Hey guys...
When I was leaving the Steeplechase I noticed there is a slight bend in my Nacra 20 mast.
My question... carbon has no memory right? So it can't be a permanent bend it's got to be an adjustment I have to make in the diamond wires right?
A side bend would have to mean one diamond is tigher than the other right?

Considering the mast is 1,500+ miles away right now I can't toy with it now but am going to have to get it figured out once I get down there.
Thanks,
Todd

P.S.
No one better put up a piece of toast in response to this! I sure don't feel like forking up $5,400!!!

Undoubtedly the diamonds - use a Loos guage, check both sides, use the adjustable side to straighten.

one spreader bent up(or down) - thus less tension/compression on one side ?

do you have independant adjustment on each side?

Definately check the spreaders to see if they are adjusted the same amount on each side as well as being square with the mast. Look closely at the wires for any broken strands. If one of those lets loose, you will be paying the $$.

Lee

I know they say carbon can't hold a bend but my Nacra 20 mast bends a little to port(I think) above the diamond wires. It does not really effect sailing, at least not my sailing. I think my mast spent a lot of time stored on its side in atlanta before I purchased it. I have often wondered if heat from the sun along with the way it might have been supported on its side could have altered the mast itself. But I can attest that there is a slight permanent bend. I'll see if I can get a picture to show you guys what I mean.

I think the old diamond wires don't have the single side diamond wire adjustment...think they added that in 2005. It could be different spreader rake too.

About every Nacra 20 mast I've seen has that bend. I suggest getting a new set of adjustable diamond wires and tweak it out, like Champ Williams says.

If you don't have the adjustable diamonds you can take off one end of the wire that needs tension and twist it to shorten it. Then put it back on and re-tension to check. Takes a little experimentation but works like a champ. I find I've had to re-set it every now and then. When you twist the wires make sure you make them tighter and don't un-wind/ un-lay them.
Todd

I'm gonna try the loos gauge when I get back to FL for sure.
The boat I use doesn't have the single adjustment, too bad that would make life easy.
While resetting it I am going to have to check the prebend... Matt Struble's (which is kinda old) tuning guide says minimum 1"... seems a little stiff to me?
What the general consesus on prebend these days? I was thinking more like an inch and a half?

If I remember correctly, we set my mast at 1.5 inches. Measured from a straight edge off the spreaders to the mast. That is the measurement I had been given from several people.

How much spreader rake do you have? How much diamond wire tension?

Other recommendations?

I think you are correct, carbon doesn't have a memory (unlike metals) but it will take a set. I don't have experience with carbon catamarn masts, but in windsurfing, if you leave a sail rigged too long, the mast will take a fore/aft set. The solution is to rotate the mast 180deg and then re-rig to bend the mast back the other way. So, using that logic, you could probably disconnect/loosen the diamond wire on the concave side of the mast, tighten the convex side, and let it sit there for a few days to bend it back the other way.

sm

Here's another question: Are you guys going with the minimum rake (I think it's 1.5" measured from the spreader tips to the mast) or are you staking your sail and trying to match the mast to the luff curve of the sail?

Curious what the top guys are doing.

T

Todd, don't you live within 15 minutes of Hall spars? I would ask them for their advice. You probably know people that work there too.

Mike

naw, different Todd. I live in MD. the other one lives up north near Hall.

TB

Whoops, that was meant to be directed at Riccardi, who actually started this post. Sorry about that.

Mike

Well I ended up with about 2.5" of spreader rake, applied tension to #39 on Loos guage and that yielded about a tad more than 1.5" of prebend. Where are you with these settings?

Chris,

Is that what you were using last year, or are you trying something new?

Alec

I was running around 2 1/2"- 2 3/4" of spreader rake. not sure how much mast bend I had. I was at 37-38 on the loos which I think was around 700#'s. The factory recommends a minimum of 1.5" of spreader rake which looking at your #'s suggest very little prebend

Essentially the same as last year.

Anybody else wanna share?