Ranger RT188P maiden voyage

[Dmy-rt188p]

Sorry for the long post, but as a new member, I've learned a lot from posters and am seeking input. My 2022 RT188P is my 3rd boat. Drove a 1991 22' Ranger 395VS with a Yamaha 225 2 stroke for 20 years and a 15' Gregor jon boat with a 25hp Mercury for 10 years.

For my first outing, it was 57 degrees, sunny, and glass calm. I had all of my fishing gear (only 1/2 of the storage lockers were filled), 1/2 tank of 92 octane with 2 oz of octane boost and 1 ounce of ethanol treatment. I have a Mercury 115 pro XS CT on a 6" manual jackplate set at the 2nd hole from the top. Had 2 OEM folding fishing seats, 24V Ultrex in front, 2 lithium batteries, and the OEM 24P Tempest prop w/o a plug. All speed and tach readings were from a Garmin 93sv GPS and Mercury Vessel View.

During break in, it ran 29-30 mph at 4000 RPMs and 34 mph at 4500 RPMs trimmed a little less than 1/4. There is very little rooster tail and relatively limited bow lift. The wake started around the helm at these speeds. This boat is bow heavy . When I trim it enough to get on pad, the rooster tail is at the top or slightly above the cowl. It doesn't take much throttle or trim to go from hull dragging to full pad.

At WOT, I reached 6380 RPMS and 49.7 mph max, but here's the catch. At that speed and RPMs, the rooster tail was 4' higher than the cowl (trimmed to about 5/16th), there was very little pad in the water, and I had a lot of prop slippage. I also had a warning alert of overheating which makes me think that the engine was over-trimmed and/or mounted too high. Trimmed down a bit and got 46 mph at 6000-6100 RPMs. Again, there isn't much difference in trim to go from 3' of hull in the water to less than 1' of hull in the water (completely on pad or over-trimmed).

My hole shot is very fast. My estimate is 3-4 seconds from a dead stop to on plane. Trimmed all the way down, my wake splash starts just behind the bow seat whether i am going 35 mph or 45 mph, which is a little scary. At WOT and trimmed up, the hull barely touches the water, the boat gets really light. I suspect it would not like any chop on the water.

My question is: should I consider a different prop or lowering the motor? While I would like to touch 50 mph, i don't often run at this speed, even when I had my 22' fiberglass. Sorry for the long post, but I hope it makes my issue easier to diagnose. Thanks.

[King31]

6300 is max RPM on those motors. I would be a little concerned about that. I feel like you have way too big of a prop as well since 21P are the baseline for those boats.

[Dmy-rt188p]

Before launching, I also thought I had too much prop, but I hit redline with the 24P and the hole shot was pretty fast. If I go down, the limiter should come at a much lower speed. My CT has 2.38 lower gear.

[bassfisher444]

What is your prop to pad measurement?

[Dmy-rt188p]

Haven't measured, but my recollection is 9". The engine is in the corner of my garage, so I can't measure it at the moment.

[bassfisher444]

9" is way to low, bring it up to about 5.5" and try that out first, then go up by 1/4" increments until you loose speed then drop it back down 1/4" and run it there.

[Dmy-rt188p]

Thanks. I never had an adjustable jackplate before. Can you tell me what raising the motor will do: more bow lift? Lower roostertail?

[bassfisher444]

Thanks. I never had an adjustable jackplate before. Can you tell me what raising the motor will do: more bow lift? Lower roostertail?

If you have that much motor in water it is creating drag and slowing you down, however if the motor is to high you won't get the bow lift you need.

[GeauxTide]

Mount it at hole #3

[Coastal Mountaineer]

Might want to visit the Mercury 4-stroke/Verado forum on BBC and ask your questions there.

One thing I'm puzzled by is why you're adding octane booster to 92 octane gas. Your engine is designed to run well on 87 octane gas. Running higher octane than the manufacturer calls for doesn't improve performance, costs more, and, may damage your engine.

