Sealing plywood chine interface

[Carl Schaefer]

After removing 50 years of paint from the bottom of my Penguin dinghy, I noticed that the plywood seam at the chine has a gap that will need to be filled. I intend to paint the bottom and topsides using a one part poly, most likely Interlux Brightsides or Toplac. I am going to fill and fair the bottom and topsides with a surfacing putty, also made by Interlux. However, I'm curious how best to seal the seam at the chine - I imagine that it will flex somewhat and provide the potential for the working ply to create a crack in the paint. How should I seal this? I've been considering epoxy with an adhesive structural filler (West with 404 filler). I've also been looking at Interlux Watertite or Interfill.

Any recommendations would be greatly appreciated.

BTW, I originally had thought of using fiberglass tape to reinforce and seal this joint but many have recommended against this.

[ 01-15-2005, 08:16 PM: Message edited by: Carl Schaefer ]

[JimJ]

Carl

My Hartley TS18 has a strip of woven glass in epoxy(?) extending above and below the joint about 3". The hull/transom joint is done in the same fashion

[Carl Schaefer]

Originally posted by JimJ:
Carl

My Hartley TS18 has a strip of woven glass in epoxy(?) extending above and below the joint about 3". The hull/transom joint is done in the same fashionJim, this is cloth, not fiberglass tape? What weight glass did you use? One of the comments I received from someone on this forum was that reinforcing this chine joint would substantially increase weight on a racing dinghy where weight is a premium. The boat is 11.5' long and 4' wide and weight is a premium for this class. Having said that, I think you may be right about reinforcing this area with fiberglass.

[Carl Schaefer]

Here is the chine joint gap I'm interested in closing (note that I haven't stripped the paint on the topsides yet):

http://www.futurelinkinc.com/sailing/penguin/chinegap.JPG

And here is the centerboard trunk at the bottom of the boat that I really do believe needs to be fiberglassed at the 1/4" ply gap just inside the trunk.

http://www.futurelinkinc.com/sailing/penguin/011605_D.JPG
Given that I hope to race this boat and weight is at a premium, should I tape the seams?

[ 01-16-2005, 10:48 AM: Message edited by: Carl Schaefer ]

[Stiletto]

Tape the seams and go on a diet. :D

[Chris Stewart]

Originally posted by Stiletto:
Tape the seams and go on a diet. :D Reminds me of when I was in a glider club in college. Some guy who had to be 40 pounds overweight was drilling holes in an aluminum fitting to save an ounce or two.

[Nick C]

I don't get it, what's the problem? Just mix up some epoxy, such as West System, then mix in some silica and microspheres to make a filler. Now you have a strong bonding compound that is also a filler. Use a plastic spatula and push the mix into the crach and then wipe over the crack to level it. The next day it will be dry and you sand it.

If color is a problem then darken the mix with some dye. In the end you will have a strengthened joint and plugged the crack.

As for weight, I've raced sailboats and understand weight considerations. The biggest factor is the crew and the skipper (if you have a crew). To win in light air you need to be at the minimum weight. I wouldn't worry about a pound or two on the boat.

New sails are more important than ten pounds on your boat. New sails took me from the front third of the pack to a bunch of first places.

[JimJ]

Carl

The boat was 24 years old when I bought it so I cannot comment on what weight of cloth was used. By the looks of it, I would say that it is glass cloth rather than tape.

[Carl Schaefer]

Originally posted by Nick C:
I don't get it, what's the problem? Just mix up some epoxy, such as West System, then mix in some silica and microspheres to make a filler. Now you have a strong bonding compound that is also a filler. I was only concerned that a filler would crack over time as the hull flexed, letting water in. I would really like to use epoxy and an adhesive filler -- think it will hold up? I assume this is a high stress area.

[Bob Smalser]

Sure don't look like plywood to me, fellas.

Unless the plywood (not so common 50 years ago) was made from q-sawn, old-growth Longleaf Pine or Doug Fir with butted seams instead of rotary cut.

If it were a solid false bottom applied to plywood, it would be proud of and not flush to the sides.

