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 Post subject: Leaky wooden boat
PostPosted: July 15th, 2009, 9:31 am 
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Location: winnipeg
I recently acquired yet another small watercraft. It is a beautiful 12' Norwegian sailing pram, made out of Russian pine. It was built according to plans Lee Valley re-published, is lapstrake construction, and is fastened with brass rivets. It is really beautiful to look at.

Unfortunately, I have found it is mostly good for looking at. It leaks around the centerboard box, and through some of the joints, and a bit through some minor cracks in the boards themselves. When attempting to remove the jammed centerboard, I also broke the centerboard box. The builder/previous owner had fiberglassed a portion of the bottom roughly where the waterline is, but not around the centerboard box, and the glassing is a bit rough.

Now - on to repairs. I intend to take a belt sander and remove most of the 'glass on the bottom. Then, I think I will position the centerboard box where it ought to be, and use strips of fiberglass cloth inside to secure it to the bottom and stiffen it. Outside, to seal the hull, it seems cloth and resin would make it strong, waterproof, and abrasion resistant. However, I was wondering if just west-system epoxy resin, brushed on the whole outside of the hull (and worked into joints,cracks) would adequately seal the hull. I do intend to sail the boat, but not to subject it to hard daily service. It seems that full glassing would also look worse, be heavier, cost more, and be more challenging/time consuming.

Any advice, suggestions, or experiences would be appreciated. I really like the look of this thing, but might be a bit over my head when it comes to woodworking. Also, I am confident with fiberglass repair jobs, but don't know how well I would do glassing the bottom (it isn't smooth, being lapstrake).

Thanks in advance!


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Last edited by mr_canoehead18 on July 15th, 2009, 3:25 pm, edited 1 time in total.

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 Post subject: Re: Leaky wooden boat
PostPosted: July 15th, 2009, 9:41 am 
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Joined: February 19th, 2004, 9:53 pm
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If you "paint" West on the outside, consider using their special foam rollers instead of a brush. And remember the bit about amine blush interfering with subsequent coats. If you use the 207 resin, amine blush is much less, and the coat is clearer than with 205 resin.


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 Post subject: Re: Leaky wooden boat
PostPosted: July 15th, 2009, 9:52 am 
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Location: winnipeg
Many thanks. I'll get the 207 hardner.

I wasn't aware of amine blush, so will have to consider that.

A fellow at a marine supply place suggested that simply painting the resin off would result in it cracking if the wood flexed. Thoughts?


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 Post subject: Re: Leaky wooden boat
PostPosted: July 15th, 2009, 10:42 am 
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Joined: February 12th, 2004, 9:28 am
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A few thoughts:

1) Rollers are great for smooth coats, but for the first one where you want to work the resin into the cracks then a brush is probably a good choice.

2) I've never had a problem with amine blush. The recommended approaches to avoid issues are:
a) apply the 2nd and 3rd coats within about 24 hours of the last coat - ideally you can do 3 coats in a day and be done with it
b) wash the service with water and a little dish soap - nothing harsh required

3) It is definitely true that when using epoxy and fibreglass, then the lateral strength is coming from the fibres. Now the question is what are you trying to accomplish. For sealing cracks in individual planks, then the epoxy alone should work well. If you were trying to seal between planks then that is where the boat is expected to flex and where the epoxy would be likely to crack. That is also the place where trying to apply fibreglass would probably end up looking the worst.

4) If you are trying to fill gaps between planks, then that is where caulking would come in, only you don't usually caulk a lapstrake hull. Possible options are:
a) Soak the hull and see if it tightens up. Most traditional wood hulls do rely on the wood swelling to seal the joints. Maybe it is just dried out right now.
b) If you still have gaps, then an "elastic seam compound" (don't you love it when books don't actually tell you anything) would probably be a better choice. For example one of the 3M sealants that Noah's sells - http://www.noahsboatbuilding.com/noahmain/index.asp?FSCat=27&url=IND&iFromFeatured=1
BTW that same semi-useful book also suggested using a hooked reefing iron to cut a groove along the lap to make sure there was somewhere for the caulking. For a reefing iron, picture the pointy handle end of a file with a hook to it.

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 Post subject: Re: Leaky wooden boat
PostPosted: July 15th, 2009, 10:58 am 
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I've been on the phone with several experts and come to the following:

West System does not recommend my original plan. They offer, instead, to use G-Flex 655 (pre-thickend) in between the joints. It has a 30% elongation, and is quite strong. Then, I could coat the plank surfaces with the 207 resin for a clear finish.

Splake's idea of using a sealant sounds good, so I might try 3m 5200, as that is tenacious stuff. I would sand, apply beads of the 5200 along the joints, then paint the epoxy over any exposed planks.

Thanks again for all the advice/suggestions.


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 Post subject: Re: Leaky wooden boat
PostPosted: July 16th, 2009, 9:52 am 
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Yeah, I'm already using G-flex. Great stuff, though a bit slow-setting.

Splake, on the amine blush issue, if you are using West 105/205 or 105/206, you need to get the next coat on before the previous coat has truly hardened. I was able to roll on 4-5 coats in a day. If I had waited 24 hours, it would have been >necessary< to clean off the amine blush. And the thin foam rollers sold by West will easily push resin into cracks. Rollers are somewhat a matter of preference, but West sells a lot of them for surface coating.