From the Mercury 4-stroke/Verado forum sticky:
Fuel Selection:

Make your fuel selections based on the following criteria, IN THE FOLLOWING ORDER:

-High Traffic, Top-Tier (Name Brand) Fuel
-Appropriate Octane Rating (see above info)
-Lowest possible ethanol content (NEVER to exceed 10%).
-While it may be preferable to utilize a fuel that contains lower (or no) ethanol, use of fuels that are SUBSTANTIALLY higher octane can result in decreased performance, decreased fuel economy, and potential for carbon buildup. Higher octane fuels burn SLOWER and COOLER.

[n2ratfishin]

My Rt188 115 ProXS 4S has ran regular no alcohol 87 from day one. Mine is a dual console, standard lower unit, running a 20 Laser, no jackplate running the same speeds as above. Carpet in a boat does weigh a lot and mine does not have carpet to weigh it down.

The "P" pad boats may ride better or something? They are still relatively flat bottom tin rigs. My advice is, fish and enjoy a boat without all the worry about scratching etc...

[Dmy-rt188p]

The reason I used octane boost is because I had a little left over from my prior 1991 boat with a 225 2-stroke which liked at least 92 octane. Figured it couldn't hurt. I also had to use Shell gas because the Chevron, where I filled up for 30 years, was closed for remodeling. I know higher octane doesn't hurt, and since it was the boat/motor's maiden voyage, I splurged. I don't think it would make that big of a difference, but $50 equated to about 1/2 of a tank. Luckily, I ran for 2.5 hours to break in the engine and only burned about 1/4 tank.

[cmg]

here is what i have 115 standard 4 stroke no jp mounted 3rd hole down from top 13 x 21 turning point 4 blade max rpm touches 6000 very little trim gets me on plane and running 45-46 mph its all hes got with my set up if you are over 6300 with xs that is to hi i agree 24 pitch seems like alot of prop most 150 turn that blade over trim might be issue and 46 mph is not bad if your in rpm range 6300 max you need to find that sweet spot so is to much trim motor to hi find that and i think you will be going down in prop pitch

[bassfisher444]

here is what i have 115 standard 4 stroke no jp mounted 3rd hole down from top 13 x 21 turning point 4 blade max rpm touches 6000 very little trim gets me on plane and running 45-46 mph its all hes got with my set up if you are over 6300 with xs that is to hi i agree 24 pitch seems like alot of prop most 150 turn that blade over trim might be issue and 46 mph is not bad if your in rpm range 6300 max you need to find that sweet spot so is to much trim motor to hi find that and i think you will be going down in prop pitch

He has a Command Thrust which has a lower gear ratio and uses a larger hub prop than the standard 115 so he needs a higher pitch to go the same speed.

[cmg]

that sounds about right 6380 rpm blow the motor up to get more speed

[bassfisher444]

that sounds about right 6380 rpm blow the motor up to get more speed

Going down in prop pitch like you suggested would increase the RPMs.

[cmg]

i still think to much pitch motor is set to high on jack plate or running plate to hi when this is right he will need to reduce pitch to get to wot factory specs which i think is 6300 for xs

[Dmy-rt188p]

I've been boating for a while, but never had to experiment with props. I would think that going down in pitch is not the way to go since I can consistently hit redline... unless I go to a 4-blade. My Command Thrust has a 2:38 drive. Before launching, I also thought a 24P was too much. I'm not ready to switch props after only 1 outing. Going to run it as-is a few more times before I start adjusting. I did measure the prop to pad which is actually 6", not 9". My mistake on relying on my memory.
I'm wondering whether raising the motor 1/2" would help bow lift at medium speeds / RPMs?

[cmg]

sir this is just me i would start witth jack plate all the way down and use your trim only to tune the ride if it handles the how you like it with the prop you have and at wot you are not over 6300 rpm the set up is probably ok if something is not right raise you plate small amounts and see what results you get

[cmg]

start all your testing with jack plate all the way down just use trim to tune the ride if you are running mid 40 and not over 6300 wot your set up sounds ok if not raise the plate small amounts and compare results