TAMD 63P River Use

Greg2 said:
Been researching fuel consumption for these engines and have got figures for sea cruising but can't work out what they will use at river speeds. Manufacturers charts suggest a pair will use 6.6 gph at 1000 rpm but this sounds a bit high.

Anyone have experience or running these engines on a Flybridge boat on the rivers? Interested in what sort or revs will give around 5 knots and what they will consume at that sort of speed.

Cheers
Click to expand...

After all that here are my conclusions to the OP question:

Forget the theoretical, too many unknown/assumed/guessed variables to include Latestarter1’s point on props. The 16.5 LPH and 6.6 GPH are totally unrealistic. Conclusion: we do not follow the 1R4 full load curve.

Plotting a curve for my fuel usage then, I believe my boat, an F43 with twin TAMD63P’s, not fully loaded, in reasonable sea state with a clean bottom should achieve a fuel consumption that would follow the contour of the 2R4 but sit just above it, achieving something like the following (Can anyone else with/had an F43 corroborate this):

RPM / LPH / GPH
750 / 9.5 / 2.09
1000 / 15 / 3.3 - Probably over 5 knotts - will record next time out
1200 / 28 / 6.16
1400 / 35 / 7.7
1500 / 38 / 8.36
1800 / 55 / 12.1
2100 / 76.2 / 16.76
2400 / 108 / 23.76
2600 / 135 / 29.7 - 26 knots recorded, so say 0.88 MPG

There seems to be broadly a relationship between RPM and LPH; as the speed doubles so the fuel used seems to quadruple.

Thats enough from me for now….. Others can give their views on the use of single or twin engines on rivers - jury is still out for me on that one, I still probably favour 2......
 
Well i am a ship engineer.I know how to calculate boat resistance. You divide it two parts. Wet friction and wave resistance.

Wet friction is easy. You need a renold number wet area and the speed.

The valve resistance is harder its often defined as the rest when the friction is calculated on model trials. It's impossible to calculate.

On planning boats running faster than froude volume number 3.2 wich define true planing or total hydrodynamick lift, it is possible to calculate boat resistanse knowing wet area, senter of gravity, ve angle and length and width.

Froude volume number is Frv=V/(srq(g*Ú^0.333)) Fore a 13850kg boat this is
30knots. Below that speed you have static buoyancy.

Anyway calculating this based on kinetic energy is rubbish. I think a have shown that. Multiplying work with time is rubbish. Nms or Js You can multiply force with speed and get power and you can multiply power and time to get work.

If you run only one engine on a twin engine boat you get problems. The new propeller curve will reach the upper curve before rated speed. The boat speed compared ti engine and propeller speed will change and propeller shaft torque and power will increase. The engine will be overloaded during this operation. How bad it is is dependent on how much margins engine builder have put in.

If you wonder study the curves from windys test page and compare!

http://www.windy.no/downloads/W31 Zonda - Volvo Penta D6-400 DP H.pdf
 
Ulyden, yes I agree, I think we proved to death that simple kinetics in this instance is unreliable and cannot be employed.

I understand Reynolds numbers etc albeit my dealings with fluid dynamics extends generally to turbulent flows in fixed pipes, far more precise and easy to calculate!

Thanks for the link, I will take a look. I wish I had realised when I was younger how interesting this field is.....
 
Practical experience

My old boat had 2 x Volvo Penta 63P as does my current boat , good simple mechanical engines.

I have always measured litres per mile and as I have extreemly accurate fuel gauges (Hart) you can easily measure this on a run by run basis.

Old boat Fairline 36 sedan 10.5 tons about 4.5 litres per nautical mile at cruising speed.

St Malo to Dinan and back 31 nm 2 to 3 miles at cruising rest at 5-7 knots or so 1.48 litres per n mile.

My props had a fair ammount of bite ie a fast idle speed about 5 knots. So i would expect if you had a slower idle speed in knots you would better this.

A friend of mine has the same boat in Turkey as i Have now an Aquastar 48 with 63p engines in turkey and due to spending a large ammount of time cruising he runs on one engine only but alternates engines and this seems to work well for him.
 
Bandit said:
....Old boat Fairline 36 sedan 10.5 tons about 4.5 litres per nautical mile at cruising speed....
Click to expand...

That equates well with my #46 - your figure of 1GPM at cruising (what speed/rpm was that?)

Bandit said:
....St Malo to Dinan and back 31 nm 2 to 3 miles at cruising rest at 5-7 knots or so 1.48 litres per n mile.....
Click to expand...

1.48LPNM for say 6NM in one hour, therefore 8.88LPH equates to 1.95GPH which also seems to equate well with #46 figures at tickover at 2.09GPH.

So assuming no problems with water cross-feed to shaft seals, keeping an eye on which alternator charges the batteries/domestic systems in use, ensuring that any other hydraulic systems are not powered by a pump from the inactive engine and oil feed is not a problem to the gearbox to the engine that is off when the shaft is free-rotating - all seems to be well with using just one engine.

I suppose if you were doing a lot of river work, you could always change them over several times whilst en-route and occasionally load each engine just to make sure. Jury is still out for me but would probably trial it if I did move to broads/rivers.

