Alternative to fiberglass for a Caledonia Yawl

[montero]

It's interesting how epoxy with random fabrics can behave.
The questions are , what kind of epoxy? Any textile preparation? Lamination method?
There seem to be an infinite number of combinations available these days.

I wasn't going to mention the devil's name starting with an A in this thread, but I posted the link in Portuguese.
Moving on, what would they use to make this "wooden boat": in the Amazon...

 

[wet feet]

My suggestions may have seemed surprising but your friend's selection of birch ply will cause him some difficulties.To begin with,laminating any sort of cloth around the lands of a clinker hull is very difficult to do well and he might like to experiment by trying a small test piece,say 250mm long and simply two or three pieces of the ply overlapping.Even with a good radius on the edges it will be far from easy and I would predict voids in every internal corner and quite likely on the external corners too.For a boat which is intended to be handled with extreme care at all times and never left on a stony beach it might be possible to use 2 pack paint but that is pretty obnoxious stuff and some suppliers will only sell to known trade customers.
I suggested traditional paints because the oil in them may have some penetrating capability and it won't be setting solid in a mater of minutes.The traditional Deks-Olje parts one and two might have a better chance than most other solutions.Accompanied by the type of antifouling that never sets hard,he might get a few years use of the boat he is laboriously building to a very pretty design.

 

[laukejas]

My suggestions may have seemed surprising but your friend's selection of birch ply will cause him some difficulties.To begin with,laminating any sort of cloth around the lands of a clinker hull is very difficult to do well and he might like to experiment by trying a small test piece,say 250mm long and simply two or three pieces of the ply overlapping.Even with a good radius on the edges it will be far from easy and I would predict voids in every internal corner and quite likely on the external corners too.For a boat which is intended to be handled with extreme care at all times and never left on a stony beach it might be possible to use 2 pack paint but that is pretty obnoxious stuff and some suppliers will only sell to known trade customers.
I suggested traditional paints because the oil in them may have some penetrating capability and it won't be setting solid in a mater of minutes.The traditional Deks-Olje parts one and two might have a better chance than most other solutions.Accompanied by the type of antifouling that never sets hard,he might get a few years use of the boat he is laboriously building to a very pretty design.

Okay, I am confused now - so what is the indented way to build these plywood clinker boats if the goal is to handle them as any other boat (normal amount of abuse) and have them last decades instead of a few years, then..? I see that glassing is discouraged, and the alternative you suggested - well, you yourself said that method would only get a few years out of that boat. As for birch plywood, that is literally the only choice we have here in Lithuania. There used to be exactly one company that could get Okoume plywood, but they no longer ship it because there is no market for it. Some old listings still remain on the internet, but they are all dead last time I checked (few months ago). There is nothing else except birch here.

 

[wet feet]

The way to get a boat that has a life of more than a few years is to use genuine marine ply.The original BS1088 called for such ply to be made from a durable type of wood and there are lists of species that conform.There is a different category known as 1088-gaboon for those batches known as gaboon (Americans call it occoume) which is held together with the same type of glue but made of a non-durable timber,for lighter construction.Birch is even less durable.I have witnessed birch plywood with a single coat of sealer develop blue mould spots after a few weeks storage in a shed with one open wall,and without getting wet.I believe the lobster boat builders of Nova Scotia or thereabouts on the Canadian Atlantic seaboard used some birch in their boats,as it was available to them and lasted tolerably well in their home waters.I don't believe they used epoxy.Your friend may have to use the same approach.He ought to get a few years use of the boat but his grandchildren-if he ever has any-won't be fighting over who inherits a sound boat.No point pretending otherwise.He and you are quite free to follow my suggestion of laminating any cloth of your choice over a small test piece to see how it goes.

 

[montero]

I watched a few videos about garage floors.

Here's the idea:

Priming the first layer of plywood can be done with isocyanate, as Rumars wrote, but that's a bit of an overkill.

I think priming with a thin, thinned, pure epoxy is the way to go.

After curing, apply a slow-setting, professional, non-water-based floor epoxy.

They're dropping some kind of flakes in garages. We need to come up with a good "flakes" for this boat. We need to figure out what.

Sand the "flakes" a bit and paint with a polyaspartic topcoat.

