Fiberglassing over wood

[Jim Cate]

I tremble for the fate of my strip planked/epoxy hulled boat with marine ply bulkheads.

Of course, she's thirty years old now and has covered around 140,000 sea miles. I wonder where the rot and structural failures are hidden...

And Ben, last year Joel White's son, who now runs the family boatbuilding biz gave a presentation at the Wooden Boat Festival in Hobart. While they are using modern composites in some of their builds, they also were doing some rather traditional timber/epoxy hulls as well... and absolutely beautiful their work is in both cases!

I respect your opinions on many things, but this blanket condemnation of timber is just silly IMO, and apparently in the opinion of a few other observers and builders.

Jim

[lateral]

Damn! There goes my complete Kauri re- stripplank and full encapsulation and new deck of epoxy/balsa with West syst. (All balsa penetrations with oversize epoxy annulli)

BTW the resin in some species completely retards polyester so it wont go off.
How do I know? Gluing stringers into surfboard blanks.
Never had a problem with epoxy. Horses for courses.

[boatpoker]

Originally Posted by Jim Cate

I tremble for the fate of my strip planked/epoxy hulled boat with marine ply bulkheads.

Of course, she's thirty years old now and has covered around 140,000 sea miles. I wonder where the rot and structural failures are hidden...

And Ben, last year Joel White's son, who now runs the family boatbuilding biz gave a presentation at the Wooden Boat Festival in Hobart. While they are using modern composites in some of their builds, they also were doing some rather traditional timber/epoxy hulls as well... and absolutely beautiful their work is in both cases!

I respect your opinions on many things, but this blanket condemnation of timber is just silly IMO, and apparently in the opinion of a few other observers and builders.

Jim

Huge difference between properly cold molded epoxy/wood hulls and some resin and glass slapped on an old wooden hull.

[Jim Cate]

Originally Posted by boatpoker

Huge difference between properly cold molded epoxy/wood hulls and some resin and glass slapped on an old wooden hull.

BP, perhaps you missed reading post 23 where he said:

"All of these things are bad practice. Bulkheads should never be plywood, nor should winch pads and deck fittings. In short, there is no excuse in our day to use plywood anywhere in a boat's structure.

That's what I can't agree with... and of course what you say above is true.

Jim

[Wotname]

Originally Posted by Benz

All of these things are bad practice. Bulkheads should never be plywood, nor should winch pads and deck fittings. In short, there is no excuse in our day to use plywood anywhere in a boat's structure. Settee locker lids? sure. Counter top? OK. But never, never in the structure, nor with holes coming through it from outside.

Haha, I guess this boat never got that memo - all plywood construction and still going strong 40+ years later.

https://www.cruisersforum.com/forums...ud-201221.html

[boatpoker]

Originally Posted by Jim Cate

BP, perhaps you missed reading post 23 where he said:

"All of these things are bad practice. Bulkheads should never be plywood, nor should winch pads and deck fittings. In short, there is no excuse in our day to use plywood anywhere in a boat's structure.

That's what I can't agree with... and of course what you say above is true.

Jim

Correct on all counts

[Benz]

Originally Posted by Jim Cate

I tremble for the fate of my strip planked/epoxy hulled boat with marine ply bulkheads.

Of course, she's thirty years old now and has covered around 140,000 sea miles. I wonder where the rot and structural failures are hidden...

And Ben, last year Joel White's son, who now runs the family boatbuilding biz gave a presentation at the Wooden Boat Festival in Hobart. While they are using modern composites in some of their builds, they also were doing some rather traditional timber/epoxy hulls as well... and absolutely beautiful their work is in both cases!

I respect your opinions on many things, but this blanket condemnation of timber is just silly IMO, and apparently in the opinion of a few other observers and builders.

Jim

Your boat may be one of the ones done right--there are some, and I'm happy you found one. However, when it was built (30 years ago), we didn't have the same data, nor did we have the same materials available. There was a time when plank-on-frame timber was the best the world had, and some of the better built of those survive decades later. But given the difficulty of getting it right, and the consequences when it isn't, it seems unwise to me to toss the dice these days when the menu of core materials is so vast.
Look at all the threads on just this forum about water intrusion at chainplates that rotted the bulkhead. Two bad ideas joined to produce a disaster. Look at all the boats condemned because of soggy core. This is not an isolated problem--it's all over the place. That some boats have dodged the bullet doesn't mean it's good and should be done always.

[Benz]

Originally Posted by Wotname

Haha, I guess this boat never got that memo - all plywood construction and still going strong 40+ years later.

https://www.cruisersforum.com/forums...ud-201221.html

The memo hadn't been written yet. It gets a pass

[Chotu]

Originally Posted by Benz

Your boat may be one of the ones done right--there are some, and I'm happy you found one. However, when it was built (30 years ago), we didn't have the same data, nor did we have the same materials available. There was a time when plank-on-frame timber was the best the world had, and some of the better built of those survive decades later. But given the difficulty of getting it right, and the consequences when it isn't, it seems unwise to me to toss the dice these days when the menu of core materials is so vast.
Look at all the threads on just this forum about water intrusion at chainplates that rotted the bulkhead. Two bad ideas joined to produce a disaster. Look at all the boats condemned because of soggy core. This is not an isolated problem--it's all over the place. That some boats have dodged the bullet doesn't mean it's good and should be done always.

