Propeller information

[Mick05]

Hi everyone,

New to the site and new to boating. I have recently bought an older ski boat. It is a 1650 Lynx ski boat and I believe it used to be used for some sort of racing as I can see where the steering wheel used to be mounted in the centre of the dash.
It has a 175 Mercury Blackmax on it and after taking it out for the first time today I have discovered that it doesn't preform as expected. After talking to some other boat owners they tell me that I have the wrong prop on it.
The prop that is on it is a Quicksilver Laser ll. stamped on it is Quicksilver 48 16546 A40 21P. Which I understand is a 21 inch prop and this relates to the pitch.
This setup struggled to pull two teenagers on tubes to start with at full throttle but once it got going it was ok. I have bought the boat to take the kids and the wife skiing, so getting them up and going from the start is my objective.
Just wondering what pitch would suit this application? I have been told I need a 19 or 18 inch impeller and the other thing I was wondering is 4 blade or 5 blade?
Thank you in advanced and I look forward to learning more about boating from this site.

 

[Fun Times]

This setup struggled to pull two teenagers on tubes to start with at full throttle but once it got going it was ok.

Hi there, welcome to iboats!

Tubes have an tendency to create quiet a bit of extra drag compared to water skis.

Just for a starting reference point, how does the boat perform out of the hole with no one in tow?

 

[Mick05]

Thanks for the reply Fun times,

It seems to pull ok out of the hole with no one behind it. I'm a pretty big guy and when the wife drove it with myself (120kgs and son 70kgs) it took 3 attempts to get it up on the plane

 

[steelespike]

Before making a prop change it would help to know your lightly loaded wide open throttle rpm and gps speed.
This will help us tell if the performance issue is prop related or setup or motor related.What is the year of the motor and boat?
You need to be aware that reducing pitch will increase rpm and likely lower top end a little.It no doubt will improve hole shot but you may need
to watch the throttle if the motor over revs.

 

[Chris1956]

Gee, a 175HP motor on a 16 footer should have good performance. You might do a compression test to see if the motor is healthy.

 

[WIMUSKY]

I agree, since it sounds like the boat has been raced, you may not be firing on all cylinders. I'm assuming you didn't do a compression check and it sounds like it wasn't water tested before purchase? x2 on the compression check and look at the plugs to make sure you have fire to each hole......