 

[montero]

Aromatic Polyurea, PU Top Coat, Sports Track And Field - CENTURY UNION

Bendrovės pirmtakė yra „Shandong Shangran Construction Engineering Co., LTD.“, įkurta 2009 m. gegužės mėn., o „Century Union“ – 2014 m. liepos mėn.

www.scupolymer.com

 

[laukejas]

The way to get a boat that has a life of more than a few years is to use genuine marine ply.The original BS1088 called for such ply to be made from a durable type of wood and there are lists of species that conform.There is a different category known as 1088-gaboon for those batches known as gaboon (Americans call it occoume) which is held together with the same type of glue but made of a non-durable timber,for lighter construction.Birch is even less durable.I have witnessed birch plywood with a single coat of sealer develop blue mould spots after a few weeks storage in a shed with one open wall,and without getting wet.I believe the lobster boat builders of Nova Scotia or thereabouts on the Canadian Atlantic seaboard used some birch in their boats,as it was available to them and lasted tolerably well in their home waters.I don't believe they used epoxy.Your friend may have to use the same approach.He ought to get a few years use of the boat but his grandchildren-if he ever has any-won't be fighting over who inherits a sound boat.No point pretending otherwise.He and you are quite free to follow my suggestion of laminating any cloth of your choice over a small test piece to see how it goes.

I see, thank you for the advice. The goal is to have the grandchildren fight over this boat, though. I understand that marine plywood is the right material to use with that goal, but like I said, it is simply not available anymore in our country. When it was available, I built one boat with BS1088, it had to be shipped from France by a single company in the entire Lithuania that offered such an option, and that plywood cost 6x the price of birch plywood, about $500 per 1/4" sheet. And unfortunately even this option is no longer available, unless you want to make a drive to France (closest option AFAIK) to buy it there.

That being said, I built 3 boats using this birch plywood; one was not glassed and indeed it developed the mould, cracks, splits and rot. The other two I did glass, and both of them are doing great so far (sailed every season, with moderately rough abuse), one is 7 years old, the other one is 2, no issues so far as I can tell. Of course I did not cut them open to check the state of that ply.

I will advice my friend to make samples like you suggested.

I watched a few videos about garage floors.

Here's the idea:

Priming the first layer of plywood can be done with isocyanate, as Rumars wrote, but that's a bit of an overkill.

I think priming with a thin, thinned, pure epoxy is the way to go.

After curing, apply a slow-setting, professional, non-water-based floor epoxy.

They're dropping some kind of flakes in garages. We need to come up with a good "flakes" for this boat. We need to figure out what.

Sand the "flakes" a bit and paint with a polyaspartic topcoat.

We will test this too, thank you as well!

 

[Skip Johnson]

It's a nice looking build. I second what @Rumars has said with some emphasis on filleting the laps. It's a bit more work but it is possible to do fiberglass/epoxy work with virtually no sanding. In this case probably glassing each plank separately with well filleted laps, Cut the glass on a bias +/-45 degrees, it will conform better and avoid the messy straggles trying to cut fiberglass parallel to the weave. Use peel ply !

 

[laukejas]

It's a nice looking build. I second what @Rumars has said with some emphasis on filleting the laps. It's a bit more work but it is possible to do fiberglass/epoxy work with virtually no sanding. In this case probably glassing each plank separately with well filleted laps, Cut the glass on a bias +/-45 degrees, it will conform better and avoid the messy straggles trying to cut fiberglass parallel to the weave. Use peel ply !

Okay, thank you! I got a question on that 45° angle, though: the typical fiberglass rolls are 1.5m I think, so cutting it on a bias means each plank will have to be done with multiple short segments of the glass, overlapping - and that would mean more smoothing and sanding afterwards, right?

As for peel ply, yeah, I would do it myself it were my boat, but this guy is super eco-friendly, no way I'll convince him to use a ton of non degradable fabric that will get tossed away afterwards. Up until this moment he built this boat without disposing as much as a single plastic glove, I have no idea how, but he did.

 

[Skip Johnson]

Okay, thank you! I got a question on that 45° angle, though: the typical fiberglass rolls are 1.5m I think, so cutting it on a bias means each plank will have to be done with multiple short segments of the glass, overlapping - and that would mean more smoothing and sanding afterwards, right?