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 Post subject: Re: Leaky wooden boat
PostPosted: July 16th, 2009, 12:31 pm 
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Oh I've used the rollers, but not for a first coat - eg: when working the resin into the fibreglass cloth. I would also compare it to any other "painting" job like painting wooden siding on a cottage with lapped siding. A roller would be really tempting because it can cover so fast, but it wouldn't handle the joins between siding planks well so I have to use a brush.

For the amine blush - I believe you on the timing. It will be temperature dependent too. I've always used the 105/207 combo. I've thought about getting another hardener for those jobs that won't be a clear surface, but I already have the 207 handy so I just end up using it.

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 Post subject: Re: Leaky wooden boat
PostPosted: July 16th, 2009, 5:22 pm 
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207 is low blush, so you have more latitude. If one is doing successive coats, low blush is a big help. But I had a lot of 205 and 206 to use up, so I (successfully) followed the strategy of getting the next coat on before the last one was "set." It was hot weather, too, so I mostly used 206, and it still set pretty fast.


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 Post subject: Re: Leaky wooden boat
PostPosted: July 16th, 2009, 7:55 pm 
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Location: winnipeg
I know this isn't a new story, but the deeper I dig into this project, the more exciting it gets. The previous owner apparently 'glassed over paint in some places, caulking in others, and bare wood in others. As such, removing the 'glass was interesting. I am not done, but found much peeled off by putting a screwdriver under it. Some held, and I just sanded it smooth.

I am still undecided about whether to glass the outside. If I do, and use lots of varnish on the inside, do I need to worry about rot? I live in a dry-ish climate, and the boat will not be continually in water. I have heard that one must glass top and bottom but it doesn't seem necessary.

Further, if I go with the 3M 5200, should I apply it to bare wood or glass and then paint over it, or paint first and then caulk?

I am going to repair a canoe tomorrow to restore my confidence before getting back to the lapstrake pine. I am thinking of calling her the "Antelope" after the vessel in Stan Rogers' song Barret's Privateers.

Thanks again for everyone's help. I never thought about blush before, so I learned something new already. I might have paid too much for this boat, but it is reasonable tuition for learning about boatbuilding.


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 Post subject: Re: Leaky wooden boat
PostPosted: July 17th, 2009, 8:17 am 
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I haven't actually used the 3M 5200, so first recommendation would be to read the directions. Probably double check with the supplier that it's the right choice for the job too. I would expect that applying it directly against the clean wood would be the best choice, but that takes me back to 'read the directions'. :)

Standard advice when fibreglassing is to either do both sides or no sides. That said, the folks at Giesler Boats ( http://www.gieslerboats.ca/ ) only fibreglass the outside. The argument in favour of doing both sides is to ensure the wood is sealed and stabilized. The risk of only doing one side is that the other side will still absorb and lose moisture causing it to change shape which would then stress the bond with the fibreglass on the outside. I have a 1962 Lakefield runabout built of mahogany plywood that I stripped the outside and fibreglassed the hull about 9 years ago. It has been holding up just fine (although I can't say as much about the engines :-? ). A big difference between a plywood hull and a lapstrake hull is the plywood already gives you dimensional stability.

Are you thinking of glassing individual planks, or applying a sheet of fibreglass and working it into shape around the planks?

Rot on the inside can be prevented either by treating the inside with a clear wood preservative - I'd have to dig into my old Wooden Boat magazines to make sure I suggested the right one, or by varnishing like you are planning.

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 Post subject: Re: Leaky wooden boat
PostPosted: July 17th, 2009, 8:27 am 
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The first fiberglass job was botched pretty badly, and I think that is because he worked too fast. I was thinking of using strips the width of a plank and a joint, and putting them on one at a time. This would allow me enough time to work the edge right into the corners (the last guy just draped it over, which made for voids, and didn't wet-out the cloth, so it allowed water in).

I am leaning more and more towards fiberglass, especially as this pine s not a very hard wood, and any bump will likely break through a paint or varnish layer.

I can't tell you two how helpful you have been. Many thanks, yet again.


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 Post subject: Re: Leaky wooden boat
PostPosted: July 17th, 2009, 8:31 am 
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Joined: March 10th, 2007, 1:44 pm
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Location: Mississauga ON
Splake wrote:
I haven't actually used the 3M 5200, so first recommendation would be to read the directions. Probably double check with the supplier that it's the right choice for the job too. I would expect that applying it directly against the clean wood would be the best choice, but that takes me back to 'read the directions'. :)


5200 is an adhesive as well as a sealant - and a fairly permanent one.
It is designed for below the waterline use and is very messy stuff to work with, but one of the best. I have found it very tacky and messy - given that it sticks to everything be careful of it spreading, the first time I used it I was a mess, the work area was a mess and cleanup took longer than the job! :)

If it has to be removed there is a fairly new remover, I believe it is called antibond which does work.


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 Post subject: Re: Leaky wooden boat
PostPosted: July 17th, 2009, 8:39 am 
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If you plan to add some material then an option to 5200 or Sikaflex (which is easier to work than the 3M) would be to make your own filler from epoxy and wood flour to fill any voids that may exist before you add the cloth material.

It wouldn,t be necessary for that filler to cure completely before doing your glass work as it would bond with the epoxy-cloth layer and if you were using a light weight cloth for protection you wouldn,t add much weight to the boat.

I have the plans for that boat gathering dust somewhere. Seeing your pic,s has got me thinking about them again....... :wink:


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