Top spreaders

[dave_ching]

Quick question.  Top spreaders why are they the length/angle they are?
Wouldn't different angle change the flick off point of so why don't we change for different sails or crew weight?

[JP233]

I noticed this with zero gravitas. I think (haven’t measured) their top spreaders are rather large in comparison.

Equally height of the spreaders come in to play and cap shroud layout.

Are you wanting longer/straighter spreaders as you’re more in the tubby-club than others?

[dave_ching]

No just curious. I'm just looking through our boats at things on our boats that most of ignore.
I understand that it works by operating a set force at a certain point to release the tip ( sorry engineers)
Therefore more tension equals stiffer but the pay off/balance is the amount of bend.
Seems quite a balance between the luff curve in the sail and upper tension.
I think my conclusion is we use top spreaders to get the twist off shape we want and then use luff curve and Cunningham to tune the sail.

[Phil Alderson]

The top spreaders give side support up wind and then depending on the uppers tension they let the mast fall off to leeward spilling wind as Cunningham and kicker bend the mast beyond where the leeward upper starts to go loose.

I think that with shorter spreaders you need more tension and more angle to get the same deflection to achieve the same effect. But I think that this means more static bend in the mast, needing more luff curve.
I think that because there is more tension in the mast there might be more of an on/off feel as the rig transitions through the power/depower. but its hard to know as there are so many other factors in play.

I suspect we should play with them more than we do, and I have adjusted the angle on ZG once, and I did Pocket Rocket a couple of times but it is quite a bit of work with the carboned spreaders.
I think you can get a lot of adjustment with the uppers tension which I should probably play with more than I do.