ply over glass hull leaking...help! :S

[floydrob]

hi, i just made a ply over glass hull,or glass over ply or whatever its called, i dont know much cos i'm only 15 but this is my 3rd boat made of ply but my first attemps at fiberglassing. iu got epoxy resin as advised by sum1 on here cos it is more flexible and doesnt crack so much, but i covered all the corners, chines and the keelson in fiberglass, everywhere where water could possibly get in is fiberglassed but ther is loads of tiny pinpoint holes. how do i get rid of them, cant afford another l;ayer of fibverglass and i dont have very much resin left., she floats but every hour or so i have to bail some water out.i was thinking of putting some sealant on the inside of the joints but i recon that would just cause water to get trapped between the fiberglass and the sealant and rot the ply. any help greatly appreciated :D

[KnottyBuoyz]

Sounds like you might have a leak larger than a few pinholes. That's going to be tough to track down though. If you don't find the leaks and plug them the water getting into the ply will eventually rot it out.

Have you painted the hull yet? Can you post a picture of the area you think is leaking. Coating or plugging from the inside won't help at all.

If you have a way of thinning the epoxy and recoating the areas you think might be leaking that might help. I once read about a guy who had a similar problem. He was working on a small boat and flipped it upside down. Sealed the entire boat with plastic and used a shop vac to put a vacuum on the hull then recoated the outside with thinned epoxy. The vacuum pulled the epoxy into the pinholes and sealed them up. Sounds kinda tricky!!!

[Frosty]

Cheapest way to get round that would be to mix up some paste with what you got left of your epoxy, like mix it with talc or similar, smooth the filler over all the holes and paint the whole thing with some paint,--any paint.

It'lle make it water tight.

[alan white]

Your problem is most likely too much dependance on epoxy coupled with too little epoxy to do the job. Now, how to fix the pinholes?
I see no alternative besides sanding the taped seams and adding another layer of light tape. I realize this means expense, but if the boat is small, just a quart should do.
I don't know how the chines are constructed but I'm guessing with chine logs rather than fillets over stitch and glue.
When you're short on cash, chine logs WELL FITTED AND BEDDED with polysulfide or some good below-the-waterline sealant will keep the sea out for years. It makes no sense to depend on the sealing forgiveness of epoxy if you can't afford enough epoxy to make it work.
In any case, welcome to the forum. It's great to see people of your age building boats.

Alan

[Manie B]

please post some pics
i may be able to help if i can see what you did

[rwatson]

If you have a way of thinning the epoxy and recoating the areas you think might be leaking that might help. !

Thinning epoxy is a bad idea, it lowers its waterproofing level

try a search on the subject
http://www.boatdesign.net/forums/showthread.php?t=23206&page=2&highlight=thinned+epoxy%5C

The best solution is the suggestion to go over the unpainted surface with a thickened epoxy carefully, covering all the holes.

If you have already painted or varnished the surface, then apply several more coats of that paint or varnish until every little hole is filled in.

If you have some major voids, you will need to grind them out, and refill with epoxy. Finding them is easier by sitting the boat on some old tyres and hosing water on the inside against the seams until drops appear on the outside of the hull

[kengrome]

If the boat is not designed to handle the stresses its joints are experiencing, it will take a lot of 'fixing' to eliminate these stresses before any pinhole filling will work reliably. I would like to get to the source of the problem, and this probably means posting pictures of your hull and describing how you constructed the joints ...

When most people use epoxy and glass on joints they do not do it simply to waterproof the joints. The reason for using epoxy and glass on plywood joints is primarily for structural strength. -- waterproofing is a secondary effect -- and joints never leak when the plywood panels have been welded together properly with epoxy and fiberglass. This assumes the design is well engineered to avoid stresses or distribute them rather than concentrate them in the first place of course.

Please describe the specific way you created your plywood joints, and post pictures of your boat so we can see what we're dealing with here ...

