Hi guys,
My Tohatsu 115hp tldi has a 19" stainless prop on it. 5.5m Humber Ocean Pro lightly loaded can hit 50mph (which is fun) and prop seems perfect for the (lightly laden, 3 up) boat, reaching proper revs at WOT. My issue is when the boat carries a good bit of weight. I dive and the boat is primarily for diving. When we have 5 divers and their kit in a moderate sea the boat won't plane, manages about 6mph and 2500rpm at WOT. Chucking someone and their kit out allows me to (finally) get on the plane and hit a dizzy 18mph with 4000rpm at WOT. My mates bigger Tornado (5.8m) with a 90 2 stoker on it easily leaves me in its wake. I guess I need a different prop. I'm not a speed junkie but would like the boat to get a decent turn of speed when heavily laden. I'm looking at dropping the pitch on a new prop. Thinking of either a 16" or 15". Think dropping to a 17" wouldn't be enough. Any ideas what would suit best?
Also any ideas who would supply Tohatsu props in the UK? Cant find any anywhere.
My Destroyer 5.5 with an E-tec 115 can just hit 46 miles an hour with a 19" prop though I do have the XL shaft with the V6 gearbox and a lower final drive ratio which makes it less top speed orientated and more of a load carrier. The speed does drop off as you add weight but I can easily get up to 35 mph with 7 or 8 in the boat.
For diving I'd probably look for a 4 blade rather than 3 and try a 15" initially though from what you have described you may even need to drop to 13". Steel developments mentioned by mustrib are probably your best bet.
