Drilled a 35mm hole through cored deck- sealing the balsa?

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FairweatherDave

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Fitting the swan neck cable outlet through the deck by the mast. Planning to use butyl as the sealant at the top under the lip. Was thinking a skim of resin on the exposed balsa before inserting the swan neck? The whole thing is held in position by three bolts through the deck but it is not "load bearing" unless someone stands on it.
Swan neck looks like this
https://www.force4.co.uk/force-4-st...MI4qfo5uiY2QIVLrXtCh18ywm2EAYYASABEgLezfD_BwE

So is a resin (or an aryldite) skim a step too far? I know some might use sikaflex or equivalent but I have butyl already which has it's own virtues.
 
No, far from it. I seem to remember the correct way of doing it is to rake out some of the balsa around the whole until you can get some epoxy resin /mat/ filler in the void left. If water gets into the balsa it will rot it away then you are in the doggy-do
tross
 
Personally, I would remove a 10mm or more wide ring of the core, and fill with a mixture of glass and epoxy.
 
lw395 said:
Personally, I would remove a 10mm or more wide ring of the core, and fill with a mixture of glass and epoxy.
Click to expand...

+1, except a stiff mix of epoxy plus microfibres is more than strong enough and easier to handle.
Technique is:
cut hole to 35mm;
rake out balsa core 10mm all round. (Sharpened Allen key in a drill works well for this);
seal the entire underside of the hole - several layers of parcel tape usually suffices;
fill the entire hole with epoxy mix, being careful to push it into where the core has been removed;
cut 35mm hole again in the centre.

This also resists any tendency for the fitting's fasteners to compress the deck.
 
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macd said:
+1, except a stiff mix of epoxy plus microfibres is more than strong enough and easier to handle.
Technique is:
cut hole to 35mm;
rake out balsa core 10mm all round. (Sharpened Allen key in a drill works well for this);
seal the entire underside of the hole - several layers of parcel tape usually suffices;
fill the entire hole with epoxy mix, being careful to push it into where the core has been removed;
cut 35mm hole again in the centre.

This also resists any tendency for the fitting's fasteners to compress the deck.
Click to expand...

+1

using WEST SYSTEM® 402 Milled Glass Fibre filler should give the best and strongest result ... overkill probably but you got to use something so might as well go the whole hog.

http://www.westsysteminternational.com/en/fillers/west-system-402-milled-glass-fibre-blend

Plastic padding, or similar, car body filler would make a reasonable job of it provided the swan neck was sealed in adequately, after all that's polyester resin based like the boat!
 
Excellent. Consensus...... Thanks all.
I have rebedded stanchions and grab rails before as people have described. Hence why I was uneasy and posted. It's just that its a much bigger diameter hole so lots more epoxy (or whatever). I've used the allen key trick plenty with rotten balsa but this is solid balsa and a bigger hole so less to guide the drill as it thrashes about.....
More importantly it's not exactly fibreglassing weather and I wanted to get on with reconnecting the electrics having had the mast down. So I shall butyl the swan neck temporarily until the weather warms up. I made the big hole yesterday as I wanted to get the mast cable ends out of the weather. Someone tweak the thermostat please!
 
macd said:
+1, except a stiff mix of epoxy plus microfibres is more than strong enough and easier to handle.
Technique is:
cut hole to 35mm;
rake out balsa core 10mm all round. (Sharpened Allen key in a drill works well for this);
seal the entire underside of the hole - several layers of parcel tape usually suffices;
fill the entire hole with epoxy mix, being careful to push it into where the core has been removed;
cut 35mm hole again in the centre.

This also resists any tendency for the fitting's fasteners to compress the deck.
Click to expand...

Rather than filling the whole hole with epoxy mix, I would probably use a former of wood wrapped in plastic to take up most of the 35mm. Saves a lot of drilling. Obviously ensuring the void around it is completely filled with resin is key.
 
If you have mains, then gently use a hot air gun to warm and dry everything.
Obviously not in the rain, a dry hour is all you need.
I quite often wam the epoxy as it goes on to the job.
Don't warm it to more than say 35degC in the pot as it may set very quickly!
 
If you want the best structural filler to mix with the epoxy use West High density filler. Prime everything first with unthickened epoxy. I mix colloidal silica in as well to stop in dripping or drooping (neither of which is popular!).
 
VicS said:
+1
Plastic padding, or similar, car body filler would make a reasonable job of it provided the swan neck was sealed in adequately, after all that's polyester resin based like the boat!
Click to expand...

Do NOT use vehicle body plastic pudding. It'll eventually act as a conduit for salt water into the balsa core. Stick to marine epoxy + a suitable filler. I have had great chunks of it fall out of holes patched with it by a previous owner. The first sign was blisters in the finish caused by water getting in and then evaporating. I can only hope that I've found all of them now.
 
Epoxy, HD filler and colloidal silica. This is the best way to do it! Honest, there is no better way! What would I know, I'm just a boatbuilder!!:o
 
Came to me in a brief spark of clarity in the night why I posted this. I may be wrong but my original post describes how Westerly would have done it, (when they built the boat)?.... they would have relied on the sealant at the top (and left the balsa vulnerable).
 
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