Fireball Centreboard Repair
This centreboard from a ten year old Winder-built Fireball was dropped off for repair.  I was much too polite to ask the owner the obvious question: "WTF did you do to it?"

The board is foam and epoxy filled, wrapped in glass fibre and gelcoat. Here is a close up:

A single bite would have been easy to repair with a bit of "kitty hair" glass and epoxy resin, then sanded and spray painted.  But this requires much more of a fill.  I choose to remove the glass and gel outer skin on both sides and re-lay new glass.  I start by marking the section to remove, on each side. Here is the port side.

My very good friend Mr. Dremel, with a cut-off wheel attached, makes short work of slicing through the outer skin.  I need to take care not to grind all the way through to the other side.  Peeling away the skin exposes the thickened epoxy interior.

Next, a "flapper sander" is fitted to Mr. Dremel, perfect for chamfering back the gelcoat and sound glass fibre to provide a solid surface to build upon.

Here is the starboard side...

The repair area has been carefully cleaned with acetone using an old toothbrush and white paper towels.

This tight weave length of e-glass has been cut from a piece of 100mm tape, with a stitched edge.

In preparation, a sheet of mylar film, as used in the printing industry, has been taped in place.  Epoxy resin will not stick to the film.

West epoxy and microfibres, mixing containers, a coffee stick, a brush and plastic spreaders.

I prefer to wet out the glass tape prior to sticking it in place.  The tape is on old piece sign writer's plastic sheet, the blue spreader was used to squeegee the neat epoxy resin into the glass tape, each labelled for port or starboard side.
West epoxy, thickened with microfibres to a mayonnaise consistency has been spread onto the repair area and then the wetted glass tape has been laid on top.

The mylar film has been folded over and excess resin squeegeed away to the edge.

  The same procedure was done on the opposite side, then the board was locked into the Workmate and a pair of 6 x 50 mm slip timbers were clamped in place, the upper edges of the slips exactly placed at the trailing edge line.  Most of my clamps were on anther boat in the marina, so I used the two remaining and fashioned "Spanish Windlasses" for the centre clamps.  

After 24 hours, the clamps and the mylar have been removed.  This is the port side of the centreboard.  The clamped slip timbers have forced the epoxy to ooze to the top, above the trailing edge, and a bit below, the clear ooze.  The browny colour is the microfibre thickener.

Here is a close up view, showing epoxy adhered to the previously sanded surfaces.  A small part of the glass tape at the top is dry and will be cut away from the trailing edge.

A straight line has been inked two millimetres above the trailing edge and Mr Dremel is cutting away the excess.

I use wet and dry sandpaper to begin sanding the epoxy at the trailing edge.  The reddish coloured block is my "long board," a piece of 4 x 2 planed timber with sanding sheets stapled to it.  I use water with washing up liquid to help smooth the sanding, hence the soapsuds.  It is easy to see the broken trailing edge through the translucent epoxy and fibreglass repair.  There is no powered machine that can do the sanding properly, all by hand, about one hour per side.

After sanding the epoxy, inevitable pin holes appear.  So a coat of white gelcoat was applied, allowed to dry and more sanding (thirty minutes per side).  Here is a close up of a small part of the trailing edge.  Pin holes and tiny blemishes have been filled.  The trailing edge has been sanded true using the long board and 800 grit wet paper.  The weave of the new glass is just visible.

The board was cleaned again, sanded with 800 grit wet and dry, then spray painted with Plasti-Kote gloss white.  Lastly, after the spray paint has fully dried, the board was wet sanded with 1200 paper, ready to race.
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