Let's take a harder look at the boat and be sure before wrecking it with fabric and goo if my suspicions are correct.

If single-planked solid wood, I don't see anything that won't close once it wets out, although before doing anything at all, I'd want to know exactly how the boat was made.

[ 01-17-2005, 09:48 PM: Message edited by: Bob Smalser ]

[Mike Vogdes]

I suppose the side planking is plywood, but I'm with Bob, I would repair this in kind with a properly reafed and prepared joint, caulking (corkin) and paint (Kirby's).

Once you slop some epoxy on this 50 year old girl your immenent bottom planking job will be difficult at best, perhaps plan b would be better.

[Carl Schaefer]

It's interesting that you guys noticed the difference in wood on the bottom of the boat. I can categorically say that the sides of the boat are 1/4" ply. The bottom is another story. As I was sanding down the inside and outside of the bottom, I noticed the planking you guys picked up on and that the planks seem to be held together with bronze or brass staples. The wood is 1/4" thick. They are very small, not evenly spaced, and the boards are butted up against one another. I suspect, but don't know, that perhaps the whole bottom was butted, stapled together, then draped over the bottom frames, fastened in place, then the joints filled and faired. I don't know this for sure. BTW, the building instructions call out 1/4" ply (Douglas Fir) for the bottom. This boat is a 1955 Wright Penguin built in Philadelphia and owned by several owners on Gibson Island, Baltimore, and the Eastern Shore before I picked her up.

[Bob Smalser]

If you're sure the bottom planking in your pics isn't a false bottom overlaid onto quarter-inch ply, then the absolute last thing you want to do it is either glue it together or stuff hard epoxy in between those planks. They need the flexibility to move seasonally that their fasteners alone provide and pure q-sawn wood like yours splits real easily....especially old, dry, brittle, q-sawn wood.

I take it the boat didn't leak the last season you used it? If not, then I don't see anything abnormal in a solid bottom that's been out of the water long enough to dry out.

Quarter-inch is a bit thin for a solid bottom, so I'd be thorough in my examination...quarter-inch double-planked and butted with white lead between would be more to my liking if I were the builder in 1955.

I'm guessing you are correct they are butted, and perhaps even driven planks (see any of them in the middle that are tapered?) as quarter-inch is also a bit thin for a planking seam, and I don't see any evidence of cotton in the joints. Check on both sides of the planking to make sure, using a knife blade gently from the underside only to see if you can pull out any old cotton.

If there is old cotton in between, I'd gently reef it out where I could using the knife blade, and roll in new cotton wicking firmly with a caulking wheel (or pizza cutter in a pinch) followed by red lead or copper bottom paint to saturate followed by soft seam compound. No caulking irons and no pounding.

If no cotton, then just the poison primer and seam compound followed by paint and throw it in the water to take up.

I'd also get some red lead or copper paint followed by seam compound in those fastener holes while I was at it.

[ 01-18-2005, 02:41 PM: Message edited by: Bob Smalser ]

[Bob Smalser]

I got my hunches to this construction being the Chris Craft era lamination. Here's where I shut up and listen to Mike.

[Gary E]

When I was a Sea Scout in the late 50's we had 2 of these boats. We never did a thing to them other than use typical "out of the caulking gun" stuff in those seams, then paint.

About the last thing I would sugest is fiberglass or tape or anything else. That boat has lived this long on whut it has been fed, dont change it's diet now.

Someone said copper bottom paint.. NO way if your gona race it or if you gona store it on dry land when your not init racing or just sailing .. Enamel paint, period.

[ 01-18-2005, 05:32 PM: Message edited by: Gary E ]

[Lulworth]

Carl,

Now I am confused (nothing new). The darn bottom should be plywood but that stuff looks like my red-cedar transom (which is solid).

Aside: In fact, Rhodes (the designer) gets credit for having the first (or is it one of?) the first intentional designed-in compound curves on a plywood boat. Note that the aft section adjacent to and forward of the skeg has two radii of curvature. Tortured-ply has come a long way but it is claimed to have started with the Penguin (don't ask me to prove it, an old(er) guy told me this and he's dead!)

