Mizzen Loads on Yawl

[Andy Schell]

I have a similar question to Brian Duff's about mizzen mast loads. I'm attempting to re-design the mizzen mast on my 35' yawl to eliminate the need for a triatic stay. I intend to add intermediate shrouds 16' up on a 21' mast, and bring them forward, to replace the triatic. Is there a magic angle I need to provide that staying? It's currently approximately 25" forward of the mast base, and I read somewhere that one inch fore/aft is minimum for 1 foot of rise on the mast.

Also, the rig used to have aft-swept spreaders. I'm wondering if I can do away with them...this decreases the shroud angle to 9 degrees, but the mizzen sail is only 50 sq. ft., so the forces are very low - I'm using 7mm dux rigging. Obviously there will be more mast compression without spreaders, but can I compensate by pre-tensioning the uppers more than I would with spreaders?

[Ian McColgin]

Ahoy Andy,

Why? Properly a triadic is a very light stay as not much pressure is needed at that angle to keep the mizzen from falling back when on a beat - considerably less than the weight of a pair of stays leading steaply down.

Whether you'd save anything with the elimination of swept spreaders is also a question. I never liked carrying the mizzen off the wind anyway - more fond of the staysail.

But, different boats, different long splices.

G'luck

[Brion Toss]

Hello,
Have you looked at the section on mizzens in the "Apprentice"? It covers the cans of variables that you are opening. I like getting rid of springstays (not triatics; those are for square-riggers, steamships, and schooners)when possible, but not when the sum of the new vectors makes things worse. As for the optimal angle, an inch per foot gives you less than 5 degrees. Better to have between 5 and 7. The more you get, the less compression and the less tension needed to keep the stick forward. The limiting factor will likely be the main boom.
Fair leads,
Brion Toss

[Andy Schell]

Thanks for the input (sorry for the faux pas Brion). I've done the re-rig with Dynex Dux, so weight with the added intermediates is not an issue. I managed to get them far enough forward to give me about 7 degrees, and the boom clears them, though I need to re-route the mainsheet, which I was going to do anyway. The mizzen now has uppers led slightly aft, lowers led further aft, and the intermediates led forward, and I hope should work just fine. The sail is only 75 sq feet, so the loads are fairly small. It also has running backs for when I set a staysail on it. The Dux is excellent, easy to splice and very light. Plus, the deadeyes on the old yawl look very cool. Thanks for the input.