Home Built Wing Masts

nah - this was just the very end of the mast. I think he made it a couple of feet longer and then cut a foot off each end. 43 feet long and hand built though - I'd bet there's a small void or two!

This does not include the glass (not sure if that is obvious.)

 

If that mast had longer chord and proportionate thickness, like 3 or 4 to 1, (not 1.5 to 1 as here) then it would be a better aerodynamic shape plus have a gain in stiffness ... so then you get rid of the spreaders and extra rigging ... which surely destroys, through turbulence and drag, the original intention of having an airfoil rig.

 

I'm sure that stuff has an impact up there. I'm also sure I'm not going to change it!

Tell me about the 1.5 to 1 you mentioned? The cross section is 8 X 4.

 

"Tell me about the 1.5 to 1 you mentioned? The cross section is 8 X 4."

My "Nugget", with a 30 ft mast, had a cross section of 6 X 2 and limited rotation.
But then it had three spreaders.
Worked well though.

 

Sorry Paxfish, 2:1. Still too short though.

 

Too short wing?

You may be interested to know that Gold Coast Yachts (in St Croix, USVI) uses a 2:1 mast. They've been using that for a long time, and it can get dicey in that area. I'd say it's probably a very good compromise, since it's unlikely to make the boat "sail" at anchor.

I'm personally looking to purchase plans for such a mast, in Carbon fiber. They don't seem too keen to sell me plans, yet. But I'm working on them.

Our boat has been built using resin infusion, so their resin infused mast would be a familiar construction method for me.



Cheers.
Paul.

 

You can't find the gougeon plans, each set was custom engineered to specifics. Mostly a mater of adjusting the number and lay of the tapes.

One of the things that has to be accounted for over time is that the accepted dimensions for spars have grown enormously. There are a lot of things that can be efficiently done in wood if you have certain objectives. But at some point you cross over into a land where carbon is the main solution. Given that carbon can make a spar that doesn't required any stays, and at relatively modest wall thickness's, one is really pushing some wood if one requires carbon on a wide stayed boat like a trimaran, in a fat section spar like a wingmast.

Is this spar for one of Richard's little tris? Seems oneought to be able to make that relatively easily out of wood. In my world of whimp sailing, I don't really understand the size of rigs on trailerable tris. They maintain similar proportions to much larger tris where the righting moment increases much faster than the rig area.

 

You can't find the gougeon plans, each set was custom engineered to specifics. Mostly a mater of adjusting the number and lay of the tapes.

One of the things that has to be accounted for over time is that the accepted dimensions for spars have grown enormously. There are a lot of things that can be efficiently done in wood if you have certain objectives. But at some point you cross over into a land where carbon is the main solution. Given that carbon can make a spar that doesn't required any stays, and at relatively modest wall thickness's, one is really pushing some wood if one requires carbon on a wide stayed boat like a trimaran, in a fat section spar like a wingmast.

Is this spar for one of Richard's little tris? Seems oneought to be able to make that relatively easily out of wood. In my world of whimp sailing, I don't really understand the size of rigs on trailerable tris. They maintain similar proportions to much larger tris where the righting moment increases much faster than the rig area. if it is 17 or 18 feet long it ought to be good with a 20 foot , and the construction need not be huge.

I would recommend looking on the Yahoo group for trems, where like a decade ago they posted the specs for a trem gougeon spar.

At one point gold coast did a lot of spars in 1/2 softewood with 10 oz each side. Run that thought the computer and see how heavy it works out, then adjust given that the scantlings are for much bigger boats.

In the 30th anniversary issue of Epoxyworks, or thereabouts, there was a fairly detailed review of the new mast on Ollie, Meade's boat. It was significantly changed from the earlier versions of Gougeon spar that it essentially rejected.

The specs for the Wharram spars are online. They run fairly heavy as they do not use diamond wires. I would guess one could probably squish the circles into aero shapes, use strip and glass and make some weight savings for a stick with diamond wires.

One of the best deals out there for a small boat is Bernt's batwing rig for his trailerable cat. Very interesting rig that is designed to be extremely easy to raise.

Another interesting one, but unproven is Ruel Parker's rig for his Conch design, I think it is called.

