Volvo Penta maximum revs - time limit?

[Heckler]

I think most people would regard operating at maximum speed for hours on end to be abuse, but where to draw the line?
Marine engines are not like car engines, they frequently run for 24 hours at a high percentage of their max rpm.
Many are related to generator engines which only run at one speed.

It's normal to check the temperature from time to time, or have an alarm you can hear.
Also to check oil and coolant periodically.

When we built the base camp in Angola we put in 3 Cat 3306 engined gennies. They were so called "high speed" They came set up as 50 hz gennies, they were set to run at 1500 revs. I adjusted them to run at 1800 revs to get 60hz to suit the American 110v domestic stuff. We used to run them continuously for a week then switch to the next whilst we changed the oil and filters. They were turbo charged and the turbos used to glow red hot, they were rated at 135 kva. We used to use all of that power. As we put the load on them on start up the rev counter would stay at 1800 rpm BUT the exhaust note would deepen as the injector pump fed more fuel to them and the turbo would spool up.
A, to me, beautiful sound!
Those gennies went for 3 years before I did a rebuild
The point I am making again, speed of the engine is not relevant its the load!
Stu

 

[lw395]

...
The point I am making again, speed of the engine is not relevant its the load!
Stu

That's true.
But on a boat, the load is related to the speed.
The charter co knows
a) whatever the charterer has said
b) possibly an hour meter reading
c) that the head gasket has failed.

My feeling is that an awful lot of yacht engines would overheat, if run at max power for any length of time. To do this, you'd have to be either punching into waves and weather, or pushing up a big bow wave.
But maybe it's more likely the problem was caused by a lack of seawater flow due to weed or something?
Why was there no overheat alarm to save the day?
Was there some other fault in the cooling system?

I think there's a reason hire companies rent out brand new cars and change them after a year. People rent out boats that have years of minor faults waiting to cause a problem.
Some people treat other people's property with kid gloves, other people think hire cars are there to be thrashed....

 

[vyv_cox]

Sorry I cannot answer all the questions. My friend insists he did not run at high revs. Sounds like the charter company is trying to blame him for a prior problem.

 

[jwilson]

Almost every new Yanmar 3YM30 when they were first introduced would overheat if given 5-10 mins high revs. The owners that found this out complained and eventually Yanmar offered free improved heat exchangers. Despite this mine can still be persuaded to overheat occasionally, alarm goes off, drop back the revs and it goes off after a short period. There are probably still early 3YMs about that have the problem but the owners never run their engines hard.

I have had other engines overheat on other boats sea trials - a deliberate 10 minute burst of full revs - unless the boat is underpowered and you'd likely want to run at full revs for long periods it's not necessarly a big problem. I have had boats like that - old yachts with tiny engines. I at times ran a Volvo MD1 with 7 hp flat out for hours in a boat of at least 8 tons - it gave about 4.5 knots - but didn't overheat.

Any charter boat should at least have a working overheat alarm. If a charterer ignored this then they would be at fault, but proving it is virtually impossible.

 

[Lancslad]

That's true.
But on a boat, the load is related to the speed.
The charter co knows
a) whatever the charterer has said
b) possibly an hour meter reading
c) that the head gasket has failed.

My feeling is that an awful lot of yacht engines would overheat, if run at max power for any length of time. To do this, you'd have to be either punching into waves and weather, or pushing up a big bow wave.
But maybe it's more likely the problem was caused by a lack of seawater flow due to weed or something?
Why was there no overheat alarm to save the day?
Was there some other fault in the cooling system?

I think there's a reason hire companies rent out brand new cars and change them after a year. People rent out boats that have years of minor faults waiting to cause a problem.
Some people treat other people's property with kid gloves, other people think hire cars are there to be thrashed....

 

[Lancslad]

I believe that the engine was most probably a Volvo Penta MD2020 (18HP). There was apparently no temp gauge or oil pressure gauge or overheating alarm. Does anyone have experience of this specific engine?

 

[pvb]

I believe that the engine was most probably a Volvo Penta MD2020 (18HP). There was apparently no temp gauge or oil pressure gauge or overheating alarm. Does anyone have experience of this specific engine?

Even the most basic Volvo Penta control panel for the 2020 has audible alarm and warning lights for overheating and low oil pressure.

 

[Paul Kelly]

To clarify, the charter company claims that 3 minutes at maximum revs is the limit.

