SB3 (20) bow repair
 
 
The National Yacht Club annual regatta was sailed last Saturday, 23 June, in rather boisterous conditions of 20 - 25 knots.  In the SB3 (SB20) fleet, a couple of boats were damaged.  Above, a bad bang at the bow.

Below, a closer look at the crushed laminate on the bow.
 

MONDAY, 25 June
Mr Dremel with a grinding wheel is the man to cut away the damaged area.

Here is the opening after all of the damaged fibreglass has been cut away.

One of two chunks of de-laminated fibreglass after cutting it away from the hull.

The laminate is quite thick, and so is the the gel coat (grey layer at the bottom).

I create a "blind backer" from from a sheet of fibreglass made up at home. 

The inside of the hole has been sanded and washed with acetone.  A mix of epoxy resin with microfibres was liberally smeared on the inside and also applied to the edges of the backer.  The backer was then inserted into the hole and the strings serve to pull it tight to the inside, thus providing a solid surface to laminate upon. 

The strings were tied to various points on the trailer and tightened with sticks to make a spanish windlass.

Finally, with my surgical gloved finger, I wiped away excess epoxy ooze and left it to cure overnight.

Time involved:  one hour
 

TUESDAY, 26 June

The backer has fully cured, the strings have been cut away and Mr Dremel with a coarse sanding drum has chamfered the edges of the repair area.  The backer was sanded with 80 grit to provide better adhesion and thoroughly washed with acetone.

Three pieces of "combi mat" have cut to size and numbered, each a small bit larger.  Combi mat is a powder bound layer of chopped strand mat needled to a layer of woven roving. Very strong.  It is much easier to laminate each layer with resin using a plastic squeegee on each side rather than trying to tack them each in place and saturate with a brush.  That's a piece of white sign makers plastic that I am using as a laminating board. 

Each layer has been placed on top of the backer using gloved hands, hence no pictures (I don't want epoxy on the camera!)  Because it is a very warm day here in Dun Laoghaire, I don't want to apply more than three layers lest the epoxy "kick off" or exotherm too quickly which would result in a possibly weak repair.  A piece of see through polythene has been placed over the three layers so that I can poke and prod the laminate tight and smooth.  When cured, the plastic simply peels away.

Time involved:  one hour