:)

[rwatson]

Ooooohhhhh - now i remember!!!!! Floydrob has already posted a picture of his boat previously - just did a search.
I am not surprised the joints leak Floyd - they are amongst the roughest joints I have seen, and unless you used several layers of cloth very well saturated with epoxy, then the fact that you dont sink is a credit to you.
I am interested in the 'foam' you used to 'glue' the edges together. Is it what the call Balcotan of somthing like that?

Ken gromes interest in the flxing joints might be well justified too.

Have you applied paint yet? It will be easier to fix if not. lets know what stage you are up to.

[kengrome]

I just did a search and found these pictures:

http://www.boatdesign.net/forums/attachment.php?attachmentid=23001
http://www.boatdesign.net/forums/attachment.php?attachmentid=23002

floydrob, if this is your boat I applaud your effort as an inexperienced teenager, but as much as I hate to hurt your feelings I'm going to tell you the truth because I think you should hear it from someone:

You did a whole lot of things really badly on this boat, starting with the design itself and progressing to the use of inappropriate materials and really bad construction techniques. I'm not saying this to discourage you, but I think you should stick to building boats designed by professionals -- or at least experienced amateurs -- because this one is a real mess.

Why don't you get some plans for a small and simple boat, and then build it properly -- by following the designer's plans very carefully. You have enough materials already if you take this one apart and clean up the pieces. Why not use them to build a proven design?

[Dane Allen]

You've shown a lot of creativity, resourcefulness and drive for someone your age...but I want you to live. So, go to your library and check out some books and DVDs on boat building. Also, practice joining small pieces of wood and also laminating small pieces together and chalk this boat up to experience. It would make a great sandbox in a school yard.

[Dane Allen]

I'm probably going to regret this but I have to take exception with something Kengrome said about epoxy and glass being primarily for strength and waterproofing secondary. I know Ken has a lot more posts than I but this was nagging at me.

While fiberglass does add some strength to joints I have always understood to never think of it as structural component. Rather, the main benefits of fiberglass are (in no particular order) 1. Reduce hull maintenance 2. Improve appearance 3. Waterproof the hull and 4. Protect from impact/abrasion. I derived this list in parts from Ken Hankinson's "How to Fiberglass Boats"., Glen L. Witt, Naval Architect, "Boatbuilding with Plywood" and several other publications and on-line references.

Let the flames begin :- )

[kengrome]

While fiberglass does add some strength to joints I have always understood to never think of it as structural component.Well, I guess you can think of epoxy and glass however you like, but you're missing some very important information I'm afraid ... :)

Practically every plywood joint I build is held together with epoxy and glass, I've been building this way for almost three decades, and I have yet to see or hear of any of my joints failing because the epoxy wasn't structural.

There's not a single nail or screw or staple or rivet or any other mechanical fastener remaining in this Tolman Seabright skiff I'm building -- it is ALL held together with epoxy and fiberglass -- and if that's not 'structural' I don't know what is:

http://www.bagacayboatworks.com/images/seabright01/
http://www.bagacayboatworks.com/images/seabright02/
http://www.bagacayboatworks.com/images/seabright03/

These boats and tens of thousands like them are built using the extremely common "stitch-and-glue" technique ... which means they are all being held together with epoxy and glass which creates the structural bond between the panels. Using epoxy and glass PROPERLY along a plywood joint produces what is essentially the same effect as if you were to be able to weld the two panels together -- it is stronger than the wood alone.

Rather, the main benefits of fiberglass are (in no particular order) 1. Reduce hull maintenance 2. Improve appearance 3. Waterproof the hull and 4. Protect from impact/abrasion.I'm glad you think so ... :)

Don't get me wrong, these are all acceptable reasons for using epoxy and glass -- but you're definitely missing something on your list here -- and it's a biggie.

Perhaps it is hard for me to understand how anyone in this day and age can fail to recognize epoxy's exceptional performance as a structural adhesive because I've been using it for so many years in this role ... but epoxy and glass are absolutely structural in my everyday use of these materials -- and I'm sure in many many other builder's use as well.