I think that having a rig for trailering, and a rig for the club makes a certain amount of sense. Usually the sky scraper rigs are overkill for cruising, depending on your weather, and there is something to be said for simple rigs that can be hoisted without a lot of rigging. Both Newick and White have used the traditional and tech rig approach on the same boat. Newick designed B2 to use a lug or a fractional.

 

In a couple of weeks I am going to start building a wing mast for my 18m catamaran. You learned gentlemen have a lot more experience than I have so I would really appreciate some comments. Here are the main characteristics of the design.

1. Composite 20 m wing mast: 3mm ply shell (with ribs and stringers), overlaid with 3mm glass and carbon epoxy laminate
2. Airfoil section: Truncated and mirrored Clarke Y airfoil. (Elongated D shape advocated by A J Marchaj and F Bethwaite)
3. Mainsail luff: 20 m
4. Mainsail foot: 6.75 m
5. Mainsail area: 100 sq m
6. Mast chord: 450 mm at base, 500 mm max chord, tapering to 300 mm top
7. Mast max depth (thickness): 180 mm at max chord
8. Mast prebend, ie curvature in fore aft plane: 100 mm
9. Mast compression at 30 knots, standing rigging + halyards + mainsheet + forestay + weight of sails: 13.5 tonnes
10. Standing rigging: uppers to 16 m above stub, lowers to 8.5 m above stub
11. Mast max load before long wave failure (Eular buckling): 22 tonnes
12. Mast max load before short wave failure (Brazier buckling): 22 tonnes
13. Mast stays attach to webbing at leading edge to facilitate rotation
14. Cars allow lateral travel so lee side of mast flows onto lee side of sail
15. Windward side has a step transition to sail

Thank you

 

Send a PM to Steve Clark including your info above.
Steve Clark https://www.boatdesign.net/members/steve-clark.4416/
Click on "Start a conversation"

 

All sounds good but ... you are going to have to watch weight build up. There is nothing worse than an over heavy mast creating pitching moments; a killer of speed and beating efficiency. Need to cut to a minimum all the interior structure; meaning you don't need stringers, just the central I beam and leading /trailing edges in basic stringers plus the frames at 1 metre or so. The skin is going to take a large percentage of the loads, interior construction conservatism can end up being just dumb weight and achieves nothing. Uni directional carbon up the thickest section does an excellent job of creating stiffness. Cars are just dumb stupid conformism if you are aiming for aerodynamic efficiency; I mean, a draggy gap just where it is causing the most aero harm.

 

You might consider doing a very careful review of Kurt Hughes' paper on wing mast design and construction.

For me, this paper has major implications for less complexity and reduced weight.

http://multihullblog.com/wp-content/uploads/wingmast17f.pdf

All thanks to Kurt for publishing this.

 

Greetings. For those looking for an effective, proven way to build a carbon-fiber wing mast up to 11 metres, you may be interested in checking this out. Several have already successfully been built by amateurs and the prototype has been tested for 5 seasons without issues, and no vacuum-bagging needed. Far too many carbon-fiber masts have failed due to insufficient wall thickness so hand layup here is not all bad if you can live with a few extra pounds. Yes, it has a central web and there are good arguments for it, such as: assisting with carrying the high compression; dividing up the interior between halyard space and a sealed volume, and making it easier to build straight
http://www.smalltridesign.com/Carbon-Fiber-Mast.html

 

While here, I'd also like to add this as possible guidance for others. Adding fiberglass to a wood mast is really only to protect the wood from water absorption. It does very little to help the strength as it can only offer a small proportion of its ultimate strength in this application, being far more elastic than the wood it is protecting. For such masts, the wood has to be calculated to take all the loads. Adding carbon fiber UNI can help keep a wood mast stay straight though, so that the vertical loads are kept more in column. The mention in earlier posts of masts with multiple layers of fiberglass would only result in a very heavy mast with significant flex ... to such an extent that the wood would likely fail, leading to total collapse. So only one layer of glass is suggested over a wood mast, but make sure your design has enough high quality wood for the job. mike/

 

Can you say what you mean by "fiberglass"? Laminated UD S-glass has a modulus approximately 4 times higher than typical spruce, or similar timber, and thus will carry load and contribute to stiffness in preference to the timber. Woven roving laminated E-glass has a similar modulus to the same timber, so will carry compressive load equally with the timber, and more of the bending load due to its location on the outside of the section. CSM has a lower modulus, but also a terrible surface finish, so not an obvious candidate for coating a wooden mast.