Prop Change Question...

[SunkenShip2]

I have a 2000 Larson 186 Lxi with the 4.3GL. I emailed Larson and the excellent team there tells me the boat left the factory with a 14.25 X 23. I found this boat a few years ago with a 14.5x19 and am considering putting the original prop back on the boat since the current 14.5x19 is lightly damaged. Boat performs quite well now, but what change in performance can i expect with the original prop? Thanks.

 

[Maclin]

Welcome Aboard!

Need to know a few more details, like what is the top RPM that the engine can hit now under load at WOT? What speed is that?

If your engine can get past the upper RPM in the manufacturer's recommended range for the engine (probably 4200-4600), then you may see an increase in speed. If it is only in the recommended range with the 19 p then you would hear your engine lug, lose holeshot performance and top speed would not increase, maybe lose some MPH. Going from a 19p to a 23p is a big jump.

So, what numbers are you getting now out on the water?

 

[SunkenShip2]

Thanks for the reply and welcome Maclin.

I would estimate the motor is reaching the upper-end of the RPM range. Unfortunately, I can't tell the exact RPM since the gauge is off.

With a light load I can see 47-48mph and 42-43 with a full load of around 550lbs+ a full tank of 30 gallons.

My holeshot is currently impressive along with torque; it will come right out of the water full trim down upon demand. Gotta say I really like this Larson.

 

[Bondo]

I would estimate the motor is reaching the upper-end of the RPM range. Unfortunately, I can't tell the exact RPM since the gauge is off.

Ayuh,..... Welcome Aboard,..... That's Critical information,......

Borrow a shop tach, 'n see exactly what it does,.....

 

[SunkenShip2]

Thanks Bondo.

Will try to get an exact number on the RPMs. From listening to it I am thinking it is exceeding recommended limits. The engine has no problems turning this prop. Hopefully, will get number within the next week.

 

[SunkenShip2]

RPMs are reaching right at 5300 at WOT with top speed of 46mph. May have reached 5400-5500 if I would have held it open. Tach is off by exactly 500RPMs

https://ibb.co/fGRw4y

 

[ahicks]

If you like the performance it has now with the 19", you'll be turning it into a complete dog with a prop change 2 sizes bigger like you're suggesting (23"p).

For max performance, especially where water sports are concerned, you want the engine to turn max rated rpm with a light load. It sounds like you are there now with the 19"p. That's where I would stay.