Plywood hulls in the tropics, real live experiences?

[Franziska]

Hi,

I know there are a lot of DIY plywood boats built with epoxy and fiber reinforcements cruising down south.
Ours, will eventually be one of them.

If everything is well encapsulated in epoxy, fiberglass and paint all is well.

Still, I'd like to hear from some folks around cruising the tropical climates.
What are your experiences with mold, torredos, funghy and similar.
How do you keep on top of maintenance.

Would you recommend sanding the whole underwater thoroughly and adding an extra layer of biaxial & epoxy on an older boat before heading down south?

It will be interesting to hear if your experiences, good, as well as bad ones :-)

Thanks for sharing.

[s/v Jedi]

Not first hand but met countless over the years in the Caribbean. Plenty who had problems with rot but all of that caused by rain, not the sea.

If the fiberglass outside skin is not there or damaged then adding a layer is wise. Otherwise, a good barrier coat with new anti fouling is great.

But I recommend to put effort against fresh water damage, i.e. possible leaks around fasteners, leaking hatches etc.

[Chotu]

Originally Posted by s/v Jedi

Not first hand but met countless over the years in the Caribbean. Plenty who had problems with rot but all of that caused by rain, not the sea.

If the fiberglass outside skin is not there or damaged then adding a layer is wise. Otherwise, a good barrier coat with new anti fouling is great.

But I recommend to put effort against fresh water damage, i.e. possible leaks around fasteners, leaking hatches etc.

Exactly what I was going to add, but hesitated because it’s all second hand experience.

I’ve seen lots of rot on plywood/epoxy boats. All of it from fresh water. Remember, salt water isn’t what rots wood. It’s fresh water, in the form of rain and leaks around the ports and hardware.

The boring animals are not a threat when you have an epoxy coating. Even less so with some fiberglass in the mix. So the original construction of a quality Woods catamaran is more than enough to keep the borers out.

Mold is a real concern, but it’s going to be in your shoes, provisions, bedding. Keep the airflow up to slow that down.

[Copacabana]

Franziska, I can't speak from experience, but there are a lot of epoxy-plywood boats in Brazil. The designer Roberto Barros ("Cabinho") designed a number of boats for amateur construction and his 28-foot epoxy-ply multichine was (is) very popular, allowing the middle class to get out cruising. These boats are holding up very well. I'm not sure there are any special precautions in tropical waters. If everything is sealed up with epoxy, the temperature shouldn't matter.

[Franziska]

Good, one biggie of the list than we will do a thorough refit next year and focus on the superstructure and hardware.
I know about the constant battle on a wooden boat.

Glad we may only need new antifouling. The hulls are already glassed from the outside :-)

[Paul Howard]

I own, for four years now, a 38ft. catamaran with cedar/epoxy/fiberglass hulls and plywood topsides and decks that I bought in Florida and sailed to Cuba and Bahamas. The boat had been in Florida and the Caribbean for about nine years.
The topsides above the cedar/epoxy is a high grade marine plywood, some kind of mahogany, and has had no problems.
The decks are marine grade fir plywood that had not been covered with fiberglass when originally built.
The decks were epoxy coated and well primed and painted a light off-white colour. When I bought the boat there were many high moisture spots on the decks where the plywood had weather checked, then water got in and the plywood layers started to rot and delaminate in the hot and humid conditions. I marked each of the weather checks and high moisture spots, ground/sanded back to solid wood, sometimes through a couple laminates, then dried, epoxy treated and fiberglassed over, faired, primed and painted. The first year I did this it was a big job. Now, in the Great Lakes, there are still a few weather checks that appear every year that are small and easily given the above treatment. Also watch for any places where there sharp corners that are fiberglassed over, like deck edges or bows. A small crack can lead to water intrusion, swelling of the wood, further cracking and rot.
I contacted West Systems help line, stating keeping the deck solid was like playing wack-a-mole keeping ahead of the small spots. They said I was doing the right method. The only alternative to spot patching would be to sand the whole deck back to sound wood, then epoxy and fiberglass. Given the large deck area, the amount of hardware and hatches, this would be a bigger job than I am ready to tackle.
The boat was professionally built and was launched in 1997.

[s/v Jedi]

