Screws inside of cabin

[john6206]

Hi Everyone,

C-18 owner here.

So far, I have not put any screws into the boat. I have hung some things up suing 3M command strips, and a little Velcro, and have been pretty happy with the results, but...

I have an idea of hanging a paper towel dispenser on the inside of the hull, and a fire extinguisher on the inside of the bulkhead. 1/2 screws seem pretty long, would 3/8 be strong enough?

Is this dumb?

What would you suggest?

 

[Don S/V ILLusion]

Fiberglass doesn’t like screws. Is there no interior wood?

 

[AaronD]

@thinwater has some very useful info at https://sail-delmarva.blogspot.com/2017/02/stainless-steel-bolt-specifications.html, including screw / bolt strengths and thread depth needed to hold in various materials (steel, fiberglass, G10, etc.). Bolt/screw strengths are pretty much proportional to their area, so you can extrapolate down to #8 and #10 screws from his charts.

The applications you're talking about are pretty low load, so you definitely don't need full screw strength (especially for a paper towel holder). I think you should be able to mount with #8 or #10 screws. If your fiberglass liner isn't thick enough to thread into, you can drill through the inner glass and screw into the wooden core with wood screws or sheet metal screws (I'm guessing your bulkhead and deck are probably cored with plywood, but you probably want to confirm that before drilling through it).

 

[Project_Mayhem]

You could probably use some double sided tape that's made for automotive body panels for the paper towel holder. VHB is really strong after it has time to set properly. The fire extinguisher should be bolted or screwed in place

https://www.3m.com/3M/en_US/company...gth-Molding-Tape/?N=5002385+3293241071&rt=rud