rahagel

Hydromotive 4 blade creates lots of stern lift but narrow beam single likes smallest diameter to the near point of cavitation. Hydromotive is large diameter, less positive rake, with more blade area at tip. Works well on counter rotating twins, but a handling problem for narrow beam single. As diameter is cut down, sime stern lift is lost. Also, bottom being right is more work but preferred, leaving minimal final prop tuning.

TxHawk

iTrader: (2)

I don't claim to know how all of these boats progressed. I understand that my 27 is somewhat of a stretched 24x7. It is less than 6' wide at the transom. Notched transom and lower chines run full length, ending in the notch. I'm running a LH Bravo 4 blade 1-9/16" below bottom. It does have some cavitation while planing and throws a small tail at neutral trim. With that, no torque lean. It runs very flat and doesn't start to chine until 75+ when I assume it's trying to get onto the lower chines.

Info from a 27 you may or may not need...

professor_speed

Those pics are from Tomas Wallin's boat.

phragle

iTrader: (3)

As for the stern lifting/hydromotive..

I tried a standard cleaver on my boat, could not get the bow up at all, even with trimming way out it still lost speed and bow steered all over the place. In fact it was the first time the boat ever made me nervous...

I did try a Mach Sterndriver labbed small diameter 4 blade, lifted the whole boat out of thewater, ran pretty flat and handled great. Didn't quite have the motor to pull it all the way thru, but still matched previous top speed with no ill handeling. New motor should pull it wasily... In fact I think I like this prop so much that if its good with the new motor, I will hunt and kill untill I find another one and send them both to BBLades to have this one cloned,

rahagel

Professor. I was wondering if those were pics from Tomas' boat. I sent him a FB friend request. Haven't received confirmation yet. My thought is to create some 6" long hardwood strake extensions to temorarily screw and caulk with 5200. Test it with different fuel levels and passenger loads to find the sweet spot and without bow steer.

phragle

iTrader: (3)

I dont think I would screw and 5200 stuff on... , just remember, basic fiberglass is paper mache' for big kids...

rahagel

Glue and screw for testing is what many of the OEMs do. Much faster for verification. Once they get it close, then comes the glass. I've done glass, agreed not rocket science. Next question, curious if anyone has CAD math data of a 24 x 7 I could import and manipulate?