Newbie Hull Accessory Installation Question

[inAjet]

Hello,

I'm relatively new at hull work, and boat work in general. Just wondering what is the correct/best way to prepare an above waterline screw hole after drilling but prior to inserting the screw on a wood core, fibreglass hull; for example, when fastening a horn or VHF antenna.

Appreciate any advice!

Cheers,

Chris

 

[inAjet]

Any thoughts? Someone here must have some insight...

 

[briangcc]

Not saying its right or wrong but what I did on my Four Winns when I added some cleats was this...

Drilled next size up holes for the bolts I was installing.
Took a tooth pick and liberally coated the hole with 2 part Epoxy to seal it.
Calk down between cleat and hull to seal that potential opening.
Torqued the bolts/fender washers/nuts down as needed.

Underneath I already had conveniently placed (by factory) backer blocks to support the cleats.


I'll be doing something similar when I add some fender clips to the Chap when it warms up...alot.....(snowed this morning).

 

[dingbat]

Personally, I would avoid drilling holes into wood if at all possible to minimize the possibility of rot. It's not if, it's when it starts to leak

Thru-bolting is the the preferred method of attachment on a boat.

Trapping water between the component and the mounting surface is also a problem. Be sure to "bedded" the component as part of the installation process.

https://www.boatus.com/expert-advice/expert-advice-archive/2019/february/bedding-deck-hardware

 

[tpenfield]

I'd be filling the hole with epoxy, let it soak in a bit, and then putting in the screw.

 

[inAjet]

Thanks very much, all, for the replies and great articles - a very useful read. I've read about the bedding technique before, and there is no doubt this is the "best" way to prepare a hole in a deck, and no doubt something I would be doing if mounting a cleat or a stanchion.

That said, from a practical standpoint, if mounting a battery tray on the cabin floor of a bow rider, would simply filling the hole with something like 3M 5200 before inserting the screw suffice? I say this only because I am near certain that Sea Ray did not bed the screw holes when mounting the factory-installed battery tray, fire extinguisher, windshield supports, etc. - perhaps rendering this extra effort somewhat pointless when the 21-year old boat has already been tainted with un-bedded screw holes? This was also the technique used when replacing the garboard drain fitting, which has far more exposure to water than the above waterline deck.

 

[JASinIL2006]

Yes, that will work. It’s a good way to protect the wood from water intrusion.

 

[dingbat]

5200 is an adhesive with sealing properties.

Sealing screw holes, you would be better served using 30 minute marine epoxy.

Fill hole with epoxy (tooth pick) before installing screw.

 

[Scott Danforth]

drill hole thru fiberglass
chamfer hole with counter-sink tool so not to crack gel coat when you insert the screws
fill screw holes with 3M 4000 UV
back-butter what ever it is you want to install with 3M 4000 UV
insert the screws and drive home
use acetone and a rag to clean up the oozing 4000 , leaving a nice fillet to seal and make it look pretty

 

[froggy1150]

So for everything that gets screwed down that i have done so far gets put on an individually wrapped in glass piece of wood that is then glassed down. There will not be a hole in my deck. Too muck work. For my captains chair i put t nuts in a piece of plywood, glued down with resin glass mixture and then layed glass over the top. For the furniture i did with 2x4s so i could put screws in horizontally. If these areas get wet and rot its just a piece, not the whole deck.

 

[inAjet]

Thanks, guys - appreciate all the feedback! Sounds like epoxy is the best solution, but 3M 4000/5200 is also a suitable alternative. Given the treatment of the existing screw holes in my hull, I am leaning toward the latter.

On a similar note, when enlarging an existing cutout in the hull above the waterline to insert a surface-mounted horn, would epoxy be the preferred way to seal the edges of the exposed core around the new opening?

 

[inAjet]

Any recommendations on an epoxy for this application?

 

[lprizman]

5200....be sure it is where you want it...once it's set...it is SET!!

 

[inAjet]

5200....be sure it is where you want it...once it's set...it is SET!!

5200 is great stuff! But would you use it to seal the exposed core along the edges of a cutout?

 

[lprizman]

I've done after others had and suggested it...zero issues....like I said... make dang sure you want it where it is...once that stuff sets up...you Ain't moving it!

 

[inAjet]

I've done after others had and suggested it...zero issues....like I said... make dang sure you want it where it is...once that stuff sets up...you Ain't moving it!

Good to know! Thanks for the tip. Would always prefer working with this stuff instead of epoxy if I can.

 

[lprizman]

Make 100% certain you want it there...do all your prep correct...cause once applied and set.... " It's over Johnny "

 

[inAjet]

You bet. I’ve worked with the stuff before, and it does the job really well - ONCE! Thanks for the reminder.

 

[inAjet]

So I as under the assumption all along that I was dealing with a wood core; however, it now appears that I may have been mistaken - which would be great news.

Maybe I could appeal to the trained eye of one of you more experienced boat builders on here to confirm from the attached photos that I am indeed only dealing with fibre glass here?

 

[lprizman]

Just fiberglass 10-4!