Prop inspection and sizing

[skiierjeff]

Hi:
I bought my 1977 SRV 240 Weekender last year to fix up. Target first launch Spring 2012. It has a MCM 260 Mercruiser 350 small block, Alpha drive and a displacement of 4400 lbs.

It came with two props:
Aluminum #48-78118-17
14 1/2 " 17 pitch


SS- 48-88438A4 17P
15 3/4 17 Pitch

The aluminum one was mounted and the SS was in the cabin. I'm assumig that there may be something wrong with the SS one if it wasn't being used. What can I inspect on my own?

Do you think either of these are the right prop? I'm primarily seeking fuel economy over hole shot or top end speed.

Thanks in advance for your advise.

Jeff

 

[blaster]

There are a lot of variables when finding the best prop. I suspect the steel prop didn't preform as well as the aluminum because the boat is heavy and doesn't have the horsepower to make use of the wider diameter. Most of the time the wider diameter prop's are used on big block setups with more than 300 horsepower. I think the thing to do is run both props and note your speed and rpm's. GPS is the best way to get an accurate reading. Note the wot range for your motor. Don't hold me to it but I'm thinking 4200~4600 your best prop will be near the top of that range. Make sure you are trimmed out almost until it ventilates. Once you know how the props you have preform you will be able to make an informed decision as to weather you need something different than you already have.