surfresearch.com.au  renwick : foam plastic board, 1958

In 1953, Bill Reid suggested a method whereby the blank was first covered with muslin cloth between two coats of a plastic sealer before fibreglassing with standard resin.
See:
1953 Bill Reid : Fun on a Plastic [Styrofoam] Surfboard.
Popular Mechanics Magazine July 1953 Volume 100 Number 1  pages 157-159.

This method was employed by some New Zealand surfboard builders in the 1950s-early 1960s, as balsawood and polystrene blanks were difficult to obtain due to import restrictions.

Stryofoam, or Coolite, in combination with expoxy resin was used for a short time in Australia by McDonagh Surfboards in the late 1950s.
The styrofoam-epoxy combination may have also been used by some American manufacturers.

The method became an accepted manufacturing method beginning around the mid-1990s, following years of intensive and expensive development by sailboard manufacturers, now comonly called epoxy boards

HOW TO BUILD A
foam plastic SURFOARD

Here's a plan you've all been waiting for. Building this surfboard is so simple that Grandma could do it. Cost won't be a problem either!

Eight feet is the recommended length for the board, but if you weigh over 13 stone it would be wiser to make it nine.
Cut one ft. each off two of the Coolite blocks and glue them together with Epoxy Resin so that the glued together Coolite measures eight ft. by two ft.
Stagger the small blocks of Coolite so that no single join extends right across the board.
Once the board is glued together .the top shape can be cut out.

The width of the board should be about  22 in.
The Coolite should be shaved away at the nose, from the underneath, and starting from about three ft. back.
The edges of the board at the nose should be very narrow, towards the centre they should be rounded and at the tail quite narrow, though not as narrow as at the nose.
Like the nose of the board, the tail should cut away from underneath until right at the tail it is about 1 1/4 in. thick or less.

Coolite can be shaped with a carving knife, or a bread knife.
It is extremely easy to cut.
Cut out the top shape and round the side roughly with a knife, finishing off with fairly fine sandpaper. It is important that the finish should be smooth, and extra work on the shaping will pay dividends in a much better final finish.

Once the shape is finished, the whole board should be covered with two coats of epoxy resin, which seals it from the chemical action of the normal fibreglass resin.

Now comes the time for laying the fibreglass.
This can be bought in lengths 54 in. wide.
It is laid in the board and cut so that it completely covers one side with a few inches hanging over to wrap around to the other side.
The resin is applied with a brush, working from the centre of the board out to the edges, and towards the ends.
Enough resin is applied to completely impregnate the cloth.
Rather than put all the little tips about fibreglass down here (they would be much too confusing) have a talk with the fibreglas (sic) dealer from whom you buy your materials.

Once you have completely fibreglassed one side, apply resin to the overhanging pieces which should wrap around neatly to the other side of the board.
Repeat this on the other side and then sandpaper off all the rough pieces.
More resin is now applied to get a glassy surface.

Fibreglassing is very easing - there are no complicated processes- but a talk with the dealer will cer- tainly be advantageous.
Use a thick brand of fibreglass cloth for the job, and don't spare the resin.

After the fibreglassing is finished the fin should be placed about one inch from the tail, secured firmly with fibreglass.

Father and son, Army and Greg McDonagh are pioneering in foam plastic surfboard development.  The boards behind them are (left to right),  pig board 9 ft.,  hot dog board 8 ft. 6 in.,  teardrops 8 ft., 7 ft. and 6 ft.,  and a bodyboard.

"Coolite" blocks are glued in  such a way that no join runs  the full width of the board.

Renwick, Ross:  How to build a foam plastic surfboard. Australian Outdoors November, 1958, pages 11 to 12. This article contributed by Mick Kershler, with many thanks, October 2008.

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