Spreaders angle question......

[alahol2]

Sailorman, don't take offence, the remark wasn't aimed at you but at the whole thread...
I fully agree with what everyone has said about the maths of the situation. What I don't understand is why so many boats are designed and built with horizontal spreaders if that adds a weakness. It can't be a cost saving exercise because a tilted spreader isn't going to cost any more than a horizontal one. I can't believe that designers don't know the maths.
Is it that the out-of-column forces are so slight as to be negligible? Aesthetics? I don't know the answer, that's why I'm asking.

 

[dukes4monny]

I didn't realise that my original post would end up with such an interesting thread, thanks for all input so far.
I'm now more confused as there do appear to be valid arguments for and against.
As a compromise to this issue, what do the learned forumites think of this suggestion:
The problem appears to be one of lack of support of at the tip of the spreader with a horizontal spreader that does not have the tip clamped to the shroud, thus allowing, in an extreme case, the spreader to collapse (downwards) which would be followed thereafter by the mast folding / collapsing............
Instead of altering the angle of the spreaders and clamping at the bisecting angle, I am now planning to clamp a 'stop' to the shroud below the spreader tip, but not connected to it. This will leave the shroud able to still slide in the spreader end up to the stop, but the spreader will not be able to move down below horizontal.............if that makes sense /forums/images/graemlins/confused.gif

I know that the method already fitted to my Jag27 has obviously worked for years, but I'm planning to be doing some extended offshore passages next year, I just want to minimise the risk of any serious problems if I'm 'caught out' in a blow.

 

[alahol2]

That system was used on 2 of my boats, the other 2 had (has) the spreader clamped to the shroud, both appeared to work satisfactorily. I have only had close knowledge of 3 or 4 dismastings but all of them were caused by the lower shrouds parting. In each case the lower shrouds were of a thinner gauge than the main shroud.
Just as a cautionary, I found yesterday that one of my u-bolts holding the masthead shroud had sheared inside the deck and has started to lift. All the u-bolts are covered by the headlining so they are not something that I have checked since I bought the boat 4 years ago. I shall now be checking all of them every year.