I have been trying to locate a mast for my IP 24 motor sailer as yet with no luck!
I intend to rig her as a cutter rigged Gaff ketch,as i have information for a "Hebridean 750" which is based on the same hull and has this rig.
I have been offered a seasoned length of Douglas fir that is 22 feet long by 4"x4"which is too short for my needs,i have also the opportunity to purchase a 17 foot long spar that is already shaped and is approximately 3.5" tapering to 3".
My question is would it be feasable to scarph join the two and achieve a mast length of 28 feet ?
Also which is the more stressed section of a timber mast?compression loads at the base or if joined at the mast head would the stresses be higher at the top of the mast?
I have reasonable woodworking skills and have read of others making there own masts ,but would appreciate input as ultimately i need to be confident that sufficient strength is built into the finished mast.
All useful information appreciated! thanks.
hi yes i had to add 10 ft to the my mast. i would use the new timber length to make a 4inch diameter section tapering to 3.5" using the old mast for the top section a scarph joint should be at least 4x the mast diameter. you need to keep the joint below the hounds
Hi, I would agree with the previous commenter except on scarf length. The scarf on a stressed memeber such as a mast should be at least 6:1 and preferably 8:1. I would also suggest that the lower part be tapered from each side to the center and the upper part V'd to receive it. This reduces the scarf length to about 16" and each half of the scarf will shed water from the joint edge helping to prolong the life of the joint. I would suggest an epoxy glue with a high strength filler or microfiber thickener for gluing the joint. If the mast is deck stepped it does not need to be rounded or tapered from just below the gooseneck as a square section is easier to fit in to a tabernacle. If keel stepped then the mast can be tapered from just below the deck to the foot by about 20%. Best of luck with the project.
David