Finding right prop for 20' seacraft.

[syxx]

We're finishing my 1977 20' seacraft and I'm trying to find the right prop for it. We've put a new floor in, well, console, filled transom in, and put a hermco bracket on the back with a jackplate. The bracket is 24" setback and the jackplate is another 6" to give full tilt for engine. Engine is a 150 4 stroke yamaha. Nobody I've talked to really knows what kind of prop to put on given all the modifications to the boat, any ideas out there?

Thanks,

Rick

[HeadHunter]

Try a 14.25 X17 3 blade, or something close to that....should give you a good idea of where you need to be.

[Bushwacker]

You're running the same setback as I am with an even heavier motor, so you will definitely need a 4B prop to get some stern lift and maybe some sort of fin on the AV plate, for decent low speed planing.

[bobbert]

Ditto 4 blade suggestion. Also give Turning Point Props a look. Their Hustler line looks very interesting. Am trying them out on the Bertram. They also have dealers that allow prop swapping to find the right one. Their online feed back is also very good.

[syxx]

Thanks guys, luckily have some boat rental guys next door that have plenty of props I can borrow till I find the right fit!

[FishStretcher]

Originally Posted by Bushwacker

You're running the same setback as I am with an even heavier motor, so you will definitely need a 4B prop to get some stern lift and maybe some sort of fin on the AV plate, for decent low speed planing.

I second that one. I am a big fan of the hydroshield skeg mounted fin. You can plant at slow speed, and you slowly settle the boat coming off plane, rather than a noticeable transition. I bought a Solas Amita 4 blade prop for stern lift, too. About $100 in aluminum, not sure if there is a SS version.

[Bushwacker]

Michigan Wheel Corp. also makes an aluminum 4B, the "Vortex" that was a little over $100. I tried a 14 x 20p that was a little too much pitch for heavy loads, so I had repitched to a 14x18 that's perfect and I use as a spare. I finally ended up with a PowerTech SS 4B 15x15 prop that works real well for me with heavy loads. It uses the same 2-piece hub system as the Michigan. The Yamaha is down about 15 hp compared to the E-Tec, but I'm running a 1.87:1 gear ratio; if yours has a 2.0:1 gear ratio, you might be able to turn the same size prop on the lighter SF hull.

[McGillicuddy]

Denny,
Which PT Prop 4-blade model did you get? ELE4?

[Bushwacker]

Yes Gillie,

The model no. on my prop is ELE4R15P-MS275. The PowerTech guy I talked to said the blade profile was very similar to the old OMC SST prop. I ran a 13 3/4 X 15P SST on my old 115 and it was an excellent prop. I was able to raise the motor an inch and pick up about 3 mph compared to what I got with the same size aluminum Michigan prop. I averaged 2.8 mpg with it over 6 Bahama trips carrying a very heavy load, which I thought was pretty decent for a 1975 vintage 2-stroke! Denny

[syxx]

Well with the powertech SCE4 I'm turning about 5200 RPM max with the jackplate up and trim tabs all the way up. Getting about 35 mph. At 4300 RPM I was getting 32 mph which is ok, but I was hoping top end to push a bit more. I'm going to try there recommendation and I may try to see how swinging a 3 blade with high pitch works out.

Unfortunately I think my engine and bracket are sitting a little low in the water, I am pretty much running with my jack plate up all the way. Water comes over the bracket with ease even with nobody standing in the back. The counter bouyancy of the bracket does seem to offset it from going down too much further though when people do stand back there which is good. However it's tightly sealed no water inside the bracket, just having to be careful coming off plane not to swamp the engine, as well as when running as if it's not trimmed right water seems to want to shoot up at the cowling.