On the wind performance

[Ron]

Alex -

1,750 pounds of tension (or 800 kg) is too high for 1/4 inch 1x19 stainless wire, and your 6 mm is actually slightly thinner and weaker. You're over 22% of the breaking strength (which is around 7300 to 8200 pounds depending on who you ask) on this static measurement. 5 mm wire is close to 7/32, and 500 kg would be around 1100 pounds on the upper (or cap) shrouds - or over 18% of the wires breaking strength (5600 to 6300 pounds). These numbers are the absolute breaking strength, and are somewhat greater than the safe working loads. Note that Tony is recommending about 600 POUNDS (he converted when he came over) on the 1/4 inch cap shrouds on the new 28. The intermediates are 5/16 and the lowers are heavy stainless steel tubing.

Add some wind. especially on a multihull which cannot heel and bleed it off, and you could easily exceed 100%. I'd check the wire size and borrow a reliable tension gauge to see where you are at. Most cruising boats want to be at 15% or less for safety reasons. This is all theory. There may be something about the 26 or 8M rig that allows more, but you still have to worry somewhat about what sort of tension the wires can take before snapping.

There is stronger wire available, but it is hard to get and fairly expensive. Some boats have stainless rods instead of the wire, also stronger. I don't think you have either of these 2 options.

Here's a link to one of the websites listing the characteristics of various stainless wires -

http://www.sailingservices.com/standrig ... 19wire.htm

[ajaxpc]

I checked my rigging loads when I was up at the boat a week or two ago, and the numbers now are more like half of those quoted earlier - I don't know now whether I mis-remembered, or whether things have slacked off a bit over the last few months. The difference in load, though it sounds large, is only a small amount of wire length.

What I didn't do was to check the book that I used to set the rig up - it's on the boat as well. I'll have a look at this next time and see what it says - I took the loads from tables that it contained. I thought they sounded high at the time, but kind of trusted the author ...

I'm probably lucky I didn't break something.

Or unlucky that I haven't found it yet ...

[Ron]

Alex -

Regardless of the measurement system (and I find it funny that you English use the metric system and we colonials prefer to use the English), you don't want to be above about 18 percent of what the wire is capable of handling. Remember, this is a static load and all hell could break loose when the rig is loaded. If you're curious, attach the gauge to the upper ("cap" in the Queen's English) shroud on the weather side in 20 knots of wind. Bet you it won't be 15 percent anymore. Maybe you shouldn't do it - you may not go sailing again.

[ajaxpc]

I've twanged it with my finger a couple of times. It's indistinguishable from a solid rod.

You're right - I'm not sure I want to know the numbers...! And stumping around on the wing deck with a tension guage may not be my preferred occupation in these conditions.

I'm going sailing this weekend - to move the boat to a winter mooring (an 80 mile trip, approximately). I'll get another chance to look at the book.

It occurs to me, though, that monohull rigs may be set up tighter initially, since the boat can ease the load by heeling. This may be why the numbers in the book were on the high side? Although this would also suggest that multi's should just have heavier rigs (as they do...), because once a real load comes on the initial static tension will just be a small fraction of it, surely?

Though now I'm definitely speculating beyond my knowledge.

[Ron]

It occurs to me, though, that monohull rigs may be set up tighter initially, since the boat can ease the load by heeling.

Yes and No. Maximum static tension depends more on the design of the boat and rig (wire size and type, strength and location of chain plates and mast fittings, etc.). Since you can't safely heel that much in higher wind speeds, it's up to you to reduce sail area as required.