Weatherbeaten plywood- Can it be saved?

[Stan C]

I am in the process of building a stitch and glue boat ( Bolger's SWEET PEA ) and have just discovered that some of the 1/2" plywood was left out in the sun and is badly checked on the surface. This was not good wood to start with ( B/C fir- I think ) and there are many loose surface knots as well. I know that nobody would recommend using material like this for any kind of boat but it won't live in the water although it might spend a week or so at a time afloat since it will weigh about 300 lbs. and will probably need a trailer to launch and retrieve. The 1/2" ply is structural, the hull will be planked with 1/4" A/C that is yet to be purchased.

I need to just make the best of it because my partner in this project is unwilling to trash the work that has been done and he is covering all of the materials costs. I'm doing this mostly for the experience because I'll be moving to the opposite coast soon and don't expect to be able to take it with me. I was hoping that I could at least get to sail solo in my own boat before I leave in 3-4 weeks. ( I've only had a couple of sailing lessons and don't know anyone who sails so this would mean a lot to me right now. )

Most of the structural pieces were cut a while back, the worst part is what I cut a couple of days ago from plywood that should've been tosssed: the stem piece and the 4 cheek pieces which will need to be laminated 2 to each side of it. If we were going to use epoxy then I could saturate and fill the surface veneer with that before laminating but all epoxy construction is not within the budget. It is my understanding that once epoxy has been used that I would not be able to finish with polyester or vinylester due to their not being able to bond to epoxy. The plans call for covering the hull in glass cloth. I'm totally new to all of this.

So what I want to know is can the less expensive resins do the same job in filling the badly cracked surface veneers? My building partner has said that he wants to get resourcinol or some other glue to do the laminating. The decision needs to be made quickly before he goes ahead and glues up the stem as it is. I'm trying to have some input but the "shop" is 60 miles from where I live so I can't have a lot of control over what happens except when I'm there.

If this boat isn't completed during this month of june then it probably never will be finished.

Any advice on how to proceed will be greatly appreciated.

Stan C

[Bob Smalser]

Epoxy will fill the checks and fix the knots.

Gentle heat gun action will thin it so it seeps beneath the knots and any delamming going on. Then a sandable filler mixed with the epoxy over top of that will provide a good surface for primer.

The price of it is up, so expect to go thru a hundred bucks worth or more for a S&G skiff.

[Stan C]

Thanks but I knew that. The heat gun is a useful bit of info.

My question is can I use polyester or vinylester the same way to fill the cracks? The amount of resin needed for this boat is about 3 gallons and that's more like $300.

[Bob Smalser]

Sure, if you can find a polyester resin that sticks well to wood these days.....not all of them do like they did in the 1970's.

Had that problem last year restoring a plywood boat bathed in the stuff and woulda spent more on trying out resins than the epoxy cost.

[Venchka]

Originally posted by Stan C:
...The amount of resin needed for this boat is about 3 gallons and that's more like $300.Shop around. $40/gal. is out there. There's a company in Southern California selling quality resin & hardener for a lot less than $100/gallon. FGCI is <$40/gal. With shipping, it should be less than $50/gal. GOOGLE epoxy resin and $AVE!

How much brand new MDO can you buy for $300 worth of epoxy to fix the B/C fir you have?

Wayne
In the Swamp.

[ 06-01-2005, 09:44 PM: Message edited by: Venchka ]

[Stan C]

Venchka you're the best. I've come to expect the best responses when I see your name.

I had intended to go over to Tap Plastics which is very close to where I live to get the resin because of my lack of experience and their large selection. When I called the guy sounded real knowledgeable and he said the company was founded by the guy who invented bondo, for whatever that's worth.

My mistake, I should've GOOGLE'd it weeks ago cause now there may not be time for mail order. I won't be taking anything but a picture of my boat when I move to the east coast next month but I'd hate it if I can't complete the hull before I leave.

Given our budget I think I will be trying something other than epoxy unless there's a cheap and easy to way to get polyester to go over it. I asked Dynamite Payson when we bought the plans and he recommended polyester over epoxy because of cost.

Stan C

[davebrown]

Why not find someone to take it off your hands when you are done and get a donation of $100 or $200...those sweet peas are damn fine looking boats for what they are...or is that the role of your buddy?

