Buccaneer 24 Trimaran

wing mast for B24?

Jetstreamer
This stuff has been posted here before - but here are some images anyway. The last one is of two 6.5 metre unstayed wing masts for a planing skiff. These have been built with an alloy tube in the mid section with reinforcing at base. The others can be built in tensioned ply or foam sandwich with I beams and cutout light frames with carbon reinforcing. Flash Harry's 9 metre mast is now almost 30 years old and still going strong, despite some brutality from sailing conditions and the owner.

 

Thanx

 

I will be sure to peruse the rest of this fine forum for some more info on this subject!

 

Thanks Gary About what was the finished weight of Harry's spar? Bruce

 

30 foot wing mast

hi Bruce
Flash Harry's rig is light, built with 4mm ply I beam and cutout frames, skinned in 3mm ply with a thin kauri or kahikatea strip at leading and trailing edges, with 10mm inside diameter alloy track glued and glassed to trailing strip for sail luff. The hounds are unidirectional glass and carbon laid diagonally upwards (in line with forestay angle) around the wing to the thickest section, drilled with basic shackle to hold rigging. Wing mast weighs approximately 20 kgs with all rigging, running and standing, easy to pick up and to mount. The mast bearing is wood core with multiple layers of glass, ball and socket setup - this simple, light cup and bearing has lasted the course well. However you have to ignore the cracking and banging coming from the bearing in fresh, gusting winds, it's just noise, no problems result from it - the lubricant gets washed away eventually and the glass on glass can stick a little. A slightly stiff bearing is preferable than a too easily moving one, you don't want the wing to flap about. The mast spanner is wood, glassed and carboned and is controlled by simple two part rope purchase to cam cleats.

 

light mast

Gary, that is really light, and it has stood the real world test Thanks for the details. Is it covered in any glass or carbon? Bruce

 

some wing mast sheathing

hi Bruce
The leading and trailing edges are glassed with one layer 6oz box weave and there are a few metres of strip carbon uni-directional running up and down halfway between hounds and mast base. This is epoxied at the mast's thickest section, two layers where the bending loads are greatest. However most of the mast is just epoxy and paint coated.

 

light mast

That makes our alloy spars look pretty heavy and over-kill, I know I have about 50kg with my spar, wires and roller furler. That is about 6-7% of my boat's weight, all up in the air Does Flash Harry use a jib or reacher? Also, in the pictures, the front of the mast looks straight and the rear tapered, is that normal for a wing mast and/or am I imagining it? Bruce

 

light wing mast

hey Bruce
That is 20 kgs, not lbs. mate. Actually I was being conservative, it is probably lighter than that. But remember Flash Harry is also a very light boat, lighter than an A Class, therefore the mast does not have to handle high loads. Boat carries no headsails, but uses a reacher for off wind sailing.
At the moment I'm making some much needed changes: the half wishbone boom and vang are going and a lighter conventional boom to be fitted plus a semi circular main sheet track for decent vang control.
The straight up leading edge and curved above hounds luff is just an aesthetic thing on my part - but it does reduce sail twist-off at the top a little and flattens that area too. I've built three wing masts with the opposite (more conventional) design too. IMO, not as attractive. Remember those early C Class English catenary wing designs like Thunder, Manta and Lady Helmsman, also Thompson's later foiler Sebago - they all still look good to me.

 

light mast and the metric system

Gary, Harry's mast does look "right". I have been trying to guess what your boom was in the pictures Thanks! I once tried a full wishbone on a hobie 16 rig and I still couldn't get enough leach tension without everything getting way too heavy and complicated. The USA is still a little? behind the rest of the world, and here in the southern US, we definitely have not "metricated" but I do try to convert all my posts to metric. Most of the time it works Bruce

 

curved wing luffs

Mistake on my part, the C Class cats Thunder and Manta did NOT have catenary luff shapes, in fact they were both straight luffs- but a number of the MacAlpine-Downie C's did, as did Sebago and and that superb Spirit of Apricot. The idea of reducing sail area through having a deeply curved luff and larger wing mast area seems to have fallen from of favour, but still a good design concept IMO. Supplejack's first wing was this shape, although that mast was too heavily constructed and made the boat pitch. You can just see the slight outward curve near the base in the jpeg.

 

light masts

I think we were still carving trees fresh from the forest when you were building well developed wing masts. Is there an easy way to cut the individual sized frames for the tapered sections? Bruce

 

Finally sorted out my old computer and found these, not sure what the Cad drawing I dont have Cad anymore so cant open it... hoping its one of my drawings for the new beams I made...

 

beam drawing

Thanks Samnz, the drawing opened fine with a free program from autodesk. Those beams certainly up-dated the 24. Do you know the lay-up that was used? How did your rudder problem/repair go? Bruce

 

Thanks for posting the Beam info, Samnz. The boat looks great. There is some scantling info back on page 6 of this thread:

http://www.boatdesign.net/forums/multihulls/22-24-trimaran-23449-6.html

Even more info would be better. Those beams are wild light. Anything I have seen by name designers is probably about 2-3 times that in wall section. Say a Newick Tremolino, or Horizon.