Mattg29 11:02pm, 11 November 2013
The first job I'm hoping to tackle on my new A24 is tidying up the decks, coachroof and cockpit. There is a plethora of screw holes to fill, and one small balsa repair necessary.

If I may, I have a few questions:

1) Received wisdom states that expoy work should wait until warmer weather, but I'm loath to wait until spring before I get filling. I'm considering using polyester resin plus extremely careful preparation instead. Does anyone have any positive or negative experience with the substance to share? I have used it to good effect in the motor world. Does anyone know of a winterised epoxy I could use instead?

2) Can anyone recommend a good source of small quantities of end grain balsa with reasonable postage? By the way, how thick is the balsa on an A24? It looked like 3/8 of an inch to me.

3) My deck is scattered with various bits of hardware, not all of which I have ascertained the likely use of. Seeing as I will be presently filling holes and re-bedding everything else, it seems like a good opportunity to assess what might be removed. To this end, I'd love to see a picture or two of other forum member's deck fittings and lines.

4) My final question is about the "ventlite" cabin vents/skylights that are fitted to many of the boats in this group. I have two, one in the main cabin, and one in the forehatch. I don't like them much. Do you? Has anyone removed one from their boat, and do you have a good method for filling in the sizeable aperture?

Many thanks for taking the time to read this rambling post, and I look forward to any suggestions you might have.
Matt
pjbharrison 5 years ago
Hi Matt

For screw holes that are not to be re drilled for fittings you could use Plastic Padding Marine fillers. It goes off in 15 minutes.
For areas that are to be drilled its best to drill out a large hole, fill it with thickened epoxy, let it set and then drill a hole through the epoxy to attach the fitting. This adds strength to the deck and prevents water ingress into the balsa core. dan.pfeiffer.net/boat/hdwrinst.htm

I've used several epoxy resins over the years but none set as quickly as West Systems epoxy. It's also the dearest! I used some in my unheated garage in the last few days and in the current temperatures it took overnight to be touch dry.
SHAMAL411 Posted 5 years ago. Edited by SHAMAL411 (member) 5 years ago
Hi,
We have used polyester resin extensively in repairing Shamal during winter months without problems . As you say , preparation is key - abrade back to a fresh surface, clean with acetone and warm the area with a heat gun , repeat this for each additional layer .
If you haven't come across it before I recommend thickening the resin with cab-o-sil (fumed silica) for areas which would otherwise drip such as drilled holes and acute corners.
For full curing in winter one tip we got from a boat builder is to cover the worked area with an ordinary electric blanket,insulate with bubble wrap and keep the temperature at 20-25 C for four hours.This is for areas that will be under water and hence too cold all year to complete the cure to full strength.
For finishing and matching the gel coat we use polyester 'flow-coat' with good results .
If it was me I would leave the vents alone ,they work , they don't leak , A24's are not prone to condensation , and the glass inserts are replaceable .
We have not had to do any work on the balsa core so I'm keen to know how you tackle this , the conventional wisdom is that epoxy is
a lot better at bonding wood than polyester.
All the best
Mattg29 5 years ago
Good morning, and thanks for the speedy replies.

I'm glad to hear you've had good results on Shamal with Polyester. I had thought about using a ready-made filler product for the screwholes, but I believe these are usually polyester based anyway, so I may as well use my own mixture.

I've been advised by a veritable old salt that the danger with polyester is expecting it to be as adhesive as epoxy is. He advised that to prevent little plugs in the deck from coming unstuck as the boat flexes under sail, the following procedure should be used: (1) Dribble in thinned polyester. This is adsorbed partly into the balsa core (2) Let that set a bit. (3) Syringe in thickened polyester for the plug. The idea is that the plug polyester can now chemically bond with the part-cured resin in the balsa, rather than trying to bond mechanically with the wood.

Perhaps I'm being a bit hasty in my dislike for the vents, and I'm glad to hear the bit of (opaque yellow) glass can be replaced. I may well still try and get rid of the one in the forehatch, as I have a lot of other work to do on the hatch. A previous owner has put rather a lot of screws through it to hold a home-made gasket on.
bengunn2 5 years ago
Hi Mat,
G4 primer is a much better product for bonding new polyester (filler or laminate) to old laminate substrate and timber/balsa. BUT it is imperative that you go in with your new laminate/filler whilst the G4 primer is still tacky, G4 will penetrate much better than any poly resin, I have been using it for years and it works. There are some very good low temperature epoxies, West and SP do a fast hardener and we have worked down to below 10deg. with very good results. Don't be tempted to increase the ratio of hardener, epoxy does not work like that. Mixing very small amounts of epoxy calls for very accurate measures, we try to get a large number of small jobs prepped and then batch fill, ideal for you if you have lots of holes etc, this helps the acuracy of the mix.

good luck Ian
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