Hull Blister Repair on H16

I'm hoping for a bit of seasoned Hobie advice. I'm new to Hobies, not to sailing.

This summer I sold a 20' O'Day and purchased an old H-16. Being a avid reader of these forums, I followed the advice given to another new Hobie sailer - get the boat in the water while in season, and repair everything during the winter months. Having sailed it twice now (very cool!), I'm now pulling it apart for winter repairs. The person I bought it from obviously didn't understand sailing or Hobies, as much was rigged wrong.

I'll be repairing one soft spot and MANY hull blisters, then repainting the hulls. I suspect that the hulls sat out for a long time, based on the number of blisters. About half of the blisters also have cracked gelcoat (perhaps frozen blisters popping in the winter?). I'm planning to carefully open up the blisters and fair them out to where the gelcoat is in good shape. My question has to do with the material used to fill the voids. Looks like most everyone likes Marine Tex, but since this is a different material than gelcoat, will it expand/contract at a different rate and cause problems in the future? Also, do you recommend using a primer on the entire hull before painting, or should I just jump right to the finish coat (planned for Interlux one-part).

I'll be posting photos - so you'll get to see your good advice applied as I go.

Thanks for the forum - and thanks for your help. This forum is just one of the reasons I chose Hobie - the community of owners is second to none.

Gel coat blisters are caused by leaving the boat in the water for a long period of time (months). Osmosis allows moisture to penetrate the gel coat and collects between it and the underlying laminate, forming a blister.

Marine-Tex is an epoxy filler. It's very hard when cured - much harder than the surrounding gel coat. You will have a difficult time fairing the surface because of that.

The boat is made from polyester resin and unless you are making structural repairs, stay away from epoxy. If your plan is to paint, then use a polyester-based filler, like Evercoat Formula 27. Its hardness is similar to gel coat and you'll get much better results fairing it in.

90% of the work in painting is preparation. Be meticulous about fixing every little ding on the boat - they will show up in the new high-gloss finish.

MBounds -

Thanks for the insight. I'll abandon thoughts of Marine Tex and go with your recommendation. Anyone have thoughts about how to prepare the crazed surfaces? Should I just remove the gelcoat and fill it (everything appears solid under it)? Thoughts on priming before painting?

I've posted some photos to document the process.

H16 as purchased: http://www.flickr.com/photos/scottdflicr/5147490302/

Crazed areas: http://www.flickr.com/photos/scottdflicr/5146891105/

Blister that has split: http://www.flickr.com/photos/scottdflicr/5147492830/

Faired blisters: http://www.flickr.com/photos/scottdflicr/5146893931/

i had a similar crazed area on the side of my starboard hull. turned out to be a fairly large soft spot I'm re-gelcoating over the winter so i'm just sanding mine out

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'73 hobie 16 restored 2011
'00 Seaswirl fishin boat

Not to dispute any advice here but...my hulls were stored lying flat on damp ground for at least ten years. Each outside freeboard had dozens of blisters. I carefully opened them with a dremel tool and sanding wheel, filled them with Marine Tex, sanded, finished and painted the hulls with polyurethane. That was five years ago and there is still no visible evidence of any hull blisters. I wouldn't say Marine Tex is the best solution but it is certainly good enough.

I am into a similar project on a 1984 16. Would like some comments regarding decal removal before painting. Priming and paint type used. I have what looks like a lot of beach wear on bottom of hulls. How can I form-up the old edge with epoxy (?) and get the edge back to new shape? Can paint replace the gelcoat there? Thanks.

you can use polyester (fiberglass) resin and mat if your keel is really beat up but in most cases body filler from US Chemical (not a fan of bondo as it gets too hard) would do the trick. Like MBounds says Epoxy is best for structuraly applications like delam but not as good for cosmetic or exterior fixes.

coming from a guy that is currently stripping someone elses paint off an old hobie.... please don't paint your hulls. If you plan on beaching your boat paint won't last anyway. you might as well do it right and gel coat them so it lasts and when a cheap bastard like me buys your old beat up boat it will be much easier for me to restore it

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'73 hobie 16 restored 2011
'00 Seaswirl fishin boat

OK, I'll bite on that "gelcoat vs. paint" comment (I've been reading a lot of old posts about this too). I've painted the hull of a monohull in the past, so I'm familiar with the roll/tip method. From what I've read, gelcoat behaves quite differently.

I plan to to this myself...and I don't have the equipment or space to spray, so my solution will need to be hand-applied (roller vs. brush?). Can anyone tell me of their own experiences either brushing or rolling on gelcoat? If the process is reasonably similar, I'll gelcoat (sounds like gelcoat rolled on may take some extra sanding/buffing, but that's not a problem).

I have one hull nearly fully prepped...one to go, then I'll be ready for the finish coat.

Thanks for the advice - these forums are a wealth of information!

PS-one additional question...while prepping a hull, I flipped it to get to the other side, and it sounds like there's a chunk of something loose inside. Is this anything to worry about, or is it perhaps some flotation material?

everything i have read claims that you can roll on Gel Coat but it will be uneven and you are prone to getting small bubbles. So although you can you shouldn't.

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'73 hobie 16 restored 2011
'00 Seaswirl fishin boat

I have to admit that I'm not being left with many good options for the final surface (gelcoat vs. paint).

Without the ability to spray gelcoat, I may still go with paint (still working on the hull repairs, so I have a little time for this decision). Has anyone used Supermarine Revolution (SM-1000) vs. Interlux? thebeachcats.com has a few comments about this epoxy-ester paint, and it sounds a little too good to be true. Wondering if anyone has some experience with it.

Also, does anyone have thoughts about the loose clunking inside my hull? As I'm working on the hulls, I turned one over and there's something loose inside (from the sounds/feel of the thunk, I'd guess it's smaller than a football, but larger than a softball - and no, there are no access holes for something that large to be inserted).

Thanks for your advice!

It's the foam flotation block. It's part of the boat. Don't worry about it.

mbounds -

Thanks! That's one less thing to worry about.

To keep documenting the restoration of my H16, here are some new photos and narrative of the delam work...

http://www.flickr.com/photos/scottdflicr/5599003147/
The hull delam was a max of 23" x 10"

http://www.flickr.com/photos/scottdflicr/5599586398/
Laid out a 2" grid for the holes - drilled with a 1/8" bit, going in just 3/16".

http://www.flickr.com/photos/scottdflicr/5599007099/
Used a syringe to fill the 50 holes. Epoxy ran out of adjacent holes when filling them. Plugged up the holes with a tape "plug" - but a lot still ran out. This entire section still only took 6 ounces of epoxy, and dried rock hard. (West System 105 Epoxy and 206 hardener)

I have just a few more blisters on this hull to grind and fill, then it's on to the next one (it was too cold over the winter to work in the garage). The starboard hull has no delam problems, but still has lots of blisters.

I've purchased Interlux InterProtect 2000E (white) for the finish coat(s). May require some sanding/buffing to achieve the final gloss I'm working toward.

Wow, the Interprotect is potent stuff (with both garage doors open and a fan, it was still pretty intense). Looks to do a nice job of sealing everything, but it's definititely NOT a finish coat - and it cannot be buffed into one.

I've sanded/wet sanded it down to a 800 grit - and am ready for the final coat. Since I now have some experience with 2-part paints, I'm going to go with Interlux Perfection (sorry to you Gelcoat proponents). Going to turn my old orange hulls into modern white.

Go get yourself a good full faced respirator if you haven't, that stuff is toxic.

Here's the blister job that I'm working on. I'll prime the hull with something similar to the Interprotect called 545 from AwlGrip.

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