Prop suggestion for RT188p 115 Pro XS CT

[@Reel_Chris]

'19 RT188p with a 115 Command Thrust is currently getting 46 mph at 7000 rpm (according to the dash tach) using a Tempest Plus 21p while carrying one person and a full tank and live well. The boat doesn't have Vessel View, so the dash tach reading is all there is to go on. The motor is mounted on the third hole from the top, which is the middle of 5 holes. Is there a better prop for this motor? I can't imagine that running at 7000 rpm is too good for the engine long term. Also, is there an inexpensive prop that would work as a spare?

[Moose21]

No way the engine is actually running 7k rpms.

[n2ratfishin]

No way the engine is actually running 7k rpms.

Agreed, get your tach fixed, which may be something as simple as a switch on the rear of the tach? I have been running a 2017 (bought in 2016) RT188 with no jack plate 115 Marc ProXS 4S and the old standard lower unit since new. I run a 20 LaserII. The Tempest should be good on your rig with the CT lower unit. 46 is doing OK this time of year with a full load. I have been running about 42 at 5500 RPMS and two of us on board this week. I've hit 50 a few times, but the weather and water conditions have to be perfect to do it.

[Ted-LA]

First you need an accurate RPM number. I think the limiter comes in around 6,250 RPM. If that's the case, you shouldn't be running 7,000. Here's a similar thread that may help you.

https://www.bbcboards.net/showthread.php?t=1131587

[@Reel_Chris]

Thanks all. Vessel view is on order. Once there are some trustworthy RPM numbers I'll update.

[@Reel_Chris]

UPDATE:

Vessel view reports 6070 rpm at 46.2 mph. The water wasn't flat so I couldn't really play with trim and throttle as much as I would have liked, but I think there was more revs in there. I think I could use a higher pitch prop, but I don't know how high. 22? 23? Holeshot is great now but I'd trade a little bit of that for a higher top speed.

Also, the tach was reading about 250 - 300 rpm high throughout the rev range. I suppose I need to figure out how to adjust that.

[2jerrylee]

I have a 2021 and have a 24" Fury. Manual jack plate and on vessel view the most rpm's I have seen was 5,600 and 44 mph. It comes out of the hole very well, full gas and gear. I am totally satisfied.

[@Reel_Chris]

I talked to Ranger and they told me that the original prop was a 14 5/8 diameter 23 pitch Tempest plus, Marc part number 48-8M0151384.

[PatriotAW4]

22" pitch fury does the best on those from what I have seen. A 6" jack plate really helps as well, set it to about 4.5" prop to pad and move it up 1/4" at a time until you no longer gain speed.

[Ring King]

Must be nice. I'm running a Ranger 170VX with a 115 Etec and only get 42mph. I'd be very happy with your numbers! LOL

[@Reel_Chris]

Further update:

With a 23 pitch Tempest, the boat maxed out at 48.1 MPH with a full tournament load, one passenger and empty live well at 5860 rpm according to vessel view. At 45 mph it was running about 5600 rpm. There was no obvious loss in hole shot but it is possible to trim up too far and unsettle the boat after hitting the slightest wake.

Incidentally, the tach reads between 250 and 500 rpms high. As far as I can tell, there's no adjustment for that. Vessel view is nice, but I'd prefer using the tach since it's right there on the dash. Anyone know a way to dial it back somehow?

[tnbassin]

I used to have a 2017 with same motor and a Tempest 22P worked best on my boat.