Shaping the 'Rampant 10-5 concave hull design

Today the 'Rampant' surfboard hull design starts to take shape. The plan shape is cut out a quarter inch outside the marked line. In this case it has been done on a band saw, but a hand saw does just as well. Using the band saw is quicker but requires two people and a lot of space as the board rotates around the saw during the cutting. The board is only 2 & 3/8" thick, it looks thicker at this stage because the rail is square. The rocker curve can be seen here. It is identical to that used for the 'Hotkurl' 10-5 pintail.

Rough cut paulownia 'Rampant' surfboard

Once cut out, the board's rail is sanded down to the planshape line with a hand held belt sander. It's important to keep the sides of the rail at right angles to the bottom of the board, so we check this frequently with a 'T' square. This task must be done as perfectly as possible as any bumps and hollows ignored now will show up later, since the lines which will be marked for the first rail facets are scribed from the finished curve.

Five layer parallel profile surfboard blank

It's always encouraging to have the fins ready and waiting for the surfboard hull to be completed. These Kahikatea fins use the same tunnel plus one setup used for the Hotkurl, this time with a powerful 6 inch diameter vort-X  tunnel rather than the four inch  tunnel used on the 'Hotkurl' and the larger 'Makaha' 12-9 longboards.

Dynamic fin design

Even with a power tool fairing the curve took five hours. Next we'll be cutting the first rail facet, which is when the shaping starts to get exciting. The weight of the craft at this point is 30 pounds. Extra thickness has been added to the deck and bottom panels (10mm compared with 5mm on the 'Hotkurl' in order to allow for deepening of the bottom concave and deck shaping)

Fairing the planshape curve