never read of this in the building and repair sections? Seems it would be noticeable when a restorer posts pictures of an old boat or atleast the mention of such more than I have seen than on this very thread. Just curious here,not argumentative.

[steelcrazy]

Screws keep me feel more secured. But yeah, there are bigger boats that are just glued. You make your choice.


___________________________
Jakob Inox Line Stainless Steele Fasteners (http://www.who-sells-it.com/cy/jakob-inc-814/jakob-inox-line-stainless-steele-fasteners-782.html) - The New Jakob Inox Line Stainless Steele Fasteners Catalog

[David Roberts]

So we've been doing this for a long time - building boats with epoxy. Here's what we've learned: Yes, some epoxies creep. WEST is not one of them. System 3 definitely creeps. We once had a very highly stressed plywood scarf, made with System 3, pop after a few weeks. We re-glued it with WEST on the boat and it's been fine for 20 years.

That said, when we use WEST we fasten almost everything together with screws. Then in every painted surface, we pull the screws. We use plain steel square drive washer head screws, no countersinks, so they don't leave a big hole. And you can use them over. Then we syringe the hole full of epoxy and wood flour. That's a great pain in the tush, but it works well. If you paint with Awlgrip, use dark colors, and leave the screws in, I guarantee that in 5 years you'll be able to see every screw in the boat. Metal gets longer when it gets hotter. The screw pushes up the filler. You see a bump. I don't think you'd notice it in semi-gloss latex, but you sure see it in Awlgrip. You don't see it in traditionally built boats because they get sanded and repainted from time to time. Epoxy built boats may not get repainted for 10 or more years. When we do an Awlgrip repaint, we sand everything perfectly smooth again. If there were screws, usually they don't reappear, because the filler has already been pushed as far up as it's going to go.

As far as strength goes, gluing is all about surface area. For 1/4" ply, use 7/8" of glue surface area. 3/8" ply = 1-3/8" glue surface. 1/2" ply = 1-7/8" glue surface. Those are my rules of thumb. If you have that much surface area, you don't need screws. If you don't, then you'll have to think about it. It's very possible that the glue surface will fall at the neutral axis and won't be stressed, so less surface area will be fine. If you think it's going to be stressed, like at a stem or rabbet, then either change the plans so you've got the area, or leave the screws in. Those rules are for well-designed boats with stressed skins. In many boats - rowing boats for example - there's not much stress anywhere except at the oarlocks, so it doesn't much matter what you do except for the oarlock blocks.

High speed powerboats are another story. In boats like that, we pull the screws from the planking, because the we have lots of glue surface area. BUT we leave the screws in which hold the chines and stringers to the frames. Not nearly enough glue surface area there, and you can't see them anyway. You got to use your head.

[pipefitter]

I recently discussed this very topic with a builder in the know. He had to laugh at the notion of the screws expanding and looked at me as if I had 2 heads or had a great fall at some point. His idea was not so much the screws expanding,being they get the hottest when driving them in, over what ambient temperature would affect.He thought for a minute and then laughed and said that it wasn't the screws expanding,it's more than likely the wood finally shrinking after being sealed,left under cover and in dry,warm storage while the epoxy filler stays as it is.

[David Roberts]

I recently discussed this very topic with a builder in the know. He had to laugh at the notion of the screws expanding and looked at me as if I had 2 heads or had a great fall at some point. His idea was not so much the screws expanding,being they get the hottest when driving them in, over what ambient temperature would affect.He thought for a minute and then laughed and said that it wasn't the screws expanding,it's more than likely the wood finally shrinking after being sealed,left under cover and in dry,warm storage while the epoxy filler stays as it is.

You know, I don't think 1/2" epoxy coated 9-ply 1088 Okoume really shrinks a lot in thickness as it dries from 7% MC. I expect the MC actually comes up a bit in a boat in the PNW. Also, the screws get puttied long after the little heat generated in driving them dissipates. Then the putty is sanded flush, several times, and long after all that. Just before undercoat, we also go around the boat with a heat lamp array and heat the entire hull topsides, one section at a time, to 140° for a couple of hours. That helps quite a bit. You can see every puttied screw hole plainly during the final pre-undercoat sanding.

