Ok, I just fitted my Tornado mast with the modern adjustable spreaders and set them 1 3/4" aft of the trailing edge of the mast. As I tension the daimonds, the mast takes on a graceful arch. How do I know when to stop?

Mike.

Shortly before it snaps.

LOL...

Follow this link http://www.acay.com.au/~gonzo/AUS-tornado/tunning.htm

Take your guitar tuner out and tune to a "G".
I'd like to be more helpfull, but on my used boat, I tighten it up to where the last owner did (he seemed to know what he was doing). There was a post a while back that implied that people were somehow measuring the tension on the line, but I have no idea how.
Anyone else?
Al

The tension of the diamonds all depends on the cut of your mainsail.
Also, the amount of rake on your spreaders are important. But if you have raked the spreaders back 2-3 cm, you should have 5-7 cm of prebend in the mast.
Stretch a string from the mast top and down to the rotator arm, measure the distance between the spreaders.

This gets you going, but you must study your main while sailing and adjust the prebend/spreader-rake accordingly. If the main becomes to deep, you need more rake. You should be able to flatten it completely with the downhaul and main. If you can't, you probably need more prebend.

What type of mainsail is it (sailmaker and style) and what battens are you using ?

Good luck.

I believe the catsailor store sells two brands of "rig tension guages". They are also known as a Laos Guage (I have no idea if I'm spelling that correctly). It basically has two pins that are connected by a large mechanical disadvantage and a spring such that you put the rigging cable between the pins and rotate the device so that the long foot is parallel with the cable. the amount of twist applied to the pins shows on a scale and gives you an reading of the tension on the cable.

I've always seen it spelled "Loos" gauge.

Al's recommendation about tuning it to a "G" on a guitar tuner is always what Rick has recommended, too -- but I thought Rick was just kidding.

Here's a photo of a Loos gauge. Given that the things cost $50 - $60, and are infrequently used, it's the kind of tool that an organization might want to own and share among sailors.

The easiest thing to do is contact your sailmaker. They should have a tuning guide for your sails. There is also a tuning guide on the International Tornado website.

For a Marstrom tapered mast and Ulman sails I use about 6cm. For heavier untapered Reg White or ?, you might want to post a question on the International Tornado Forum

Sail is an Ullman (anyone have an Email contact for them?)from ~1995 with a good set of foam core battens (not sure what exact type). Mast is a SailCraft of Canada ~1980 vintage...formally rigged soft. It has a taper above the main stay bracket...all Tornado's had this as far as I'm aware.

The tension measuring device is all very fine and dandy...but unless someone has a numeric value to aim for, it's not particularly useful. I think I'll use the advice to adjust the rake/tension to achive reasonable sail draft and mast curvature (~5 cm deflection of the track at spreaders from the mast ends as a starting point).

P.S. The Tornado forum hasn't been working for me for some months...can't post anything. The Admin told me it's an ongoing problem they're having trouble fixing.

Mike.

Hey man, thanks for the link...extremely helpful...more than just for the pre-bend thing.