I haven't tried but if you know how to use Google I'm sure a search there will pull up more than you every wanted to know about the structural applicaitons of epoxy and glass fibers, not only in boatbuilding but in automotive applications, industry, aerospace and many other industries.

[Dane Allen]

Excellent points. In thinking back, I think the gist of the "epoxy as a structural component" discussion arose from people who thought that they could use, say, 1/2 inch ply in conjunction with fiberglass instead of the 1 inch ply recommended in the plans (to save money, of couse.)

Suppose you T-bone a submerged log at a certain speed, will the fact that you used fiberglass on a thinner than recommended hull keep your hull from opening to the sea? I completely understand and agree that epoxy is a wonder jointing adhesive that makes many fiberglassed boats what they are today. What, triple the peel of Ployester with much more wood saturation?

But, and maybe this is splitting hairs, I don't see that fiberglass cloth/mat applied to the hull strengthens the hull to the extent that the urban folklore prostyletizes. Otherwise, why even use wood? We would just make a fiberglass skin like that on the old canvas skinned bi-planes, soak with epoxy and call it a day.

[the1much]

you dont need wood,,,at all,, for anything in a boat,,,BUT,, now a days,, im sure its the wood giving a little strength to your glass? instead of how it use to be as the glass giving a little more to the wood.,, most use wood just for the "form" ,,does sand give aluminum strength?,, or does the aluminum give the sand strength?,,cause if you step on plain sand,, its pretty easy to squish,,or if you step on a can, its just as easy,,,,,,,,but,,,,,if you step on a can of sand,,,,,hmmmmmmm <<<<damned soda can analogy ,,hehe :D

[tom28571]

Excellent points. In thinking back, I think the gist of the "epoxy as a structural component" discussion arose from people who thought that they could use, say, 1/2 inch ply in conjunction with fiberglass instead of the 1 inch ply recommended in the plans (to save money, of couse.)

Suppose you T-bone a submerged log at a certain speed, will the fact that you used fiberglass on a thinner than recommended hull keep your hull from opening to the sea? I completely understand and agree that epoxy is a wonder jointing adhesive that makes many fiberglassed boats what they are today. What, triple the peel of Ployester with much more wood saturation?

But, and maybe this is splitting hairs, I don't see that fiberglass cloth/mat applied to the hull strengthens the hull to the extent that the urban folklore prostyletizes. Otherwise, why even use wood? We would just make a fiberglass skin like that on the old canvas skinned bi-planes, soak with epoxy and call it a day.

Dane,

The epoxy and glass in the joints of S&G boats ARE structural and that is their primary reason for being there. The proof is overwhelming and I suspect you misread something that was in Glen-L's material.

Floyd could benefit greatly by taking his advice seriously also but I doubt that will happen. Some tried to steer him in the right direction when he first posted but were accused of being spoil sports and too negative to a young and enthusiastic builder. No one is done any favor when they are told that a bad idea is a good one.

[Dane Allen]

Ah, I stand corrected. I wasn't aware this was a stitch and glue boat, I thought it was ply over frame based on the pictures. What I was reading was in regard to the belief some people have that fiberglass greatly increases the strength of the plywood panel itself. I see now the focus of the conversation was on the joints.

[kengrome]

I think the gist of the "epoxy as a structural component" discussion arose from people who thought that they could use, say, 1/2 inch ply in conjunction with fiberglass instead of the 1 inch ply recommended in the plans (to save money, of couse.)It almost never saves money on construction costs to use epoxy and glass on thin plywood rather than just using thicker plywood and no epoxy/glass. Plywood costs a lot less than epoxy and glass, that's all there is to it.