[Todd Bradshaw]

Back in the days when we use to cover strippers with polyester resin and fiberglass we found that we got the best bond and highest peel strength by priming the raw wood with a laquer sanding sealer. We used Pratt & Lambert "Vitroloid Sealer". It smells like bananas and the fumes are down right explosive as well as bad for you, so good ventillation and a mask are needed (you should have them anyway as polyester resin fumes are also very explosive and a serious health hazard). We would roll-on a couple thin coats of the sealer, let it dry overnight and then apply the resin and glass. It made a big difference in the quality of the bond, compared to resin applied over bare wood. We always used laminating resin (without surfacing wax) for all bonding and filler coats and then added surfacing agent to the last filler coat to get the surface to cure. It took a long time to find a resin that really worked well. We finally wound-up using Techniglass (U.S. Polyesters) #329-2 laminating resin, but I don't know whether it's still made or who might sell it. There was no question that the non-surfacing resins worked better than those containing the wax. I've got one boat out in the back yard built with 329-2 that's about 30 years old and doing just fine. As for vinylester, I suspect it would be a waste of money to upgrade from polyester to vinylester. It won't stick any better to wood than polyester. It also doesn't seal wood any better and a plywood boat is never going to flex enough to take advantage of the characteristics that make vinylester a tougher resin.

I'm about 90% convinced that some polyesters will take more abrasion than epoxy, but in terms of workability and general durability of a resin-sealed wooden construction, there is no question that epoxy is superior. ...but you already know that.

[Venchka]

Hey Dirt,
I use the Aero Marine from JGreer and like it OK. I have scarfed with it so
far and results were fine. I'm going to 'glass my boat this weekend and I
can let you know how that goes if you want...

Craig
----- Original Message -----
From: "dirtsailor2003" <dirtsailor2003@...>
To: <MessaboutW@yahoogroups.com>
Sent: Tuesday, May 31, 2005 6:54 PM
Subject: [MessaboutW] Epoxy

> Ahoy,
>
> Well, I know we have touched this subject many times here but, I would
> like too know, If anyone is using the Cheapo Epoxy that Duck works
> offers, and how it is to work with, and also the epoxy from JGreer. I
> need to get some more soon. The prices of both are very tempting, but
> still hasn't conivinced me to steer away from the tried and true!
>
> Dirtsailor
Duckworks above refers to an e-magazine. The owner is a nice guy. Texan, what else! He sells epoxy. GOOGLE Duckworks. GOOGLE knows where Aero Marine is. They are in California.

JGreer (http://www.jgreer.com/)

Do you really want to start your boatbuilding career trying to put a poyester band-aid fix on B/C fir? 1/2"x4'x8' MDO is like $50/sheet.

I make mistakes everyday. I try not to repeat today's mistakes tomorrow. That's the beginnings of a pattern. ;)

Wayne
In the Swamp. :D

[ 06-01-2005, 11:13 PM: Message edited by: Venchka ]

[RodB]

Usually in a case like this I wouldn't even bother to comment but what the hell. If the boat will be used at all and have any realy life expectancy, why not do it right. Like the old saying goes, "If its worth doing at all, its worth doing well". I like the idea above of getting someone to fund the materials for getting the boat later.

Use epoxy, the least expensive you can find. Everything you have described exactly fits epoxy's uses... and the boat will be strong, and last a long time. Hell, stitch and glue and epoxy are almost synonomous... In the big picture, is it good or bad if the boat lasts many years?

Alternatively, lots of boats have been glassed with polyester resin in the past, but you have to find some input from knowledgable sources.

RB

[ 06-02-2005, 04:23 AM: Message edited by: RodB ]

[Stan C]

Originally posted by Venchka:

Do you really want to start your boatbuilding career trying to put a poyester band-aid fix on B/C fir? 1/2"x4'x8' MDO is like $50/sheet.

I make mistakes everyday. I try not to repeat today's mistakes tomorrow. That's the beginnings of a pattern. ;)

Wayne
In the Swamp. :D [/QB]This is why I was hesitant to even mention my problem in this forum. Frankly it is embarassing that I am proceeding with such inferior materials and it isn't the way I wanted my first project to be done. I wouldn't want a potential employer to think that this is the way I would choose to do things.

The short answer is that I have no control over the funding and can't contribute anything myself at this time. If this boat gets built it has to be right away and with what the other party is willing to go for, with me supplying about 75% of the labor. Otherwise the project will end up abandoned, with no one on this side of the country willing to do the work.

