Coaming screws

[Guinness]

Sometime back I inherited a daysailer. At some point the coamings and other wooden trim were removed. The screws which attached the wood to the boat have since gone missing. Is there any sort of listing as to what size screws were used to do this?

-Guinness

[GreenLake]

I've had to upgrade the screws to a longer size, possibly also bigger, not sure. They screw into a bit of wood that's encased loosely in fiberglass. Technically, that kind of support for the side deck is called a "carlin". The carlins in the DS are subject to rot, because once they get wet, they don't dry out well because of the fiberglass, but the fiberglass does a poor job of keeping them dry in the first place. Hence, you will find that your screws may not hold well at the original size.

The design calls for oval head wood-screws with finish washers. Stainless, of course. These are the washers that are like a half-donut.

The best thing would be for you to test this with any old wood-screw, or rather several of different dimensions, but of course shorter than the thickness of the coamings and carlins combined, which you can easily guesstimate once you are at your boat.

That way you can also tell quickly whether some of the holes have gone softer than others, and therefore need bigger screws.

Finally, you could see whether you need to restore the carlins, either by replacing, or by treating them. One system for restoring partially rotted wood is the End Rot kit from System Three. It consists of a Borax-based solution to kill fungus, followed by a very thin, penetrating epoxy. This system is a good choice for treating localized rot, like around screw holes. If the wood is in good shape, you should still seal the screw holes with epoxy, because that's one place where water gets in.

Also, the original design calls for some sort of gasket material between deck and coaming. That was missing on my boat, and I didn't find out about it until after I had remounted the refinished coamings. There's some discussion of that in the repair or DS1 forum, just search.

Good luck.

[kkearns]

I agree with all of Green Lake's suggestions and cautions about the rot. When I restored my coamings, I chose to replace the original screws with stainless bolts of the same diameter but naturally a bit longer. I drilled completely through the carlins to the outboard side, then pushed the bolts through the coamings and the carlins till the end emerged on the "back" side. I used washers, of course, and jammed a bit of sealant into the hole and around the bolt as best I could. I'm not near my home right now so I can't take measurements on the bolts (I have several spare), but I recall that they were about 2 inches long. Naturally, there are risks to this approach in that you create a second hole for water to seep in (on the back side of the carlin), but I guess I felt that this would creats a stronger anchor for the coamings. I found that the curvature of the coaming creates a fairly high amount of tension, especially at the mid points, and I just did not feel confident that the original holes would hold, even if reinforced with epoxy. However, I might do it differently if I was doing it today.

Kevin

[K.C. Walker]

The carlins under the deck are 1.5" thick. I use #10 X 1.75" stainless self tapping Phillips oval head and they work great. Wood screws have smaller threads and have a tendency to strip out unless you size the pilot hole exactly right. Using self tappers means that you need to have good clearance holes on the coaming, though.

KC