Is driving a planing boat at displacement speed a false economy?

[Hurricane]

I dont know about your boat, Mike, but there's a huge difference in fuel consumption between 7kts and 10kts with my boat. At 10kts, my boat is consuming nearly 3 times as much fuel as at 7kts. Don't forget that for a 53 footer such as mine, 10kts is pushing way beyond theoretical hull speed and is beginning to plane. My attitude is that if you're going to pootle, you might as well do it properly and save as much fuel as you can


Is that because fuel costs less in S Carles?



My combined figures for both engines are according to the Cat engine instrumentation
7.3kts 11 lph 3.0mpg
10kts 30 lph 1.5mpg
24kts 166 lph 0.66mpg
So you can see why I stick to 7.3kts when pootling



I'm glad you're so relaxed about it. I'm looking at used 68/72 footers at present and the difference in asking price between high hours and low hours boats is as much as €400k although of course I dont know actual transaction prices. Either way high engine hours definitely costs a lot of money

I think your own consumption figures make my point.
The difference between planing consumption and displacement consumption is by far the biggest.
So, my point is that there isn't a huge difference between 7 and 10 knots but there is between 10 and 24 knots.

As you say, none of us know the actual difference that our boats would sell at with high or lower engine hours.
However, even pootling, we haven't run up a huge number of hours - charter boats of similar ages have more hours on them.
I suspect that when we do come to sell (a long time off I may say) there will be more things to consider than engine hours.
We just need to put everything into perspective.

BTW fuel is slightly cheaper on the islands than mainland Spain
I just don't want to have to spend my time in port in the islands when I don't need to.
Filling up can take half a day when you consider the upheaval of planning - checking the fuel berth is open etc etc
And sometimes the pumps in the smaller marinas are really slow.
Its more convenient to refuel after we get home.

Anyway, it great that you have discovered "Pootling"

 

[BartW]

Hi Mike, About your OP
I don’t believe that your example would be real,
First of all, people with a 45ft planing boat are probably not considering to sail at D speeds,
If they are, they will have a D- boat, as there are many around,
And all of them are used to sail at lo speed, similar like the zillions of sailing boaters
I’m not sure but I doubt that a 45ft plaining boat cruises nice at D speed

Also your numbers are not real (imho)
Here is my real live example
The first season (2011) we have sailed 99% at planing speeds with BA,
And as you know, last season (2012) we have sailed 80% at displacement speed with BA
In 2011 we did 160hrs,
in 2012 we did 200hrs, 40hrs of that was the service trip to and from Rome
so actual hours of cruising in season was more or less the same
when your mind is set at Displacement speed, you just do your planning differently

then there is the value depreciation,
perhaps your example counts for a young, mainstream production boat,
but as soon as you’re out of that league, sales prices of boats can go anywhere. As you surely know

If I was looking for a boat, and had to choose between two boats,
One with a logbook, of a well caring owner, doing many miles at D-speed, and giving the boat regular and good maintenance,
And there was a compareable boat with less hours, but nog reliable track report,
I wouldn’t mind the higher hour count, but more careful and less punishing useage
I agree that we rarely know that for sure.

I learned here on the forum that certain engines / models don’t like to be ran a lo RPM,
but I have been confirmed from 2 independant sources, (one was MAN Germany guy)
that my (old model) turbo charged MAN engines, don’t suffer from running at lo RPM

We all know that 500hrs or 1000 hrs or 2000hrs for a boat engine,
is not much for a diesel engine

Mike, I think you’re trying to find reasons to buy a D boat, and not to buy that tempting offer of that 70ft planing boat,
And excuse my opinion, but I think you’re just like me, not yet ready for that  
Yes the consumption at 20+knots is eye watering,
But I’m afraid that ones you’re in a boat that’s unable to go 20kn, is eye watering aswell 

Last week I had guests for just three day’s, (sharing expenses)
But they insisted to do that fairly long, 2 x 50nm trip to St Tropez (weather was perfect)
But their budget was tight so they asked me to sail at economic speed,
I sailed 2 x 10nm at 20kn and all the rest of the trip at 10kn and actually the guests didn’t notice much difference in sailing experience.
During this period of the season, when the weather was good, but the water very cold, they didn’t mind the long sailing time, and less “at anchor “ time.

