Trailered Boats and Bent Spreaders

[Ray Bowles]

This week when I went to raise the mast on my San Juan 23 I thought that the spreaders seemed to be bent where they attached to the mast. When I removed the spreaders from the mast the 8" long by 3/8" thick spreader mounting bolt was bent on both ends. Needless to say I removed and replaced this bolt. 2 days later when preparing to raise the mast on my brother-in-laws SJ 23 we found the same problem. Now we have found that 4 of the 6 boats here had bent spreader bolts.
We all have trailered our boats some distance when we either bought them or brought them to this marina. In all cases the mast was supported front, rear and in the center when the boats were trailered. It appears that just the weight of the spreader ends along with the weight of the shroud wires is enough to flex the spreaders and thus bend this bolt. Bent spreaders prevent the mast from being properly tuned or placed in relation to the rest of the boat.
I now remove the spreaders for transport as it simply requires the removal of 2 small screws on either side.
This will effect the boats ability to point when sailing up wind.
This might not be a problem on other trailerable boats but I think it is more common than not.
Ray

 

[catsailor]

Are you sure the pre-bend was not intentional? There are some boats where the spreads go up a bit (they split the stay angle).

 

[Ray Bowles]

Absolutly certain. The bolt securing the spreaders was 8 inches long and bent so badly that it couldn't be removed without cutting or straightening. Additionly, not all the spreaders were bent the same way. Where the orininal problem was noted was when tuning the mast. Equal tension, as measured with a Loos gauge, always ended up with the upper portion of the mast bending to port. With the new bolt the problem was solved. Masts with B&R rigging mount the spreaders differently than the SJ 23.
Ray

 

[sailingdog]

All spreaders should split the stay angle. IF they don't then there will be a torsional force on the spreader, and if the spreader collapses, due to the torsional force, you'll very likely lose your mast.

Spreaders are supposed to be in COMPRESSION ONLY. This means that the forces on the spreader from the stay have to be equal, and that requires the spreader to bisect the angle formed by the stay.

Are you sure the pre-bend was not intentional? There are some boats where the spreads go up a bit (they split the stay angle).

 

[Ray Bowles]

I think we've, or I've, lost track about this issue. I do totally understand the compression requrements of spreaders. When 1 spreader points up and to the rear and the other points north then something is wrong. That turned out to be badly bent bolts passing through the mast that the held the 1" round by 2" long aluminum base that the spreader tubes were mounted on. That caused the spreader to exit the mast side at a very wrong angle. New bolts allowed all 4 boats to be tuned properly. That's all. No more or less. If you tow your boat with your mast resting secure and your spreaders hanging loose are your spreaders still positioned correctly?
Bye, Ray.