I find that hard to believe. I have just come back from a 500 mile trip round the Channel Islands and Brittany in a 7 ton boat with an 18hp Volvo Penta 2002. The last leg was a 12 hour motor from Brixham to Poole at max revs (c 2500-2600).

I am going to check the engine oil when next on board, but that aside, I would expect an engine of that sort to be able to manage that sort of performance. It's what Diesels are good at. I accept that running in the higher temperatures of Greece may have a bearing on matters but surely the engine cooling system ought to mitigate that.

 

[Tranona]

I find that hard to believe. I have just come back from a 500 mile trip round the Channel Islands and Brittany in a 7 ton boat with an 18hp Volvo Penta 2002. The last leg was a 12 hour motor from Brixham to Poole at max revs (c 2500-2600).

I am going to check the engine oil when next on board, but that aside, I would expect an engine of that sort to be able to manage that sort of performance. It's what Diesels are good at. I accept that running in the higher temperatures of Greece may have a bearing on matters but surely the engine cooling system ought to mitigate that.

That is running at well below maximum which is 3200 on a 2002. The revs you were using are a high cruising speed, although if that is indeed the maximum you can achieve perhaps you need to look at your propeller as you should be able to achieve at least 3000 with the correct prop.

 

[Paul Kelly]

Many thanks, that confirms my thinking too! I have a three blade folding Brunton - a good prop, so I need to get the engine looked at.

Motoring against the tide past Durlstone Head at 2.5 knots flat out was a bit painful.!

 

[Heckler]

That's true.
But on a boat, the load is related to the speed.
The charter co knows
a) whatever the charterer has said
b) possibly an hour meter reading
c) that the head gasket has failed.

My feeling is that an awful lot of yacht engines would overheat, if run at max power for any length of time. To do this, you'd have to be either punching into waves and weather, or pushing up a big bow wave.
But maybe it's more likely the problem was caused by a lack of seawater flow due to weed or something?
Why was there no overheat alarm to save the day?
Was there some other fault in the cooling system?

I think there's a reason hire companies rent out brand new cars and change them after a year. People rent out boats that have years of minor faults waiting to cause a problem.
Some people treat other people's property with kid gloves, other people think hire cars are there to be thrashed....

Not arguing, pointing out a good example of what I have said. Paul Kelly post. The engine, although I am presuming on full throttle, wasnt making full revs, as Tranona has pointed out. Yet I bet the fuel injection was putting full fuel in to the engine. I suspect as T said perhaps it is over overpropped. So full load on the engine at less than full speed. The thermal load will be equal to full load and yet it isnt overheating.
Stu

 

[[70521]]

A friend is in dispute with a charter operator who claims that he ran the engine of a yacht for long periods, causing failure to the cylinder head gasket. I totally disagree with the fundamental hypothesis but am searching for information that can help him.

I pretty sure you will have asked them how they came up with that diagnosis and lots of other pointy questions about the service history, instructions to the skipper when they handed over the boat etc., etc sounds like either they don't have a clue or trying to pass the cost for any work done/engine replacement to the skipper.

I had a head gasket go on a Yamar and it was not being over revved.

 

[mattonthesea]

A few years ago we chartered two yachts. Owing to a mix up the second had to be changed for another yacht which then lost the prop-shaft connection. We towed it into port (an interesting experience in itself). The charterer was very grateful and did his best to sort out a third yacht and agreed to a refund. At that point the silent partner in the company stopped being silent: he refuted all the issues and then accused us of damaging our yacht's engine by over revving it to tow them in. We ignored this because a) we hadn't and b) it was nonsense. (two miles in calm conditions at about 3 kts) Eventually it was sorted by a mediator.

On another trip from Falmouth to Scilly the Bav 36 had an engine that overheated above 1800. 16 hours to get back in the calm!!!

On JEKAPA I hardly ever go above 2200 (Volvo Penta 2020) and get a bit worried at 2500. Am I being over cautious?

 

[PetiteFleur]

On JEKAPA I hardly ever go above 2200 (Volvo Penta 2020) and get a bit worried at 2500. Am I being over cautious?

Well, I had a VP 2020 on my previous boat and when I bought it the owner said 'I never go above 2500rpm' BUT when we had bought the boat it WOULD'NT go above 2500... On investigation there was a tiny in-line fuel filter in the fuel line which was blocked with black gunge, the dreaded fuel bug... Once removed the engine went to 3600 rpm under load! It was like a new engine!

