another prop question

[ccruser1]

Hi everyone. I have a 2300scr with a v6 4.3XL married to a alpha one outdrive. The other day I found myself grounded on sand and was able to pull boat off and get underway. Once under way however found I could not plane out and got back to marina at slow speed. Seemed like a spun prop but now I am thinking maybe I just did not have the trailoring switch all the way down for the drive unit.
Anyway, started shopping around for a new propellor and all the charts were saying to use a 14.25X17 prop. This is way smaller than what is on the drive now. The current prop looks like a 16 inch maybe with a 16 pitch. Number on prop does not come up when googled (48 16440-CI-16). This prop comes within 1/4 inch of the flat part of the lower unit that has the trim zink ( I have one that does not have the fin) This seems like it is too big to me. Anyway, I try'd the 14.25 X 17 and the boat struggled to reach 3000 rpm and hardly moved at WOT. I normally cruise at 3500 rpm and do roughly 20-25 mph depending on conditions.
I took back the 14.25 X17 and got a 15.25 X 15 prop and now it revs up quickly to 4500 rpm and still does not plane out.
Does anyone out there have this same boat configuration that could tell me what they are using?
Any help is appreciated. My next step is to try a prop shop to try and determine what I have.
thanks,
CCRUSER1

[jrsick]

I don't have same boat as you, but have seen this same topic discussed in sport cruiser section of this forum. May want to look there while waiting for responses to your post.

[shrew]

The 4.3L should have a Max. RPM range of 4,400 -4,800. If you got up to 4,500 rpm at WOT, I would say you are in the ball park. In my mind 4,600 would be the sweet spot, but I've read where you want to get as close to max rpm as possible. Personally, I think the range is a bit more variable depending on your goals. If hole shot is your goal, then closer to 4,800. If cruising speed is what you're looking for, then closer to 4,400.

If you're still not getting up on plane at 4,500 rpm's there is a problem somewhere else, IMHO.

How is the condition of the bottom and drive in regards to marine growth? What is the load you're carrying (e.g full fuel, loaded with gear, coolers and passengers)?