Screw holes in varnished wood

[Fascadale]

I plan to attach a varnished piece of wood to the outside of the hull.

Having spent hours applying coat after coat of varnish I'm not sure how to deal with the screw holes.

How do I make sure no water penetrates round the screw head ?

Thanks

 

[samwestwood]

I suppose you could put some varnish into the hole and coat the screw thread to be sure tighten up and clean excess.

 

[wooslehunter]

Best way is to plug the holes with wooden plugs glued in. Then varnish over the top. The screw holes have to be counter drilled so the heads sit well below the surface. If you cut the plugs from an ooffcut & make sure the grain runs in the same direction you can make it almost invisible.

Look up plug cutter on google & you'll find cutters for both the plug & the counter bore.

 

[rogerthebodger]

On my previous boat I bolted the rubbings on to the side of my boat and then glued a scond layer of wood over the top using PU glue . First layer sealed with sikaflex.

Result no screw holes showing on outside and no break in the surface varnish.

 

[Refueler]

Blob of varnish into hole before screwing up ... make sure screw head can sink in a touch ... then wood stopper, a sort of clay that is used to fill wood cracks etc. You can get it to match the wood you have. Only problem is it dries out and sometimes shrinks a touch - so once that happens you apply a little more to fair off.
Stopper is waterproof and used to be the standard material to use on rubbing strakes.

 

[Poignard]

That's a clever idea but how did you clamp the outer piece onto the inner piece whilest the glue set? Was the rubbing strake near enough to the gunwhale to enable the use of G-clamps?

Reason I ask is that, in my experience, polyurethane glue foams as it sets and exerts a powerful force pushing the joint apart so it has to be well clamped.

 

[jon]

If you wish to remove the piece for easier varnishing in the future, I would recomend a recessed machined screw cup stuck in with epoxy before varnishing, cleaning out the countersunk, and drilling out. You could also use some non setting mastic around the head of the screw.

 

[rogerthebodger]

Yes the rubbing strips were near the gunwhale but I could not use G-clamps as it was on my ferro hartley.

I made up some special angle type clamps that was clamped with U-bolts to my stanchions and went along the top of the deck and down the side of the hull with tapped holes for the clamping screws to hold the second layer of wood while the PU glue set. I also used G-clamps vertically to align the sides of the two layers of wood. This at the stanchions also helped to hold the angle clamps in place.

Dont have any pics of the operation else I would post some.

 

[absit_omen]

Second vote for wood plugs. Simple, cheap and - although you will see the plug - it should look as though it is meant to be there.

 

[Danny Jo]

Jon's is the most elegant solution. Or, with two layers of epoxy, you can get away without the cup. Counterbore the screw hole 0.5mm larger than the outside diameter of the screw; and as Jon points out, it will need drilling out again when the epoxy has set. Tighten the screw gently by hand or at a lowish torque setting on the clutch of a power driver.

Or, if you are sure you are never going to want to remove the screw, recess it, set it in epoxy and epoxy in a wooden plug to cover it.