What cruising rpm for 83 Sea Ray 245?

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chris0061

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Jun 17, 2007
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Hello, We picked up a 25 foot sea ray cruiser a couple month ago and have had it out about every weekend, runs great. This is the biggest boat we have owned and I was just wondering about what rpm should she plain out at and stay plained? The lowest I can run her is about 3500. 4000 rpm she really plains good. Is this normal for a boat that size? It's got mercruiser 260 with gen II out-drive. 19 pitch stainless apollo prop.
 
Philster

Philster

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Sep 15, 2009
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3,342
Re: What cruising rpm for 83 Sea Ray 245?

Are you trimming the drive up? Although, those boats take some serious oomph to get plane and stay there.

What is the max RPM she will run at when you apply full throttle AND trim the drive up???
 
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chris0061

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Re: What cruising rpm for 83 Sea Ray 245?

It hits the top end, 4600 and still a little left. I noticed 4800 the first time I wot and just bumped it back to 4600. Yes I trim it all the way as far as I can without rpm jump or cavitation.
 
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HT32BSX115

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10,083
Re: What cruising rpm for 83 Sea Ray 245?

chris0061 said:
It hits the top end, 4600 and still a little left. I noticed 4800 the first time I wot and just bumped it back to 4600. Yes I trim it all the way as far as I can without rpm jump or cavitation.
Click to expand...

If you can get 4800 at WOT after trimming for MAX speed, (no cavitation etc) It appears you're running good and "propped" correctly.


When you change the RPM, you'll usually have to re-trim the drive a little.

Try running as slow as you can run again while staying "on-plane" and see what the RPM is. Then experiment with the trim setting. (don't use the gage, use feel)

That's a fairly big heavy boat. It'll take a lot of power to get it going and a fair amount of power to keep it on a plane.

If you have cockpit adjustable tabs, you'll have to experiment with them too.....


Cheers,


Rick
 
Philster

Philster

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Re: What cruising rpm for 83 Sea Ray 245?

Three-bladed prop?

A 4-bladed prop would be better.

You have the engine running right. About all you can do it keep tabs in the water, drive down, apply a lot of power and get on plane.
 
H

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: What cruising rpm for 83 Sea Ray 245?

Yeah that would be a great thing to try. Most prop shops will let you try one.

I would try an 18P 4 blade.....


More blades in the water will always improve hole shot!!
B3.gif
 
jtmarten

jtmarten

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Aug 2, 2004
Messages
825
Re: What cruising rpm for 83 Sea Ray 245?

Sounds right for that size/weight boat with a single drive.
I can keep mine on plane as low as 22-2300rpm, but I've got twins pushing.
 
C

chris0061

Chief Petty Officer
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Jun 17, 2007
Messages
446
Re: What cruising rpm for 83 Sea Ray 245?

OK great feedback, I'm playing with my trim tabs a little just to keep her level as the old lady moves around the cabin and deck. Seems like keeping those down a little struggles the engine a little more. But I will definitely play with it some more. I only use the gage before I start out and when I trailer it. I don't like to bring it all the way up so I got a spot on the gauge were I try to stop. Next time out I'll see how low I can go. I'll also keep my eye out on a 4 blade. I've heard allot that those are better. Thanks for the great advice.
 
A

Aloysius

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Aug 21, 2010
Messages
484
Re: What cruising rpm for 83 Sea Ray 245?

3500 rpms is considered high cruise for a small block Chevy like yours. Up to 4000 for short durations. These engines aren't really designed for sustained full throttle operation.
 
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