Need help setting up new Suzuki outboard

[Gamaliel]

I have replaced an old Evinrude 9.9 with a Suzuki 9.9 efi and can't get into the 5000 rpm range. I have raised the engine to where the ventilation plate is running about 1/2" below the water surface and redistributed the weight to where I think it is as good as it is going to get. With the oem 9" pitch prop I'm at 4600 rpm at wot. I bought a Solas 10" pitch prop and that is running at 4000 rpm. My boat is a 16' aluminum deep v that weighs approx. 700 lbs. At wot the oem prop is getting about 9.5 mph where the old Evinrude was getting around 11.5 mph. Also the bottom of the boat at the transom is about 5" below the waterline creating a rather sizeable wake. What do you experts recommend for my next propeller? Pitch? 3 blade, 4 blade? Suzuki or aftermarket? Thanks so much for your help.

[2014DF25ARS]

That sounds like a big boat for a 10 HP motor. I have a 25 HP Zuke on a 250 lb aluminum boat, and the factory prop was about right for my boat - getting me to 5850 RPM.

Given that you are replacing 10 HP with 10 HP, I would expect that the pitch & diameter of your new prop should be about the same as the pitch & diameter of your old prop on the Evinrude. What were you running before?

[Harper]

I agree that it's a lot of boat for a 10 HP motor. You mention the depth that it now sits in the water at the transom, which would indicate to me that it did not sit so deep with the previous motor. So how do the weights of the two motors compare? Sounds like your new Suzuki is quite a bit heavier. All things considered, you seem to be overpropped (too much pitch). So, although it might mean that you go even slower yet, opt for a smaller diameter prop or less pitch. You won't necessarily lose more top speed, since you'll be able to get closer to the proper RPM at WOT, but you will be doing the motor (and consequently your pocketbook) a favor to not lug it at WOT.

So, the OEM props that I see are all aluminum, and the only 9" pitch that I see is also 9" diameter. If you're getting 4600 with that, then maybe you should try the 7" pitch. That should get you up into the prescribed RPM range. The 10D/5" pitch would not only cost you 3X as much, but would probably get no better results. Or you could probably stick with the 9/9 OEM that you have, since the 4600 is close to the recommended WOT specs. But I would NOT be running with the Solas 10" prop, as the low RPMs are too much strain on that motor.

[38 Angler]

That boat is simply too big and heavy for a 9.9 HP motor equipped with a 10" pitch prop . --- Install a "lower-pitched" prop and you"ll get better performance (without lugging the engine) . --- Keeping the anti-cavitation-plate level with the boat-bottom generally "helps" too . --- I "run" a 9.25" diameter with a 9" pitch on a DT15C (15 HP) Suzuki . Top-speed at ~ 5500 rpm/min is (according to my GPS) ~ 22 mph (~ 35 km/hr) . Total weight of boat (deep + wide 14-footer) , motor , tank , fishing-gear and my-self amounts to ~ 700lbs. ---