Next week Ill be there, with other guests, and If weather allows, we will sail to Cassis at planing speed,
And I’m glad I’ll be able to do that

I believe you know BA’s consumption
at 10kn 7l/nm
at 20kn 15l/nm

 

[Deleted User YDKXO]

I don’t believe that your example would be real,
First of all, people with a 45ft planing boat are probably not considering to sail at D speeds,
If they are, they will have a D- boat, as there are many around,
And all of them are used to sail at lo speed, similar like the zillions of sailing boaters
I’m not sure but I doubt that a 45ft plaining boat cruises nice at D speed

Of course not, Bart. As I said in one of my posts nobody buys a planing boat to go everywhere at D speeds but I posted the calculation to make what I think is a very valid point in that slowing down to save fuel costs you in terms of extra engine hours and extra depreciation

The first season (2011) we have sailed 99% at planning speeds with BA,
And as you know, last season (2012) we have sailed 80% at displacement speed with BA
In 2011 we did 160hrs,
in 2012 we did 200hrs, 40hrs of that was the service trip to and from Rome
so actual hours of cruising in season was more or less the same
then there is the value depreciation,
perhaps your example counts for a young, mainstream production boat,
but as soon as you’re out of that league, sales prices of boats can go anywhere. As you surely know

So in your second season, you must have cruised a lot less miles than your first season if the hours were similar so its not such a valid comparison. Yes I agree when a boat is older engine hours make less difference but most people run newer boats and engine hours make a big difference to value

If I was looking for a boat, and had to choose between two boats,
One with a logbook, of a well caring owner, doing many miles at D-speed, and giving the boat regular and good maintenance,
And there was a compareable boat with less hours, but nog reliable track report,
I wouldn’t mind the higher hour count, but more careful and less punishing useage
I agree that we rarely know that for sure.

Yes the well cared for high hours boat would be of interest to me too but I would certainly want to pay less for it compared to an average hours boat. There's no getting away from the fact that high hours cost money

We all know that 500hrs or 1000 hrs or 2000hrs for a boat engine,
is not much for a diesel engine

Engine hours is only one factor in engine life, the others being age, number of cold starts and regular maintenance. I know of marine engines in boats needing rebuilds after only 1000hrs or so and others going on for thousands of hours. One thing is for sure and that is all things being equal, engines with high hours are nearer the end of their lives than engines with low hours. As you know part of my business is trading in used construction machines and engine hours is a major factor affecting value and its the same with boats

Mike, I think you’re trying to find reasons to buy a D boat, and not to buy that tempting offer of that 70ft planing boat,
And excuse my opinion, but I think you’re just like me, not yet ready for that  
Yes the consumption at 20+knots is eye watering,
But I’m afraid that ones you’re in a boat that’s unable to go 20kn, is eye watering aswell 

Yes you're right, Bart. The recent trip has really brought it home to me that I like having the option of speed and I like driving a boat at speed so I'm not ready to slow down completely yet. Maybe I will be ready for a D boat when I have a lot more time on my hands and I want to go much further. Yes we're still looking at used planing boats and we will be checking a few out in the next couple of weeks

Last week I had guests for just three day’s, (sharing expenses)

Not only do I need friends like yours to fix my boat but I need guests like yours too to pay for it

 

[BartW]

So in your second season, you must have cruised a lot less miles than your first season if the hours were similar.

interesting question,
will check it out in the logbook and let you know,
but I never had the feeling that we didn't sail enough miles last season


just out of interest, in your building machine business,
how many engine hours / year is average ?
after how many engine hours you would normally expect a rebuild (average)
how many engine hours would you normally consider as "end of live" , or machine not suited any more for reliable professional work ?
just ballpark figures

 

[Deleted User YDKXO]

just out of interest, in your building machine business,
how many engine hours / year is average ?

