Restoring HC16 - problems with Gelcoat

My 1984 HC16 suffered a bit of damage last winter. I managed to repair the large nicks caused by the HC moored alongside mine. After filling the nicks with fiberglass resin I sanded to get a nice smooth finish. I also took the time to fill other links nicks and scratches in the hull surface.

Now my attention has turned to covering the damaged area with gelcoat to finish the job off.

I used gelcoat with approx 2% catalyser and a roller. I applied the first coat and left it to cure for a few days. However, I noticed that even after a few days, the gelcoat still felt tacky and in places the sand kicked up by the wind was adhering to the surface. I left the first coat a bit longer and when satisfied that it had dried sufficiently I used a 240 grain paper and with running water smoothed out the first coat.

I went ahead with the second coat. Things didn't go well here either. We have had real heavy rains for past few days. Yesterday, with a break in the weather I went to check out my work. Basically, the gelcoat had turned grey - a sort of cloud effect. I can only assume that the gelcoat had not cured sufficiently. But I am no expert.

I really need some help with this. Would it be better to spray than roll on. Could I have a list of products that I need to get the job done properly. Is this something I can do on the beach or would it be better to take the hulls home and do the job inside. I have a garage that I can use.

I live in Italy so I guess many of the products available in the US are probably not available here.

Thanks for any help you can give me.

Standard gel coat will not cure completely when exposed to air. It's meant to be sprayed into a female mold and the tackiness helps it adhere to the subsequent layers of fiberglass.

There are two ways to deal with this:

Easiest - After application, you spray or brush the area with polyviynl alchohol (PVA). It's a water-soluble mold-release wax. After the gel cures, you just wash it off.

Harder - add a surfacing agent to the gelcoat when mixing. As the gel coat cures, it rises to the surface and provides a barrier to the air.

Hardest - use an additive like Duratec High Gloss.

All of this is discussed in the "This Old Hobie - Spraying Gel Coat" in the July/August 2008 HOTLINE Magazine - http://www.hobiecat.com/hobieclass

Thanks for the information.

Just another point to add. A club member told me to forget gelcoat, because of the difficulty in applying it, and instead to spray the hulls with an acrylic paint, insisting that it is better to concentrate on other boat tasks that require attention.

Are there any disadvantages to using an acrylic paint?

Thanks

Jim, The Italians make some awesome boats, and parts for many. I just bought a steering wheel for my power boat..."Made in Italy". You should be able to find everything you need for your repairs. It may take some time to locate a good composites / plastics retailer, but don't give up. Painting a hull is usually faster & easier than re-doing the gelcoat. Gelcoat requires more work, but in my opinion, is better than paint in the long run.

The problem here in Italy is that many of the products listed in the HC Hotline magazine article such as Duractec High Gloss Additive and surfacing agent are not either not available to the general public or are not sold in small quantities. PVA for example is only available in 25 litres containers.

This leaves me with the gelcoat and catalyser which I have. I have already laid down two thin coats of gelcoat and the finish is slightly orange peel and a little tacky. Before putting down a third and thicker coat I will get some PVA and see if this gives me the tack free finish I want.

But then, all being well, how can I get the shine on the new gelcoat. Perhaps a coat of acrylic paint? Wax?

Jim, Sorry to hear getting materials is so hard to do in Italy. keep looking, there has got to be a cheap source out there somewhere for you. To get an eggshell glossy finish to a new gelcoat finish is more work as I said, than spraying some paint. Using Duratec High Gloss additive and some surfacing agent (wax) will definitely help. When I catalyze gelcoat (USA factory white) & depending on how hot it is outside, I may use between 15 - 20 drops of MEKP (catalyst) per ounce. Euro white gelcoat is a totally different ratio. I'll add about 40 - 60% Duratec to the gelcoat and about 6 - 8 drops of wax per ounce. Duratec already has some surfacing agent in it, but I've found adding some extra helps. If your mixture is a little too thick to spray try adding some Styrene Monomer (NOT Acetone) to thin it..but do so very little at a time. After your sprayed gelcoat begins to set up (kick / cure) try spraying a good coat of PVA over it. Let it finish curing over night then wash the PVA off with some water and a sponge. To get a smooth finish try wet sanding. Depending on how smooth the finish is when you start sanding you should be able to begin with 320 grit, working your way up to 600 grit or finer. After you finish sanding use a good quality rubbing compound and a power buffer / polisher to get the gloss you want. (You may find after sanding and polishing that you didn't apply enough gelcoat. This happens when you're learning. You'll learn as you go) Follow all this up with some Gel gloss, or a good car wax. If the water you sail in is really clean you might not need the wax.

Still no luck on the products but I am pretty satisfied so far with the gelcoat I have applied. I did manage to find PVA and I have noticed that it gives a far better cure than without. Yesterday I started wet-sanding and realised, as you mentioned might happen, I need one further coat. I think I made the mistake of starting with 240 wet/dry paper. I will start next time with 400 and then move to 600. I reckon with good sanding, buffing and waxing I will get a nice finish.

Thanks for the advice.