IOMICA Forum

What is the current thinking on Side Stay Height? High as allowed for a stiffer mast, or lower to allow the mast to bend off in a puff and a stiffer mid section.


Can't find too much on this topic, looking for opinions of which I suspect will be many and varied.

regards,

Dan Field

If you want some statistics to compare, try this link:
http://www.radiosailing.org.uk/european ... survey.pdf
It's the most complete survey of competing IOM yachts that I've seen; well done.

very nice detailed report, thanks.

I only began looking, first thoughts are , heights are all over the place.

will have to weed out a bit see what shows up.

Since the top boats are very different, I suspect they are actually looking at the sails/masts and determining what is needed. If so, there is the real question.

regards,
Dan Field

I also wondered about this a while ago and made a drawing with the numbers then available to me.
See my IOM-Info page at http://www.helsinki.fi/~awallin/iom/
or the document itself directly at http://www.helsinki.fi/~awallin/iom/rig ... 3feb01.pdf

From looking at the number I have labeled "C. shroud attachment height in % of leech length" you can see that Bantock recommends a constant
75%, the earlier higher position that is found on the Roberts rig plan is around 85% and Craig Smith recommends a much lower position of between 60 and 69%.

You are very right in that the mast material and maybe also the way the mainsail is cut will have a big impact on where you want the shrouds attached...

From looking at the number I have labeled "C. shroud attachment height in % of leech length" you can see that Bantock recommends a constant

Not having seen your document (yet) I find it strange that you would provide shroud attachment height in terms of a leech length ratio...

Surely you mean - luff?

Marko

Secretary wrote:

From looking at the number I have labeled "C. shroud attachment height in % of leech length" you can see that Bantock recommends a constant

Not having seen your document (yet) I find it strange that you would provide shroud attachment height in terms of a leech length ratio...
Surely you mean - luff?
Marko

Yes, sorry my brain is working in swedish where we have för-lik and akter-lik (approximately fore-leech and aft-leech) and whichever is meant is usually known from the context. It should ofcourse be in % of the _luff_ length.
In view of the shrouds' task to keep the mast upright it might not even be the best way to express it rather you would express it as a length or as a % of the free unsupported mast. So for a TS-2 you would measure from the bottom of the cockpit deck and for the boats with mast-partners you would measure from the top of the foredeck... anyway my pdf gives a rough idea of the sort of numbers that are used out there.

I've been using the Easton 12.4mm 7075 T9 mast (2 piece) exclusively up until this last summer, when I started using the same material in the 11.1mm diameter (still havent figured it out.. re: US Nats ). Since I have had no time whatsoever for testing, I've temporarily gone back to the 12.4mm stick.
My upper shroud attachment point is 620mm below the upper band, and my spreaders are at approx. 1150 below.