Tapered Pontoon stern

[RadioDave]

Ran the 10 8 part number.
description I got on the Internet was replacement for 25 to 30 hp mercury.
mercury prop matcher described a prop and pitch much larger.
I wasn't convinced.
lead tech at Marine Propeller Warehouse said 12x9, like Mercury did.
​​​​​​Im still a little skeptical about going that big.
this I do know.
I ran a program for aircraft efficiency I have just to see the difference thrust and speed would.
remember the numbers are false, it is the change you are looking at.
only 3 percent faster, but 2.2 times thrust.
Assuming both pops can tach 5000 underway.
Big assumption.

 

[ahicks]

So I had some extra time this morning and dug in on this prop issue. The 10" is way too small, it's no wonder the boat accelerates so quickly. It looks like you're after something like a 12x8 or x9 after all, which agrees with what others have told you. Which one is going to work best is anyone's guess. You're so far removed from what's on there, what it's doing now isn't relevant. Here's a link showing a prop for $67. That would likely be my first try.....

https://www.iboats.com/shop/propell...-force-40-hp-1995---2017-8-11503584&finder=40

 

[RadioDave]

I feel ignorant in what we discovered yesterday.
the joy of ignorance is that it is curable!
​​​​​​I was actually off work yesterday, made measurements.
Went to the prop warehouse, and showed him pictures.
either it is 12x8, or 12.5x8.

 

[RadioDave]

What we discovered is, that the face of the prop is black, except the tips, the entire prop on the exhaust side looks like it was sandblasted.

 

[RadioDave]

And the bow port pontoon sloshed loud, stern pontoon very loud, starboard bow slight, starboard stern somewhat loud.
I am waterlogged!!!!

 

[RadioDave]

Pulled the plugs, Swabbed dry.
was the fuel I heard.

 

[RadioDave]

Pulled the plugs, Swabbed dry.
was the fuel I heard.

 

[RadioDave]

Sadly enough, I will test, but believe I have solved the mystery.
1900 pounds total including motor.
I can account for 1800 Pounds with a third in the front.
greenhorn operator.

 

[RadioDave]

Guys, thanks for sharing.
I'll soon find out if I was right.
sometimes you have to eliminate what isn't wrong to see what is.