Filling a hole in a grp /balsa deck

[anubis]

Apologies if this has been covered already in detail. Just quickly I have two 10mm holes through the deck which need filling. I have access underneath...what is the best method? Deck is a GRP Balsa sandwich. GRP /Balsa core /GRP below. Many thanks
A

 

[oldsaltoz]

G'day Artic,

Make sure it's dry.

You just need to remove a small amount of the balsa and fill with an epoxy and suitable closed cell filler.

Micro Balloons would be OK, but Micro Spheres might be better as they are white and may be easier to cover.

To remove the small amount of balsa, I use a standard drill with an Allen key, just cut the short end off at an angle and drill away, ensure the material that falls out is very dry.

Stick some tape over the hole below deck.

After curing you will to add some paint or Gel-coat to avoid UV damage to the epoxy.

Avagoodweekend......

 

[Birdseye]

I simply used some gaffer tape to block up the holes from beow and poured a mix of epoxy thickened with micro fibres into the holes to just below surface level. Leave to cure, abrade the surface and finish with gel.

Epoxy is wonderful stuff. Sticks like the proverbial. Still have some stuck to a pullover from a job I did 10 years ago.

 

[snowleopard]

In fact you should use the same technique when making new holes in balsa core. Drill through the laminate, remove the core for 1/2" around as oldsalt describes, fill with resin and allow to set, then drill the final hole. You now have (a) sealed the core to prevent water ingress and (b) provided a pad between the layers so you can crank your bolt up tight without squashing the core.

NB Oldsalt is Australian. You will need to put tape over the opposite side of the hole to prevent the resin running out.