Boom Vang Part

[TomP]

I would not recommend you follow this.

I understand what you are trying to do. But if you look closely at thr slot, you will find that it is no very thick. Add the point pressures on such thin walls and you could get yourself into some trouble. With your 15 foot boom, and the huge main the '36 has, you could quite easily pull the fitting thru the slot.
I would recommend attaching a hound to the mast at deck level. This way, the hound will be mechanically fastened to the mast with no less the 3 fasteners on each side. One must try to spread the load whenever possible.
If you have an original C&C Spars mast, they were built with an extra 1/8 aluminum bar on either side of the mast wall that runs the entire length of the mast. With the proper size fasteners rated for shear strength you would have a almost bullet proof installation

The C&C '81s came with a deck crown. Thru bolted. Yours does not have this?

[bwindrope]

My recent experience may shed some light on the truth of the previous advice. Just this morning, my family went out for a morning sail from our home port here in Friday Harbor, San Juan Island, Washington. We sail a Gulf 32 Pilothouse named Aeolus. We were beam reaching in about 10 knots with gusts below 20 when all of a sudden our boom vang popped loose. I went forward to find that the eye that was in the mast track had popped its welds!!
Mind you, we've sailed this boat extensively and in some high winds for the past couple years. I'm just glad this thing popped close to home and in relatively mild conditions.

As a stop gap, I connected the boom vang to the mast pad as was also recommended here. Don't know if it is an ideal place, but it is sure as hell stronger than anything placed in the mast track and subjected to those loads.

If it is truly OK to leave it on the mast pad, I'll do that, and save the expense of some special gooseneck for the boom vang like what I've seen on some other boats.