Some of you know I'm leaving the island state of Hawaii and moving to the mainland next month. On the way, I'm going to be visiting my older brother and his family in Washington state. You could say that he's really my big brother as he stands at 6'5" compared to my 5'9". And while we are both very different, we are alike in some ways as brothers are.
Since I'm bringing my new favorite bow with me to visit my brother, it seems only fair to bring its big brother along too.
I'm calling it my Big Brother bow, my 14th official bow of the year. It pulls 50 pounds at my brother's 31 inch draw and is 48" long nock to nock. It's a little longer than my bow and started at 51" compared to my bow's 48". All in all it's a fast little bow and while it safely takes a 31 inch draw, it's still only around 46 inches strung. If all goes well my brother might get bitten by the archery bug.
This bow is a good example of how to scale a bow design up or down to fit a certain weight or draw length. My two latest PVC bow books (Simple PVC Bows and Take-Down Archery) have charts that show how to get certain draw weights and lengths by changing the length of the starting pipe. This bow was scaled up using the same idea as the charts.
Basically I use a simple rule of thumb that applies to most bow designs and sizes. Keep in mind that as you get very close to or very far away from a pipe's comfortable length (the length is performs best at) this rule of thumb won't work as well.
Adding or subtracting 1 inch from the starting length of pipe will change the draw weight by about 2.5 pounds (give or take about 2.5 pounds or so). If you want to keep the same draw weight but change the draw length, add or subtract 1 inch from the pipe for every inch of draw. So this bow went up 3 inches to increase the draw by 3 inches. The 3 inches extra also dropped the weight at 28" to about 40-45 pounds.