 

[Tranona]

On JEKAPA I hardly ever go above 2200 (Volvo Penta 2020) and get a bit worried at 2500. Am I being over cautious?

Yes. 2500 is a good cruising speed - about 70% full power. If it has the correct prop it should achieve at least 3400 and close to hull speed. Typically 2500 should give you a speed in flat water of somewhere between 5-5.6 knots at full revs high 6's.

The extra 1000 revs is there to help maintain speed in adverse conditions. Good, though to give it short bursts at over 3000 from time to time. Won't do any harm and maybe reduce the build up of carbon in the exhaust elbow.

 

[2Tizwoz]

Engine manufacturers must supply engines capable of providing their rated horsepower under stated conditions.

https://cumminsengines.com/ratings-and-definitions

Cummins describe a variety of conditions in the link.

The minimum period of overload from continuous use is one hour.

Volvo similarly describe their ratings. http://www.volvopenta.com/SiteColle...lish/Marine Commercial Rating Definitions.pdf

Again one hour in twelve is advised for pleasure output rating.

This engine power output rating is clearly an essential part of the description of an engine and has been in place for decades.

3 minutes of full throttle being the maximum an engine installation can withstand is an admission of a fault. Presumably your friend is pursuing the charter company. They appear to have admitted being at fault.

 

[Spyro]

So the charterer saying that the engine has been run for too much time and that has caused head gasket problems is full of cack! They have no way of telling for how long the engine has been run under maximum load! All they might have is an engine hours meter, it coukd have run for a long time but under no load!
Stu

They would have been tracking AIS so on certain days with no wind they may have judged by the speed shown that they were running flat out. I know there are many variables like tide, wind, waves etc but they would probably have a good idea how their boat performs.

 

[Tranona]

Engine manufacturers must supply engines capable of providing their rated horsepower under stated conditions.

https://cumminsengines.com/ratings-and-definitions

Cummins describe a variety of conditions in the link.

The minimum period of overload from continuous use is one hour.

Volvo similarly describe their ratings. http://www.volvopenta.com/SiteColle...lish/Marine Commercial Rating Definitions.pdf

Again one hour in twelve is advised for pleasure output rating.

This engine power output rating is clearly an essential part of the description of an engine and has been in place for decades.

3 minutes of full throttle being the maximum an engine installation can withstand is an admission of a fault. Presumably your friend is pursuing the charter company. They appear to have admitted being at fault.

You are talking about very different kinds of engines than the simple, naturally aspirated low specific output engines that are the subject of this thread. Volvo do not publish ratings for these engines as they will run continuously at near maximum. Remember they are fitted to low speed displacement boats that normally cruise at around 70% of available power.

 

[owen-cox]

from my experience of yacht charter companies ( working for them) nothing is ever the clients fault as they are all assumed to be idiots anyway. if the engine overheats above a certain throttle position we used to wind down the maximum revs screw so it couldn't do it. Either way the charter company would be hard to prove that a client damaged the engine especially a head gasket which should have been impossible if the high temperature alarm went off. If it didn't then its clearly the charter companies fault.

 

[2Tizwoz]

You are talking about very different kinds of engines than the simple, naturally aspirated low specific output engines that are the subject of this thread. Volvo do not publish ratings for these engines as they will run continuously at near maximum. Remember they are fitted to low speed displacement boats that normally cruise at around 70% of available power.

http://www.volvopenta.com/SiteColle...lish/Marine Commercial Rating Definitions.pdf

The link is to Volvo Penta's ratings system which includes R5 which is their Pleasure Duty. This specifies full power being used for 1 hour in twelve.

https://pubs.volvopenta.com/ProdDocs/Home/Disclaimer?publication=47709049&lang=en-US

The above link is to the specifications for a D2-40 which is rated for R5 use.

A Formula 1 engine is designed to produce very high output for a very short period so that engine life is very short. The same engine used to drive a pleasure boat, if used to drive a generator would have an unacceptably short life with the pleasure boat power output. To increase engine life output is reduced. The various types of vessel being driven by the engine require different engine life. A cargo vessel engine would be expected to perform for many years at full output with limited maintenance. The pleasure boat, at the other end of the scale may run for a few thousand hours only before requiring extensive overhaul, but the owner would achieve those hours over many years and be happy to accept a more stressed engine as it costs less and takes less space.