Jim, Thanks for the excellent information. I did not known how high the boom should be set, but with trial and error I coincidentally came up with exactly 19" above the tabernacle base. My boom measures 8' 2.5" long from the mast to the end of the aft fitting, or about 8' even without fittings. This setup overlaps the backstay about an inch if the boom rises, so trimming off 2.25" would be perfect, with no drawbacks that I can foresee. I too prefer to dispense with a vang if I can help it. Incidentally, what is a "bow shackle" ? Your solution sounds elegant, but I can't visualize a shackle that adjusts tension. Maybe a small turnbuckle would also work. Tom Jenkins On Sep 11, 2009, at 1:26 PM, James Poulakis wrote:
Tom,
This is another rigging oddity with late model M-17s (I think you said yours was a 2004). According to Jerry M. the aluminum boom extrusions should be about 7'9" (without the end fittings). The newer boom extrusions are over 8' long and can hang up on the backstay. This is with the gooseneck correctly positioned at 19" off the deck (per Bob Eeg).
My solution was to cut 2-1/4" off the boom, which allows it to barely clear the backstay at all angles. I would have cut it down to Jerry's 7'9" but that would have been too short to accommodate the foot of the now stock Elliot Pattison mainsail.
This mod also means doing away with the clew outhaul cheek block. I now lash the clew to a bow shackle attached to the boom end fitting. I actually like this better because it gives me more control over the foot tension and is stronger and simpler.
A properly tensioned boom vang should keep you out of trouble as well. However, Spirit is docked in my driveway and I find that more stuff to rig at the launch ramp = less time (and energy) for sailing.
Batten hang-ups are another common issue with the later rigs. So far this has just been a minor annoyance for me in light winds.
Jim
On Sep 10, 2009, at 2:54 PM, Thomas Jenkins wrote:
I'm just a learner with my 17, so surprises still abound. I found that an accidental gybe (always a risk in the fluky winds where I am sailing) can hang the boom in the backstay if the main is single-reefed. I generally pull the boom across by hand to cushion the shock of a gybe, so the boom does not ride up, but big gusts can be unpredictable if they are not touching the lake surface. Anyway, a vang seemed unnecessary with the mainsheet in mid-cockpit, but now think a small four-part might hold the boom down enough to keep it clear of the backstay under unusual conditions. Any thoughts?
On another sail subject, I arbitrarily set the boom at a height that put the head of the main maybe 6 inches from the masthead. I tried raising the main to the top of the slot, but the roach in my (presumably stock) Elliot-Pattison main puts a good chunk of the sail--and the upper batten--a few inches outside the backstay. Has anyone had a broken batten or a hung sail during tacking with this configuration? I prefer not to learn the hard way.
Thanks,
Tom Jenkins 2004 M17 Scintilla
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