DIY Retro Twin Fin Surfboard, Part 2: Tools & Shaping

Once the design of the board has been decided, it is time to shape. When researching how to make a board the majority of the stuff I read said use a template, then conveniently posted a place to buy said template.

Tracing out the retro twin fin.

Well, I saved a few bones and went free hand, marking measurements off the stringer every six inches the entire length of the board, both sides, to give the design some symmetry. The shape, as I mentioned in a previous post, is retro twin fin, with a quasi longboard nose (rounded with a bit of a point), tapers in the tail, with a channel running along the bottom. Lightly drawing by hand with a pencil, I ran a line along one side of the board to a predetermined point measured from the stringer. Once the line was correct, I measured every six-inches and mapped them out on the other side. Then I took a Staedtler 24-inch Flexible Curve ruler and bent it to match the drawn line. Using the curve of the ruler, I traced it out along the other side with the mapped out measurements, finishing the nose. I repeated this the length of the board, making it as symmetrical as possible before cutting the board. Once the board is traced out, look at it, envision it cut, shaped and ready to ride. If its off, tweak until it is perfect. But remember, this foam is incredibly soft and easy to take off more than expected. So for the first time board maker, I suggest giving an extra inch to the overall width (half inch all the way around), there will be an inevitable mistake or two, so that extra foam will help when shaving down the blank to make it uniform.

Cutting out the retro twin fi

Using a jigsaw, I cut out the board. When cutting the blank, maintain a 90-degree angle with the blade in relation to the blank, this will help maintain the dimensions originally traced out. The rest of the shaping process was all through hand-tools and good old elbow grease.
There are two trains of thought on shaping: electric and hand-powered. Most pros go power because, well, they are pros. Using power planes, power sanders and routers is great, but most people do not have these tools. And for a first foray into building a board, I would shy away from the power tools; the power planer will eat through the foam in the blink of an eye, and a random orbital sander will put 'smiles' throughout the blank, requiring hand sanding to even everything out while reducing overall foam volume (i.e. floatation). The board will be ruined well before it is glassed.


Surf stands are a key part when making a custom board. I would suggest making a set before undertaking the project. For this first board, I had some padded stands used for boats, but for next project, a set of stands will be the first on the 'to do' list.


Going sans electric (minus the jigsaw and a few steps down the line), I used the whole portfolio of Stanley Surform hand tools, a 6 ½-inch block plane, a Fred Tool for the rails, block sander (hand sized and a flexible custom 22”x3 ½” closed-cell foam ditty I put together), and sandpaper [80, 120 and 220 grit].

Hand tools of the trade.

Shaping is tedious but essential to the overall performance of the board, so take ample time and maintain a close eye to detail; and remember, symmetry is key to a smooth riding board! I started with planing down the stringer, then sanding my way to the rails. I suggest a lengthier block sander, the smaller ones will put dips all over the foam, while the longer ones tend to follow the line and give a smoother, cleaner finish. Sand with complete tail to nose strokes, parallel to the stringer but stop sanding at the nose curve (about 4 ½ feet up from the tail on my board)! It is very easy to gouge into the nose curve, causing a rather unsightly gash and weakening the overall strength of the board. So once the curve has been reached, begin sanding perpendicular to the stringer, gently following the natural curve of the deck of the board. Smooth by hand if needed, but a block should be all that is needed.


Remember, do not to concentrate solely on the deck. Though these preformed blanks come pretty clean, the bottom still need to be fixed up and shaped. Don't take too much off the deck, or it will leave very little room for improvement below.


The bottom is much easier to shape, essentially following the curvature already in place. Take a large block sander and follow the curve smoothly and evenly, with long continuous strokes. When hitting a dip, continue easy strokes and fare it out versus small scrubs, this will only accentuate the problem.

 

 

Shaping the twin fin. Enjoy the Shore Life!