RT 188 Merc 115 Po Xs Command thrust vs standard gear case?

[PatriotAW4]

I have seen several RT 188s with both the regular 115 Pro xs and the Command thrust. I know the Command thrust has a larger gear case and hub with a lower gear ratio but is there any performance advantage to one over the other? From what research I have done they both typically will run 45-50 MPH depending on load with the standard gear case working best with a 19-20" pitch prop and 22-24" pitch prop on the Command thrust.

[tcesni]

I’ve wondered the same as I’m looking at a used RT188 with the ProXS having the standard gear case.

[Johnnyred]

I believe one of the main benefits of the CT is you have a wider choice of Merc props to run... Tempest, Bravo, Fury, others. Larger diameter props might have other running advantages compared to smaller diameter ones. Having said that, the Trophy and Laser are great choices for the regular gear case. I also think the skeg is larger on the CT motor which may present a trade off between steering control and steering effort.

[GeauxTide]

I think a 14.5" prop on a 1300# hull, with no lifting surface, is ridiculous. I asked my dealer about it and there is NO speed difference. The CT was designed for heavy applications. Back in the day, I had a Ranger 340, having a 24.5" transom. I ran a 25" Turbo and the steering torque was horrendous until I trimmed it.

[n2ratfishin]

They were not putting the CT lower unit units on the RT188 when I bought, so I have the standard lower unit turning a 20 pitch Laser II. Knowing that these are not blue printed hulls, they don't have a pad, even the supposed pad boats have a very small pad, each one is different from the other via welds and bottom variations.

Some try to eeek out ever mph from things they own. I was that guy for years. I finally grew out of it and now am happy with a boat that does nothing the "best" but it does most fishing task pretty darn well and it did not cost $50,000 plus.

[tcesni]

I believe one of the main benefits of the CT is you have a wider choice of Merc props to run... Tempest, Bravo, Fury, others. Larger diameter props might have other running advantages compared to smaller diameter ones. Having said that, the Trophy and Laser are great choices for the regular gear case. I also think the skeg is larger on the CT motor which may present a trade off between steering control and steering effort.

So the Laser II doesn’t fit the CT gear case?

[Johnnyred]

So the Laser II doesn’t fit the CT gear case?

No, the Laser II is for 4.25" gearcase applications. The CT has 4.75" gearcase.

[GeauxTide]

The best prop for my RT188 has, by far, been the X7. Great stern lift and handling at hole #3. Haven't put the 20 Laser on in 3 years.

[tcesni]

No, the Laser II is for 4.25" gearcase applications. The CT has 4.75" gearcase.

Thanks, I’m picking up a 2018 RT188 on Saturday that has the CT lower unit and I was hoping my 24” Laser II laying in my garage might get some use. It will remain a heavy paper weight.

[ddement]

Thanks, I’m picking up a 2018 RT188 on Saturday that has the CT lower unit and I was hoping my 24” Laser II laying in my garage might get some use. It will remain a heavy paper weight.

The laser II comes in large and small gearcase models.

[tcesni]

I’ve wondered the same as I’m looking at a used RT188 with the ProXS having the standard gear case.

I ended up buying a 2018 RT188 with the 115 ProXS Command Thrust lower unit, it came with a 21" pitch Tempest so I am curious how it will run.