I just recently purchased an older Herman 17' catboat. Although it is a fiberglass boat the mast, gaff and boom are douglas fir. Unfortuantely the current mast is way overbuilt and extremely heavy at 6 1/2" dia. and 1 1/4" thick birds mouth construction. This is not the original mast. I wish to remake the mast at a more modest diameter, like around 5" with douglas fir again in birds mouth style construction. How thin can I make the staves and still have a strong mast? One additional piece of information. Unlike most catboat that only have one fore stay this boat has an additional port and starboard chain plate, which although are not being used on this mast, could be used to offer additional support to the new mast. This makes me think I could get away with a somewhat lighter mast. I also plan on making a tabernacle for this mast as well, hence my desire to make it as light as possible without compromising strength.