Douglas Fir

Hi all! Thanks for your invaluable help. Originally I was planning on using Southern Yellow Pine for my frames on my 20' power dory. Now I am reconsidering and thinking about Douglas Fir for frames. It would help reduce the weight. However, I don't know about the strength factor. Any thoughts would be appreciated. The plywood skin is going to be Hydrotek ( a marine grade Meranti plywood) which is ideal for boats but is 20% heavier than Okuome so I would like to compensate for that added weight with lighter frames if possible.

 

Honestly, I wouldn't be all that worried about the weight gain with Meranti over Okoume. A 20' dory would be hard pressed to use more then 8 sheets of plywood. This means your Meranti hull will be about 40 pounds heavier then a Okoume hull. Hell, that's just a cooler full of beer or a battery for running a boom box. Douglas fur is significantly weaker then southern yellow, too.

 

stick with the pine. if you want a weight savings in the framing, switch to a hardwood like white oak, you can go thinner for the same strength, and save yourself some weight there. as par said, don't worry about the hull.