Right Prop?

[maxum_man]

I had a mechaninc ask me if I had the right prop on my boat. I am only getting 2500 rpm's at WOT with only me (215 lbs) in the boat. It was on there when I bought the boat so...not sure if it is right or not. 1992 Maxum 2100 LDC with 1992 Force 120 hp L Drive motor. Prop size is 13x19. Speedo doesn't work in boat so no top speed reading. But like I said, I only get 2500 RPM's out of it. I have changed other parts and pieces, but he told me to start all over at the basics. Thanks!

Bryan

 

[thompy]

Re: Right Prop?

sounds like more than a prop problem, but i would think it is over proped as well

 

[steelespike]

Re: Right Prop?

Something is screwy.Really need to have speed for any fine tuning.we can get by with an estimaste to start with.Is the boat planed out at 2,500?About how fast keeping in mind that 25 to 30 seems faster than in a car.Prop could be too much but if it isn't planing you can't tell where you are prop wise.You need to confirm its running on all cylinders,that the carb is opening all the way.The stator is advancing as it should. Lync and sync set right.Don't assume any of these things are right unless you have checked.

 

[maxum_man]

Re: Right Prop?

Oh...I've been testing and replacing parts...New stator, fuel pump, timing recently set to spec., new rectifier on its way, new plugs. I just didnt know if that pro sounded like too much pitch or not. He was saying that for a 21' boat with 120 hp motor should be around a 17 pitch or so.

 

[steelespike]

Re: Right Prop?

Does the boat get on plane?about what speed?If your on plane at 2500 wot
(wide open throttle) a prop change isn't going to solve anything.
I would agree that a 17" prop is probably closer to what you need.
In my opinion you should be on plane but way below rated max rpm probably about 4000/4,500 or so rpm.

 

[maxum_man]

Re: Right Prop?

oh yeah I forgot that info...not on plane. It points to the sky!! not sure on speed either as speedo doesn't work. I would guess around 10-15 mph.

 

[thompy]

Re: Right Prop?

is the hull foam full of water, i would think a 15-17 pitch with a big boat like that. my brother ran a 17p on his 15.5ft chrysler speed boayslert that was pretty light with a 140 hp chrysler, but it did alot of pulling

 

[thompy]

Re: Right Prop?

is the hull foam full of water, i would think a 15-17 pitch with a big boat like that. my brother ran a 17p on his 15.5ft chrysler speed boat that was pretty light with a 140 hp chrysler, but it did alot of pulling

 

[maxum_man]

Re: Right Prop?

Good and dry! Im pretty sure this is an ignition problem, but i was told to check the prop size/pitch.

 

[Babylon519]

Re: Right Prop?

My 120 Ldrive has a 15" prop with 17 degree pitch. It's not the original - the original was that size but was cupped or flared at the trailing edges. I recently bought the lower end and gearcase from a 90 hp Ldrive that came with a new prop - it's a little smaller at 14.5 inches, and it's also a 17 pitch. I'll try it out on my 120, but I suspect I'll just keep it as a spare.