(AND...the most inappropriate thing about this post is the title!) WHAT ARE self-tapping screws and are they appropriate for use on a sailboat? Can I use them to attach a Porta-Potty to the floor? How about for above-deck uses? Can they be sealed? I assume they are not for heavy loads, but could they secure a flagpole socket on the corner of my transom? If no to all of these questions, what do people use for universal non-backed screwing? Richard H23 "Invictus"
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Your header certainly got my attention! 
And everyone else's too, I'd bet! Self-tapping screws are pointed...you only need to drill a tiny pilot hole to start them instead of a hole the entire length of the screw. Wood screws are self-tapping, and they hold as well as any other type of screw in wood provided you use the right size--length AND diameter--for the job. In applications where it might be necessary to use a little sealant, only a little under the head is needed...just be sure it's NOT 5200 or any sealant that won't allow you back the screw out again...use a silicone sealant. Since most portapotties come with hold-down brackets and the screws to put them down, I recommend you use them.
And everyone else's too, I'd bet! Self-tapping screws are pointed...you only need to drill a tiny pilot hole to start them instead of a hole the entire length of the screw. Wood screws are self-tapping, and they hold as well as any other type of screw in wood provided you use the right size--length AND diameter--for the job. In applications where it might be necessary to use a little sealant, only a little under the head is needed...just be sure it's NOT 5200 or any sealant that won't allow you back the screw out again...use a silicone sealant. Since most portapotties come with hold-down brackets and the screws to put them down, I recommend you use them.
hmmmm
And I thought this was going to be some really useful information! I would use some steel plates to reinforce any dodads that you wish attach to your deck or transom. Forget about the self tap screws and just use some SS bolts, washer and nuts. The self tap screws might be good for snaps but that is about it.
And I thought this was going to be some really useful information! I would use some steel plates to reinforce any dodads that you wish attach to your deck or transom. Forget about the self tap screws and just use some SS bolts, washer and nuts. The self tap screws might be good for snaps but that is about it.
Metal screws...
I usually think of metal when talking about self-tapping screws. They are machine screws that have a self tapping end to cut the threads as you start them, and I believe the pilot hole dimension is pretty critical for success. The package will usually indicate the pilot hole size. For fiberglass, I like to use a large washer or backing plate, and don't like to rely on the threads biting the glass except for non-critical applications like snaps as was mentioned in another post. Here, I think sheet metal or wood screws would be more usefull than self tapping machine screws. Fair winds, Tom
I usually think of metal when talking about self-tapping screws. They are machine screws that have a self tapping end to cut the threads as you start them, and I believe the pilot hole dimension is pretty critical for success. The package will usually indicate the pilot hole size. For fiberglass, I like to use a large washer or backing plate, and don't like to rely on the threads biting the glass except for non-critical applications like snaps as was mentioned in another post. Here, I think sheet metal or wood screws would be more usefull than self tapping machine screws. Fair winds, Tom
Self-tapping screw...
From my experience also, the self-tapping screws are for metal. Also, in fiberglass, if the pilot hole is too small, the screw will break out some fiberglass gelcoat. Or, you'll have a loose screw (if the shoe fits...;D) if the pilot hole is too large.
From my experience also, the self-tapping screws are for metal. Also, in fiberglass, if the pilot hole is too small, the screw will break out some fiberglass gelcoat. Or, you'll have a loose screw (if the shoe fits...;D) if the pilot hole is too large.
Screwed all over the boat this weekend
Yeah in the process of reinstalling everything. Screwed the floor, the setees, the new holding tank hoses, the a/c, the hot water heater, Used around 350 stainless steel screws, drilled pilot holes in the fiber glass with bits a little over 2/3rds the width of the screw. found that sizing that way works well without cracking out the fiberglass.
Yeah in the process of reinstalling everything. Screwed the floor, the setees, the new holding tank hoses, the a/c, the hot water heater, Used around 350 stainless steel screws, drilled pilot holes in the fiber glass with bits a little over 2/3rds the width of the screw. found that sizing that way works well without cracking out the fiberglass.
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