Prop size for 50hp 2 stroke yamaha

Im not getting ANY straight answers in my search for the correct prop. I want better top speed while retaining load.
I have a 2001 Lund 1650 Rebel which weights 635 pounds. 2004 yamaha 50hp 2 stroke is around 300 pounds. Two people at 170 pounds each in boat
Add 200 pounds for trolling motor and gear. Thanks

Re: Prop size for 50hp 2 stroke yamaha

You have done a very good job of getting us the information on your setup.
In order to suggest a prop we need to know how your present setup is doing.
We need the prop size and the lightly loaded wot rpm and gps speed .The only way to know if your present setup seems right.
The whole key to prop selection is to get the motor so it can rev freely within its rpm rating,
with a wot rpm close to the max rating.Any prop is a compromise so you need to decide what you want most
speed or load carrying and hole shot.Keep in mind if we include all brands,styles,pitches,materials and cost there are probably 20 props that would work on your boat if we play with the various results.
I can be fairly sure that a 12" pitch will work well for you but suppose your boat is dogging it
with a 12 now.If you get is the information we'll get you set up.

Re: Prop size for 50hp 2 stroke yamaha

I cant really provide that info. Its
a tiller without tach and speedometer. I never gps'ed it. Going to canada next weekend. Delayed because i havent been able to get answers. I will go with whatever the expert opinion is a try that prop

Re: Prop size for 50hp 2 stroke yamaha

Try a Solas Amita or Rubex 12" pitch prop. A prop listed for your motor will be the right diameter.
When you get settled buy an induction tach like a Tiny Tach Be sure to tell them its for an outboard.
Do some test runs and get us the information.
Its important for the performance and health of the motor that it operates within its rated wot rpm range.
Rpm too low and it will cause poor performance and ,in time, premature repair problems.
Too high could produce engine failure. Have a good time and don't sweat it over the short term.

Re: Prop size for 50hp 2 stroke yamaha

If the yamaha performance bulletion lists 10 5/8 x 12 for a similar boat that weights 805 pounds for hull and mine is 635 pounds. If boat is lighter, do I go to a bigger prop diameter as in
10 5/8 x 13?

Re: Prop size for 50hp 2 stroke yamaha

The Mercury prop selector has a Yamaha program.

With your stated weights, it calculates a total weight of 1543lb(with 12 gal gas), and says with a 13 pitch prop it should do about 5250 rpm @ 30.9 mph. With a 14 pitch it drops the rpm to 5000, but the speed stays about the same.

This calculates to about a 14% slip, which is OK for that type hull.

So it appears that the 13 pitch would be the better choice for over all performance, since your rpm range is 4500-5500 rpm.

A Solas prop will work fine, since they make the props for Yamaha.

Note: the 2 stroke 50 weighs 190lbs according to the owners manual, while the 4 stroke 50 weighs in at 249lbs. So we can deduct 110lbs from the total weight. So you might get a little more rpm/speed from the 13 pitch prop.