height of backstay split

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Stu Jackson

#15
Ed, it appears that Ron was talking about taking the very high Mark II arrangement and lowering it significantly, which would make a large change in the "angle of attack".  However, Dave's solution, which I copied with different hardware, just doesn't change it that much.  It widens the angle by making it higher, rather than reducing the angle by lowering it.  I'll have to check the hardware arrangement at the transom chainplates.  I'll get a picture this afternoon and post it here.
Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."

dave davis

Ed,
One more thought on the hole subject.
Lets not loose site on what we are trying to do. We are trying to lower the peek of the triangle by various mechanical configurations. This can be measures by using a tape located at the peek and brought down to a common point on the transom. You use that measurement to determan the efficiency of each rig. My movement was last measured at about 1 and 3/8" from slack to full tension. that doesnot sound like very much, but it has a tight feeling on the forstay. I can not measure the tightness of the forstay due to the roller furling. You could loosen the forstay which will effect the movement number but now you have to be carfull about too much rake and too much weather helm etc. I rather not open that whole bag of worms.
Good Luck, Dave
Dave Davis San Francisco, 707, Wind Dragon, 1988, South Beach

Stu Jackson

#17
This is a description of what I had planned to photograph, will soon.

The Chainplates come out of the transom about 6 inches.  They are tied into the transom in the lazarette a few feet below with at least three bolts. 

The connection to the backstays are a single hole in each of the chainplates.  At that attachment point, we installed a toggle.  As a result, the backstay standing rigging can move in BOTH directions: port,/starboard, fore/aft.

For the backstay adjuster connection points on each side, we installed large long-D shackles through the same single hole in the chainplates.  The D shackles for the split backstay running rigging are setup on  the inboard side of the standing rigging of the backstays, to pick up the starboard vang for the adjuster and, to port, the line from the adjuster.

The toggle really helps to avoid off center loads on the chainplates. 
Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."

Ed Shankle

Stu,
Thanks for that detail; very helpful. I'll review with the rigger. Also, can you clarify something from the drawing for me; Is the 9ft "loose" measurement from the split to the stern rail or to the cockpit sole? It looks like the stern rail, that is, the same level as the chain plate. Just wanted to confirm.

thanks,
Ed
Ed Shankle
Tail Wind #866 1989 m25xp
Salem, MA

dave davis

From the little teak stepping block on the transom.
Dave
Dave Davis San Francisco, 707, Wind Dragon, 1988, South Beach

Stu Jackson

Dave's right.  You can tell by the fact that it's on the same line as the base of the backstay splits.
Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."