crownline 250 prop

[jhilton]

I have a 1994 250 cr with a 454 and bravo 1, I dont know the gear ratio its worn off. I want better gas milage. My prop now is a 21 pitch mirage, the rpms are 4450 at 40 mph with a normal load for us and a half tank of gas, no reason to haul an extra 40 gallons of gas for a 10 mile trip. I can stay on plane at 3400 rpms and 29 mph. Will a 4 blade 20 pitch be a good choice? The boat weight is supposed to 5100 plus gear.

 

[steelespike]

Re: crownline 250 prop

Hopefully someone better aquainted with larger craft will be along.In the mean time I'll try to get you started.
Do you have trim tabs?Heavy boats do produce higher slip numbers
Usually a 4 blade prop will help stay on plane and help keep
slip numbers down.Try to stay with same brand same material.Usually suggested to drop one inch in pitch going to a 4.Your motor will use 10% of its hp rating in fuel per hour @ wot.
A 350 hp would use about 35 gph @ wot.Your best cruising speed could be just on plane or signifigantly higher.Experimentation or a flow meter is the only way to tell.No flow meter you may have to top up the tank a few times and test run a few times to a favorite destination.

 

[jhilton]

Re: crownline 250 prop

Yes, I do have trim tabs. I was looking at the apollo 4 blade 20 pitch. Thanks for the reply good info.