Call the local Hunter Dealer
You can use a dock fender for a mast float, it’s the cheapest way to go or you can call Hunter up and see which model Hobie Cat mast float Hunter recommends for the Hunter 170, this is the most expensive way to go. If you look at the Hunter website, a mast float was one of the options you could get with the Hunter 170. If you look at the archives, previous Hunter 170 owners have said that Hunter sells the Hobie Cat mast float as the mast float for the Hunter 170. Hobie Cat sells two types of mast float, the "Hobie Bob" and the "Baby Bob". I think you need the "Baby Bob" mast float, but I'm not sure. You can order the mast float from Hunter or get it directly from Hobie Cat or find a Catamaran parts dealer in your area or on the Internet. Click on the link for the Hobie cat mast float.Fair Winds.Clyde