Tell you what: drive a #8X1" screw into a Fuller bit drilled hole, then stick your finger in the hole and feel it. Not that that matters. Next put a piece of ply, painted black, outside in the sun in July. About 4:00 just try to hold your hand on it. Better yet, try the screw, epoxy putty, epoxy coating, and shiny dark paint thing yourself. Try several different fillers (I like wood flour the best). And I'm not entirely sure that it's just the screw getting longer. Another component might be the air in the glass or phenolic microspheres, which are in a lot of epoxy putties, expanding, so that the putty itself expands. Put the test panel under a heat lamp for a week, or on the front porch in the summer, when you're done. Please let us know what you find out. A good motto is to never believe anything that you're told. I think I learned that from my parents. Or how does that go: nothing that you hear, little that you read, and only half of what you see? Test, test, test. Oh, and don't tell me only a fool would paint their boat black unless you're placing an order. :)

Another fun thing is to glass and epoxy the panel and do the same thing. The glass weave will show up clear as anything. Differing physical properties of the resin and glass account for that. You can try several different loading compounds in the resin overcoats to see how they affect the print-through. I like aluminum powder the best.

It is a worry that high surface temperatures will degrade epoxies. I've had boats go into the tropics and the only glue that's failed there has been Weldwood. So much for folks who say you don't boil your boat, eh? Both epoxy and Resorcinol have held up well, so I think it's not such a big worry.

[marc1]

Interesting debate.
If I may add my 2cents...I have never built a boat however, as a carpenter and cabinet maker, I have glued a few pieces of wood myself.

My observation, and please correct me if I am wrong, is as follows:
Epoxy is the best glue around no doubt. If you glue solid wood you can rely on epoxy every time.
However ... We are talking about plywood, so epoxy is actually only gluing the last veneer with the frame or with the first layer of veneer on the next piece of plywood. If you stress test two pieces of plywood glued with epoxy on the flat side, obvioulsy the epoxy joint will not give, but the layers of playwood will brake apart.

In such a joint, we are relying not on epoxy but on the glue that keeps the fist veneer glued onto the second....and this underwater! What happens if some moisture happens to get inside the plywood and soften things up a bit?
A screw would keep the layers of plywood pressed together however will also brake through the moisture barrier that the layers of glue represent, not perfect.

However I think I would sleep better knowing that the plywood is glued and screwed.
A hull built with successive layers of thin solid wood is of course a different matter and would be OK with no screws since it is a solid mass of epoxy and wood and no other unknown uncertain manufacturers glue and dubious quality internal layers of veneer.

[pipefitter]

I didn't say it couldn't happen the way you said. Just another scenario. It doesn't end there. I go into his shed 2 days later and he has this plastic hinged lid box and he's holding it carefully up to his ear while shhhhhhsh'ng me. Then he puts it up by my ear and asks if I can hear anything and then he shakes the box a little. So I have to ask what's in the box and he says..."shhhhhhhh...mexican jumping screws,the heat from your hands wakes them up". :)

I also wouldn't say about painting a boat black.But then again,I wouldn't own a black car in Florida for more reasons than just the heat but because it shows the light color dirt here always,even 5 minutes after you wash it. I am not traditionally haunted enough to say such a thing. I used resin rich, ground fibreglass filler to fill the screw holes with a skim of phenolic microballons over that. No screw pops but there was also a year passed before the final sanding and color sanding after that which suited me fine for just knowing how long primers shrink after the fact. I have seen glass print through but for some reason,I didn't get any of that either.Seems more an issue with the more volatile based paints backed with heavier prime coats or that seemingly,the strong solvents initiate yet another shrink stage of the primer and even the resins,polyester included and let us not forget sand scratch swelling.