complicated question!

Let me start by saying this is my first real boat and I know NOTHING.

I just purchased a '76 reinell 24 ft cabin cruiser with a flybridge. It has a Mercruiser 351w ( 233 ) that has just been rebuilt and runs good. The problem is that the outdrive has been completely removed and discarded. I can't seem to find an actual 233 outdrive used anywhere.

I am trying to figure out what outdrives are compatible so I know what to look for. I know the original gear ratio was 1.32:1.

I am trying to get this thing in the water as inexpensive and as easy as possible.

I have been told to buy a 1.50:1 ratio outdrive and reprop it.

what pitch of prop should I use to compensate for the ratio difference?

What are my options?

Any help would be greatly appriciated.

Re: complicated question!

Newfie, how much HP do you have, I can't seem to find that boat with a 233 HP option. But if that is what you have these are my recommendations for your boat. I am assuming your WOT range is about 4,400 RPM to 4,800 RPM.
Normally with a 1.32 to 1 gear ratio that boat would need a 14" Pitch prop with a total allup weight with people and gear about 5,100 pounds. By changing to a 1.5 to 1 gear ratio that changes your prop to a 16" Pitch for the same performance with the same weight. And with a Prop Slip of about
30% for large cruisers you ought to be doing about 34 MPH at top end speed.

Here are the results of my calculations.

Re: complicated question!

Thank you hwsiii
that info gives me a good idea where to start.
my wot according to my book is 4,200 - 4,400rpm.
I think your right on for weight though, judging by what the scales say.

Re: complicated question!

Newfie, since it only turns 4,400 RPM then you will need to change Prop Pitch to 18" for the same weights and speed.



H

Re: complicated question!

you are awesome!
thank you very much hwsiii.

Re: complicated question!

Newfie have you tried the boat yet, I would like to know what the new numbers are.

H