wot for a long time?

[Chaparralboater]

been boating my whole life ( 24 years old)..but my familes boat was a 32 foot cruisers rogue and it was too big for me to drive..so my pops got me a ski from the age 16 and on. So I have been driving skis pretty much. And who doesnt drive them less than wot. So now being 24 and having my own boat, I am wondering if boats are capable and tolerant to be driven like my jet ski was ? its a 3.0 mercruiser. I have a crazy addiction to speed. I cruise mostly but I am nervous to hold the throttle down for more than a minute. maybe because its my money this time..but is it ok for like 5 mins?

 

[Alpheus]

Re: wot for a long time?

As long as its propped right and staying within the manufactures RPM limits, you can run it all day...

 

[45Auto]

Re: wot for a long time?

As long as its propped right and staying within the manufactures RPM limits, you can run it all day...

Just don't count on it lasting as many days as it would if you ran at LESS than WOT .....

Higher rpms equates to higher piston speeds, which equates to higher rod, rod bolt, and wrist pin loads, which equates to higher rod bearing loads, which equates to higher crank loads, which equates to higher main bearing loads, etc.

Higher engine loads also equates to higher rod, rod bolt, and wrist pin loads, which equates to higher rod bearing loads, which equates to higher crank loads, which equates to higher main bearing loads, etc.

At WOT you're running at combined high RPM and high engine loading conditions.

 

[IES99]

Re: wot for a long time?

been boating my whole life ( 24 years old)..but my familes boat was a 32 foot cruisers rogue and it was too big for me to drive..so my pops got me a ski from the age 16 and on. So I have been driving skis pretty much. And who doesnt drive them less than wot. So now being 24 and having my own boat, I am wondering if boats are capable and tolerant to be driven like my jet ski was ? its a 3.0 mercruiser. I have a crazy addiction to speed. I cruise mostly but I am nervous to hold the throttle down for more than a minute. maybe because its my money this time..but is it ok for like 5 mins?

5 minutes? No problem. I do that all the time. But I do limit WOT with my 3.0 to a few minutes most outings. The only time it may be a longer interval than that is if the skier being pulled wants to go that fast.

There is more wear at WOT, but I say: enjoy, rebuild, replace when needed. Boats were made for fun. I suspect if you have a real need for speed, sooner or later you are going to have a boat with a V8.

 

[Alpheus]

Re: wot for a long time?

You're right.

Go ahead and trade in that boat you got and get yourself a pontoon boat, putt around and get old...

Anything you do is going to put wear and tear on your engine. They wear out. Yes you can wear them out a little faster by going real fast,pulling tubers or skiers. (Having Fun)

Run it!!!

 

[haulnazz15]

Re: wot for a long time?

While I don't know the top speed of the 3.0L in your boat, my boats WOT speed is around 50mph, and I wouldn't pull a skier or tuber that fast under any circumstances even if they requested it. (barefoot skiing notwithstanding)

 

[guyaverage]

Re: wot for a long time?

As long as its propped right and staying within the manufactures RPM limits, you can run it all day...

I agree. I have run my gawdforsaken 470 at full throttle for 10-15 minutes or more at a time avoiding or outrunning storms, or trying to get back in before it gets too dark. I do this several times a year, or so it seems. Even outside that, I seem to have 2 engine speeds, idle in the no wake zone, and 4000+ rpm out in the main lake. Unless I am pulling people on the tubes, I dont spend much time in the mid-range. Except last year when gas was 4.75 a gallon at the marina. Good grief.

Winterize properly, replace bellows every 4-5 years, lube the gimbal & u-joints every season, replace your impeller every year or so, change the oil at regular intervals, keep an eye on your oil and temperature gauges, inspect your manifold and riser every season, and run it until you or it drops. You will get sick of this boat and trade it or sell it long before you wear out a 3.0, full throttle or otherwise. Keep the oil clean, dont overheat it, slap the throttle forward as far as you want to and have fun.

 

[Chaparralboater]

Re: wot for a long time?