Originally Posted by Paul Howard

I own, for four years now, a 38ft. catamaran with cedar/epoxy/fiberglass hulls and plywood topsides and decks that I bought in Florida and sailed to Cuba and Bahamas. The boat had been in Florida and the Caribbean for about nine years.
The topsides above the cedar/epoxy is a high grade marine plywood, some kind of mahogany, and has had no problems.
The decks are marine grade fir plywood that had not been covered with fiberglass when originally built.
The decks were epoxy coated and well primed and painted a light off-white colour. When I bought the boat there were many high moisture spots on the decks where the plywood had weather checked, then water got in and the plywood layers started to rot and delaminate in the hot and humid conditions. I marked each of the weather checks and high moisture spots, ground/sanded back to solid wood, sometimes through a couple laminates, then dried, epoxy treated and fiberglassed over, faired, primed and painted. The first year I did this it was a big job. Now, in the Great Lakes, there are still a few weather checks that appear every year that are small and easily given the above treatment. Also watch for any places where there sharp corners that are fiberglassed over, like deck edges or bows. A small crack can lead to water intrusion, swelling of the wood, further cracking and rot.
I contacted West Systems help line, stating keeping the deck solid was like playing wack-a-mole keeping ahead of the small spots. They said I was doing the right method. The only alternative to spot patching would be to sand the whole deck back to sound wood, then epoxy and fiberglass. Given the large deck area, the amount of hardware and hatches, this would be a bigger job than I am ready to tackle.
The boat was professionally built and was launched in 1997.

Yes, but you can do a full deck fiberglass job in sections

[Door Sail]

I am in the middle of the 30 year refit on the 36' sharpie schooner that I designed and built, and have found zero structural issues, if fact no evidence of water intrusion anywhere. We did spend most of the first decade in salt water with several winters in the Florida keys and the Bahamas, but I suspect that the freeze/thaw cycles are actually more challenging for it.


I was fastidious about sealing any checks in the deck fiberglass, and always kept a winter cover on her.

[barnakiel]

Met very many plywood / epoxy boats in the tropics. It is a very very popular material to use in French boats.



They split into two types of stories:


- happy stories (about 90%),
- unhappy ones (the reminder).


I believe the dividing line runs along build quality + maintenance mantra = "good design, good materials/build + regular maintenance makes a happy and safe boat".


Humidity and heat of the tropics will accelerate any critical issues (e.g. wet core).



If your boat is sound and has no quality issues, there is zero zilch nil reason for concern.


b.

[Cadence]

I bought a SR31 from a couple that had done 12 yrs. sailing it the tropics. Not a sign of problems with the plywood. Glassed on the outside painted on the inside. Apparently he did not allow any fresh water intrusion on deck.

[barnakiel]

PS I would add a layer of epoxy / glass only if the existing outmost layer looks aged. If the outer layer looks good, I would strip all old AF paint, add two coats of primer epoxy wet on tack-wet and then slap first AF coat on this 2-coat tack-wet epoxy primer. Add more AF paint as dictated by the time to be spent in the water.


If the AF is soft, invest $ in one extra layer of AF paint. Two coats, imho are a bare minimum. 3-4 coats are nice to have if headed for the Caribbean.



I hope to meet you here in Las Palmas or on the other side in the Caribbean when you get going!



Cheers,
barnakiel

[Franziska]

Hi Barnakiel,

thank you and the others for your input.

Yep, that sounds like a good plan. Remove the old AF, check, 2 x Primer and new AF.

We got a huge list of things to do next year, but at last we have no real time pressure. My boyfriend goes into early retirement and I take das3Dstudio with me on the boat.
Though next year I will organize it in a way that the focus can be on the boat project, luckily my clients give me a fair amount of liberty.

Hope to head down towards the south in 2022 at last, providing everyone stays healthy.

Would be great to meet you!

Have a nice evening,

Franziska

Originally Posted by barnakiel

PS I would add a layer of epoxy / glass only if the existing outmost layer looks aged. If the outer layer looks good, I would strip all old AF paint, add two coats of primer epoxy wet on tack-wet and then slap first AF coat on this 2-coat tack-wet epoxy primer. Add more AF paint as dictated by the time to be spent in the water.


If the AF is soft, invest $ in one extra layer of AF paint. Two coats, imho are a bare minimum. 3-4 coats are nice to have if headed for the Caribbean.



I hope to meet you here in Las Palmas or on the other side in the Caribbean when you get going!



Cheers,
barnakiel

[keyway]

I have a plywood boat. It was built in 2001 and has been in the water ever since. Of course not when I haul it to paint etc. I have had some issues with Rot. All which can be traced directly to a steel fastener breaking the integrity of the epoxy. I have gotten rid of all the screws that aren’t necessary. Some such as chain plate fastener are unavoidable. I haul every two years for bottom paint. I have never had any problems below the water line. There are no through hulls or prop shafts. So yes if the boat is sealed up good you really shouldn’t have too much of a problem. Btw I do a lot maintenance as a routine. I generally spend about $2000 usd every haul out on paint and epoxy for a 30 ft catamaran. Got to love it. 🙂. I almost forgot the boat is in Florida

[Fore and Aft]

Franziska the oldest plywood yacht I have surveyed here in Queensland was built in the 1970s and she still looks good. Some of the interior plywood that's been coated with epoxy looks like new! My own yacht is plywood and I have had no issues. It all comes down to build quality, no interior leaks and ventilation.
Cheers

[Franziska]

Thanks guys, we'll be good I guess after your answers, being a trained boat builder I am confident that we can keep her together.

Still having no personal experience with wooden boats in the tropics, I thought I'd rather pick the brains of folks like you.

Thanks so much!