Rob….Geoff says that there is probably no “proper” size. With the boats being made by so many different manufacturers there may well be differences in the different marks. There may also be wear in the pintles which will also affect the size of the bolts. Geoff's suggestion is to measure the hole and to fit whatever fits the tightest. We currently have an HT 27 here, an on that one there is at least 1/16 inch play in the pintle bolts on that one if that helps. If you decide what you need and can't get it in USA let us know and we can post you some I am sure! Good luck. Cheers
Chrissie
