Hi Brian,
I don't rate myself as either a skilled sailor or an expert, so I'd welcome other views myself, but here's my understanding.
The function of spreaders are both to hold the mid section of the mast so it does not bow and to enable the the top of the shroud to meet the mast at a more efficient angle for holding it straight. On a design like the SeaHawk's, the triangle formed by the two shrouds rising from a common point on the cabin to either end of the spreader is an extremely effective method of stiffening the rather lightweight and somewhat flexible mast found on the boat.
Shrouds on the leeward side of the boat are largely redundant and it is quite permissible for them to go slack. However, excessive slack indicates that there is not enough tension on the windward side and it is the opposite side that needs tightening. But don't rush to tighten the shrouds!
As the SeaHawk has no backstay a major function of the shrouds is not only to stop the mast flexing sidewards but also to stop it bending forward when running and this backstay function is the reason the spreaders must be swept back. Obviously, tightening the shrouds excessively means the top of the mast begins to move further aft than John Bennett's drawings indicate it should be - 6" aft of the base of the mast.
So, to prevent lee side shrouds becoming excessively slack, it is quite likely that you should be tightening the forestay. Looked at from above the rig is essentially a triangular structure with the mast in the middle, though somewhat off-centre, and you should take up slack on one side by balancing the tension in both the other two.
As for pivoting spreaders, that's not just because it's a cheap and easy way to attach them. Because they are only doing their job when under tension there's no need to have them fixed. A fixed joint would not only be under a lot of strain, if not aligned absolutely correctly, it would also be more easily damaged when the mast is lowered for trailing or when in winter storage.
When it comes to damage to the main sail, I'd say there were two points. Consider altering course slightly when running to avoid going straight downwind and make sure everything on the tip of the spreader is as smooth as possible.
I understand that not going directly downwind is a standard technique for large yachts on ocean going cruises. The idea being, that once off the wind you are no longer in danger of an unexpected gybe, and the boat goes marginally faster as it moves to be on a broad reach. On a SeaHawk, with shrouds after of the mast, the main will never set properly when running directly downwind anyway.
On my original, almost 40 year old, mast I found that, after some thirty five years, the cap the end of the spreader through which the shroud passes had become firmly welded into the spreader tubing. I needed to replace the shrouds to keep the insurers happy - they looked fine! I ended up breaking off the sharp bits of the split pin that held the cap and just rubbing all the sharp bits smooth.
It was the rigger who came out from Jeckells, to assist me, suggested I do that. He was a guy who had worked for Jeckells since leaving school and claimed to have been sent out to Reedcraft to rig just about every SeaHawk built there. I took him to be a man who knew what he was doing.
Just my thoughts...
Locked