As for peel ply, yeah, I would do it myself it were my boat, but this guy is super eco-friendly, no way I'll convince him to use a ton of non degradable fabric that will get tossed away afterwards. Up until this moment he built this boat without disposing as much as a single plastic glove, I have no idea how, but he did.

I admire your friends convictions even though I don't have them other than a mighty oath to never use eps again.

Yes it would require several strips of glass per plank. The most expedient reasonably eco friendly approach that I can think of would be to apply the strips via wetting them out on a sheet of plastic (theoretically reusable) . Such an approach would leave you with a fairly smooth surface without hard ridges to sand but would require more fairing than using peel ply.

 

[gonzo]

Fiberglassing over the laps after making transition fillets will make the boat look lumpy.

 

[wet feet]

The builder of the boat will be disposing of a great deal of sandpaper,whichever approach he adopts and will have to live with the fact.If he radiuses the lands and includes a fillet at the root,it will look little different to the faux lapstrake GRP boats that are widely available,but there will be lots of sanding.

One further suggestion,when doing tests with various schemes for covering the boat be sure to try applying oil to a sample to compare penetration to those substances that cure in a few hours and thus can only penetrate for that time span.

 

[laukejas]

Fiberglassing over the laps after making transition fillets will make the boat look lumpy.

Well what is the alternative? Not glassing the boat means that with this plywood it will only last a few years before it starts to develop mold and rot. Like I said, I had the same issue with my own boat that I didn't glass. No matter how much I tried to keep her dry, clean and warm when out of the water, the issue was unstoppable.

The builder of the boat will be disposing of a great deal of sandpaper,whichever approach he adopts and will have to live with the fact.If he radiuses the lands and includes a fillet at the root,it will look little different to the faux lapstrake GRP boats that are widely available,but there will be lots of sanding.

One further suggestion,when doing tests with various schemes for covering the boat be sure to try applying oil to a sample to compare penetration to those substances that cure in a few hours and thus can only penetrate for that time span.

Yeah, sanding is unavoidable, we both know that. And it's okay. Not fun, but unavoidable. As for the penetration test, we will to do it as well. Problem is evaluating the result - since the goal is longevity, it would be difficult to test how these samples would fare after a few decades, when we only have weeks.

 

[gonzo]

Well what is the alternative? Not glassing the boat means that with this plywood it will only last a few years before it starts to develop mold and rot. Like I said, I had the same issue with my own boat that I didn't glass. No matter how much I tried to keep her dry, clean and warm when out of the water, the issue was unstoppable.

I am not sure what you coated your boat with, so it is difficult to say why it failed. However, plywood of medium quality (non marine) is used in construction of many structures continuously open to the weather. With common water based coatings they last decades. For example, the siding on a house. The expected longevity of anything is something that has to be accounted for in the original design and choice of materials. If this was intended to be a heirloom that lived outside and lasted for several generations, cheap plywood was a poor choice. Further, fiberglassing it would make a beautiful boat ugly, which would likely not be appealing to the next generations.

 

[laukejas]

I am not sure what you coated your boat with, so it is difficult to say why it failed. However, plywood of medium quality (non marine) is used in construction of many structures continuously open to the weather. With common water based coatings they last decades. For example, the siding on a house. The expected longevity of anything is something that has to be accounted for in the original design and choice of materials. If this was intended to be a heirloom that lived outside and lasted for several generations, cheap plywood was a poor choice. Further, fiberglassing it would make a beautiful boat ugly, which would likely not be appealing to the next generations.

Well, like I said, my friend wasn't cheaping out, it was simply the only plywood available here... As for that my boat that failed, it used the exact same plywood, with 3-4 coats of laminating epoxy, followed by 3 coats of polurethane alkyd enamel paint. The paint held up great, but the plywood rotted. I used water based paint on another boat (which was glassed), and that paint chipped away very easily during the years, requiring repainting every 2 years. Perhaps it just wasn't the quality kind.

As for fiberglassing, why would it turn the boat ugly? Every time I glassed my hulls, the fiberglass would become completely transparent when wetted out. Granted, I painted all of my boats, but that's more because I was not good enough with my woodworking skills and the defects would show up too much if varnished. But I don't recall fiberglass making it any worse..