Soft deck spots

SailingLoto · Mar 4, 2026

patrickfarley said:
The deck in front of the mast gives a little. Never used to give a little. The small piece of deck just to the right of the main hatch has been soft for about 10 years.

I plan to fiberglass a few small supports to these areas. 1" oak bar in front of the mast.
a small support next to the main hatch.

Both areas are fiberglass with no wood center.

I was going to cut the skin off and recore mine. There should be wood there. I'm digging into mine later this week. Is th

dlochner · Mar 4, 2026

Almost all decks are cored with wood. Once water gets in the core and starts to rot, the deck gets soft and it spreads. Supporting the deck from below doesn't solve the problem, as there is nothing but mushy wood between top skin and the bottom skin. The only solution is to remove the rotted core and replace it. This usually involves removing the upper skin, digging out the rotted wood, replacing it, and creating a new skin. On some boats this can be done from below, which preserves the nonskid on the deck.

Apex · Mar 5, 2026

patrickfarley said:
...Both areas are fiberglass with no wood center.

good advice above, but if there is no core, then your FG is delaminated...similar cure: grind back and replace

dlochner · Mar 5, 2026

patrickfarley said:
Both areas are fiberglass with no wood center.

Are you certain there is no core? How thick is the fiberglass in those soft areas? What kind of support is below the deck? Is this a deck stepped mast or keel stepped?

SteveHughessails · Mar 5, 2026

I am quite sure there is no wood in mine either. I guess it’s possible it’s thicker than it looks. Mine however is not soft. The M25 has a deck stepped mast.

dlochner · Mar 5, 2026

SteveHughessails said:
I am quite sure there is no wood in mine either. I guess it’s possible it’s thicker than it looks. Mine however is not soft. The M25 has a deck stepped mast.

Interesting, usually there needs to be some core material to get the strength needed for the mast. I would have guessed the core was plywood, not balsa. I found some photos that show a fairly beefy compression post under the mast. That would allow the deck to be thinner. Still, if that area of the deck is solid glass then there must have been some damage to it for it to become soft. Glass doesn't usually become soft all by itself.

It would be wise to inspect the compression post to make sure there is no rot and it is supporting the mast as designed. Best to get to the cause of the soft deck before trying to repair it.

dlochner · Mar 9, 2026

patrickfarley said:
The wood was hard and appeared dry.

Great! The wood looks like plywood which was often used as a core. One problem with large pieces of plywood as a core material is difficulty in getting the wood to bond with fiberglass. Plywood typically has large sections of hard grain, resin does not bond well with these sections. In between the hard sections are softer porous grain areas, resins can penetrate these areas and the glass bonds to the plywood. Over time the fiberglass separates from the hard grain areas, the deck feels soft because there is some flexing where the bond failed.

If this is truly disturbing to you, there is a fix. Drill a pattern of holes in the soft areas and inject epoxy into the holes to rebond the fiberglass to the core. This is a good fix if the deck will be painted, otherwise there will be a bunch of visible epoxied filled holes in the deck.

SteveHughessails · Mar 9, 2026

patrickfarley said:
View attachment 236865

Another plus for the Mac25. Thanks for letting us know.

Soft deck spots

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