Sealing a skin fitting hole

[saltyrob]

Hi ,

I raised the subject of capping off a redundant, below the water line, skin fitting a while back, but have decided that removing the skin fitting and sealing/glassing over the hole is the best solution. Advice on how best to carry this out would be gratefully appreciated, The hole is approx 1.25 inch redundant holding tank outlet.

Many thanks and good wishes to everyone for a happy and safe forthcoming season

Rob

 

[catalac08]

I would grind out each side of the hole tapering to about 4 inches diameter (assume that hull is 8mm this should give about a 6:1 taper) and proceed as follows. At the centre cut a piece of woven cloth suitable for EPOXY resin and stick this in the centre using a little thickened epoxy and stiffen the cloth with epoxy on it. When this has gone hard but still tacky you have something to press against for laminating so proceed to layer it up with increasing sized layers of cloth/thickened epoxy from both sides. You cannot do it all at once as it will get too hot so 2 sessions of laminating is best but whilst the epoxy has just gone hard otherwise you would need to sand down the epoxy to get a good key. For peace of mind the inside you can finish with a bigger layer. Finish the outside slightly low and finish flush with polyester gelcoat of the appropriate colour but only after a week or two when the epoxy has fully cured and then flatten and polish to finish.

 

[Tranona]

While that is a good procedure if it is structural it is a bit OTT for filling in a small hole. If you have good access on the inside, grind the hull surface clean and laminate a patch about 10cm larger all round than the hole using 2 layers of glass cloth and epoxy, plus an extra layer 5cm larger all round to blend into the hull. Grind a taper on the outside edges of the hole then build up with epoxy glass to fill the hole. Finish with a coat of epoxy to fair with the hull, then prime and antifoul. No real need for a gel coat or getting a superfine finish below the waterline.

 

[VicS]

I have a similar job waiting for some warm weather although a hole just over 2" diameter


The technique is as above to grind a taper around the hole but ITYWF that the recommended taper is 1:12 ... that makes a big area though in a thick hull.

I found a coarse sanding disc on a small angle grinder the best tool .. the angle grinder itself was too aggresive.

You cut a series of circles of glass mat ranging from the size of the hole up to ( almost) the size of the prepared area and prepare a patch to lay into the prepared area . The largest circle is the first one onto the laminate overlapping the whole of the prepared area .. the samllest the last one, ie outermost one
(Support is required for holes over 1".)

For detailed instructions

see the Wessex resins user guides
http://www.wessex-resins.com/westsystem/use-guides.html

and in particular the "Fibreglass boat repair and maintenance" pdf

http://www.wessex-resins.com/westsy...glass-Boat-Repair-and-Maintenace-Jan-2012.pdf

 

[catalac08]

While that is a good procedure if it is structural it is a bit OTT for filling in a small hole. If you have good access on the inside, grind the hull surface clean and laminate a patch about 10cm larger all round than the hole using 2 layers of glass cloth and epoxy, plus an extra layer 5cm larger all round to blend into the hull. Grind a taper on the outside edges of the hole then build up with epoxy glass to fill the hole. Finish with a coat of epoxy to fair with the hull, then prime and antifoul. No real need for a gel coat or getting a superfine finish below the waterline.

On reflection this is probably easier and quicker than my way and of course there is no need to gelcoat under antifoul.