Need info for building a wooden mast

Converting WWP-15* to a Lateen rig. Need plans / building details for a wooden un-stayed mast. Length 11'-12', thinking a square mast 3"x3" tapering to 1-3/4"x1-3/4" at top. Sail area 100 sq ft, boat weight 500#. At moment thinking a solid mast.

Q's. Will a wooden mast if these dimensions be strong enough for 100 sq ft Lateen sail. Would I be better going with a hollow mast. Both upper and lower boom will be 14' - 14-1/2'. What would be best wood for the mast and booms.

Rig will be basically the same as a Sunfish rig but with slightly taller mast and longer booms and 12'- 14' additional sq ft sail area.

Are there any site where this info might be found?

*West Wight Potter - 15

Thanks.

 

A 3" mast heel tapering to 1.75" at the head is nearly ideal for your mast, though a solid wooden mast is just a waste of wood, but more importantly excess weight aloft.
If it was a solid mast it would weigh about 10 pounds if white spruce, about 13 pounds if Douglas fir and around 11 pounds if sitka spruce.

If you built a hollow birdsmouth mast and assuming a 20% wall thickness a 12' long mast of the above dimensions in white spruce would weigh about 6 pounds, around 8 pounds if Douglas fir and 6.6 pounds if sitka spruce.

If building a birdsmouth mast, make the masthead 1.8" (1 - 11/16") to 2", with a 3" heel, so it's not too bendy.

 

Thanks PAR .... first mast wooden mast. Based on your info and what I have found on the web think I'll be going with a sq. hollow mast.

 

I've never been a Whiffer, but in all the Wood Boat stuff I've read there was a very good treatise on building a wood mast.
I think it was Six sided. They made a Jig and cut all six pieces of wood to mesh, then used F/Glass for glue.
Hollow inside, accommodating some important mast stuff, it actually had some 'give' to it.

I think there is an Engineering reason why Four sides wont work. Can't recall the details though.

 

There are a lot of 4 sided masts out there and they work just fine. They are easy to build, but may carry a bit more weight than a round or oval.

 

Thudpucker ..... thanks for the comments. Since this is my first mast build ... my reasoning for a square mast is the ease of construction vs. a round mast. On strength ... my thinking is since a boxed beam of plywood has adequate strength for construction purposes .... and my mast will only be 12' max. ...... thinking should be able to build one which will be strong enough ..... guess I'll find out when Sail the boat.

I'm a fan of the Lateen sail rig and have converted several smaller boats to it using aluminum tubing ..... decided for the WWP-15 I'd like to try wooden mast and spars.

 

Aw man your blithering me LOL, my crazy hunting partner wanted me to help him build a 12' sail rig for our Alaskan lakes.
Phoooey on that, them waters is cold! Whiffer drivers are always wet when they get to the beach.

But I looked at plans with him and that's when we came across that six sided Mast article and one of the 'asides' in the article gave an idea why Four sides were not as good as six.

If I were you I'd build the Four sided mast, and test it with weights just to see if your idea is gonna work.

Remember to anchor it just as it'd be anchored in the boat, only parallel to the ground.
Then apply the weights along the length of the mast.
Photograph it and let us in on the results.

The "Weather" is the part you cannot test. You wont care for several years though, and by that time you'll be working on your Three masted Passage voyager.

 

One more thought on your Four sided Wood mast.
After spending countless nights trying to sleep near an Aluminum Mast with lines Clacking against it all night long, I think your Wood mast Idea should be a National Requirement.

 

If you do use a 4 sided box section assembly, make sure to rabbit the ends of side staves to receive the forward and aft staves. This greatly strengthens the mast for very little extra effort and more importantly offers more gluing surface to hold the thing together. 20% stave thickness is satisfactory, though with a box section you can go down to 17% without worry. If you use something other then epoxy for the adhesive, insure lots of clamping pressure during assembly.

 

The "Antenna" of your lateen rig can't turn around the mast if its square.
Lister

 

PAR ... thanks again for your input.

 

Lister ..... I will be using line rather than the brass Sunfish type of goose neck lower boom -to-mast attachment. I'm betting the additional clearance and flexibility ..... and the "small" size (3" max) of the mast will permit the boom to swing around the mast freely enough. Keep in mind I'm not intending it for racing ..... but to be easy to rig and sail ...... important for an old duffer like me.

 

I have another thought.....atop this Mast, make the deck for the 360 light, as a Water proof roof for your mast so that no moisture collects. If the bottom is open most the Condensation will dry up before any Rot starts.

 

It's a very short mast on a small, but relatively heavy boat. I'd be tempted to make my mast building project short and simple by epoxying a pair of 2x4 spruce or DF boards together and then cutting the taper. Unless you enjoy the woodworking project of multipart masts.

 

Doubling or tripling the weight of a mast in a small, easily capsized boat isn't the wisest choice and a solid stick would do just that.