Catarmaran Mast - Diamond Tension

[nfbr]

I have a 65ft mast with 3 diamonds to side / rear and 2 diamonds forward.
These are set to provide correct mast bend.

Mast has typical catamaran 3 (actually 6) shrouds.

There is plenty of discussion of shroud tension

I can't find anything on diamond tension. As the 3 diamonds oppose each other, you can tension without increasing bend.

Normally they stay tight, but on some reefs, you'll see some slack in the windward side diamonds. Not pumping, but a clear slackening.

Any tips for tuning diamond stays?

Thanks

[team karst]

I would like to know also. Mine are "shockingly tight" I would say. At least they won't warp the hulls.

[Richard Harper]

From Seawind 1000 manual:


The spreader diamond wires (aft spreader wires) control the mast pre-bend aft and ensure that it cannot bend sideways. The mast is initially set up with approximately 3” of pre-bend (ie the mast has a gentle bend aft with the head approximately 3” behind the mast foot). This is achieved through tensioning the aft spreader wires with the forward spreader wires completely loose. With the correct pre-bend achieved, continue to adjust the aft spreader wires to get the mast completely straight in a sideways plane. At this stage, the aft spreader wires should be very tight. (“guitar string” tight).

Once this is achieved, re-tension the forward spreader wires until they are tight enough to stop the mast from “pumping”, but still leaving the pre-bend.