How To Cut The Bow Angle

How To Cut The Bow Angle
By David "Shorty" Routh

If you have been around boat plans for a while, you might have noticed that our specified class legal side panel is measured a bit differently than most of the plans out there. Most boat plans start from a straight edge on the top of the panel, then have 2 measurements down. The first is for the curve of the gunnel, and the second is for the rocker curve. Since our boat has a variable height gunnel that is determined by the builder, the side panel is measured from the bottom up. That way you can use the same dimensions for drawing the rocker, no matter what height or shape of your gunnel, or side panel.

There is only one slight problem, if you are building a hull that is anything other than 18" high, then the overall length is going to be different than 8', and you have to understand how to measure, mark and cut the proper bow angle. To understand this, lets look at making an 11" high hull such as the very quick to build, plank style of construction.

The shaded area of this sketch shows a standard 18" high hull. The white area shows an 11" high hull, which is shorter in length to make it class legal. So as you go to cut the side panel from a 1x12, you dig thru your old school supplies to find your protractor, or possibly make a trip to the store and buy one just to come back and discover that the bow angle isn't marked on the class drawing! Well, it doesn't need to be marked, and you don't need the protractor which is a common cause of many boat building mistakes.

To properly measure and mark the bow angle, one simple method is to clamp another board behind your side panel so that you can measure 18" up, and and mark from there.

The next problem might be if you are making a hull that is higher than 18", or want to make a hull longer than 8'. This sketch shows 2 possible hulls, one that is 24" high and the other is around 20" but has a bow that curved out with an additional bow sprit. To make them class legal, the lower 10" has to be identical which is the shaded section. Notice the kink in the bow, that is where you can transition from the required hull shape to your particular custom hull shape, if you wish.

NOTE: Rule 5 stipulates that external floatation chambers are prohibited, be careful when you extend either the bow or stern to make sure that the extensions do NOT touch the water, otherwise you could be disqualified for having external floatation.

So as you can see, there are a lot of possibilities for making a variety of hulls that are class legal, just have to understand to keep the lower 10" the same, including bow angle as specified.

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