Hello, im new to these forums, and am new to the mosquito class, after purchasing my first wood mossie in late september (1547). So far im very happy with the mossie, however after taking her for her first race at my local sailing club (Bribie Island, QLD) i noticed several cracks on the deck on both hulls infront of the forward cross beam whilst i was washing the hulls down after the race. There are 3-4 cracks on both hulls and range in size from about an inch to about 2.5 inches. From what I can tell, they appear to just be cracks in the gellcoat/paint, as i couldnt find any evidence of the crack on the inside of the hulls and the decks dont have any give in them. The cracks run roughly fore->aft and correspond to where the fore->aft supports underneath the deck join to the deck. Any advice on what kind of cracks they are (are they just gellcoat cracks, or do they look like they might run deeper), or how to ascertain what type they are, what may have caused the cracks, how i can fix the cracks/stop them from reoccuring in the same location/else where on the boat, and where i can get the materials/supplies neccessary for the repair. The following pictures are of several of the cracks as well as the inside of the hull just directly below where the cracks on one of the hulls are located. Any help/answers to these questions is greatly appreciated.

Thank you.
Michael.


Crack1

Crack2

Crack3

Crack4

Inside Hull

Looks like the just the paint cracking, had this happen on my first mossie after re painting it in 2 pack automotive paint. the decks flex the paint doesn't, causing the cracks in the paint.

you will need to rub back the paint to bare timber and re paint, you might have a stain in the timber now from the cracks, but that is not a problem.

Re coat with decks with a thinned down epoxy, give two coats sand back lightly and re paint with either marine paint or use automotive paint with a bumper bar additive don't know what it is called but it allows the paint to flex.

Micheal,

Welcome to the forum. Great to see another Mozzie racing in QLD. Hope you enjoy the experience as much as the rest of us. I believe Ben Cutmore was the last owner of your Mozzie so it has seen some serious racing in the last few seasons. Just a couple of questions for the register: Did you re-name your Mozzie ? Do you race from Bribie Island Yacht Club ?

I agree with Rob; it's just flexing of the paint that has caused the cracking. It is also usually seen on the deck where you normally sit. Maybe someone was sitting in front of the front beam which is not uncommon in very light winds.

When you get around to repainting then use a thinned 2 part epoxy which will sink into the timber and make everything alot stiffer. I did my decks a few seasons ago with Everdure and haven't seen a crack since.

Regards,

Peter

Thanks for the advice guys, ill get onto this weekend, is fibreglass resin as the epoxy, if not couldnt you suggest a brand as well as a store i can buy it from (fairly new to boat repairs).

Also, for the register, i bought the mozzie off Danny Raar from Harvey Bar Sailing Club on the 28th September 08, who purchased it from someone in the Sydney area, not sure if it was Ben Cutmore. The boat as is, is unnamed (there is no name on the hulls), however i will be naming/renaming it in the very near future. Also, yes i do sail it from Bribie Island, however i do like to travel to other clubs in SE QLD that have good Catamaran Fleets such as Humpybong and Lake Samsonvale, as we only race about once a month here at Bribie and currently only have a small fleet, however it is growing ; before i joined it was a maricat 4.3 and two nacra 5.8s, i joined and raced my first cat, an old windrush 14', but am now happily racing my mossie, in addition we have a new member who has an old wooden taipan, so im looking forward to some close competition, and hopefully, when i get around to putting a spinnaker on my mossie, i can give the 5.8s something to worry about.

Thanks again for all the help.

Michael.

Hey all,
This was my mozzie Here are some details on the painting process. http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=69371&page=5

I didden't race or sail this boat much only about 5 times.
Good to see that its out sailing.
The 2009/2010 nats should be confirmed in the next month and should be just north of syd it would be gr8 to see some mozzies from further north attend. I haven't been sailing much (House work & new dirt bike klx 450) has side tracked my sailing but still will be at the nats Looking foward to getting some practice in soon.
Cheers

Michael,

After sitting exactly in front of the front beam during last Saturday's race in light winds I can see why you have the surface paint cracks.

With my full weight on the deck I suddenly remembered your comments from this forum. Damm, I need to keep concentrating during races.

Regards,

Peter

Mike,
I have seen boats less than a season old develop cracks in the deck like that .
The grain of the ply seperates a little and lets some moisture in. It happens more easily on decks with smaller radius camber.
This has happened even when treated with epoxy or evedure.

In my experience building a variety of 16 ft cats I have found that a light layer of plain weave glass ie between 90 and 135 grams makes this problem go away for the life
of the boat.
If you use 86gm per m2 plain weave glass and can wet it out with a resin glass ratio of 1:1 you should add something like 400gms to the total weight of your boat.
This will significantly reduce maintenace by eliminating this problem.

Just something to think about.

Regards,
Phill

Actually i was considering doing just that, sanding it back and applying a thing layer of glass before repainting, as i know the ply wood likes to "breathe". Is there however any potential downside/danger to glassing one area of the boat and restricting its ability to expand/contract whilst the rest of the boat is still free to do so, particularly at the junction between where the glass ends and meets the ply that is free to expand/contract? Also where is a good place to get the painting supplies from? Bunnings ok? or will i need to go somewhere more tailored for boating like bias boating or a chandler?

Mike,
I agree with Phill, when we built our boat we used two coats of Timber Tough resin (a thin Epoxy resin) that will sock into the wood before we painted the boat. We used 3mm ply foredecks on our Mossie and it cracked within the first season (1996). After talking with Jim Boyer he advised us to remove the paint and add 2oz cloth, wet it out and clear finish paint or paint to protect the resin from UV. The extra boat weight was not noticeable and we have not had to do anything to it since.
Regards
Peter

Mike,
Not sure if Mossies tape their gunwales.
I'd take the glass to just the gunwales if they have been taped or just around them if not.

I have always used a Dulux 2 part polyurethane industrial paint. I have also used a 2 part marine polyurethanes from somewhere like BIAS. They seemed to perform about the same for me on everything except price. You could guess which one won out there.
Good luck.
Regards,
Phill