Any issues with this custom catamaran for circumnavigation?

[smj]

Originally Posted by Andrew Grace

What are you talking about , ?



Seawinds are not ply boats,



You seem to not understand English very well

My English are fine.
Read it again, slowly.

[YARGESOL]

Originally Posted by PhiSig1071

Actually there was one for sale not that long ago that someone shared on here. (Tried to find it, but I couldn't). It had been built as a coastal minesweeper, then transferred to the naval academy where it became a training boat, then it was sold into private ownership.

Karelian warf Avangard built 64 units of Yakhont designe minesweepers during the years 1972-2000. One of the latest wasn't accepted by navy and,was offered for sale. Another ship designe BT-435 "Base minesweeper" was built in 1969 and, was on duty at Black Sea Fleet till 1993. Good enough for plywood boat ? -
- Andrew Grace :
"Correct , but how many were sailing 10 years after the war,plywood just doesnt have a very good shelf life or appropriate bonding to fibreglass strength at adjacent angle joins , even with expoxy."
The boat was built of plywood+fiberglass,with wooden beams. Low magnetic steel plates used onlly as foundation for powertraine and arms. Sure,American navy got similar boats.
My cat has a lot of plywood to. I have red ceder+WS epoxy hulls with deck and bulkhead,the bridge (over wooden beams) of the plywood. No problem,if it's coorect type and correct thickness of plywood. If it's not - then it may lead to a problem:
- I experianced a crack in the structural bulkhead linked to the chain plates- just in the middle of Bermuda's Triangle;
- that came with a 35+gust and 4 meter sea;
- 5 crew members dismissed,arriving to Bermuda (each found a reason),only me and chief mate left;
- spent 2 weeks and about 5K on repairing and reinforcing;
- studying the designe drawings I found the problem:
- 10 mm plywood+3 fiber layers designed;
- sandwich of 3+foam+3mm +fiber was used...
Maybe it was a builder mistake due to mm/inches conversions ?
So,custom cat and plywood cat ar OK,but must be checked 3 times.
You can't apply for warranty 500 miles from the shore

[Cadence]

Originally Posted by smj

My English are fine.
Read it again, slowly.

I understood you fine. I've had two ply and glass tris. Both had been transatlantic and were dry as a bone. I wouldn't want a foam core below the deck. JMHO

[smj]

Originally Posted by Cadence

I understood you fine. I've had two ply and glass tris. Both had been transatlantic and were dry as a bone. I wouldn't want a foam core below the deck. JMHO

So, my English are good😁


Sent from my iPhone using Cruisers Sailing Forum

[Cadence]

Originally Posted by smj

So, my English are good😁


Sent from my iPhone using Cruisers Sailing Forum

Yep! Mine are good.

[Cheechako]

Looks nice but it is fiberglass over ply. Many monos of that construction end up "throw away" boats. They are good for years though, but eventually fail due to delam or moisture. That would worry me for that price. Add in that it has outboards (aside from that debate) Having outboards is less value just based on cost even if you set aside the durability part of the subject.
I think most boaters would consider Solid glass, cored glass, epoxy wood system, above ply for desirability.

[smj]

Originally Posted by Cheechako

Looks nice but it is fiberglass over ply. Many monos of that construction end up "throw away" boats. They are good for years though, but eventually fail due to delam or moisture. That would worry me for that price. Add in that it has outboards (aside from that debate) Having outboards is less value just based on cost even if you set aside the durability part of the subject.
I think most boaters would consider Solid glass, cored glass, epoxy wood system, above ply for desirability.

Epoxy/ply is an epoxy wood system. Many old polyester ply boats are in the graveyard, but well built maintained epoxy/ply boats should have many more stress cycles compared to solid glass.

[Cheechako]

Originally Posted by smj

Epoxy/ply is an epoxy wood system. Many old polyester ply boats are in the graveyard, but well built maintained epoxy/ply boats should have many more stress cycles compared to solid glass.

Only if the ply was manufactured with epoxy and saturated.

[smj]

Originally Posted by Cheechako

Only if the ply was manufactured with epoxy and saturated.

Very rare for the glue joints of an epoxy saturated marine plywood to come loose

[Cadence]

Originally Posted by Cheechako

Only if the ply was manufactured with epoxy and saturated.

I'm not sure on that. I thought marine grade plywood was knot free but the bonding agent?

Anyone trying to build by using glass on ply with a polyester resin needs to have their head examined. It can be done for something like bulkheads if the wood is saturated with acetone thinned polyester first. Although West or System 3 is better and cheaper in the long run.

[44'cruisingcat]

Originally Posted by smj

So, my English are good��


Sent from my iPhone using Cruisers Sailing Forum

That's pirate English! Arrr.

[catsketcher]

Ply is not bonded internally with epoxy. Usually phenolic formaldehydes are the glues for the individual veneers.

There would be very few cats -read none- under 25 years old that are not wood epoxy. The Gougeons came out with their system in the 60-70s and when I started building my cat in 1996 everyone was loving epoxy. They had been for years before.

Joins in ply boats can be made as strong as the material either side. These are called 100% joins. Most ply, strip plank boats use layers of something like 600gm double bias over a thing called a cove to join important and loaded parts. This gives a strong and waterproof bond. The epoxy coved glass join is a lovely technique that allows amateurs to produce strong, light and totally waterproof builds.

People who say that ply always rots haven't been on good ply boats. You get around the problems of ply by designing, building and caring for the boat with a ply mindset - reduce screws into the ply, always oversize and epoxy fill any holes, glass any joins you can, coat ALL exterior surfaces with glass and epoxy. All materials have issues - osmosis, delamination, core water absorption. A well built boat must be with careful regard to the materials it is built from. A well built boat isn't made from a certain material, it is made in a method that suits its materials.

I have built boats and boat parts in foam, carbon, vacuum bagged - glass, kevlar and carbon, Duflex, ply, polycore and Nomex honeycomb, choppy and polyester. Which is the best? None, they all were used for a certain application.

As an aside there are some very good reasons for wanting a composite custom build cat - waterproofness. Many of my mono friends have issues with the hull to deck join of their monos. It can drive them crazy. Kankama has two leaks - each is from a plastic hatch that I put in the cabin front that drips onto a ledge in heavy rain (gotta replace them). No leaks anywhere else - dry dusty bilges, beat into tradewinds day after day and dry bedding - dry everywhere inside. No hull to deck join to leak.

Wood epoxy is great.

Phil

[44'cruisingcat]

Originally Posted by catsketcher

There would be very few cats -read none- under 25 years old that are not wood epoxy.

Phil

??? Maybe you mean OVER 25 years old?

[catsketcher]

No - another way of saying it

all the ply cats I have seen built in the last 25 years have been wood epoxy

[44'cruisingcat]

Well yes, modern ply cat's are wood/epoxy.


But what you said before was that every cat' built in the last 25 years was wood/epoxy. I thought you maybe meant every cat over 25 years old was wood/epoxy.


Anyway, the fact that this boat is built of ply doesn't mean you should reject it out of hand. Get a thorough survey done, look into every nook and cranny yourself, tap on surfaces with a coin looking for soft spots.


If it's built and looked after right a ply boat is a good thing.