[TSOJOURNER]

I just bought a Mercator Offshore 30, Brinestormer. When I had my boat surveyed there were a couple of high moisture areas on the deck around fittings. No big surprise. But here is what's different. My deck are not sandwiched. The house and decks are plywood with a glass skin on the outside surface - no skin on the inside. No rot is detectable from the inside. I was wondering what the best way to deal with the wet? I would of course re-bed everything, but I need to get the water out and address any delamination. This is not a coastal cruiser, so I want to do it right.

Thank you! I'm getting started on a total refit that I expect will take me a few years and I appreciate this community. I have much to learn about working on boats and sailing. I have had very plastic boats and some sailing experience but this is taking it to a whole new level. If anyone is close to Olympia, Washington I'd like to make some local sailing friends.

 

[mitiempo]

It's almost the same issue. The deck fittings have allowed some water into the underlying plywood. You do not see this from the inside because the glue layers have stopped it from coming right through. You might be able to check how large the wet area is by tapping the deck with a phenolic hammer - the wet areas might sound duller than the dry areas. As far as a fix, remove hardware and top glass surface, exposing wet ply. Take the top surface back to where it is not delaminating from the ply. Remove wet ply with a grinder and/or router down to dry clean layer. Taper the edges of the hole. Build up the surface with epoxy and cloth to the original level and fair and paint.
Brian

 

[Waltthesalt]

The best reference for repairing a wet deck core is the West System booklet 002-550 "Fibergalass Boat Repair & Maintenance".

 

[mitiempo]

The West System booklet is excellent and anyone who uses epoxy should own it
(or download it http://www.westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-and-Maintenance.pdf ). I bought my copy about 20 years ago when the net wasn't an option. But there is another reference and I think it might offer more to many. Northern Yacht Restoration | Iota Project takes you to the site Northern Yacht Restoration. The site is owned by Tim Lackey, who also started and owns The Plastic Classic Forum • Index page. Northern Yacht is his commercial site. He is very experienced at all aspects of rebuilding and refitting boats, including engine swaps when needed. His site is very well documented, giving an excellent step by step with a large number of pictures showing every step of each job. In my opinion there couldn't be a better wat to learn how to do it yourself. When you explore the site you will find everything from how to install seacocks the proper way with g10 backing blocks epoxied in to how to install a sink under a counter instead of on top. The link above takes you to the beginning of a deck recore on a Pearson Triton - the finished boat is shown below.
Brian

 

[Waltthesalt]

One other reference. Google EPOXYWORKS it's the Gougeon Brothers magaine. Number 19 (spring of '02) had an fairly detailed article on a balsa core deck repair. There may be others. In this case the owner used mat to replace the upper skin. I think it's more common and practical to carefully cut out the upper skin then glass it back in afterwards.

 

[mitiempo]

Mat does not have much strength of its own and is not a good choice for this on its own. Mat is best used between layers of roving to make up for the uneveness of the weave, as it was used in the construction of most of our boats. Some mat has binders that will dissolve in polyester resin but not in epoxy resin. These shouldn't be used with epoxy. I would use a medium weight cloth at least and if the thickness allowed I would use 1708 biax. This is described below. It's much stronger.
Brian