How many revs is too many?

[pophops]

When I bought my boat the prevous owner advised that keeping the engine at between 1200 and 1400 revs would maintain a sufficient cruising speed and this has proved to be correct. He also warned that engine revs higher than this for prolonged periods would do damage to the engine. But I've been wondering what would happen if I needed extra revs when travelling against a strong current. I can't find any reference to maximum revs in the Vetus engine manual. Some guidance would be appreciated.

[bizzard]

When I bought my boat the prevous owner advised that keeping the engine at between 1200 and 1400 revs would maintain a sufficient cruising speed and this has proved to be correct. He also warned that engine revs higher than this for prolonged periods would do damage to the engine. But I've been wondering what would happen if I needed extra revs when travelling against a strong current. I can't find any reference to maximum revs in the Vetus engine manual. Some guidance would be appreciated.

The Vetus M4 14 is i think a Mitsubishi engine and develops 33hp at 3300 rpm so i'd say you can quite safely take it up to at least 2000 prm.

 

But keep an eye on things as Biggles mentions below.

Edited November 12, 2012 by bizzard

[Biggles]

I am just sumising here

 

If you have a full instrument panel watch the temperature, and oil pressure. If either go high you will know you are stressing the engine.

 

The manual will be written for ideal conditions, as every boat is different so to will be the way an engine performs in each. For example the cooling In one boat will be totally different in another. This more than anything will decide how hard you can push your engine. In time you will "know" your engine intimately and know when something is not right.

 

I would suggest you experiment in controlled conditions so you know in stressed situations what is possible. There is no point in finding out the hard way when it's too late.

[MtB]

When I bought my boat the prevous owner advised that keeping the engine at between 1200 and 1400 revs would maintain a sufficient cruising speed and this has proved to be correct. He also warned that engine revs higher than this for prolonged periods would do damage to the engine. But I've been wondering what would happen if I needed extra revs when travelling against a strong current. I can't find any reference to maximum revs in the Vetus engine manual. Some guidance would be appreciated.

 

I think you can relax. Your vendor is talking twaddle. A diesel engine has a speed governor which will not allow the engine to run at a speed higher than the engine is designed for. In theory you could run the engine all day long with the throttle wide open with no damage occurring.

 

I say 'in theory' because there are considerations to do with the installation which are beyond the engine manufacturer's control which can cause damage, e.g. skin cooling tanks too small. This could eventually damage an engine run at full throttle for long periods, and the previous owner may know the engine overheats on higher speed settings and wants to delay you discovering this.

 

Not easy to test this if you are on a canal though, without drawing disapproval CRT/other boaters for speeding!

 

Mike

 

 

(Edited for spelling)

Edited November 12, 2012 by Mike the Boilerman

[Iain_S]

The manual (Page 60)lists 3200 as max no load rpm, The max. power outputs are stated as measured at 3000 rpm.

 

However, your installation may not achieve this, as it is common for canal boats to be slghtly overpropped. The limiting factor may be engine cooling. Copperkins has a Vetus 4.17, and, before we got the cooling sorted, 2000 was the max continuous useable rpm, Any more, and it would overheat. I don't think we quite make 3000, though, due to the propellor gearing. Usually runs 1000 to 1200 on canals. (I'm sure a co-owner will be along in a minute to berate me for speeding )

 

Gamebird has a Vetus M2.04, which is not strictly comparable. Max. rpm for this is listed as 4000; she will get to 3500, and has run at that for several hours at a time without any problem. (Respectable canal cruising speed is 1500 - 2000 rpm)

 

Iain

[bizzard]

As well as the governor there should be a maximum throttle opening stop screw lock nutted and sealed at the throttle lever on the injector pump. If this screw has been tampered with or the seal broken, sometimes wire with a coloured blob seal on it be a bit cautious.

[Tonka]

The seller tells you not to overrev the engine but you still buy the boat. And now you are worried. Too late mate

Should have walked when you had the chance

[Keeping Up]

Most engine manufacturers de-rate the engine for marine use, to ensure that it will be reliable if used continuously at full speed.

 

My own (Perkins) engine, for example, is rated at 42hp at 2800 rpm for marine use and can be used continuously 24x7 at that speed. In other applications the very same engine is rated differently, up to a maximum of 4000 rpm for short-term use and 4500 peak (equivalent to the orange and red lines on a car's tacho). I was told by the marinisers (Duffields) that every single one was bench-tested at 5600 rpm before leaving the factory.

[Richard10002]

I have the 4.14 and run it at 2500 rpm without thinking about it if I'm in a hurry. I generally run it at 2000rpm on a trip, and tootle at 1500rpm if enjoying the scenery without a destination in mind.

 

Your seller was either ignorant of his engines capability, liked to look after it, or knew something he wasn't telling you.

[Proper Job]

I'm not a Vetus owner, but I would have thought that running up to 2000 rpm wouldn't cause a problem.

 

As others have said, the limit may be the cooling capacity of the skin tanks. Keep an eye on the temperature gauage.

 

Rather than finding out when it's needed, get out on to some deep water and give it a damn good thrashing to see if it over heats before you have to do it in anger

[bowten]

Find a winding hole and do some manoeuvring if yer can't find deep water.

[spannerman]

I have the 4.14 and run it at 2500 rpm without thinking about it if I'm in a hurry. I generally run it at 2000rpm on a trip, and tootle at 1500rpm if enjoying the scenery without a destination in mind.

