screws through fiberglass-what is best?

[scott scharhag]

I would like the pros and cons of using either threaded screws with nuts or self tapping screws to attach toe rails through fiberglass. Also, what is best for sealing the screws so that they don't back out. Any advice would be appreciated. Thanks.

Scott Scharhag
Champlain, NY

[dasein668]

Machine screws with nuts and washers would probably be marginally stronger/more durable, but much much much more difficult to install. I know in my boat there are several areas that I absolutely cannot reach, so applying nuts would be impossible.

In practice, a toerail installed with self-tapping screws should be plenty strong, as long as it is well-bedded in a polyurethane adhesive like 5200 and provided you don't skimp on the fasteners. I used screws every 9 inches and a liberal application of 5200 when I installed the new toerail on Dasein.

[Tommy Bahama]

My Islander Bahama used to have an aluminum rub rail/trim that went around the boat at the hull/deck joint. The seam is glassed on the insides so I think the the joint is sound even though the rivets are long gone. My thought to improve the looks and durability outside the boat is to install a 1"x 3/4" oak or mahogany rub rail after cleaning and re-sealing the exposed hull/deck joint with 5200.

Do you experienced folks think that the wood screw from the inside would be suitable form of attachment? The old rivet holes are visible from the outside and I plan to drill through them (about every 8 inches) and re-use the holes for the rub rail. It would save alot of bung work for a small piece of wood...The other option is just to fill/fair/paint the old rivet holes but I think the wood trim would look much nicer.

Thanks,

Tom

[Tim]

I'd use some sort of adhesive caulk as well as the screws, particularly from the inside. It's definitely stronger if the head of the screw is in the wood rail, but attaching from the inside would probably work just fine.

[Tommy Bahama]

Thanks Tim,

Yes, I will seal/bed it well. The outside seam was hidden by the aluminum trim piece. The factory was sort of hit and miss with the seal job and I occasionally need to wash out the moss and dirt. I plan to scrub it well with bleach then let it dry before re-caulking. I may use a wide washer over the screws, depending on how large the heads are. I'm thinking that washers will give me more to "bed" with...I'm potentially drilling a couple hundred leak holes in my boat!

I know there are probably a number of ways to do this but if I stick with an accepted practice, maybe the next person who owns her will be able to keep her up as well...nothing like trying to repair something that has been "porked" real good.

Tom

[heartofgold]

Scott,
When I attached my mahogany rub rail, I used sheet metal screws from the inside, in addition to a cozy bed of 5200. As I was bending the rubrail several inches, there are only 6" spacing between my screws. In my case, the screws pass through the hull-to-deck joint, which had been sealed with 5200 a few weeks earlier. I looked for pictures of that part of the restoration, but I seem to have been camera shy during that project.

[Allen]

Last summer I helped a buddy put a wooden toerail on his Bombay Clipper, Mango Moon. Our experience fairly well parallels Dasein's. We started out using machine screws and locknuts. The difficulty level varied from kind of difficult to impossible depending on where we were along the hull. In the impossible places we switched to self-tapping screws, and finally decided the effort to use machine screws wasn't really worth the extra holding power.