There really isn't the time to start again anyway.
I've gotten some good suggestions to check into and the decision will probably be made tomorrow.

Thanks to all who responded.

P.S. I just looked at the AEROMARINE site and that may be the way I'll go.

Stan C

[ 06-02-2005, 05:52 AM: Message edited by: Stan C ]

[Stan C]

Originally posted by davebrown:
Why not find someone to take it off your hands when you are done and get a donation of $100 or $200...those sweet peas are damn fine looking boats for what they are...or is that the role of your buddy?Yes, that's his role. He is my father and insists that I defer to his judgement.

Stan C

[Venchka]

A valuable lesson learned. Build the boat to the best of your abilities within the current budget constraints. Try not to make the same mistakes twice.


The amount of resin needed for this boat is about 3 gallons and that's more like $300. Sweet Pea (peapod)15'x4'4"

Are you sure about the 3 gallons of epoxy? That seems high. If delivery time permits, buy in smaller quantities. Use it all up before buying more. That way you won't have a lot left over.

Wayne
In the Swamp.

[Stan C]

Originally posted by Venchka:


</font><blockquote>quote:</font><hr />The amount of resin needed for this boat is about 3 gallons and that's more like $300. Sweet Pea (peapod)15'x4'4"

Are you sure about the 3 gallons of epoxy? That seems high. If delivery time permits, buy in smaller quantities. Use it all up before buying more. That way you won't have a lot left over.

Wayne
In the Swamp.</font>[/QUOTE]I don't have the plans where I am now and the 3 gal. figure is from memory. I am sure that the design calls for covering in fiberglass cloth.

My latest idea is to buy ( from U.S. COMPOSITES ) 1gal. of "standard layup" polyester resin for $27.50 for the filling and lamination of the damaged plywood and 1 1/2 gal of the 635 epoxy with slow hardener for $51.50 to finish the rest of the build after I run out of polyester. I would not add the finishing wax to the polyester, and the slow epoxy hardener is supposed to be "no blush".

I still want to try to get more info on whether this polyester will bond well to plywood and about if I should use some type of "laquer sanding sealer" as was mentioned earlier in this thread.

Stan C

[ 06-02-2005, 11:06 PM: Message edited by: Stan C ]

[Todd Bradshaw]

Make no mistake about it - there isn't a single polyester resin in the world that's formulated with sticking to, or sealing wood in mind. If you want proof, go to any fiberglass boat graveyard and look at all the rotten transoms built by trying to stick a sheet of plywood between a couple layers of polyester fiberglass. The laquer sealer that I mentioned is a trick which can often improve adhesion and peel strength of the laminate, but it's never a sure thing with polyester. We fooled around with different brands and formulas of resin for three years before we found one that really produced good results and without the sealer/primer, even it wasn't so great.

The idea of mixing polyester and epoxy work on a first-time glassing project is pretty much just asking for trouble. If the two come into contact, I'm not even sure epoxy will stick to the surface of unwaxed polyester (which is, and stays, sticky until surfaced). Toss a bunch of suspect plywood into the mix and you may be building nothing more than an expensive bonfire. Also, the idea of trying to fix the wood with resin which doesn't stick well to it and then overcoat that with resin that would have stuck pretty well to the bare wood seems pretty crazy. It well may be time to start thinking about how much money and time you're willing to risk, because at this point, with the plan as it seems to be presented here, it really IS at risk.

[Bob Smalser]

Forget the polyester.

There are many other ways to skin this cat short of 3 gallons of epoxy....even with plywood.

Going thru the shop records the other day and I've either built or rebuilt one boat a year for the past 5 years...

...and I've used exactly one gallon of epoxy a year.

[Stan C]

OK. I'll rethink that approach. I had heard that you could use epoxy over polyester but not the other way around and for that reason was hesitant to start out with epoxy. The root of the problem is our budget which I personally can't control, but if polyester is really that bad at sticking to wood then I'll try to influence the decision away from it.
I still remember that when I called Dynamite Payson he said why use epoxy when it's so expensive and is stronger than what is really needed. He also recommended A/C ply over marine because the hull will be glassed over.

I would have liked to use okoume and epoxy to assemble the hull and then saturate the whole thing with CPES before covering it with glass and epoxy, but it just isn't going to happen that way.

