I would measure the bearing points for the frame first of all. On an h25 I would want those points to be in the toe rail rather than in the glass. Then I would look at measurments that clear the boom, mainsheets, and backstay. Headroom measurments are next. No good having a bimini if you get a crick in your neck after sailing for two hours. If I had to open the bimini to accomodate the backstay, I would have no problem with that. All that said, a bimini looks like hell on an h25, acts like a brake in light wind, but increases your anchor-out living space be 60%. Ask me how I know. Also, my admiral loves it. Fair winds, Jim