Repower Mercury SEA PRO 60 prop question

[windypatrick]

Folks,

I've found an engine I can buy for my 26X without waiting 5 months. The Mercury 60 Sea Pro, their work motor. I will be in salt water and storage on a slip and the robustness option has an appeal. The rub is that they reduce the top end to 5,500 RPM from the recreation motor's 6,000 RPM. In combing the site, the best input I could find was that a 14-10 prop was good for a 60 Bigfoot. So does a 14-9 make more sense here?

Any input would be appreciated.

[windypatrick]

...or am I looking for a 14-11??

[Jimmyt]

The sea pro, and the big foot seem to have the same lower unit gear ratio (2.33:1).

If you are going to run the engine at a lower rpm, you’ll need more prop pitch for the same speed on the same boat. But since you don’t mention what boat was using a big foot with a 14-10 prop, it’s difficult to extrapolate. Pontoon boat props are typically a good starting point.

Your loading, etc will be different from others. Also, where you try to pick your best performance might be different. For instance, are you trying to get max speed with light loading, or lowest fuel consumption at hull speed?

I’d probably start with the 14:11. I ran a selection using around 4,000 lb boat and crew, and overall performance, and got both 14-10 and 14-11 selections.

See this spot for one approach to picking the prop. https://www.mercurymarine.com/en/us/pro ... !/step-one

[kurz]

I have the merc60 BF on my 26m. So I think it is quite similar.

The 14-10 is perfect for me. 14-9 stays at home, it is definitely to small. With the 14-11 that stays in the bilge for emergency, I did not come over 4800rpm, so it is too big.

Top end at 5500 rpm was not imports for me. You will not ride long with 6000rpm, no big difference!

[windypatrick]

Great input, thanks!

[windypatrick]

Additional info for the thread:

I ran the boat (finally) with the Bigfoot 60 Pro. Light seas in the bay. It maxed out at just under 5200 RPM with a 14"-12 3 blade prop, empty boat, ballast full, 2 people. IDK the speed as I was focused on the engine.

Best Regards.

[Jimmyt]

Well, you were just under the recommended 5,500 rpm max. So, how did it feel coming out of the hole? How was it at low speed/maneuvering? It would be good to have boat speed to go with the info, and an empty ballast data point, too - speed & rpm; if you ever feel inclined.

I'm thinking with the ballast out, you're going to hit 5,500 rpm, or be very close. So, barring a report that you were only doing 12 knots at 5,200 rpm, I'd say you nailed it.

Congratulations! Got it on the first try!