The thickness flow, or foil, refers to the distribution of foam from the nose to the tail while looking at the side of the board.

Consider the board as being divided into three parts: the front third or nose, the middle third, which supports your torso when paddling; and, the rear third or tail area. The transition between these areas should be very smooth and flowing. Varying the amount of foam in a particular area will alter the way the board reacts and performs. The thickness of the rails should be even and consistent from side to side. Experienced shapers can feel and sight blanks with amazing accuracy. Any asymmetrical or unfunctional dips or bumps apparent to an uneducated eye would be an indication of an unprofessional shape job.

Boards should be matched to your body weight. Take into account that a wet full wetsuit weighs about nine pounds. The thickness of a board is essential for support while paddling, catching waves, and riding through slow or flat spots. The faster the wave moves you, the less thickness you can get by with.

Nose thickness – Some surfers feel that thinner noses react faster to turning input. With a thinner nose there is less weight at the nose that the surfer has to swing when turning.

If the rails just ahead of the wide points are too thin, they sink into the face of the wave when the surfer moves forward in trim. This causes the board to pivot around the wide point. When this occurs it causes the tail area to release from the face of the wave, which results in slide or drift and disrupts control.

Middle Thickness – The thickness of the middle part of the board should be set according to weight or preference.
Most boards are between 2 1/4″ and 3 1/4″ thick. If your weight or preference demands more floatation, width is added to the template dimensions.
A board that is too thin will paddle and catch waves poorly. When paddled, or ridden at low speeds, excessively thin boards feel sluggish as though they are dragging through the water.
A thick board will paddle and catch waves easily. When ridden, excessively thick boards may feel excessively buoyant, making them resistant to being leaned on edge and difficult to control. thicker boards are stiffer and less likely to break in half than thinner boards.

Tail Thickness – Thicker tails make the board paddle and catch waves easier. Thicker tails turn more easily and carry speed in slow, small surf better because they don’t sink and drag.

Thinner tails provide more positive control. They hold in better in fast and hollow surf.

With single fins one limitation a shaper has been shaping tail thickness involves the fin box. The box is about one inch thick and its rear edge should be no further than six inches from the tip of the tail. If your weight or preference demand a really thin tail, get a glassed on your fin.

Deck Contour – The deck contour refers to the shape of the deck 90 degrees to the stringer. Some shapers utilize flat decks while others use a domed (also referred to as crowned or rounded) deck contour. Most contemporary boards have fairly flat decks because of thin overall thicknesses utilized in conjunction with full, boxy rails. This keeps the thickness quite uniform from rail to rail, resulting in a flat deck contour. A shaper may utilize a thin, tapered rail that is easier (especially for a smaller, lighter surfer) to sink and lean on edge. A shaper may concentrate or increase the amount to foam down the stringer (mid-line) of the board to maintain or improve flotation when a thin, tapered rail is required for control. this is typically utilized on gun boards, as a thicker stringer is more resistant to breakage. A rail that is thin in relation to the stringer thickness results in a domed deck contour as the thickness smoothly tapers from the thicker stringer to the thinner rail. Deck contours influence the way a board feels when you pick up, paddle it and ride it. Note the types of deck contours you’ve grown accustomed to and keep that in mind when evaluating a new shape.