 

Your seller was either ignorant of his engines capability, liked to look after it, or knew something he wasn't telling you.

 

I run at 1200rpm on a trip and tootle at 1000rpm - no wonder i get shouted at for passing boats too slowly (not that I'm accusing Richard of speeding)

[mykaskin]

If you want to give it some work, tie up in a full lock (preferably wide to allow water to get to the prop) when it's quiet and let the engine stretch it's legs, keeping an eye on the temp etc.

 

Mike

[bottle]

I think you have the answer but just to add my bit (for a little more assurance), if the engine and cooling system have been set-up correctly then all should be OK.

 

I run a Beta 43 and regularly run it at 2,000 rpm for 8 hours against the flow on the river Severn.

 

On canals run at about 1250rpm.

[pophops]

It seems to be that engine temperature is the key thing to watch. I like the idea of running at full revs in a lock for a while. Thanks for all the good advice.

[matty40s]

It seems to be that engine temperature is the key thing to watch. I like the idea of running at full revs in a lock for a while. Thanks for all the good advice.

I recently ran a Vetus 2 cylinder for 3 days(36 hours to those used to part timing) and I found that 1100-1500 revs was about right, and had to dump leaves from the prop when the engine slowed or complained (red light).The engine was very capable of good cruising speeds and only faltered when the leaf muck became too much

[jelunga]

Most engine manufacturers de-rate the engine for marine use, to ensure that it will be reliable if used continuously at full speed.

 

My own (Perkins) engine, for example, is rated at 42hp at 2800 rpm for marine use and can be used continuously 24x7 at that speed. In other applications the very same engine is rated differently, up to a maximum of 4000 rpm for short-term use and 4500 peak (equivalent to the orange and red lines on a car's tacho). I was told by the marinisers (Duffields) that every single one was bench-tested at 5600 rpm before leaving the factory.

Ah but Allen, these engines of ours are no longer young and like to be treated gently. Dont they?

[Proper Job]

One of my previous boats had an MC42. Damn good engines.

 

I remember once punching up against a strong stream from Abingdon to Oxford. Set the throttle to 2,500 and there it stayed for several hours non stop.

 

Because of the way the boat was propped, 2,500 was just below black smoke so it was working really hard. It ran as sweet as.....

[Keeping Up]

Ah but Allen, these engines of ours are no longer young and like to be treated gently. Dont they?

 

It's not so much the engine as you and I Keith, who are no longer young and need to be treated more gently. I certainly don't treat my engine gently, it gets unhappy if I don't give it enough exercise.

 

It is propped so that it will just reach its rated 2800rpm, and it seemed perfectly content to run at its absolute maximum for an hour when we were in danger of losing the tide in the Bristol Channel. The gearbox got a bit hot though (I've since improved its oil-cooling arrangement)

 

It coked up once until, after a year of running on 3 cylinders, I had it booked into Braunston to have the head taken off. Then we had to hold position against a fast ebb tide outside West Stockwith, running at 2700 rpm for nearly an hour, and it burned away all the coke and ran sweetly on all 4 cylinders again so I cancelled the boatyard booking.

Edited November 14, 2012 by Keeping Up

[Gibbo]

Watch some "White Van Men". They seem to drive around with the engine permanently banging against the rev limiter.

[nebulae]

Very difficult to judge the best revs for different canals.I check my revs against on board G.P.S.Its been said many times that running the engine hard gives a greater impresion of speed,without the boat actualy going any faster.In the O.P.the vendor stated max revs.Perhaps this was his way of hinting that thrashing the engine was pointless on canals.

[Albion]

The vast majority of modern marine diesels in use on the canals are based on industrial engines. In that environment they are expected to run hard for hours with neglected servicing so it is almost impossible for anyone to abuse a de-rated marine version to cause damage. Where you will risk your engine is running hard where where the boat builder hasn't specced the size of a skin tank correctly or hasn't fitted baffles to an apparently correctly sized tank (both of which seems to be rather prevalent these days). In that case continuous high revs under load risks damage due to overheating rather than mechanical failure.

Roger

[PaulG]

When I bought my boat the prevous owner advised that keeping the engine at between 1200 and 1400 revs would maintain a sufficient cruising speed and this has proved to be correct. He also warned that engine revs higher than this for prolonged periods would do damage to the engine. But I've been wondering what would happen if I needed extra revs when travelling against a strong current. I can't find any reference to maximum revs in the Vetus engine manual. Some guidance would be appreciated.

Get rid of the rev counter, mate.

I don't have one on my boat, and I've noticed that my stress levels are noticeably lower as a consequence...

[Guest]

Watch some "White Van Men". They seem to drive around with the engine permanently banging against the rev limiter.

True, I was one for a while. The bedford van that I drove (mostly flat out) was as sweet at 110,000 mls as it was when brand new. Other than routine servicing, the actual engine had 50p spent on it in repairs. Soembody else drove it for ages after I left the company. I believe a good diesel is bullet proof if looked after.

[Proper Job]

Very difficult to judge the best revs for different canals.I check my revs against on board G.P.S.Its been said many times that running the engine hard gives a greater impresion of speed,without the boat actualy going any faster.In the O.P.the vendor stated max revs.Perhaps this was his way of hinting that thrashing the engine was pointless on canals.

Your revs/speed should be only set by one thing - your wash.

 

If you've got a breaking wash, you're going to fast. If you haven't, then your doing fine