[floydrob]

hi, i take ur comments onboard, its now alot further on and i cut off all the foam, it was kinda expoetimental, i bought a dremel with a cutting blade and cleaned up al the joints one by one, all the edges and replaces all the crap wood towards the bow and got a better transom. it is all fiberglassed on the joints, sanded down smooth and then painted with primer and antifoul on the bottom and exterior gloss on the side which is nece and thick so it soaks into the wee pinholes. the construction is chine logs which the ply is screwed to with brass screws and fiberglassed over. i think the problem came when i filled it with too much water, done my calculations and it holds 1.5tonnes of water, so maybe thats why it started bursting little leaks.lol.

would it be worth flippin the thing upsied down, getting a load of filler and smoothing everything perfectly and then use it as a mould to make a double skinned fiberglass hull and then add the cabin afterwards? i was just offered 3 binbags of fiberglass from my best mate who got it from the boatyard.

my phone is getting repaired soi cant post pics, soz, i took onboard all those comments, they dont piss me off, they make me think, read up on it and then i 99% of the time, i apply what has been sed, but wat dus piss me off are naysayers and ppl like tom lathrop who recon i dnt take anything onboard like a typical teenager :-
"Floyd could benefit greatly by taking his advice seriously also but I doubt that will happen"
tbh, if ppl tell me i cant it just makes me more determined to prove them wrong...if u can constructively criticise my work ant tell me of improvements i can make...dont be afraid to, but dont tell me that u doubt i will take them onboard cos i will if i have good reason and at the end of the day, its my boat, if it sinks, i'm responsible. :D

[rwatson]

Well done Floydrob. Bouncing back like that and getting stuck into the fixes is the only way to go.
In my not so humble opinion, I think thoroughly waterproofing your existing hull, and having a bit of fun with it is the way to go.
The full fibreglass version with all the spare leftovers should be reserved for your next big project, because (whack on the chin) the current hull design is ahem.... very experimental, and you will do a much better job next time, I am sure.

[kengrome]

would it be worth flippin the thing upsied down, getting a load of filler and smoothing everything perfectly and then use it as a mould to make a double skinned fiberglass hull and then add the cabin afterwards?

No, don't do this yet. If the boat turns out to be good enough to be molded you'll learn that AFTER you've had it on the water for a while.

[floydrob]

ok, thanks. the actual plans were adapted to make them easier for me to build from the "firefly" plans which can be found on svensons.com, i didnt have the tools to cut a curved bow frame, so i made it sharper, which i like better for looks, and i just put a flat deck on the bow and added a water tight compartment to the bow too, i want to have a watertight compartment in the stern and one midships too, so if she flips or anything happens, i can take her out the water and adjust it and repair it. i wanna put it in the water with some weight in it at the transom to replicate the engine (still have no clue what size) and some weight on the seat in the cabin, then i can see if it floats and how it sits in the water....one problem=my dad sed it aint goin near the water till i can prove there is no leaks, but he doesnt understand that putting that weight of water inside the hull will just create leaks and push the sides apart. any other methods i can use? i dont want it to float from the inside, preferably the outside. spur of the moment....i'll build a lake in my garden...lol, ko.
thanks for ur help again :D

[the1much]

build a small cradle to put your boat in, if he's stuck on that method,,,,,make him help ya since its his test,,,hehe :D

[GTO]

I built my boat from plans at http://www.instantboats.com.
Dynamite Payson has a couple of books out that describe in good detail how to build simple, relatively inexpensive boats using plywood, nails, and glue, along with the stitch and glue method for some designs. The books contain small copies of some of his plans. Maybe you could find the books at a library or bookstore and review it for some help.

He also has this powerboat that might be a fun build for the future.
http://www.instantboats.com/skimmer.htm

To test the hull, just drop it in the water with a few sandbags/weights equaling your hoped for payload and let it sit for a while. If it doesn't leak, start off with slow and easy trips near shore where its easy to beach if a leak does occur. You should be able to use a paddle or oars (you can make those if you don't have any) to test the boat out, before worrying about an outboard or electric motor.

Good luck and just be safe!

