Volvo Penta maximum revs - time limit?

[Tranona]

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.

As i suggested all this is irrelevant for the sort of engines and applications being discussed here. These engines are very low stressed - The D2 40 has a specific output of approx 26hp/litre, about one third of the specific output of even the most basic auto diesel. The R5 rating suggests it can be used for a planing boat - can't imagine what sort of boat would plane with 37hp inboard!

Contrary to what you suggest small yacht engines are very lightly stressed as they are derived from low output industrial engines that run at high loads for long periods of time, such as generators or small construction machines which typically run 8-10 hours a day non stop. So engines have an easy life in a yacht - in fact the biggest problem is owners do not run them long enough or hard enough, then leave them unused for weeks on end! Heavily used engines such as those in charter boats or small commercial boats easily clock up 10000 hours+ without any problems.

The 1 hour in 12 full power use is irrelevant because in a low speed displacement boat you rarely need to run above around 70% power (approx 2200 rpm on a D1 40) as this usually (if the prop is correctly specified) gives a cruising speed of around 80% of maximum. Achieving that last 20% doubles fuel consumption and is noisy and uncomfortable.

 

[superheat6k]

Your friend is in dispute it would seem over a claim that I very much doubt can be proven against him.

The charter firm cannot in anyway prove what prior abuses the engine may have suffered, after all it is a charter boat. It may have failed on your friends charter, but that in no way de facto makes it his fault / responsibility. Indeed this circumstance is broadly similar to that of an engine failing when under sea-trial by a potential buyer - a seller is hardly going to get far blaming a would be buyer for wrecking his engine just because the buyer ran it at WOT.

It is not mentioned but would I be right to assume your friend is owed a deposit and they are attempting to retain it for the reasons stated ?

I would send a strongly worded Solicitors letter - one for JFM perhaps, found on the Mobo forum mostly, but an all round good guy, and whom I am sure would provide sound advice here, but would need to know your friends situation in further detail.

I simply can't see a charter firm laying out their own hard earned cash to sue someone over something like this though. So if he is not owed money by them I would suggest he advises they go forth and have children.

 

[grumpy_o_g]

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....

Loads related to drag though, so speed's a huge factor but weight, sea state, windage and especially dirty bottom can make a massive difference. I wonder if the boat was getting a little weedy and that caused the charterer run the engine a little harder to keep the speed up which in turn meant a hot engine? Add in a weedy intake as you say and it's recipe for something to give way, with the head gasket being up there with the favourites.

 

[Leonidas]

Skipper Stu,
All the points you made are correct. except that the engine is not designed to run indefinitely in overload condition if the propeller and hull are fouled., or the engine timing has been fiddled. One will see the water temperature elevating pretty smartly. and lots of smoke. On the other hand, as you say, if the cooling water side is correct, the coo;ling pump impeller is not on its last leg and the heat exchanger is not fouled , the engine will run at reduced rpm without problems. Charter boats however are not always skippered by competent ( or caring) people and checks for oil and cooling water are often omitted. So if you are the unfortunate charterer who has hired a boat that had been mistreated by the previous charterer who happened to have run the engine without sufficient cooling water, it is possible that all conditions leading to a blown gasket may have already occurred during the previous hire and only manifested themselves during the current hire. It is up to the charter company to investigate and prove their claim.

 

[vyv_cox]

Thanks for all the comments and suggestions. Unfortunately I have heard no more from the charterer since he originally requested my assistance, so I cannot update his progress.

 

[Heckler]

Skipper Stu,
All the points you made are correct. except that the engine is not designed to run indefinitely in overload condition if the propeller and hull are fouled., or the engine timing has been fiddled. One will see the water temperature elevating pretty smartly. and lots of smoke. On the other hand, as you say, if the cooling water side is correct, the coo;ling pump impeller is not on its last leg and the heat exchanger is not fouled , the engine will run at reduced rpm without problems. Charter boats however are not always skippered by competent ( or caring) people and checks for oil and cooling water are often omitted. So if you are the unfortunate charterer who has hired a boat that had been mistreated by the previous charterer who happened to have run the engine without sufficient cooling water, it is possible that all conditions leading to a blown gasket may have already occurred during the previous hire and only manifested themselves during the current hire. It is up to the charter company to investigate and prove their claim.

I was digressing. People dont get diesel engines! They dont get the fact that full "throttle" and no load is totally different to full " throttle" and full load. High idle and low idle is a foreign concept to the vast majority of people. As is the word "throttle"
Stu

 

[PaulRainbow]

I was digressing. People dont get diesel engines! They dont get the fact that full "throttle" and no load is totally different to full " throttle" and full load. High idle and low idle is a foreign concept to the vast majority of people. As is the word "throttle"
Stu

Is this what you mean Stu ?

http://i.dailymail.co.uk/i/pix/2011/05/07/article-0-0BE824F400000578-859_468x339.jpg

 

[Heckler]

Is this what you mean Stu ?

http://i.dailymail.co.uk/i/pix/2011/05/07/article-0-0BE824F400000578-859_468x339.jpg

Si!
Could do that sometimes!
Stu

 

[Lancslad]

have followed the link you gave to Vovlo and it says:
'Rating 5 - Pleasure Duty
This power rating is intended for pleasure craft applications, and can be used for high speed planing crafts in commercial applications with special limited warranty, see warrant handbok. Running hours less than 300 h* per year.
Full power could be utilized maximum 1 h per 12 h operation period. Between full load operation periods, engine speed should be reduced at least 10% from the obtained full load engine speed. '
I wonder if this means that running at longer than 1 hour in any 12 will damage the engine or are they saying that in order to maintain the engine efficiency it should be run maximum revs for 1 hour in every 12.

 

[Bobc]

Stu

Why don't you just go to the MAIB or whatever the industry authority is (or the RYA). Other option is to threaten to name and shame if they don't drop it. It'll cost them more in lost business and damaged reputation than the cost of replacing a head gasket.

 

[Heckler]

Stu

Why don't you just go to the MAIB or whatever the industry authority is (or the RYA). Other option is to threaten to name and shame if they don't drop it. It'll cost them more in lost business and damaged reputation than the cost of replacing a head gasket.

Not me Bob, ive only been answering questions.
Stu

 

[Tranona]

have followed the link you gave to Vovlo and it says:
'Rating 5 - Pleasure Duty
This power rating is intended for pleasure craft applications, and can be used for high speed planing crafts in commercial applications with special limited warranty, see warrant handbok. Running hours less than 300 h* per year.
Full power could be utilized maximum 1 h per 12 h operation period. Between full load operation periods, engine speed should be reduced at least 10% from the obtained full load engine speed. '
I wonder if this means that running at longer than 1 hour in any 12 will damage the engine or are they saying that in order to maintain the engine efficiency it should be run maximum revs for 1 hour in every 12.

Welcome

See my post#41. That statement is largely irrelevant for the sort of engines we are talking about. It applies to the massive turbo engines used in high speed planing craft which are designed to run at just below WOT continuously. They are very sensitive to exhaust gas temperature which rises rapidly if run at WOT for extended periods and shortens what is already a relatively short design life.

This is a very different mode of operation from that of a sailboat auxiliary where the biggest problem is not running them hard enough for long enough periods of time.