less speed and more list

[Renny_D]

Hi, I have an interesting situation that I am trying to understand. I bought the Bayliner listed in my sig. The original prop that came on it was badly dinged so the owner gave me what he said was his spare prop. According to the manual the original prop was a 13 inch 19 pitch prop. The one that has replaced it is a 14 inch 17 pitch prop. I lost about 8 mph top speed but the boat goes on a plane really quickly. I mostly plan on using the boat for pulling a tube so I thought maybe the bigger steeper prop would work better for that. I have noticed though the faster I turn the prop the more the boat lists to port. Is this because of the prop change. I don't have a tach so I can't tell how fast the motor is turning. It does sound like it is not able to reach the same rpm as before but other than that the boat seems to run fine? Please let me know what your thoughts and or feedback is on this.

Thanks
Renny

 

[steelespike]

Re: less speed and more list

You shouldn't be changing props without a tach.It is very likely the 17 will allow the motor to over rev.operating a motor outside its recommended rpm range (too high or low can cause premature engine failure.You need to get the tach working or perhaps get a tiny tach.or borrow a shop tach to check the rpm.
You may be able to get the 19 repaired.Listing to port can result from prop torque and can be agravated by poor trim angle,weight placement,hull deformation,and or waterlogged hull.

 

[Frank Acampora]

Re: less speed and more list

You should not be using that 14 inch diameter prop on the 85 Force as anything other than a spare. It just has too much blade area to keep the engine happy. I would not be surprised if the engine was turning less than 4500 RPM. That's why you lost 8 MPH. Either repair the existing dinged prop or buy a nice used stainless in the same 13X 19 pitch. Stainless will give you about 200-400 rpm more than the equivalent aluminum prop and a couple of MPH more also. Would not hurt to get a tach and check that your RPM is within the 4500-5500 operating range at wide open throttle with the 19 pitch prop.

 

[Renny_D]

Re: less speed and more list

Thanks for the feedback. I just dropped my old prop off at the shop and will have it back next week.

Renny