Teach me about RPMS and Trim

[titanxt]

Hello! I have a Reata 1850VS with a Yamaha F150. The motor seems to have enough power as I can get on plane and run 40 mph with 6 people in the boat (4 adults and 2 children). What is the optimum RPM range and how exactly do you use the trim to tweak the performance of the motor as you are running?

I also have a SS, three blade prop if that means anything...

Thanks!

Andy

[Jim Ordway]

The max rpm can be found in your operation manuals or you dealer can help you. Max rpm is mostly based on load, prop and wind. Your load and weather will very often so you may not hit you optimal rpm ever time you run. Also, unless you do a lot of prop testing, you may not be able to hit the max rpm in any case. Most folks are happy if they run withing 2 or 3 hundred rpm of the max. Whatever the case of load and prop, you will get max speed by beginning to tilt you motor after getting on plane and running around 3k rpm. At some point, your motor will stop increasing rpm as you slowly tilt it under speed and even start to lose speed. Find that sweet spot and you are the best that you can be with your setup.
Forgive me if this is too elementry and I am reading the question wrong.
Take care,

[jopes]

Your prop should provide your enginge to get into the max operating range of the engine. Thia does not mean you nees to run there all the time. It just means your running the engine with the proper load on it.

Too low if a max wide open rpm will lug the engine and cause premature wear on it.

[titanxt]

I just checked and I have a 14 1/4 x 21 " propeller. From what I see on the internet it seems to be the size I need??? What do you think?

[bob1]

I have a 14 1/2 x 21 on my Reata 1850.

Bob

[T Mac]

The key is...to get max speed with trimming.....Do this:
After your boat planes out ... trim "up". Once you get trimmed up about half way...I like to do the rest of thre wat up in short bursts -(itermittently) myself.
Watch the speedo and the tach they will both go up...to a point where the speed starts going down.
Trim back down to that spot. That's it.

The exact amount of trim will never be exactly the same due to load variances and running conditions.....and speed.
-But, there will always be a best trim height for whatever you have going on at the moment. .

[yarcraft91]

Originally Posted by jopes

Your prop should provide your enginge to get into the max operating range of the engine. Thia does not mean you nees to run there all the time. It just means your running the engine with the proper load on it.

Too low if a max wide open rpm will lug the engine and cause premature wear on it.

As said above, you want the WOT rpm to be in the specified range for your outboard, which is 5000-6000 rpm, if I'm looking at the right specs. Choose a prop that gives you those WOT rpm with your normal load in the boat. If you were only making 40 mph (by GPS) at WOT with 6 people, I'd wager your engine was turning less than 5000 rpm, which means a 21 pitch prop is too much for that load. If that's going to be your normal load, consider a 19 pitch or even a 17 pitch.

[titanxt]

That makes a lot of sense, thank you all. I am not sure what our "usual" load will be in the boat as of yet since we just got it. Some days there are just two of us fishing and other days we are loaded down tubing....

I do notice that my trim guage ranges from the halfway position to the full position. It never goes all of the way to the left. Is that an issue? With the motor all of the way down, the gauge reads half.

[T Mac]

Originally Posted by titanxt

I do notice that my trim guage ranges from the halfway position to the full position. It never goes all of the way to the left. Is that an issue? With the motor all of the way down, the gauge reads half.

It isn't adjusted right on the sending unit... is my guess.
Easy to adjust (by dealer).

[SD-walleye]

I just bought a 2008 Reata 1850 with the F150 Yamaha on it and I have been trying to figure it out also. I was running at about 5100 rpm with my 3 blade 21M Yamaha prop and I was getting about 44 mph with 2 people and normal fishing gear in the boat. The hole shot was slow and the rpm was running in the lower range, operating range of the Yamaha F150 is 5000-6000 rpm. I talked to propman and he set me up with a PowerTech 4 blade 18 pitch and hole shot is way better, rpm's are running at 5600, and top speed is 45 mph. Propman was a great help and I am sure he can assist you with your setup. Thanks Propman.

As far as your trim gage goes, if your motor is older like mine there is a little plastic piece that goes over the bar where the motor swivels while tilting. This plastic piece has broke on many people and now they make the replacement one out of metal, I have yet to order my new one but they aren't very expensive. This could throw of your trim gage if you have the same problem I did. The higher I trim the motor the faster the boat goes, I can trim it up as far as I can with the Powertech blade and I don't have blow out.