1500-2000hrs/yr is average but the engines in construction machines are not comparable to marine engines. Engines in construction machines have much lower power ratings because their duty rating is usually for continuous use at max load. Marine engines for pleasure vessels can have much higher power ratings because their duty is intermittent with a much smaller proportion of time at max load. So a construction engine with 5000hrs will usually have much more life left than a marine engine with 5000hrs

after how many engine hours you would normally expect a rebuild (average)
how many engine hours would you normally consider as "end of live" , or machine not suited any more for reliable professional work ?

Well the engine manufacturers wont thank me for saying this but this has been getting less and less over the years as end users demand ever increasing power from lighter engines and regulators burden the engine manufacturers with ever more onerous and stupid emissions regulations. Years ago 15,000-20,000 hrs was not uncommon in my industry but now if an engine gets beyond 10,000hrs, we are pleasantly surprised. Its the same with modern marine engines. More power + tighter emissions regulations = less life

 

[MapisM]

So in your second season, you must have cruised a lot less miles than your first season if the hours were similar so its not such a valid comparison.

I agree that the comparison is not valid, but for the opposite reason.
If Bart spent 200 hours in his second season rather than 160, it means that he enjoyed boating MORE, not less.
I can't think of one single reason for measuring life in terms of distance logged, rather than hours spent enjoying what you're doing.
For anyone who like cruising, of course. And for those who don't, why bother with boating at all, I wonder...

 

[Deleted User YDKXO]

I can't think of one single reason for measuring life in terms of distance logged, rather than hours spent enjoying what you're doing.

Which is more important for an Italian man like you, the number of women he's made love to or the amount of time he's spent making love to them?
Whilst the journey is enjoyable, I like to visit many different places in my boat

 

[Robg71]

love it
absolute quality

 

[MapisM]

Which is more important for an Italian man like you, the number of women he's made love to or the amount of time he's spent making love to them?
Whilst the journey is enjoyable, I like to visit many different places in my boat

Well, believe it or not, if there's anything which most Italians would think of when asked to give a prime example of something where quality matters more than quantity, that's sex!

Anyway, leaving the forced (but admittedly funny!) metaphor aside, actually I also enjoy visiting different places, but unfortunately there's just no way to do that with a boat - any boat.
Myself and swmbo spent 5 of the last 7 months away from home, and we've been in places ranging from 38°S to 64°N, and from 147°W to 153°E. And we are already planning to go further.
We used to think that we could have done that with a boat, some years ago.
Then we did some math, and it doesn't take a lot of it to understand that life's too short.

 

[Deleted User YDKXO]

Anyway, leaving the forced (but admittedly funny!) metaphor aside, actually I also enjoy visiting different places, but unfortunately there's just no way to do that with a boat - any boat.
Myself and swmbo spent 5 of the last 7 months away from home, and we've been in places ranging from 38°S to 64°N, and from 147°W to 153°E. And we are already planning to go further.
We used to think that we could have done that with a boat, some years ago.
Then we did some math, and it doesn't take a lot of it to understand that life's too short.

My SWMBO and I both like to go boating with a destination in mind. For us, arriving in a new place using our own boat is probably more enjoyable than the journey itself. Yes I know it doesn't make sense in terms of finance or time but we get a far greater sense of achievement in arriving by boat than by car or other form of transport. For us, just whizzing about at sea, whether fast or slow, burning fuel for the sake of it is not hugely enjoyable

 

[MapisM]

Fairenuff, absolutely nothing wrong with enjoying more the destination than the journey.
THAT is a good reason for cruising "fast". No need to pretend that slowing down is a false economy!
You will slow down because you will eventually appreciate that, not to save money.
It's just a matter of when, not of if...

 

[Portofino]

Mike, I think the question is summarised in not so much whether a saving is made either way but is the differential between the two that great that it warrants consideration. If no, then clearly, using the boat for what it's designed for is the way to go, planing. If the boat owner cannot afford that, then it's time to consider purchasing a true displacement boat where I presume it's expected that it'll have the high hours for the reason you've stated but they known it's not been thrashed so it'll hold its price

I think this sums it up - fuel prices have doubled in the 8 y we have been " planning " in the Cote d Azur ( by the way it's not snowing here
It's one of the reasons along with purchasing a bigger mooring ,we have dicided not go larger .
Cos we just like blatting about and going far and visiting new places .Only Pootle when fishing really - until boredom sets in !

