define "cruise speed"
 

You always see brokers advertising cruise speed of a boat. Seems to me that they are getting faster and faster cruise speeds these days... You see a boat with a top speed of 105 and they list the cruise at 95...to me that doesnt sound right.

So what is your definition of "cruise speed"

I've always heard it was the point where the speed and fuel consumption point is at it's most efficient. Or for some folks, the most "comfortable" for both equipment and passengers.

Cruise Speed is an RPM where your Not hurting the motor by running a Long distance at that speed/RPM. Usually about 3500 rpm, anyone who has a cruise rpm much higher than that doesn't grasp the idea. You Can gear & Prop your boat to be fast at cruise rpm, but acceleration and Top speed will suffer.

I was under the impression that cruise is around 65% throttle

I've thought cruise speed to be 2700-3500 rpm

Cruise speed : The speed at which a woman's breasts gentle sway as the boat move over the water.

non-Cruise speed : The speed at which a woman's breasts flail about as the boat moves in a jerky manner thru or over the water.

Hahahahaha! Pertect! :lolhit:

Yup...pretty much.

Agreed!

Was always told that cruising speed was the speed that the boat operates at max fuel efficiency.............

WwW

This. Although I know plenty of people that cruise 4000 - 4500 rpm all day and never think twice about it.

For me, it is just under where the secondaries open up :) So just under 3400.

+1. Although go-fast are kind of an odd duck cause the "cruise speed" could be pretty fast and not what most would consider cruising at all. Depends on the hull, and torque/hp curve on the engine.

So for my sea ray its 3100rpm cause thats where the manufacturer told me and it does get really good fuel consumption at that range, even though I prefer speeds closer to 2900-3000rpm for what I consider crusing. For my Apache I don't have a clue and will likely never know until you get some fuel burn readings to run the numbers with.

rule of thumb for a mpi engine take divide horse power by 12-12.5 and that gives you fuel burned in gallons per hour at wide open throttle.

6,250 gallons per hour seems reasonable for a 500hp engine.

I've always heard the same as this and that it comes between 3000 and 3500 rpm's depending on the motor and which carb it has.

See ya,
Kelly

The speed where the wife quits b****** about going too fast.
I agree with carburated motors just before the secondarys open and on injected motors about 3500

W.O.T. No really the Cig 38ts 525s seams to be about 3800 rpms The boat loosing up an fuel ecno seems right. Artie :whistle:

415hp / 12 = 34.58 gallons per hour X 2 = 69.16 gallons per hour twin 502's. Looks reasonable, but their carbed motors not mpi.

3,500

I agree that was very well said. However, most people will have different viewpoints and perspectives on this matter anyways.

I also agree with you....

for Big Blocks, now for the 60 hp Johnson o/b on the back on my 15' Boston Whaler, that is another story

28 Daytona twin 496 mags
top speed 90 @ 4900 rpm
Cruise 70 @ 4000 rpm

37 Spectre twin Yanmar diesels
top speed 55 @ 3800 rpm
cruise 38 @ 2900 rpm
Fast cruise 45 @ 3300 rpm

The eliminator had to be going over 50 to ride well, no tunnel spray ect, and fuel economy was the same from 40 to 70 so usual speed was 70.

the spectre i usually run around 38 upper 40's if i am in a hurry, I can run those diesels forever at 3400 rpm, but economy is better around 38. I know it's dead slow compared to a go fast but different kind of boat, although it does ride better as you speed up!

We did agree you cover my fuel bill for the first month of owning the boat. I am sure we will go throw a few gallons the first weekend out at LOTO. See you tomorrow.

What ever you come up with just keep in mind motors don't like to stay at the same RPM for long periods of time. Move that stick around every now and then.

For me and my Baja, cruise speed depends on safety and comfort of passengers.

For my pontoon.....wfo all day long............. "Are we there yet"

A lot of it depends on the build of the motor. I know mine have a 6100 limiter so I think 4000 or right below is a good cruise....

My boat likes 3500-4000 better.

depends on the boat + power. For our 388, 3500 rpms seems to work real well. In the hdrostream, it's about 3000 rpms, but it's a mod-tunnel hull also.

It varies for all. I run with twin outboards that do not like low RPM's. My top end is 5900-6100 RPM's, but I cruise at 5400-5700. The motors are made for that. 5 boats ago, I would cruise at 4000 with a Merc outboard. It all depends.

I've always heard 75% of max RPMs. For example, @ 5200 RPM max, that's a cruise @ 3900 RPM.

The formula is different for carb engines the 12-12.5 number isn't for carbed engines it is just for mpi.

I have twin procharged engines and I just consider cruising anything without having boost. For me that is anything under 4000 to 4200 rpm. Mine will very on speed depending on water conditions and load. It also depends on where I run the tabs and drive for a good ride. Most of the time 3500 to 3800 from 66 to 68 mph.

As you can see from the variety of responses here, cruise speed is an arbitrary and meaningless number. You can just ignore it.

Michael

i like post 6. boobies flailing. means the smaller busted your woman, the faster your cruise speed is. also need less left tab. it is defined though as best miles per gallon speed. so you gotta compare gph and mph...note; idling on 1 engine doesn't count...

I agree with the "lots of factors" idea. My cruise speed and RPM will vary with the fuel and passenger load. My 382 likes to cruise at about 3800 and with a little tab with a full load of people and fuel. I do listen for the secondaries and back slightly off from them opening. When I am lighter its lower. Water conditions play in also.
Just my .02

Bravos break most often between 3-4K rpms so I keep it above that :daz:

anything under 3500rpms with cubic inches and twin blower motors or you will need a fuel bardge and all major gas cards at your conveniance

Not sure I understand when people say hurt the motor. For the most part stock engines (Merc for example) have an operating range. It says nothing about "hurting" the motor when using a motor at any point in the operating range. Sure at WOT you are burning a ton of fuel and maybe accelerating wear a bit. But as long as the engine is operating within its normal parameters for any given RPM, you are not "hurting" the engine.

I do know some boaters that absolutely cringe when they push their boat motors toward WOT. I guess it is the noise that freaks them out?

Marine engines are tough! Don't be afraid to use them from idle to WFO. Just keep an eye on your gauges.

Cruise? It's the point where speed/fuel efficiency is at its peak for any given boat. There can be no "standard" as there are too many variables.

My 382 with 500 EFI's cruises at 3800 rpm's and is running at 43-45 mph depending on water conditions. I always wanted to change prop pitch to see if I could obtain a better cruise speed at the same rpm's. My max wot rpm's are 5400.