using vang attachment for preventer line
I have a 2003 H356. I have two lines tied with a bowline to the attachment point for the vang at the boom. I run each line through the hole in the mid cleat and then back under my dodger to my winches. If running, I attach the line to a winch on the downwind side. To gybe, I take the line off the winch and take up slack, or in heavy wind, leave a wrap around the winch and take up the slack as I go through the gybe. At midpoint, I hold the line and let it back out gradually. This system works for me. If you want a better angle than the mid cleat, run the line through the stanchion braces just forward and the angle is better. Either works about the same. One through the gybe, secure the opposite line to the new downwind cleat. Very simple and all you need is a little line.
I used exactly that type of arrangement for years. One time while running dead downwind in heavy winds/seas, the helmsperson experienced an involuntary gybe. The preventer caused the 3/8" bale that served as the vang attachment (on the boom) to pull off and it shot down like a bullet. Fortunately the only damage that time was a rather significant chip out of the top of the heavy hatch over the head on my 1991 Passage 42.
I continued to use the same system. Years later, while sailing DDW offshore in a mild 15 knots, we experienced a dramatic and unpredictable wind increase. In just one or two seconds we had 30+ knots pinning us down to our toerail, with very little steerageway. The wind then shifted 180 degrees, still with little steerage, so we experienced an involuntary gybe. I was at the helm and I was unable to bring the boat around quickly enough, so we had all that force on the preventer. This time the vang bale held, as did the spectra line I use for my vang. But the boom snapped into two pieces like a twig, right at the preventer attachment point. The sail snapped around, with the broken boom, and then hit the shrouds with such force as to break the top spreader. All the starboard shrouds went slack and I was astonished that we did not lose the mast. (The epilog is that we then had to motor the 250 miles back to Tonga VERY CAREFULLY, stabilize the mast, buy a bunch of jerry cans, and motor the 1200 miles to New Zealand with only a trysail on the mast).
Although I knew better at the time, I later talked to a number of people who knew of this danger, and even a couple who had experienced it themselves. I just don't want you to go through what I did, Jerry. I now attach my preventer only at the aft end of the boom, where you get the full strength of the entire boom in the event of an unplanned gybe with the preventer in place.