Well up until the age of 18 I lived in Cleveland ohio. That is where I had the boat and jet ski. And then moved to Raleigh nc at the age of 18 ( high school ended) and sold everything to move into an apartment. Bought a crotch rocket (r1) 1000cc..after 4 years got bored and realized the love for water can't be forgotten and traded the bike for the boat. I will get bored yes and kinda of have. But you guys are great and funny. I will run the thing hard till it sinks from either high rpm or wood root. But thanks fornthe heads up and for throttle advice. Be safe.

 

[dsiekman]

Re: wot for a long time?

I've gotten to know my mechanic pretty well...I like to do as much work as I can, but I know my limits. Anyway, I'm a pretty conservative guy. I run my twin 5.0's at about 3200 rpms most of the time which gets me about 30 knots. Sure, she'll run 50+ , but those things are absouletly screaming at 4800. Anyway, my mechanic buddy tells me he has clients with go-fasts that run WOT, or WFO as some like to call it, all the time. However, these guys also have enough money to rebuild or replace every season. Some of his clients even keep a spare engine at home ready to drop in so they don't miss more than a day on the water. I'd say it all depends on how deep your wallet or mechanical abilities run.

 

[whitney]

Re: wot for a long time?

I've raced and tracked cars for a long time, including 24 hours of lemons ($500 junkers which are raced for 24 hours), and I can tell you that a healthy piston engine can be run HARD for a long time as long as it gets good oil pressure, good cooling, and good fuel mixture. Basically don't run out of oil, overheat, detonate, or run lean and she'll be FINE.

Now I am new to boating so I have no idea how much the drive mechanism can take. I shopped for cheap boats for a long time and every one I saw with an engine replacement could be traced to improper winterization, flooding, or one of the problems above. Never seen a boat whose motor just "wore out" from hard use.

 

[Philster]

Re: wot for a long time?

I don't usually hit WOT very often. When I do, it doesn't wind up being more than a minute.

I do run well above so-called 'cruising speed', which is 42 MPH. I can squeak out the low 60's, but darn if that engine and all the mechanical pieces just don't sound better when the engine is turning around 4k RPMs instead of 4900-5000 RPMs. So, for me, it feels and sounds good to run around 4/5th max throttle/speed.

When you double overall MPH or double the engine speed, you don't double the energy or double the stress. Any physicists want to chime in, because I think it's an order of 10 times the energy and 10 times the stress (or more).

 

[45Auto]

Re: wot for a long time?

Any marine engine in decent shape will probably run several hundred hours at WOT. Since the average boater puts less than 50 hours per year on his engine, that's easily 3 or 4 years at WOT.

It's not really that big of a deal, just depends on what you want to do with your boat. If you want to run in the front of the pack on most poker runs (see the OSO or Scream & Fly forums), or you have to prove your 3.0L is the fastest boat on the lake every time you go out, then plan on an engine replacement every few years. If it's a cheap boat and you don't plan to have it but a few years anyway, don't even worry about it.

Mercruiser recommends in their owner's manual that you operate at 3/4 throttle or lower, with no prolonged operation at full throttle. Up to you to decide what "prolonged" means - just remember, if you want to play, you'll have to pay!

Caterpillar has some similar recommendations for their diesels in boats, which are built to MUCH heavier requirements than any GM gas engine:

From Caterpillar Managing Marine Engine Power:

Get the Most from Your Engine​

A maximum power rating is specified for every marine diesel engine. Running at WOT (Wide Open Throttle) is fine for short periods of time to get somewhere fast, to outrun a storm, or just to demonstrate your boat?s maximum performance. However, diesel engines for planing hull boats are not designed for continuous wide open throttle operation.​

? Wide Open Throttle:
WOT operation should be limited to short periods of time such as acceleration to on-plane and other limited time duration situations where it is essential to use all the power the engine can deliver. Operating at WOT up to eight percent of the total time or up to 30 minutes a day is generally acceptable; however, WOT operation is best limited to short periods of time (five to 15 minutes).​

I know lots of diesel charter boat captains who run WOT all the time. They claim it costs them money to run slower. Just like a gas motor, there's nothing wrong with it, just means that somebody gets to replace a motor sooner.