Drilling the hull

[Tugw]

Im looking at installing a extra bilge pump and would need to drill the hull for the skin fitting,The drilling is not a problem or the installation of the pump but is there something i should be doing with the inside surface of the new hole?
(i mean the exposed glass fibre after i drill the hole)

any help/tips gratefully received

 

[prv]

When I did it I painted some epoxy on the inside of the hole, to stop any possibility of water wicking along the fibres. Don't know if it was strictly necessary or not, but seemed sensible to me.

Pete

 

[Old Troll]

Drilling the Hull

I am not an expert and no doubt others will be along to give advice. When I drilled the hull to put in for example an extra seacock I drilled the hole slightly oversize and then filled the hole with epoxy resin. Trying to keep neat and tidy prior to sanding off as if a finished job. On the epoxy hardening I then drilled the hole required to size. I have followed this procedure above and below the waterline when drilling holes and believe this method to be okay.

 

[flipper]

I am not an expert and no doubt others will be along to give advice. When I drilled the hull to put in for example an extra seacock I drilled the hole slightly oversize and then filled the hole with epoxy resin. Trying to keep neat and tidy prior to sanding off as if a finished job. On the epoxy hardening I then drilled the hole required to size. I have followed this procedure above and below the waterline when drilling holes and believe this method to be okay.

+1

Lots of advice and user manual downloads on the Wests site - very useful:

http://www.westsystem.com/ss/use-guides/

 

[Tugw]

Both these ideas seem OK to me,Its the thought of wicking that bothers me,the skin fitting will be a good 18" above the waterline but i still get the feeling something should be done with the rough glass.

 

[Old Troll]

Drilling the Hull

Also "Sailboat Hull and Deck Repair" by Don Casey published by The International Marine Sailboat Library is an excellent book and is good value for DIY repairs.

 

[VicS]

Both these ideas seem OK to me,Its the thought of wicking that bothers me,the skin fitting will be a good 18" above the waterline but i still get the feeling something should be done with the rough glass.

I would have thought that if you fitted the skin fitting properly with some decent sealant that would seal it all quite adequately.

If you try that and find in ten years time I am wrong please dig me up and let me know.

Mine were fitted 35 yrs ago using nothing more special than Sealastik. There is no evidence of any problems

 

[Caer Urfa]

I would have thought that if you fitted the skin fitting properly with some decent sealant that would seal it all quite adequately.

If you try that and find in ten years time I am wrong please dig me up and let me know.

Mine were fitted 35 yrs ago using nothing more special than Sealastik. There is no evidence of any problems

I totally agree with VicS, I have drilled many a skin fitting up to 40mm dia over 35 years of boats, clean the hole up after drilling and use say Sikaflex 'BOTH' sides then tighten up and leave to set.

One tip, 'always' check before you drill from the outside that the 'inside' of the hull does not have a bulkhead or stiffening rib at the back of it AND you can access it.

If your boat sinks you will have two of us to dig up!

Mike

 

[davidpbo]

You will see from my other posts that I am no expert on fibreglass but I would have thought best practice was to seal the inner surface of the hole in some way, at least a coating of epoxy or as other have said, drill oversized, fill then drill correct size. It is what I have bee told to do for shroud fixings.

 

[prv]

drill oversized, fill then drill correct size.

That's vital for cored decks (or cored hulls if you have such a thing). But I can't see any benefit of it on a normal solid hull layup.

Pete

 

[VicS]

You will see from my other posts that I am no expert on fibreglass but I would have thought best practice was to seal the inner surface of the hole in some way, at least a coating of epoxy or as other have said, drill oversized, fill then drill correct size. It is what I have bee told to do for shroud fixings.

With shroud fittings or any other through hull or deck fittings that are stainless steel or use stainless steel fastenings it is vitally important that the fittings and fastenings are properly sealed to prevent water ingress into the joint.

These are prime sites for crevice corrosion of stainless steel and this is your no 1 enemy here.

If sealed to prevent crevice corrosion causing water ingress there will be no problem from water entering the GRP layup.

 

[davidpbo]

In my case I do have a cored deck, but I would be tempted to seal the inside of any hole in addition to any other necessary sealant.

 

[LittleSister]

The related question is whether there should be a strengthened area and/or backing pad to spread the load, as recommended in some circles, especially for a tall skin-fitting/sea-cock/hose-tail assembly that could get knocked around or pulled about and exert a lot of leverage.

 

[Tugw]

A good "sikaflexing" it is then---thanks all

 

[Boathook]

A good "sikaflexing" it is then---thanks all

I would also add a backing pad with a chamfered out side edge. Stops the hull flexing by the hole and braking the plastic fitting - it does happen !