Darryn,
Do you have your spreaders set up cat rigged with the tips level with the back of the mast ?
I've just repositioned mine to this location because I thought the rig was too stiff/powerful and wondered what sort of tension you use.
I haven't had the mast on the boat yet due to beam rebuilding and had started to tension the diamonds and noted a significant increase in mast bend so I stopped tensioning. I also recall that with the diamond wires more in line with the mast centreline I could induce a reverse camber with any sort of stay tension. The new setup should overcome this to some extent.
The Glenn Ashby Catamaran Tuning DVD indicates that a 4 cm distance from the diamond tips to the rear of the mast was a good starting point but that was on a F18 with a much bigger/stiffer mast section so I wondered how relevant it was to the "softer" Mozzie mast section.
Regards,
Peter
Hi Peter, I have set mine level with the back of the mast. I did a fair bit of stuffing around with them after the Lock sport Nationals were I had lots of power but couldn't point. At Lock sport I had negative bend without the sail on and the mast straightened with the weight of the sail hanging on the hook, lots of depth in the sail but cannot point due the fat leading edge, lots of downhaul made it work sort of but the sail I was using didn't tranfer the load from the downhaul attach point very well so I ended up with an ugly looking sail.
When I got back from Lock sport I started working on a better looking airfoil with the goal of pointing rather then power, so raked the spreaders to kick the middle of the mast forward when the downhaul and mainsheet are hauled on thus flattening the middle of the sail plus I learnt a lot about sails from helping Chris Dean and Gary Saxby develop these UK Halsey sails I am using. So now have an airfoil with less depth in the sail but max depth is at the right place and as the downhaul and mainsheet are applied the sail flattens in a linear fashion, not in patches as most other sails I have used do.
As for diamond wire tensions I cant give you mine as I dont know what they are, I set them up as I said further up this thread, on the water with my weight on the trap and thats the way you should set them up too as you will weigh more or less then me. I will measure them for you though next time I have access to a Loos gauge.
I haven't tested a F18 mast section so I cant really comment on how they set up their spreaders. I would move the spreader tips forward of my current position if I put on 10kgs and change the luff curve on my sail.
Darryn
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