Jim, Your verbal description did the trick. There they are in catalogs and in my can of stainless fittings, but I never knew they had a special name. I will need a new location for the topping lift shackle, but your solution will work for me. I will even get a free block for my reefing system. Thanks again for your advice. Tom Jenkins M17 Scintilla On Sep 12, 2009, at 11:17 PM, James Poulakis wrote:
Tom,
A bow shackle is just like a U-shaped pin shackle except it is more rounded - like a horseshoe (I'll email you a picture of my setup tomorrow). The bow shackle itself doesn't do anything to adjust tension, it simply provides a "loop" to pass a few turns of 3/16" line through. The line runs through the bow shackle and the sail clew grommet a few times to give a purchase so it can be easily pulled taut (unlike the stock setup). It is then tied off in a reef knot. There's really nothing elegant about it. In fact, its the kind of simple, strong rigging that would look right at home on a 19th century fishing boat.
With the boom extrusion cut down to about 7'10" there simply isn't room for fancy outhaul fittings (not even a cheek block). The thing to consider carefully is the foot of YOUR particular sail. Pulled drum-taut, the clew of my stock EP main is left with over an inch to spare for old age stretch (Jerry M. recommended 1/2").
The actual surgery is really simple, but I went through a measure... think... measure... think... process that lasted over a month before I finally got the courage to cut into my brand-new boom. I'm happy with the result.
Jim
On Sep 12, 2009, at 5:03 PM, Thomas Jenkins wrote:
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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