What RPM shoould I be at?

[JustPhish]

29' Chris Craft Catalina 281 with two Mercury (I believe) 350's. Since I've had engine troubles which have been addressed, and I had a chewed up prop which I am addressing now so I don't yet know what speed I should be at. Where should I be for RPM's? Last season I had it up to 4500 or so but I kept worrying I was going to do damage to the engines so I mostly kept it at 2800 or so. First time owning a boat. Like I said I couldn't tell if 2800 was good enough because my starboard prop was all messed up so I wasn't getting speeds over 13-15knots even at 4800rpm.

Thanks,
JP

 

[Boatist]

Re: What RPM shoould I be at?

You need to get the exact data for your motors. Year and Brand and model numbers before anyone can help you. Max RPM change over time as motors changes are made.

To get the best fuel mileage you then get props to put your max RPMS at the at the low end of the Max RPM range.
For the best hole shot prop for the Prop for the Max RPM range.

Boats get heavier as they get older and when you add more gear so over time the max Wide Open RPMs will go down Slowly.

 

[25thmustang]

Re: What RPM shoould I be at?

4800 RPM and 13-15 knots, yes there were issues, but sounds like you took care of them.

On that boat, my guess would be a 3000-3200 RPM cruise (if it will plane at a lower RPM, keep her there) and probably 18-20 knots. Top end should be in the 4500-4800 RPM range, and the boat should probably be in the mid 20, maybe upper 20 knots.

These are all guesses, only a true GPS on the water will tell you.

 

[TyeeMan]

Re: What RPM shoould I be at?

What I've always known is, (not saying it's correct but I've heard it alot and it works for me) find your WOT range, it's usually listed on the engine someplace along with other engine specs. Say it's 4400-4800 rpm, put all the stuff you would NORMALLY have in the boat when your out including a full tank of fuel, batteries, etc. If you're propped correctly you should be able to run up to Max rpm and have to back off the throttle just a hair to maintain 4800. This way if you take some extra stuff or a couple extra people you will have just a little extra throttle to work with if necessary.