A few rigging questions

[woodspars]

Hello,

I have recently built a wooden mast, but it is too flexible and I want to devise some standing rigging for it. How does one decide: a/ where to attach the chain plates; b/ where to attach the stays to the mast; c/ where, at what angle the spreaders should be attached and, also, how wide they should be?

I want my mast to be of the rotating variety, does this affect the chainplate position? I've built this mast for a Laser, so it's already designed to rotate, but it's woefully too narrow and, thus, too flexible. Yes, I realise that I will have to cut windows in the sleeve of my sail to accomodate a stay attachment point and, possibly, attachment points for diamonds. Cutting windows in the sleeve is not a problem, International Moth sails are commonly built this way.

I appreciate all feedback, even from those whom have repeatedly told me that I'm crazy for building a wooden Laser mast. The naysayers are likely correct, but we won't know for sure until I get this boat in the water.

Thanks.

-Tyler Compton

[Ian McColgin]

Make a new mast.

There is no practical low-tech cost-effective way to make the mast rotate with spreaders and stay tangs and all that. Stays rather wreck the point of a Lasar anyway.

Call it experience, maybe use it for a flag pole or an outrageous fishing rod, and carry on.

G'luck

[Woxbox]

I'd just stiffen the spar with some carbon fiber. Easy and reliable.

[woodspars]

Thanks for the input.

Rather than carbon fibre, could garden-variety fibreglass do the trick? I realize that there are different types of 'glass cloth (some additional research is needed on my part), but carbon fibre sounds awfully expensive and I'd rather use 'glass if possible.

I would like to go stay-less, but I'd thought that it might be the cheapest (if not easiest) way to go.

Thanks again.

-Tyler Compton

[Jay Greer]

Fiber glass will not hold up under the constant flexing the mast will be subject to. While you may gain sufficient support from using carbon fiber, I would opt to build a new mast myself. I would suggest you study the cross sections of Finn and Kite masts. These are unsupported masts that are eliptical in cross section with the major axis laying athwartships. Here you will gain the stiffiness needed as the boat heels and the sail shape can be controlled by the fore and aft bend of the mast as controlled by the sheet.
Jay

[rbgarr]

I suspect that to rotate it would have to be some combination of jumpers, diamond stays and running backstays. All of that sounds like much more work and expense, with no surety of success, than it's worth.

[kc8pql]

Start over again. There isn't anything to be gained by turning a miscalculation into an expensive mistake.

[Dan McCosh]

I don't know if it's worth the effort, but rotating stayed iceboat masts used to be quite common. The stay ran from a support point near the top of the mast, over a short strut, to the bottom of the mast, rather than to a chainplate. Iceboat masts, however, are very beefy fore and aft, and thin in cross section--like an airplane wing. The support stays, when used, duplicated the effect of an airplane support strut and wire. A round section mast would end up with some complex jumper stays as well. Might look at a Star to see how goofy this can get.

[Pernicious Atavist]

You have a few weeks before iceout, so build a new mast.
What's the wood, length and diameter of the one you're using now?

[soba]

Carbon fibre is a good idea, but it is stiff stuff, and really hard to make it conform to the mast properly. Even with a vacuum bag.

Using glass will put way too much weight aloft, and your Laser will spend more time with its mast in the water than out.

I vote for the new mast idea. Trying to attach standing rigging to a Laser is asking for a world of hurt...the hull just isn't designed for those stresses. I've had the deck off both a Laser and Laser II, and there is a SIGNIFICANT difference in the areas where the standing rigging is attached.

That said, why a wood mast for a Laser? Composite masts go for about $300 around here.

[woodspars]

I chose to build a wooden mast because, around here, even used aluminum spars are very expensive and hard to come by. Also, I wanted some experience in building a wooden mast (I used the hollow, bird's-mouth technique).

It sounds as though carbon fibre will be expensive and hard to work with so that option is at the bottom of the list for now. As for standing rigging, I could beef-up the hull at the attachment points (any suggestions?).

The mast I've made is ~20ft in length, 2 1/2" (I think) in diameter, at the base, and 1 1/2" at the top (I think). It's fairly light, but really flexible. If I were to make one with a larger diameter, it wouldn't fit into the stepping sleeve.

I'm not familiar with Finn masts, but having the major axis of a elliptical section lying athwartship seems as though it would interfere with air flow over the sail. I'll look into it.

Thanks all.

-Tyler Compton

[woodspars]

Hello Soba,

Do you have any pictures of a Laser/LaserII with the deck off? I'd like to see how the hull is constructed in the areas surrounding the rigging points.

Because a Laser mast is keel-stepped, I'm wondering If I could get away with less reinforcement than if the mast were deck-stepped (like a Laser II)?

What if the mast were rigged so that it couldn't rotate - would this require less engineering on my part? Certainly spreaders would go a long way toward stiffening the mast.

Thanks.

-Tyler

[Andrew Craig-Bennett]

Well, I feel a bit like the bumble bee, which according to legend cannot fly because its wing loading is too high.

My son owns and sails a Firefly, a 12ft two man dinghy designed by Uffa Fox. The Firefly was designed with a rotating mast, and ours still has hers.

It has diamond stays and a pair of lower shrouds and a forestay. The lower section is an aluminium extrusion (I seem to recall that the Firefly, used as the singlehander in the 1948 Olympics, was the first boat to have an alloy mast?) with a wooden top panel, because the art of tapering alloy spars had not developed at the time the boat was designed.

[rbgarr]

Penguins have a similar rig to what you describe on the Firefly, but adding chainplates and altering the mast step/partners on a Laser...?

[woodspars]

Hello,

I've done a bit of research concerning the mast of a Firefly. I've managed to find a .pdf with measurement diagrams and it appears that the wooden topmast accounts for about a third of the total mast length. There is no description regarding the type of wood, rate of taper, or manner of construction of the topmast, however. Is it hollow or solid? How does it attach to the lower section? How much overlap exists between the upper and lower sections?

I'm thinking that this type of spar may solve my problems. I have an aluminum extrusion of appropriate dimensions for a Laser bottom section so, naturally, I'm wondering how to modify my wooden mast to mate with it. Unfortunately, the aluminum section is only 10 ft in length, thus the wooden section would be required to form the remaining 10 ft of the overall mast length. I'm worried that this might be asking too much of my hollow, spruce mast.

Any suggestions?

-Tyler