I've been studying the kits available for a future build and I have found that in the Shearwater 17 kit, for instance, if you click on the "complete kit", all the parts are listed and it states the kit comes with 360 feet of western red cedar strips and 160 feet of white cedar strips.  I don't know what length the strips would be but probably 6 to 8 at 18 feet and the rest diminishing in length down to 6 feet or so.  I think you could also order the strips alone from CLC.

If you don't want to do the math then One Ocean Kayaks has a strip calulator. Nick Schrade has just created one as well over at Guilemot Kayaks.

It'd be so much easier in metric, but even in feet & inches it's not that difficult, especially if you're willing have a little extra on hand. You just pretend that the boat is rectangular instead of pointy.

1. First multiply the length of the boat in inches by the max beam in inches to get surface area in square inches

2. Divide the surface area by the width of the strips in inches to get strip amount in linear inches

3. Divide the strip amount by 12 to get linear feet (the quantity needed in your order)

So, for the WD12 hybrid, which is 12 feet long and 30 inches wide:

12 feet x 12 inches per foot = 144 inches long

144 inches x 30 inches = 4320 sq inches

4320 square inches / .75 inch = 5760 linear inches

5760 linear inches / 12 inches per foot = 480 linear feet

The CLC kit contents show 400 linear feet of strips so you end up 20% over. If you want to save that 20%, you need to do a better approximation of the shape of the deck. That makes tha math more complicated, but if you don't mind simple trigonometry you can get pretty close to the CLC figure.

Laszlo

I just started my forth build with strips and have always milled my own cedar.

I have found that there is always lots of waste so you need to mill more than you think you need.

When you start jointing strips together and trying to match colors and grain of the wood, you find that you have lots of wood but nothing with the color that you need.

When you finish your build you will have lots of wood left over for another day.

Lou

Another way to skin the cat: If you have a sensitive scale, lay out a rectangle on a piece of cardboard that has the same proportions as the boat. Cut it out and weigh it. Then lay out the deck outline on that piece of cardboard, using the same length and width. Cut that out and weigh it. The difference in weights will give the the proportion to reduce the estimated area based on Lazlo's rectangular calculations.

You'll need to adjust for the deck camber. Draw a right triangle as high as the camber and half as wide as the boat. Measure the ratio of the hypotenuse to the half-width. Multiply your area estimate by that ratio. (It's not precise but gets you in the ballpark.)

Then add back 20%-30% for all the reasons Lou mentioned. You will need extra.

The good old cardboard analogue computer! I used to use it in high school to "calculate" fin sizes and placements for my model rockets. It also works great for sails for boats and appendages for boats and aircraft.

Laszlo