Repairing a stripped screw hole in bilge floor

[MattS]

I noticed that one of the screws holding the bilge pump strum box to the bilge floor has come loose. The hole looks like it might have stripped, and has cracked a little around it anyhow.

It doesn't look like the screw was previously applied with any sealant etc. so I'm guessing that on the rare occasions that water has collected under the cabin sole it could have soaked into the fibreglass a bit.

I have no idea whether there is any kind of wooden core in the hull of the boat, or if it's solid fibreglass? There was certainly some fibrous material that came out with the screw.

On the assumption that I need to do a 'proper job' to make sure the strum box is attached properly and that the screw hole is sealed, what steps might I need to take?

My starter for ten:

- Make sure the hole is left exposed and kept dry for as long as possible (there's no massive rush to reattach the strum box I don't think)
- Fill the hole with something (epoxy?) - maybe I need to drill it slightly larger before doing this?
- Drill a pilot hole in the epoxy for the screw
- Re-attach the strum box, using some sealant around the screw to try and seal what hole is left

Does this sound right?

Anything else I need to consider or check?

 

[Daydream believer]

Make sure that you do not use longer screws. You do not want to end up screwing the boat to the dock, otherwise you will not be able to go anywhere

 

[PlankWalker]

Why do you need to screw it down?
Any screw hole in that vicinity is a recipe for water ingress,
mine, same as yours, has been left unscrewed for donkey's years, and hasn't moved much.

 

[ghostlymoron]

I'm always wary of screwing to the bottom of the hull in case the screw protrudes through it. If you want to ensure it doesn't move, stick it down with Sika or something cheaper.

 

[Sea-Fever]

I would fill it with epoxy and forget it was ever a hole, I wouldn’t drill into my hull….asking for trouble.

 

[Restoration man]

That is seriously clean bilge

 

[mikegunn]

I would suggest installing a stainless steel blind self tapping insert, Say M5 x 10mm, but other sizes are available. Firstly, ensure that the affected area is thoroughly dry. Next screw in an insert, which will cut its own thread into the fibreglass. Then, remove the insert, coat its external thread with Araldite and reinstall. When set the strum box can be refitted using M5 set screw(s) of suitable length and heads of choice. Sealant will be unnecessary and the strum box can be easily removed at any time.
Incidentally, I have found blind self tapping inserts to be invaluable when needing to ensure that water cannot run along a thread into another area.

MIke

 

[Slowtack]

Just glue.. No screw... As he said

 

[William_H]

Previous commenters seem to think that the screw taps straight in to the hull. I doubt that is the case if it is, one would be horrified. Normally there would be a piece of wood or similar glued to the hull for attachment of the strum box. In which case not too much worry about just adding epoxy and replace the screw. However if the box is screwed down to the hull I would remove all the screws and fill holes with epoxy then glue the box down or use a false floor. ol'will

 

[Stemar]

I'd fill the holes and, if I think it necessary to hold it in the lowest place, stick the box down with a small blob of external grab adhesive - not too much, you may want to get it off again! It's far from critical, so Toolstation's cheap and cheerful would be fine.

 

[MattS]

Thank you everyone. I'm so glad that the overwhelming advice is "don't screw it to the hull". This was my initial gut reaction, and it's good to have that validated. I don't like the idea of any unnecessary holes in my hull, no matter how small / shallow... there's no evidence of a false floor for it to be screwed into so I have to assume it's straight into the GRP... idea of a hole into the GRP with seawater seeping into it seems bad to me!

That is seriously clean bilge

And yes - I'm really lucky (touch wood) for a 36 year old boat - they're generally bone dry other than a little fresh water ingress from *somewhere*! Which is why I stand a good chance of actually getting the holes dried out so I can fill them and pretend they never existed...

 

[mucklestone]

Other vote from me to fill the hole with epoxy and either leave the box loose or secure it other way.

If the bilge is shallow a piece of scrap foam on top could wedge it down under the soul boards