"Woodscrews and Floors" by Mark Casper
Several years ago, I was waterskiing behind a Vector I used to own, when all of a sudden the rope jerked loose and into the water I went. When I looked up, I saw the ski pylon flopping around behind the motor - it was not a pretty sight! After returning to shore, I peeled back the carpet and there it was: the floor had rotted around each of the 8 mounting screws for the pylon base. The previous owner had installed the base without any care or concerns for the future. I looked at the gas tank mounting screws; same thing: rotting around the screws as well as some that were completely gone. Needless to say, I did some floor replacement work that summer.
How many of you have had to replace your floors or had them replaced by a previous owner? It seems to be a common problem and one that can be avoided. When I bought my current V-King, one of the first things I did was go through and check everything. The floor was new. Screws were everywhere: foot throttle, gas tank, seat brackets, battery box, wire holders, etc. Removing the screws showed the wood was already getting soft. So I went through and did everything the right way. Here is what I do:
Any kind of component that has some weight or experiences stress, I don't use woodscrews. I use wood inserts (see picture at right) instead. As most of you know, anything that can vibrate loose on a boat, will. Wood inserts provide a permanent solution without the possibility of a future leakpath to the wood. Gas tanks, seat brackets, and ski pylons are a must for these, while battery boxes and foot throttles are desirable. Wood inserts come in either brass or stainless steel and in different sizes (I usually use 1/4-20). Brass inserts are available at your local hardware store while stainless inserts (not cheap!) can be purchased at a marine store such as West Marine. I use stainless for the high stress components and brass for the less critical. To install, drill a hole in the wood the same diameter as the body of the insert. Be careful when drilling - especially around the edges of the floor! The last thing you want to do is drill into the hull, or the unenviable job of recoring the hull may be in your future. Coat the inside of the hole with a waterproof epoxy (I use West System). You can install the insert with a screwdriver, but it is much easier to use an installation tool such as shown at left. Install the insert while the epoxy is still wet. This glues the insert in place while also giving you a good seal. Be sure the insert goes in straight! Make the final attachment with stainless machine screws and lock washers where possible. Be careful not to use screws that are too long - again, you could do damage to the underlying hull.
For less critical areas (cable holddowns, etc.) where regular woodscrews are acceptable, make sure you coat them with a marine sealant that is made for sealing beneath the waterline.
Finally, the use of woodscrews deckside should be used sparingly. The reason: they can cause the gelcoat to develop stress cracks. Wherever possible, drill a thru-hole and use machine screws. If you don't have access to the back and must use woodscrews, slightly chamfering the hole will help minimize cracks.
Doing the work now will take some effort and cost, but it will be well worth it to avoid headaches, more costs, and lots of work down the road. A future article will deal with the situation when things really get bad: recoring your hull.