Question about the right propeller for my boat

[Freeman1982]

Hello guys, I have question regarding my propeller, I have regal 2100 with Volvo penta engine. I bought it with15x17 three blade propeller, after checking with techs found out this is not the right application for my boat . I am here to confirm if the information I got is right .
They told me the right propeller for my boat is 14.25 X 21 with three blade .
But when I made my research I saw people saying the best propeller is 14.25 X 19 with four blade . So can you please advise me with the right one.
By the way when I have more than 7 people in the boat I am facing hard time to coming out the hole. Also it’s hard for wakeboarding comparing with other boats.

My boat info

40869324
A196003
50gxic270r

I appreciate your help

 

[Scott Danforth]

What is the WOT RPM you are currently able to get the motor up to running flat out.

 

[Freeman1982]

WOT reach 5000 RPM with 4 people in the boat

 

[Scott Danforth]

then you are prop'd correctly

 

[dingbat]

I bought it with15x17 three blade propeller, after checking with techs found out this is not the right application for my boat.

There is no right or wrong application for your boat. You can run any prop you want that lets the motor reach recommended rpm range at WOT

They told me the right propeller for my boat is 14.25 X 21 with three blade .
But when I made my research I saw people saying the best propeller is 14.25 X 19 with four blade .

Best at doing what?

Generally speaking, 4 blade props give more lift on the low end but require more HP to twist. They also loose efficiency as they increase in rpm compromising your top end speed.

It all comes down to what performance traits do you want or what performance issue are you trying to solve

By the way when I have more than 7 people in the boat I am facing hard time to coming out the hole.

At that point, the vessel is likely overloaded and you’re out of horse power. Need to lower the pitch of the prop to gain RPM

Bear in mind the number of people noted on the boat’s capacity plate assumes each person weight #150 pounds.

 

[Scott06]

As other have said if you are hitting 5k at WOT with a normal load you are propped right.

if you normal load is 7 people go down in pitch , 4 blade will help if you want to do water sports. As stated above how you use the boat will dictate propping. My normal use is 5-6 adults for watersports. I run a 4 blade because of this (21 ft sea ray / 5.0 Mecruiser). Pulls strong out of the hole ,r sure I am giving up some top end but rarely is it smooth enough to do much WOT. Also gives some stern lift.

Have you checked out the tune up state of your engine. My neighbor last summer who is an avid water skiier complained her boat didn't pull her up as well anymore (VP MPI 4.3 in 20 ft larson).... I'm thinking its because she is in her mid 70's and wont admit it... Flame arrestor was covered with fuzz... made a big diff in holeshot. Reason I mention is I would think except for when you have a ton of people in the boat (probably all in the back...) you should have pretty good holeshot with a 17 " prop unless your boat is heavier than I think. You have a 270 hp 5.0 right? On my 5.0 I found a vented prop helped the engine get in the fat part of its torque curve sooner allowing a little slip.

 

[Scott06]

There is no right or wrong application for your boat. You can run any prop you want that lets the motor reach recommended rpm range at WOT

Best at doing what?

Generally speaking, 4 blade props give more lift on the low end but require more HP to twist. They also loose efficiency as they increase in rpm compromising your top end speed.

It all comes down to what performance traits do you want or what performance issue are you trying to solve


At that point, the vessel is likely overloaded and you’re out of horse power. Need to lower the pitch of the prop to gain RPM

Bear in mind the number of people noted on the boat’s capacity plate assumes each person weight #150 pounds.

Dingbat this was a great response laying out the give and take of different props.

 

[airshot]

You might need more than one prop, depending on the load and what your going to do for rhe day. Heavier loads require less pitch, light loads more pitch but if your skiing or wakeboarding, then a different pitch might be needed. No one prop will do everything perfect...