Assuming that your bottom is some kind of funky plywood meant to be faux plank-on-frame then fill with epoxy and microballoons or whatever and fair. I would repeat my earlier suggestion to remove the bottom screws along a section (let's say 2 ft or so) of the chine and see how tight the glue at the bottom/chine log interface is. Chances are it's long gone and you would want to reglue. In my case, the bottom ply overlaps the chine but in your case, the sides overlap the bottom making the process a bit more complicated. First remove all the screws then gently pry the bottom away from the chine log from the inside by sliding a putty knife along the bottom. If I were doing a full-on refinish job, I'd make darn sure the bottom is glued on! If it isn't, it'll leak but most of these boats leak a bit.

Cheers,

David

[Gary E]

Mike,
You asked.. do you remember if any of the planks has any light through them at anytime? Not that I remember, we just kept some sorta compound in the seams, we never used so much as a power sander on the boats, teenage kids ya know, lots of elbow grease, and wet samded the bottoms, then a coat of some enamel, as the boats were stored out of the water at the lake.

Maybe it's just old fashioned me from the school of if it aint completly broke, dont fark withit. And because it's a 50+ yr old boat, why screwit up with so called new and improved goop that may or may not help matters.

Eddit..
I want to add that I have again taken a good look at the photo's and see nothing out of the ordinary, prime with several coats, caulk with whatever but NO epoxy, and paint with several coats of enamel wet sanded tween coats.

Dunk in the water and go.

[ 01-18-2005, 07:20 PM: Message edited by: Gary E ]

[Bob Smalser]

Originally posted by MIke:

Bob, I came into this thread a little late, but hope I didn;t come across to bold in my initial post. This was not my intent. Okay Cleek, Fleming, whats the word from ya'lls corner?No no no....I meant it as a compliment...I'm happy to listen and learn.

I don't know squat about storebought boats.

[Bob Smalser]

I see the lines all right, but did manufacturers like Lyman simply double plank with putty between like I might out inthe barn or cold/hot mold using resorcinol or even urea?

I could envision making up batches of bottoms on a press with the fasteners just to hold it together until the press operation was complete.

[paul oman]

Use a flexible thickened epoxy or a few coats of a rubber co-polymer sealer/paint. These type of products will handle more flex than your wood and are more waterproof than the wood. If bond strength is an issue or concern, coat first with a solvent thinned epoxy which will penetrate a bit and provide a stout bonding surface.

Either way - a simple fix that will have you back in the water really fast!

paul oman
progressive epoxy polymers
www.epoxyproducts.com/marine.html (http://www.epoxyproducts.com/marine.html)

[Carl Schaefer]

wow! lots of great advice.

To answer a few questions, here are a few pix:

http://www.futurelinkinc.com/sailing/penguin/Pen3a.JPG

http://www.futurelinkinc.com/sailing/penguin/Pen9a.JPG

http://www.futurelinkinc.com/sailing/penguin/Pen9.JPG

Notice the individual planks are visible in the photo with the unsanded interior. There is not cotton between planks. They are butted up against each other and the joints are absolutely perfect -- no daylight between them.

The 1/4" bottom is thin (could be cedar), that's why there is another 1/4" ply floor that sits on top of the bottom frames (see photo). One of the photos shows the boat sanded on the port inside with the starboard inside still not sanded. Since then, I've sanded the inside completely, stripped the paint from the bottom (as you all have seen) and stripped the paint from the starboard side. Still need to strip the port side, then I'm ready to begin filling and fairing the fastener holes, seams, and blemishes. Thought I'd use a sanding sealer coat, followed by primer, then Brightsides one part poly paint.

I'm still unsure what to do about the side seam -- some want me to leave it alone, others want to fill and fair with epoxy, others want to fiberglass tape it, others want to use a sealant (I assume like 3M 5200). Lot's of choices!

I've only had the boat two months or so. I have not had it in the water. I bought it as a charity case really and want to restore it to the point where I can sail it and race it casually (in Fleet 1 on the Potomac). Don't think this boat will ever be competitive at the regional or national level. Just want to have a boat that doesn't sink and looks pretty.