Enough power?

[hepps21]

I am considering purchasing a 2004 Crownline 23 foot bowrider with a 5.0L mercruiser bravo three drive with fuel injection. I have seen it rated at 260 hp but am concerned it may not be enough power to do what I want with a full boat. The boats dry weight is 4400 lbs. and is rated to have 12 passengers. We like to tube, ski, and wakeboard and will probably have close to 10-12 people on the boat each time and want to be sure we get decent performance out of it. We currenlty have a 5.0L mercruiser with thunderbolt ignition with an Alpha drive which I believe puts out about 220hp but that is only on a 20.5 foot bowrider. I know the handling on the b3's are better my concern is the performance. Any thoughts would be great.

Thanks.

 

[HT32BSX115]

Re: Enough power?

Howdy,

Welcome Aboard! Well, depending on how big those 10 people are, that's a LOT of extra weight on any boat that is going to be used for skiing or WB.

If you're worried about it, you might do a lake test of it before you buy it.... (I would do that anyway)


Regards,


Rick

 

[hepps21]

Re: Enough power?

Thanks Rick,

They will mostly be teenagers. I am planning on doing a lake test but the difficult part for me is judging the difference in power with the boat.

 

[HT32BSX115]

Re: Enough power?

Thanks Rick,

They will mostly be teenagers. I am planning on doing a lake test but the difficult part for me is judging the difference in power with the boat.

I know the handling on the b3's are better my concern is the performance. Any thoughts would be great.

I removed an OMC 460 King Cobra (single 3 blade prop) from my 1987 21' Four Winns Liberator about 4 years ago and replaced it with a 1997 Merc 454 Bravo III.

The 460 was rated at 340 crankshaft HP and the 454 is rated at 330 crankshaft HP.....(making the propshaft HP very close)

My brother bought the boat new and it was always quite sluggish out of the hole but would top out at about 60mph at 5000 RPM (200rpm over max rec) (when it finally planed that is......it was REALLY sluggish with a bunch of people and "stuff" in it!!!!)

After I installed the 454/BIII, the difference was nothing less than spectacular!

I now just ROCKETS out of the hole and still tops out at 57 GPS MPH at the MAX recommended 4600 RPM.....(even when fully loaded! I even got pretty good performance with 8 people 3 dogs at Lake Tahoe a couple of years ago... 40 mph and jumped right up on a plane (6000' elevation)

I am planning on doing a lake test but the difficult part for me is judging the difference in power with the boat.

I believe you will be pleasantly surprised by the hole-shot performance with the Bravo III !

I think the 5.0L MPI should turn around 5000 RPM at WOT.

Look in the owners manual for the recommended MAX WOT RPM It should turn the max or close to it and that is a good way to determine if it's running correctly. It won't hurt it to do a short run at max throttle.

If it doesn't, it might be a little over propped or something else is wrong. The boat will probably have a 2.00:1 ratio drive and maybe 24p props.

The ratio should be on the side of the drive and the pitch is plainly stamped on the props.

Using a prop slip calculator (and 12% slip) it'll probably do around 50 mph at 5000 rpm.....(I used 2.00:1, 24p, 5000, 12% slip) The slip number is an approx number and you usually find it using an accurate TACH, GPS, known prop pitch and drive ratio.


Cheers,


Rick

 

[Gettinther]

Re: Enough power?

First let me say to Rick, I wish i had the unit you removed for my boat (Ford).

Otherwise just an opinion but I would have to try this boat loaded the way you intend to use it before i bought it .
hope it works for you

 

[HT32BSX115]

Re: Enough power?

First let me say to Rick, I wish i had the unit you removed for my boat (Ford).

Howdy,

Unless you are already stuck with a 460 Cobra, believe me, you wouldn't want one!!

Otherwise just an opinion but I would have to try this boat loaded the way you intend to use it before i bought it .
hope it works for you

I thought I suggested he lake test it....He did say he's going to do that....