Prop Advice for Rude 120

[Lucrestyle]

I have a 1989 Larson Senza 16.2ft with a 93 120hp Evinrude,

Currently I am running a 19 pitch prop and I am getting 5000rpm at WOT trimmed up (45mph), 4600 WOT trimmed down. The recommended operating range for my engine is 5600-6000rpm anyone have any advice on a all around great stainless prop, I would like to get something with a little bow lift, a little better hole shot and some more top end, I might be wishing to get all three. Any recommendations?

ps.. I use the boat for water sking, wakeboarding, cruising and a little fishing.

 

[walleyehed]

Re: Prop Advice for Rude 120

Before spending a dime on a prop, verify the tach.
You need atleast 5800 to be able to do what you want to do...efficiently.

 

[Lucrestyle]

Re: Prop Advice for Rude 120

how would I go about varifyin the tach? It seems to be working correctly, i mean i have had no issues since I cleaned all grounds. at WOT 5000rpm trimmed up the engine isn't screaming so I know its fairly accurate.

how would I go about generating 5800rpm seems like I would have to go down 4'' on the pitch, i know a 15 is too small. I have read that going from an aluminum prop to stainless steel can generate 100-200 + rpm

here is what i figure please tell me if i'm wrong (ps i am testing with 4 people in boat as that is my normal load)

19'' aluminum prop 5000rpm @ WOT (trimmed up)

if i switch to a stainless raker

17" stainless prop i should generate 5400 + 100 (stainless) = 5500
I am moving the engine up one bolt hole as it sits a little low i expect 100-200rpm increase when i do this, according to my math this would equal around 5800rpm

Does this sounds right? or am i lost in the fog!

 

[walleyehed]

Re: Prop Advice for Rude 120

Alot depends on hull design, but generally you will lose 100RPM going to SS in the same pitch...I have seen this go the other way if the SS reacted in a more positive manner of over-all lift.
You mention Raker...you won't find one in any odd number pitch..it'll be an 18, 20, 22 etc...
The Raker will also add alot of bow-lift which can be good on the right set-up, and yes, lifting the engine is a good Idea as long as you can maintain water pressure.
Another item to keep in mind is just because you have 2 props in a like pitch don't mean they will turn the same RPM. I only wish it were that simple.