Wot ?????

[whatisup02]

Ok im new to boats but not to engines. Why am I reading that you need to run your boat at WOT or your shorten you engines life? You don't do that with your car and if you did you would kill it fast. Can someone explain why?

 

[Don S]

Re: Wot ?????

Why am I reading that you need to run your boat at WOT

You need to run it at WOT in order get the proper prop. Other than that, there is no reason.

PS: That is being run under load, not sitting in your driveway on muffs. You DO NOT for any reason go to WOT with no load.

 

[emoney]

Re: Wot ?????

And your "cruising speed" will be quite a few RPMs less than WOT. This is the "sweet spot" for the motor for fuel economy and "longevity".

 

[ktbarrentine]

Re: Wot ?????

Ok im new to boats but not to engines. Why am I reading that you need to run your boat at WOT or your shorten you engines life? You don't do that with your car and if you did you would kill it fast. Can someone explain why?

Just curious....where are you reading that?

 

[achris]

Re: Wot ?????

That statement should be... Your engine needs to be able to run at the manufacturer's recommended revs at WOT or you will shorten the engine's life.

 

[BoatDrinksQ5]

Re: Wot ?????

I would guess it would be related to letting the engine go to a high RPM and/or WOT at least once in a while to let the engine be fully exercised and clean out engine....etc... Full flow through carb flush it better?

i know i have seen plenty of people state something to that effect on a handful of threads here.

I don't know anything about this topic - but it has always made a small amount of sense to me.

 

[fmalott]

Re: Wot ?????

reading this forum for a few years now i only see WOT when a repair is being done on a engine to see if the problem can be narrowed done to a certain thing and then when the repair is done you WOT to see if the problem comes back. If you want a boat to wot all the time buy a cigar boat

 

[whatisup02]

Re: Wot ?????

It was here and someone said that "lugging" your engine will wear it out faster. But maybe it was that if you cant hit the spec rpms that will wear it out??

 

[emoney]

Re: Wot ?????

More than likely, it was the latter, and it was most likely in the "prop" forum. Every motor will have "Manufacturer's Specs" as it applies to a WOT range, and if you're motor is not reaching those specs, then something is obviously wrong. Without knowing that, you could be damaging your motor and the problem won't surface until it's "too late". Of course, over-revving is just as big of a concern, if not bigger.

However, for optimal longevity, "cruising RPM" should be the dominant range. I've always been a "sound" person, even though I have a functioning tachometer. Not that I ignore the tach, but I can almost tell you with a couple hundred what RPM we're running just by listening to my outboard. It comes with time and use, and you'll find you will be doing the same eventually. I think we call boats "girls" because they are a lot like them in that we tend to know that "when the tone changes" we might be better off paying attention, lol.

 

[whatisup02]

Re: Wot ?????

More than likely, it was the latter, and it was most likely in the "prop" forum. Every motor will have "Manufacturer's Specs" as it applies to a WOT range, and if you're motor is not reaching those specs, then something is obviously wrong. Without knowing that, you could be damaging your motor and the problem won't surface until it's "too late". Of course, over-revving is just as big of a concern, if not bigger.

However, for optimal longevity, "cruising RPM" should be the dominant range. I've always been a "sound" person, even though I have a functioning tachometer. Not that I ignore the tach, but I can almost tell you with a couple hundred what RPM we're running just by listening to my outboard. It comes with time and use, and you'll find you will be doing the same eventually. I think we call boats "girls" because they are a lot like them in that we tend to know that "when the tone changes" we might be better off paying attention, lol.

LOL
I have a lot to learn!!!

 

[Howard Sterndrive]

Re: Wot ?????

It was here and someone said that "lugging" your engine will wear it out faster. But maybe it was that if you cant hit the spec rpms that will wear it out??

^^ that!

your propeller is chosen so as to permit your engine to attain recommended WOT rpm range, not above or below as either is detrimental

 

[Bondo]

Re: Wot ?????

It was here and someone said that "lugging" your engine will wear it out faster. But maybe it was that if you cant hit the spec rpms that will wear it out??

Ayuh,.... It was probably Me, I just typed that recently,...

Propin' a 350 to 3200 rpms, top end, will smoke it in No time...
Detonation would burn it up in minutes, maybe a hour...

Propin' a 350 to 4800 rpms, at wot, 'n then crusing at 3200 rpms,... 'n that 350 will live a very, Very long life...

 

[whatisup02]

Re: Wot ?????

This is the one I read.

"Have you run your numbers through the Mercury Marine prop selector?

It comes up with a 22.5 pitch set, assuming a 2.0 gear ratio.

But since you're only getting 3400 rpm with 24's, I'd go with 21's.

Doing the math(537 total less the 155 hrs on the new motor) indicates the previous owner managed to kill the motor in just 382 hrs lugging it like that."

 

[Bondo]

Re: Wot ?????

This is the one I read.

"Have you run your numbers through the Mercury Marine prop selector?

It comes up with a 22.5 pitch set, assuming a 2.0 gear ratio.

But since you're only getting 3400 rpm with 24's, I'd go with 21's.

Doing the math(537 total less the 155 hrs on the new motor) indicates the previous owner managed to kill the motor in just 382 hrs lugging it like that."

Ayuh,... That weren't Me, 'n without the rest of the story, it don't really help this conversation...

 

[emoney]

Re: Wot ?????

Bond-O said it earlier, if your motor is spec'd to hit "X" rpms and your prop is causing you to only hit "Y" rpms, then there can and will be a long term negative effect, because you aren't getting into that sweep spot that we call the "C spot" (get it? C = Cruising RPM...I'm such the comedian)

 

[whatisup02]

Re: Wot ?????

I got it now. I just didnt at first. You need to beable to hit spec RPMs but that does not mean you have to run them.

 

[emoney]

Re: Wot ?????

You sir, are correct! And don't fret, most of us don't get it in the beginning, and are still getting it as we cross those bridges that tend to come up. Even with all the this & that of boating, still beats any day at work!

 

[Brewman61]

Re: Wot ?????

I got it now. I just didnt at first. You need to beable to hit spec RPMs but that does not mean you have to run them.

Exactly. You'll also find out that excessive run time at WOT will get you acquainted with the folk at the fuel dock, because you'll be spending a lot of time there!

 

[BoatDrinksQ5]

Re: Wot ?????

I try to always make a point to run the full range of RPM through the course of an outing (probably a carry over philospy from 'break-in') this includes at least a 10-30 second stint at WOT if not a couple times.

Anyone else make a point of letting her rip at least once during the day (besides the desire to go fast!)?

 

[ktbarrentine]

Re: Wot ?????

This is the one I read.

"Have you run your numbers through the Mercury Marine prop selector?

It comes up with a 22.5 pitch set, assuming a 2.0 gear ratio.

But since you're only getting 3400 rpm with 24's, I'd go with 21's.

Doing the math(537 total less the 155 hrs on the new motor) indicates the previous owner managed to kill the motor in just 382 hrs lugging it like that."

@whatisup02: I'm interested to read more on the original thread (curious, as I am). Could you go to that post, right click on the address in your browser bar, and copy-paste it into a reply in this thread? Then we can get the context.

Thanks!