[floydrob]

not tryin to be a smart arse or anything, but that power boat is a peice of pish...i dont want to take a step back, i have built many boats in the past using simple techniques, herb mcleods one sheet skiff(now how simple can u get), then i moved onto a jonboat, still relativesly simple, and now i'm making this...its a good leap, but i want a challenge, at first i wanted it in the water quick, but now i have slowed down, fixed most problems, trimmed verything nicely and am now working on the inside as i am pretty confident that it will float great. i put a deck in and am gonna get some thick ply for the cabin roof and sides cos the 6mm stuff i used is rubbish for that, also it will hopefully push the bow down a bit because i was woried of the bow being too high and the stern being too low, so i'm starting with a 6hp british seagull which i will link to a steering rack of some kind...shudnt be too hard.the front deck will be replaced with decent ply, the stuff on it is rubbish. i recon i can do a good job of this boat with advice from everyone here and if i take my time. i'll try to add pics but summmit aint wurkin. grrr. lol :D

[floydrob]

pic thing aint working, i'l go on my laptop 2moz and post them.

[floydrob]

hi guys, i got my exam results today which were very good, so my dad let me put my boat on the trailer and launch it. i bought a trailer last week for $100, (i dont have a gbp sign cos i just reinstalled my computer to US keyboard format accidentally) but 50.00GBP its pretty tatty but does the job.

we put it in the water down a slip, but the trailer has no winch, so we un-tied the rope and gave it a push, so it went in fine, sat it there with some weight in it for a good half hour, seemed fine, so i got in and took her for a spin...well thats an exaggeration, she's heavy, and with a 9.9hp yamaha (i borrowed from my grandad) she was going alot slower than expected, i dont have a spedo, but i wouldnt have thought any more than 8 or 9 kts.

i now think i wanna make a full fiberglass one for myself, it would be lighter and i wouldnt need a big engine. what are your thoughts and where can i get fiberglass csm at the best prices? i pay $12 (6.00GBP) for 1M x 1M, which wont meke my nu boat cheap! lol. i want to double skin it and make fiberglass seats etc. also, where is the best place to order epoxy resin, and the best application process? rubber roler? i have no idea, i done the joints with a brush, which gave many air bubbles. thanks :D

[kengrome]

she's heavy, and with a 9.9hp yamaha (i borrowed from my grandad) she was going alot slower than expected, i dont have a spedo, but i wouldnt have thought any more than 8 or 9 kts.A 9.9 should easily get 500 pounds onto plane if the hull is properly designed to plane. Did you calculate your weights yet? How much did the boat + engine + you + fuel + other stuff weigh when you tested it?

i now think i wanna make a full fiberglass one for myself ...Who did you build this one for?

it would be lighter and i wouldnt need a big engine.Fiberglass is HEAVIER than plywood, not lighter, so you're going to need an even bigger engine if you make a similar boat in fiberglass and if you ever hope to get it to plane. I cannot help but wonder where you got the idea that you can save weight by building in fiberglass???

Sure, if you make a composite sandwich with foam core in between two layers of glass your hull MIGHT weigh less than a plywood hull -- but even if you're lucky enough to get it to weigh less, the difference will be so small that it's not worth the time and money on such a small boat -- unless there are other reasons for using this technique (which do not apply to yours) such as a round bilge design for example.

IMO you'd be better off building a second boat in plywood with epoxy/glass taped seams. But this time you might want to consider building it upside down on frames so you can start off with the correct shape. Then use high quality marine plywood of the proper thicknesses for each part of the boat.

You might also consider using the right kind, type and thickness of glass tape (+45 -45 biaxial is best) on your joints inside and out ... and no more of that foam crap you used in the joints on this boat. Use good quality epoxy not polyester or any other cheap substitute. If you do what I'm suggesting you'll be finished faster with a lighter boat and you'll have saved LOTS of money over building one in fiberglass, that's for sure!

Do you have any pictures of your boat in its current condition? After seeing the other pictures it would be nice to see the improvements you've made ... :)

[rwatson]

Couldnt have put it better myself!!!!

Right on KG.