SC

[Bob Smalser]

Trendy is expensive.

You probably don't need to glass and epoxy the whole boat....just the seams. You can forget the spendy CPES, too, if you are concerned about budget.....12-dollar-a-gallon linseed oil and 20-dollar-a-gallon porch enamel will do the same thing if you repaint the boat periodically.

Do fill those checks with epoxy, first, tho.

[ 06-03-2005, 12:46 AM: Message edited by: Bob Smalser ]

[Todd Bradshaw]

You can use epoxy over polyester. It will actually stick to it better than more polyester would - but - the polyester needs to be surfaced first and then sanded in preparation for the epoxy. Laminating polyester resin (the type that seems to stick to stuff best) hardens-up fully only when sealed off from air. After you put a coat on it will harden, but a thin layer on the surface, which is exposed to the air, stays sticky and somewhat soft and takes a very long time to harden. This is great for laminating because it makes for a better bond with the next layer. To get the finished project to harden though, you either use surfacing resin or make your own for the final layer. This is done by adding a couple spoonfulls of surfacing agent to the resin. This is just parafin disolved in styrene monomer (the ultra-stinky, explosive, brain-killing solvent used in polyester resin). After this last, waxed-resin coat is applied, the wax floats to the surface and seals it off from air so that it will harden. The difference between the hardness and sandability of a surface waxed layer and a non-surfaced, still sticky layer is quite dramatic.

Naturally, once it is fully cured the wax needs to be sanded off before you do any painting, fiberglass tabbing or other assembly or finishing steps. It is possible to laminate with all surfacing (waxed) resin, but the timing gets tricky. As long as you apply the layers rapid-fire (as soon as the layer underneath will stay put) the wax in layer #1 will float up through the freshly applied layer #2. Wait a little too long though, and you can wind-up with thin layers of wax trapped between the layers of your finished fiberglass lamination. Pretty soon, you'll have a boat with lots of delaminating fiberglass on it.

To add epoxy to the plan, over the polyester patches, you would need to properly surface wax the polyester so that it would cure completely and then sand and clean it to be absolutely sure you got all the wax off and had a decent tooth on the surface before adding the epoxy. This is one reason why I objected to starting with polyester and finishing with epoxy. The other is that the initial bond to the wood is almost always the weakest bond in a whole stack of bonds when you fiberglass a hull, even with epoxy. Using the poorest adhesive for the initial bond and then topping it off with layers of better, more expensive resin is really risky.

It's just a heck of a lot easier and a lot better to start your wooden boatbuilding career not having to know anything about polyester resin in the first place because you're using epoxy instead. I was a sculpture major in college, working with wood, bronze and both epoxy and fiberglass castings. In my spare time, I worked for one of the sculpture professors, helping him cast, sand and polish 200 lb. solid, transparent polyester resin castings which came out like big, weird-shaped lenses. By the time I got around to building boats I had a pretty good handle on using polyester. Otherwise, my first boats would have been a real mess.

[Stan C]

REPLY TO BOB:

I was just trying to show that I do care about quality when I described what I thought would be the ideal method of completing a S&G hull.
In this case economy has been a factor since the start. CPES was never going to be in the budget, nor mahogany marine plywood either.

As far as glassing only the seams, that's what I really expected when I sought a S&G design and had assumed that this particular boat needed the full covering for strength. Surely without the full glass cover the hull will be lighter and easier to handle out of the water, and it will be stored dry so I'd really like to save the expense and time of glassing the whole thing.

Do you really think I can get away with just glassing the seams inside and out, and if so would 1 1/2 gallons of slow drying epoxy do it all including laminating the stem and stern posts and mast, and making the fillets? U.S. Composites has 1 1/2 gallons for $51.50.

and-

REPLY TO TODD:

Thanks very much for the explanation of polyester resin's characteristics. I believe your statement that is best to skip it altogether and start learning with epoxy. Expense and local availability were the only reasons to have considered polyester and you have convinced me that a period of trial and error would be necessary to be certain of sucess, and that is definetly not in the range of possibilities.

I think that the info you have given me may well prove valuable in the future as I try to make my way as an apprentice boatbuilder (see the thread under: " Boatshop Employment in Maine?", if you want to know more about that).

Your comments seem valuable. They are much appreciated. I will try to memorize it all.

SC