UUnderpowered

[bratzler]

I have a 16 foot long star aluminum hull boat. with a 1961 mercury 500. with a 2 blade 12 pitch propthe boat just bogs down with a skier or wake board. but will plane and go just fine with no load. is this motor under powered or is this too much prop for what I'm doing

 

[60sboater]

I don't know what props are available for your 50hp but a 3-blade would be better for pulling skiers. Research props and how they relate to speed and power.

 

[jbcurt00]

Before you start swapping props, it'd be important to make sure the 1961 outboard is running right and at what RPM at wide open throttle.

Depending on what your 16ftr weighs, is rated for, or how much weight (people, motor, gear and gas) your pushing around, adding a skier may just overwhelm the 50hp.

You may or may not be running the right prop now. What diameter 12pitch is on it now? Does it reach the correct rpms for your motor at WOT now?

 

[bratzler]

With two people in the boat it reaches wot fairly fast running around 31 mph. Per the mercury prop guide this is in specs for the motor. Loaded down the boat has trouble planning and will not reach full speed only about 23 mph.
The prop is an 11 or 10 3/4 inch whichever it is its the biggest that will fit
I've located a four blade 10 pitch michigan wheel prop that should fit. It's hard to get an accurate description of the prop from online vendors but it is 14 spline and from the part # amc556 also 10 pitch so we'll see.

 

[jbcurt00]

At what RPM is it running at WOT at 32mph?

What's the weight capacity for the boat? And when you say 'loaded down' is that at the capacity weight, more? Less?

 

[bratzler]

By Loaded I mean at or slightly more than capacity with is 835 lbs motor and accessories. I have no tachometer but the quicksilver prop guide gives the specs for that motor with that prop. That's the best way I can judge rpm until I figure out a tachometer. Mechanically speaking the only thing that I can't say is 100% is the magneto no dwell meter I had to use feeler gauges. Plugs are good looking doesn't load up starts easily hot or cold and no hesitation throughout rpms