Props: Turbo 3 Blade 13.25 x 13 pitch
Powertech SWW4 13.5 x 12 pitch
Motor is a Yamaha F70 mounted on a 4” Bobs JP which is mounted so cavitation plate is about 1 below the top of a 6” high tunnel.
Boat I built, it’s a flat bottom with pocket tunnel 22’ includes 16” sponsons. It’s a light boat, vacuum infused sandwich foam core, boat drafts about 5 to 5.5” fully loaded… about 1/2 inch of tunnel showing when in water.
My tests have been on windy days 15 knots with gusts and about 6 inch to one foot rollers and sometimes sloppy chop.
The three blade could barely get me going, I had to really slowly accelerate with the prop blowing out the whole way. Had to keep her fully trimmed in. End of one day with the 3 blade, I had some really flat water and was surprised to get really good bite and acceleration.
I figured the 4 blade with a lot more cupping would get me that same bite and acceleration in the chop and It’s greatly improved but still blows out more than I think it should. Pretty sure it will really grab in flat water.
I trim in and jackplate down all the way to get going, any other configuration gives me excessive blow out. The motor isn’t lugging Im just not getting traction. I’m starting to think my boat drafts too little and the prop is too high on take off??
Once running I can jack the plate all the way up and trim up but keeping the motor trimmed in gives me the least blowout. Water pressure is maxed out, no problem there. The 4 blade is already too much prop for this motor/boat combo but I can get her to the rated rpm by jacking up. Can more cup be added to SWW4? I am getting about 23 mph at 4400 rpm and WOT I can get about 29-30 mph.
The boat itself runs extremely smooth and dry. I tried redistributing weight and you can barely notice any difference, it’s like I’m driving a big barge except she planes really easy once the prop bites, not much bow rise, no porpoising, can’t turn without prop blowing out and I don’t think she will turn very sharp anyway.
My thoughts are to get a Shaw Wing next .. anyone have any recommendations … Im out of Miami, wish I was in Texas where they know more about these type of setups.
Here are a few pics
and a video link to show water conditions, also check motor, does it look like it’s bouncing around too much? The other video I tried to get a shot of the runnel, hanging off the back with my phone, its not that good but maybe it shows something.
Powertech SWW4 13.5 x 12 pitch
Motor is a Yamaha F70 mounted on a 4” Bobs JP which is mounted so cavitation plate is about 1 below the top of a 6” high tunnel.
Boat I built, it’s a flat bottom with pocket tunnel 22’ includes 16” sponsons. It’s a light boat, vacuum infused sandwich foam core, boat drafts about 5 to 5.5” fully loaded… about 1/2 inch of tunnel showing when in water.
My tests have been on windy days 15 knots with gusts and about 6 inch to one foot rollers and sometimes sloppy chop.
The three blade could barely get me going, I had to really slowly accelerate with the prop blowing out the whole way. Had to keep her fully trimmed in. End of one day with the 3 blade, I had some really flat water and was surprised to get really good bite and acceleration.
I figured the 4 blade with a lot more cupping would get me that same bite and acceleration in the chop and It’s greatly improved but still blows out more than I think it should. Pretty sure it will really grab in flat water.
I trim in and jackplate down all the way to get going, any other configuration gives me excessive blow out. The motor isn’t lugging Im just not getting traction. I’m starting to think my boat drafts too little and the prop is too high on take off??
Once running I can jack the plate all the way up and trim up but keeping the motor trimmed in gives me the least blowout. Water pressure is maxed out, no problem there. The 4 blade is already too much prop for this motor/boat combo but I can get her to the rated rpm by jacking up. Can more cup be added to SWW4? I am getting about 23 mph at 4400 rpm and WOT I can get about 29-30 mph.
The boat itself runs extremely smooth and dry. I tried redistributing weight and you can barely notice any difference, it’s like I’m driving a big barge except she planes really easy once the prop bites, not much bow rise, no porpoising, can’t turn without prop blowing out and I don’t think she will turn very sharp anyway.
My thoughts are to get a Shaw Wing next .. anyone have any recommendations … Im out of Miami, wish I was in Texas where they know more about these type of setups.
Here are a few pics
and a video link to show water conditions, also check motor, does it look like it’s bouncing around too much? The other video I tried to get a shot of the runnel, hanging off the back with my phone, its not that good but maybe it shows something.
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