 

[grumpy_o_g]

1500-2000hrs/yr is average but the engines in construction machines are not comparable to marine engines. Engines in construction machines have much lower power ratings because their duty rating is usually for continuous use at max load. Marine engines for pleasure vessels can have much higher power ratings because their duty is intermittent with a much smaller proportion of time at max load. So a construction engine with 5000hrs will usually have much more life left than a marine engine with 5000hrs



Well the engine manufacturers wont thank me for saying this but this has been getting less and less over the years as end users demand ever increasing power from lighter engines and regulators burden the engine manufacturers with ever more onerous and stupid emissions regulations. Years ago 15,000-20,000 hrs was not uncommon in my industry but now if an engine gets beyond 10,000hrs, we are pleasantly surprised. Its the same with modern marine engines. More power + tighter emissions regulations = less life

Thinking about this most cars these days have service interval calculators. One of the problems with a high hours planing boat is presumably that you have to assume the boat and engines have done thousands of hours nearly flat out. Straight forward engine hours seems a very crude way of measuring wear and tear in this day and age. On the basis of actual wear and tear "Mike's" boat could have had easier life both on the boat and the engine than "Hurricane's" despite having loads more hours on the engine - or is that a false assumption?

 

[kashurst]

the boat log usually keeps a log of total distance travelled, so you can estimate average speed. My boat has done 4000nm over 1100 hours so average about 4 kns - mostly an easy life.

 

[Drewster]

the boat log usually keeps a log of total distance travelled, so you can estimate average speed. My boat has done 4000nm over 1100 hours so average about 4 kns - mostly an easy life.

That's fair enough but who records both nm and hrs ?

 

[kashurst]

the engine gauges usually have an inbuilt hours meter and the speed log keeps a total from the first time its turned on (scroll through the pages to find it).

 

[Drewster]

the engine gauges usually have an inbuilt hours meter and the speed log keeps a total from the first time its turned on (scroll through the pages to find it).

Unless you run Volvo penta engines

 

[Jim@sea]

On reading the Boat Test of the New Trusty 28 it shows that at tick over the boat will do 11mpg.

 

[Deleted User YDKXO]

Thinking about this most cars these days have service interval calculators. One of the problems with a high hours planing boat is presumably that you have to assume the boat and engines have done thousands of hours nearly flat out. Straight forward engine hours seems a very crude way of measuring wear and tear in this day and age. On the basis of actual wear and tear "Mike's" boat could have had easier life both on the boat and the engine than "Hurricane's" despite having loads more hours on the engine - or is that a false assumption?

Yes maybe buyers do need to be a bit more questioning about the actual use to which a boat has been put rather than just rely on engine hours as an indicator of engine condition. I was reading some Caterpillar stuff the other day and rather than engine hours, they think in terms of total fuel consumption as a better indicator of engine condition. For example, a 1000hr boat which has been cruised at 25kts for all it's life will have a much higher total fuel consumption than a 1000hr boat that has been cruised at 10kts. Exactly how you assess total fuel consumption for an engine though, I don't know. I have Cat engines on my boat and I have never seen this information displayed in any of the menus on the electronic displays

 

[davids0865]

Yes maybe buyers do need to be a bit more questioning about the actual use to which a boat has been put rather than just rely on engine hours as an indicator of engine condition. I was reading some Caterpillar stuff the other day and rather than engine hours, they think in terms of total fuel consumption as a better indicator of engine condition. For example, a 1000hr boat which has been cruised at 25kts for all it's life will have a much higher total fuel consumption than a 1000hr boat that has been cruised at 10kts. Exactly how you assess total fuel consumption for an engine though, I don't know. I have Cat engines on my boat and I have never seen this information displayed in any of the menus on the electronic displays

That is exactly how my BMW decides when it's next service is due, and it's really noticable, a 1000km trip to Spain on motorways may only reduce the km's to next service by around 600kms, whereas stop start short trips at home may reduce by 1100 kms. I think it's a reliable measure of an engines treatment.