Anonymous wrote:

Here some more info on the use of biocoat 3.3

you'll have to scroll down the page to get to the topic.

Hi Jan. The blogpost on the H28 is what got me started. All the boxes seemed to tick off. But I wanted something a bit bigger. So. Hurray for the internet. 

I don’t  know why bionic technology have nothing the 3.3 on their site. I’ve been corresponding with Peter Hoefnagels of the yacht “Ya” (dries out at low tides) and he’s very happy. 

Rudolf, I’ve sent you a mail with the data sheets. 

Looking very good Frederik.

I can't find info on the nanocoat you mention, could you give a link please?

Rudolf

Don't forget the 2-pot polyurethane (PU) paint.

I’ve found 2-pot polyurethane paint or varnish to be very good. It appears to stick to anything from old topcoat, bare grp, glass-in-epoxy, and bare wood, and even bare aluminium.
I painted the deck and topsides on Malena (1990-91) and the hull stayed clean and shiny without the normal need for scrubbing and polishing. The paint crept into any crack or void  -  I actually painted  the deck of Malena watertight.

The second (wooden) mast of Malena was first covered in West epoxy and then given 6--7(?) coats of West’s own polyurethane, clear varnish. After about 13-14 years, one could see that the sunny side of the mast was starting to delaminate. I think the varnish was still ok, but it had let through enough UV rays to kill the epoxy.
Therefore, when finishing Johanna’s mast after the same glass-epoxy sheathing, I used a white paint version of  2-pot PU-paint (not from West).
Broremann’s wooden mast and the wooden top mast sections of Frøken Sørensen and Ingeborg were painted in either clear or white 2-pot PU, with no glass or epoxy involved (except in the metal-wood joints). Ingeborg first got five coats of clear varnish and then three coats of white. Upon inspection of the top mast this summer, I found this coating (5 years old) to be like new.

An experiment: We found a piece of plywood and glassed half of a strip of glass tape to it, using PU paint as resin. The paint sucked in and bonded perfectly well to the plywood.
Conclusion: If I ever am to do a small glass sheathing job, I will use PU as resin. It sticks like glue (it is glue), it is tough without getting brittle, and it resists UV very well.

Arne

Anonymous wrote:

Yes, some interesting thoughts there re epoxy/polyester. I have to say that I had some doubts about the polyester-based cladding of the hull, but now I understand that it's a solid outer shell on the hull, I'm pretty impressed with the system! Also, the way Frederik's done it, with the bronze nails giving a thorough mechanical bond to the ply is rock solid!

On the other hand, in a 60 year old FG power boat with 50mm plywood transom, there has been no delamination even though the plywood has been wet. So there is a way of doing things that does work. I have read that the way to do things is to do at least one coat on the plywood with no hardener. Perhaps even thinned a bit for penetration. Of course, I think in the 60s, the resin was used without hardener and the mold was heated to cure the resin. However, there are parts of the boat where it does not seem the FG (frp?) could have been done in the mold, like the rear deck, that are also fg on plywood and these have no delamination either.

I would point out that the stories of delamination I have seen floating around have for the most part, been DIY projects. I would guess that part of the problem has also been too few workers trying to clad too large a surface with rapidly hardening resin that has no way of penetrating the plywood before it is already hard. Contrast this to commercial production where the hardener is added as part of the spray system just in time for it to come out of the nozzle (see the youtube channel "on the hulls" for some explanation of spraying resin on to the mold). Epoxy with slow hardener is probably easier for the DYI project with limited equipment and people, if more expensive but frp, done right, is not out of the question.