I would like to try making a red oak board bow. What is the shortest length I can make? I have a 26" draw. Is there a formula for figuring out length in relation to draw length?

Draw times two plus 10". But rules are meant to be broken. Myself, I would build you a 60" bow. If its your first make it longer so your chances of a winner are better. Skip the oak and go to a hickory board if its available, thats my 2.324 cents on it! Have fun!

Lots of variables here. Do you want it to be stiff-handled or bendyhandle? You can make a bow shorter if you make it wider. What poundage will you be going for? Lighter poundage bows can be shorter because the wood is thinner and can bend farther without breaking. There are some great buildalongs on this site, I would recommend reading some of them before you get started.

Under ideal circumstances and with ideal tillering you should be able to go as short as twice your draw length for the bow length.