Part of the magic of the strip and feather style of building hollow wood boards is the internal fishbone frame defines the rail shape. This is HUGE for homebuilders attempting to build their first board. Building styles that utilize solid rail construction require the builder to have a solid knowledge of the hydrodynamics involved in creating rails that will perform well in the water.
If you can “fair” a curve, you can shape rails that will perform as well as a professional shaper surfboard shaper. This tutorial will teach you how to easily create symmetrically fair rails in minutes. This is a super rewarding part of building your own board that I personally wish took longer. There is something very cool, and satisfying about working with hand tools.
Board with completed rails
This is our goal! Nice fair curves that evenly match the internal fishbone frame contours. Since 95 percent of our shaping is done before the top skin is attached it is very easy to achieve the desired result. To shape this curve we will make a series of straight cuts at increasingly shallower angles. Most rails are quite round in the middle of the board and harder towards the nose and tail. Since we are only starting with .25″ of material our goal is simply to “fair” the curves and the only real shaping occurs in the bottom .5″ of the board where the starter strip meets the bottom skin.
The first step is simply to remove the excess material from the bottom skin. For a surfing shape this is pretty close to the shape of the tail of the board so that it will bite into a wave. I usually lightly mark the bottom of the rails where I have switched angles. Working from the tail for example: 0-12″ at 30 degrees, 12″ – 18″ at 45 degrees, 18″ 30″ at 60 degrees, etc. (I will write another tutorial showing how the rail shapes progressively get softer as you approach the middle of the board.)
As we move towards the middle we just keep taking shallower cuts. Try to keep the angles flat to start so that you can compare one side to the other.
The middle of the board gets another pass as the rails move towards either a 50/50 (apex in centre) or 60/40 (apex just below centre).
This is the final pass that is only used in the middle 1/3 to 1/2 of the total boards length. It is actually pretty hard to mess this up. The only real mistake I have seen is builders stopping up at the 30-45 degree range above and having harder rails than desired. Just by reading this far you will know that the centre is always at least in the 45-60 degree range.
The starter strip is your friend! As you are shaping in the middle of the board you might cut into the starter strip. This is perfectly ok and maybe even desired. The appearance of this strip should be a HUGE warning to should slow down. The strip is only 3/8″ wide and we want as close to 1/4″ of material all the way around the rails. As soon as you see this strip you should check for symmetry from one side of the board to the other and start thinking about stopping at this point. (I usually do not see the starter strip before the top skin is applied and I am doing the final shaping.) If you have the starter strip visible for 3′ on one side it should also be visible on the other side for the board to be symmetrical.
Now that all the primary angles are cut you can “fair” the ridges by halving the angles. Simply take very thin light passes using the longest tool that you can and you will have perfect rails in a very short amount of time. I like to start with a drawknife to remove the bulk of the over hanging material. You do not need to buy one if you do not have one as you can achiever the same result with a spokeshave or block plane. Longer tools are a wise choice to start as they help keep things fair and prevent following the hollows. A spokeshave is lighter and allows you more dexterity and is the only tools that can be used as the nose kicks upwards.
If you go slowly with sharp tools you will have no problems. Your rails should remain closer to the 1/4″ thick and not get less than 3/16″ thick or they should be strengthen by adding epoxy and cloth to the inside surface. You can use you fingers to check the thickness as you work.
As you are shape the bottom rail you should watch for the outline strip to appear. This hidden first rectangular strip was the first strip applied and means you are close to the final shape. At this point you should be trying to smooth out the transition from rail to bottom panel.
The 50/50 rail in the middle of most shapes has a smooth radius and not a soft corner like you see near the nose and tail.