Install new rod diamonds on a catamaran - spreader bends

[Madden]

Dear collaborators,

I'm replacing 3 sets of diamonds on the rig of a 55ft catamaran. They all have a hard angle (>40deg) on the spreader. Usually on standard monohull rigs with spreader bends I would just run the spreaders through it's place and tension to bend.

Can I do the same in this case, or should I somehow mark and pre-bend, before tensioning?

Thanks for your advice!

Madden

[Madden]

Sorry I can't find where to edit the post. On the angle I wanted to write 140 degrees aprox, not 40 deg.

[neilpride]

As far i know Navtec recommend between 1 and 15 degress angle.
Worth to make a phone call to this guys and ask...

Navtec.
Guilford, CT 06437

(203) 458-3163

[UNCIVILIZED]

If you're truly using rod rigging, I was always schooled that the bends should be made off of the boat. And that they need to be exactly placed, as well as within +/- 1 or 2 deg. Since any acute bends in the rod work hardens it much like cold heading it's ends. Non? So I'm guessing that there are a bunch of little, critical, tricks of the trade that pro's use. But as to what they are, which are vital, & which can be skipped, & when, I've no clue. That's one where I get my experience & expertise the traditional way. Via buying it. Which, for such sharp angles, I'm guessing that it's that much more important.

BTW, are you changing out all of the rigging with the spar up? As I'd think that swapping out, & tuning the diamonds would be a heck of a lot easier to do with the mast resting on a few saw horses.

I hope your deck ape's well compensated, as I know how much work it is pulling the mastman up & down the rig 50x in one day to get the tuning on a discontinuously rigged boat right. Even when he's but half my size. Ugh!

[Madden]

Looks like Navtec USA is permanently closed, but on the other hand Ulf from BSI gave great advice and detailed instructions over the phone. The rod gets made, then the position of the spreader bend is carefully determined by hanging the rod (or getting a good measurement from the old rigging), then the rod gets bent on a hydraulic press before final installation. You're right about the maximum 2 deg deviation from the exact angle. I found an article on a 1982 cruising world magazine with a lot of interesting information, including the story of "Ceramco New Zealand" dismasting in the 1981 Whitbread, because one of it's spreader bend angles was more than 10 degrees off. READ ARTICLE HERE

[UNCIVILIZED]

Originally Posted by Madden

Looks like Navtec USA is permanently closed, but on the other hand Ulf from BSI gave great advice and detailed instructions over the phone.

Anyone know who's filling the vacuum, & or buying their tooling, etc.?
Let's see: Dyform went under, then pulled a Phoenix with Compacted Strand. Hall spars recently DOA, ditto Navtec. Stearn (twice I think, at least). Rigrite. Who's next?