I think you hit on the real reason here. You can’t have multiple bad techniques. Chain plates that go through the hull connected to a wooden bulkhead is just a disaster waiting to happen. If you are going to have a wooden bulkhead, you can’t have hull penetrations above it. Or water standing below it. The design also factors in here.

If a bulkhead is not subject to water from above or below, plywood is just fine. And I consider plywood has to be encapsulated in at least three layers of epoxy. Which essentially turns it into a piece of plastic anyway.

While I agree with a lot of your points, there’s just so many boats out there that don’t have a problem. I’m sitting on one right now. 1985 gulfstar sail master 50. Looking at this main bulkhead. Thing is in perfect condition. Has never seen a drop of water. That’s because it was built properly and looked after.

I think each material has its place. There are times to use certain things and times when it’s not as advisable. None of my full beam width bulkheads On my Catamaran are made of plywood. They are subject to more than tension forces because sometimes they are going to feel a twist. They are also outdoors. So no way I want that to be plywood. On the other hand, a J shaped bulkhead within an individual hull that has no deck penetrations above it and no standing water below it, there is no reason at all to have to use plastic. marine plywood encapsulated in three layers of epoxy is fine. It’s simply a piece of plastic at that point.

But guess what? Things can go wrong. And they do. My boat got hit directly by two hurricanes. Not just one. Lucky me. One of the hurricanes blew a window out. Clear off the boat it is gone. This put a large hole above one of the hulls. I was gone from the boat for the better part of the year so it sat with water continuously in it. Rainy season in South Florida. The bilge pump did it’s job, but that doesn’t stop a little bit of puddling.

Guess what happened to my bulkhead? My plywood bulkhead? Absolutely nothing. It was submerged in water for more than half a year without any issue. That’s because it is coated with three layers of epoxy.

Materials are just materials. They have to be used correctly. You can screw up a composite bulkhead just as well. Maybe some dope puts the wrong resin ratio. Then it’s weak. You can screw up wood based construction also. If you do either of them correctly, you have no problems.

[rslifkin]

I'm with Chotu on this one. Choice of materials requires a failure mode analysis. Basically, assume there's some water in the bilge, assume all deck penetrations, windows, etc. have a sealant failure and start to leak, stuff like that. Now with that in mind, what's going to be damaged from that leaking? If something will be, it's time to change materials or protect it better.

[coopec43]

I too am bewildered in regard to chain-plate/bulkhead failure?


My chain-plates are anchored/molded into the fiberglass hull and have nothing to do with the bulkheads

[Wotname]

Originally Posted by coopec43

I too am bewildered in regard to chain-plate/bulkhead failure?


My chain-plates are anchored/molded into the fiberglass hull and have nothing to do with the bulkheads

But many aren't, particularly the cap shroud chainplates. These are sometimes (often?) penetrate the deck and bolted to a bulkhead.

[rslifkin]

Originally Posted by coopec43

I too am bewildered in regard to chain-plate/bulkhead failure?


My chain-plates are anchored/molded into the fiberglass hull and have nothing to do with the bulkheads

That means yours is a good design. Some designs anchor them to a plywood bulkhead, so if you end up with a leak at the chainplate, you get a soggy, rotting bulkhead.

[Jim Cate]

Originally Posted by rslifkin

That means yours is a good design. Some designs anchor them to a plywood bulkhead, so if you end up with a leak at the chainplate, you get a soggy, rotting bulkhead.

IMO, this isn't a design problem nor a material problem. Rather, it is a dereliction of duty on the part of the owner. At the first sign of a leak, the caulking should be renewed, just like any other leak should be repaired. That is what good maintenance is: remediation of defects before any damage is realized.

And the chainplates that are encapsulated in the hull... that you were just lauding... isn't that a great place for unseen crevice corrosion? Like seems to be endemic in Island Packets?

Oh, by the way, our shroud chainplates are indeed through the deck and anchored on plywood based partial bulkheads (more like overgrown knees, actually). When a few drops appeared on one a few years back I immediately renewed the through deck packing and stopped the leak. No soggy, rotting bulkheads here after 30 years of hard usage.

Jim

[Simi 60]

Originally Posted by rslifkin

That means yours is a good design. Some designs anchor them to a plywood bulkhead, so if you end up with a leak at the chainplate, you get a soggy, rotting bulkhead.

I wouldn't do a composite boat with bolt in metal chain plates anymore.
Easy enough to do composite and have zero chance of leaks.

Not that leaks should affect a well made composite boat, all ply and end grain would be well sealed, bolt holes would have been drilled oversized, filled with high density glue and re drilled at the smaller size.