Overdrill, fill, and re-drill any deck penetrations...

[Mikesab]

So, in the process of disposing of the derelict Oday 25, I cut thru the cabin top in preparation for lifting the keel out thru the top (we ended up dropping it thru the bottom, but I cut the top just in case we got to the landfill and needed other options)

In cutting thru the top, I cut near a bolt that a previous owner had installed, and thought it was worthy of posting.

You can see the deck is nice and solid and then begins to decay right around the penetration.
Also, notice the fiberglass cabin headliner below the deck level, so there is no way you could tighten the bolt sufficiently, and it would continually move, eventually defeating any caulking.
you would have to cut a larger access hole for the nut to get it tightened sufficiently.

Seeing this for me totally reinforces the Overdrill, undercut, fill with thickened epoxy, and re-drill so the deck cores remain isolated from outside elements. If any leaking does occur, you know your decks are secure and you simply need to re-caulk to keep the interior cabin dry, etc...

 

[svchickadee]

There is a gap between the cabin interior headliner and the deck as you found. I found this out when rebuilding my mast step last fall. At the compression post there is no gap so the four bolts that hold the tabernacle can be tightened. Bolting thru the cabin top would require an overfill and drill as you noted or you could drill out the cabin headliner and bolt thru the deck. This is how the grab rails are installed. One good thing about the gap between the cabin headliner and deck is that water can find a way out without rotting out the deck. For example, leaking cabin ports will not rot out the side decks since the water passes between the bottom of the deck and the cabin headliner. The water will find a low spot along the headliner and drip into the cabin.

 

[Brian S]

In case someone hasn't seen it, here's MaineSail's tutorial on deck penetrations: http://www.pbase.com/mainecruising/sealing_the_deck

 

[CCrane2299]

I have two jib sheet guide pulleys bolted in about that same place and the liner is cracked inside. I was going to make a plate for it, but now I see that would be a waste of time. Thanks for the pictures.

 

[Ward H]

Another great autopsy photo. Wish I had seen it before last weekend. I drilled and over drilled for a deck organizer. Kept filling the holes with epoxy. Thickened it more and it still ran somewhere. After several tries I went back the next day and used West 610 Thickened Epoxy. That finally filled the holes.
The holes for the line clutch filled with no problem.
Of course if anyone asked, I used the thinner epoxy to saturate the wood first, then the thickened epoxy to fill the hole.

 

[Indysailor]

Interesting photo- on my 23 all the through bolts tighten to the underside of the deck, not the hull liner. And they are all accessible via cutouts, that appear to have been made at the factory. I don't recognize what that part was, but it looks owner installed. And a poor job at that.

 

[RichBone]

But then again there is not always a big gap or any gap between the liner and the deck. It all depends on what is installed and if there is a gap or not. Over drilling and filling is always a good idea though. Another picture that's worth a thousands. Love it.