[SuperSnake]

This is admittedly a very grossly over simplified analogy, but it may make the process less mysterious if you view it like the available power will determine the diameter, and the gross weight of the boat will determine the pitch.

If like boats A and B both produce the same HP, then they would use the same diameter props.
Hypotheically consider that boat A is a big block that wants to turn only 4200 rpms at WOT, and boat B has a small block that wants to turn 5400 rpms at WOT.

Considering that the same POWER is pushing the same WEIGHT the only difference becomes the RPMs at which the load is applied. This what determines the PITCH. To attain the same speed, Boat A will use a bigger pitch, which will load the engine more to hold the rpm down to 4200, whereas Boat B will use a smaller pitch, which will load the engine less and allow it to turn up to 5400.


Now, it can be noted here (again . . . over simplified) that because each revolution of the prop will move X amount of water, that it is possible to alter both the diameter and pitch of the prop and attain the same result. As you increase diameter, you can decrease pitch and attain the same result. If you decrease diameter, you would increase pitch to attain the same result.

Consequently, just because your buddy's props have different specs doesn't necessarily mean that they are wrong or even different where net result of push is concerned. I he has the same powertrain they might be much closer to the same than you realize.

We have used General Propeller in Brandenton to tune the props on my buddy's 40 footer and have nothing but good to say about them. If you're searching, I'd recommend them as well.

Yendor, that’s a great explanation, I appreciate it.

Just received confirmation that my props are ready to go I am still going to buy spares.

Holidays are over rated. Consider yourself lucky. You get to avoid all the idiots, jetskis, overpriced food and drinks.

I agree with this, but we had quite a few people coming down for the holiday, which is why I wanted it done. It will probably be one of those trips that makes me appreciate the quiet weekends.

 

[Pirate Lady]

Great they got you fixed. Enjoy the weekend. You got a great story to tell the guests.
As for spares, personally, i don’t know many people that keep inboard spare props. Very expensive for a ‘maybe might need’. An outdrive definitely carry a spare, easy to change in the water, inboards you pretty much have to pull the boat.

 

[SuperSnake]

Great they got you fixed. Enjoy the weekend. You got a great story to tell the guests.
As for spares, personally, i don’t know many people that keep inboard spare props. Very expensive for a ‘maybe might need’. An outdrive definitely carry a spare, easy to change in the water, inboards you pretty much have to pull the boat.

That’s true, I could always buy them when needed since the boat has to be hauled. As for price, it’s the same as a few full tanks of gas. Maybe I should’ve gone diesel!

 

[Woody]

That’s true, I could always buy them when needed since the boat has to be hauled. As for price, it’s the same as a few full tanks of gas. Maybe I should’ve gone diesel!

The secret is, whether or not you can find them when you want them.

 

[ZZ13]

Great they got you fixed. Enjoy the weekend. You got a great story to tell the guests.
As for spares, personally, i don’t know many people that keep inboard spare props. Very expensive for a ‘maybe might need’. An outdrive definitely carry a spare, easy to change in the water, inboards you pretty much have to pull the boat.

I keep spares on board. Around here and in GA and FL divers can change props in the water pretty easily. Twice I wish I had the spares after I ran into shoals. Since I got the spares, haven’t needed them yet.

 

[Yendor]

I keep spares on board. Around here and in GA and FL divers can change props in the water pretty easily. Twice I wish I had the spares after I ran into shoals. Since I got the spares, haven’t needed them yet.

That is the third definition of Murphy's Law . . .
As long as you have them, you won't need them.

Which is FIRST reason to acquire and then carry spares.

 

[Techmitch]

That is the third definition of Murphy's Law . . .
As long as you have them, you won't need them.

Which is FIRST reason to acquire and then carry spares.

Yep. Once again it's time for the old saying, "It's better to have and not need, then it is to need and not have".

 

[dtfeld]

How about these? View attachment 168783 View attachment 168785

Tis merely a scratch!