I am thinking to put one on my Prindle 15. Normally cats do not sail dead downwind as it pays to sail angles downwind so your app wind stays high and you use the traveller as vang. But on the Prindle it pays to sail dead downwind as the extra speed won't cover the extra distance sailed. By adding a vang you control the leech and do not loose sail area.
I will be trying it out at the beer can race next Saturday. It will be a first for me, I will let you know how it goes. Does anyone know where it should clip on the mast?
If I were installing a vang, I'd use P/N 11870000 (Deck Plate) at the bottom of the luff track. It's the part where the lower main block attaches to the traveller, but it's also used to attach the lower block of a 6:1 downhaul on the H16.......with SS screws and square nuts (ala the downhaul cleat in a standard downhaul setup).