To OP - has this excercise been any help? Have we all answered your questions?
 
John100156 said:
RPM / LPH / GPH
750 / 9.5 / 2.09
1000 / 15 / 3.3 - Probably over 5 knotts - will record next time out
1200 / 28 / 6.16
1400 / 35 / 7.7
1500 / 38 / 8.36
1800 / 55 / 12.1
2100 / 76.2 / 16.76
2400 / 108 / 23.76
2600 / 135 / 29.7 - 26 knots recorded, so say 0.88 MPG
Click to expand...

Excellent John ( and everyone else that have been crunching the numbers)!
I've been following this with interest but you lost me on the maths very early on.
I'm due to to take ownership of an F43 in a couple of weeks time so this is very relevant to me.
Would you have the speeds you would "typically" expect to acheive using the above rpm figures?
 
John100156 Cruising RPM was 2600 about 25 knots .

The river speed / consumption was with two engines running at idle.

If running on one thought needs to be given to water feed to a stern gland if apropriate and gear box lubrication if the stopped engine is windmilling in the water.
 
John100156 said:
Plotting a curve for my fuel usage then, I believe my boat, an F43 with twin TAMD63P’s, not fully loaded, in reasonable sea state with a clean bottom should achieve a fuel consumption that would follow the contour of the 2R4 but sit just above it, achieving something like the following (Can anyone else with/had an F43 corroborate this):

RPM / LPH / GPH
750 / 9.5 / 2.09
1000 / 15 / 3.3 - Probably over 5 knotts - will record next time out
1200 / 28 / 6.16
1400 / 35 / 7.7
1500 / 38 / 8.36
1800 / 55 / 12.1
2100 / 76.2 / 16.76
2400 / 108 / 23.76
2600 / 135 / 29.7 - 26 knots recorded, so say 0.88 MPG

.
Click to expand...

My F44 which has the same hull (I think) same engines and definatlely does more than 5 knots at 1000rpm. It's been in the water for over a year so will be slimy. There's an average amount of items on board. We usually cruise at 1000rpm which on gps equates to between 6.9 and 7.5 knots depending on tide. I would say on still water it is likely to be 7 knots. We stick to that speed as the hull starts to lift at close to 7.5 knots and want to avoid hump speeds. Unpleasenet sea condition will result in a increased speed to about 18knots. It's either 7.5 knots ot 18knots. Nothing in between for us.
 
I just did sime arithmatic bearing mind my post above and my boat experience. Personally when taliking fuel consumption, I am really talking about how much it costs me per mile.
So given my preferred two cruising speeds and roughly speaking:-

1000rpm = 7 knots = 7 miles per 15litres at £1/litre means it costs me £2.14 per mile.
2100rpm = 18 knots = 18 miles per 76litres at £1/litre means it costs me £4.22 per mile.

Hopefully I have manage the simple maths! There are obviously mathematical experts on here which is very impressive and interesting. Too difficult for my brain to get to grips with, but for me my simple fag packet calcs tell me what matters. How much is it costing me? And roughly how much is good enough!
 
Asteven221: Take a look back at Greg2's post the boat report figures in #16, it seems the most economical speed coincided with peak torque at 1800 RPM. Mind you, my F43 sat quite nicely and trimmed well at 2600/26k which compares well with Bandits

Latestarter1: The reason I have not included speeds against my RPM is, I am ashamed to admit, because I have never bothered to record them properly! I will of course do so when next time out, after new AF next month.
 
Many thanks for all the contributions - this has been really interesting and very helpful. 10lph on the river sounds about the max I can expect I think.
 
John100156 said:
Asteven221: Take a look back at Greg2's post the boat report figures in #16, it seems the most economical speed coincided with peak torque at 1800 RPM. Mind you, my F43 sat quite nicely and trimmed well at 2600/26k which compares well with Bandits

Latestarter1: The reason I have not included speeds against my RPM is, I am ashamed to admit, because I have never bothered to record them properly! I will of course do so when next time out, after new AF next month.
Click to expand...

Should came as no surprise, generally, all diesels are their most fuel efficient (lowest BSFC) at peak torque.

Of course, in marine applications, you would normally NOT be able to load the engine at peak torque except a very transient period during hard acceleration, (climbing the hump). This is because a vessel with the correct prop and reduction ratio (propped to reach or exceed rated RPM under maximum loaded conditions........ at least 2,860 (in your case) will prevent the forementioned condition from ever occurring.
 
Latestarter1 said:
Should came as no surprise, generally, all diesels are their most fuel efficient (lowest BSFC) at peak torque.

Of course, in marine applications, you would normally NOT be able to load the engine at peak torque except a very transient period during hard acceleration, (climbing the hump). This is because a vessel with the correct prop and reduction ratio (propped to reach or exceed rated RPM under maximum loaded conditions........ at least 2,860 (in your case) will prevent the forementioned condition from ever occurring.
Click to expand...

Yes, I follow the logic. I clearly recognise its an art selecting the right engines, prop and gearbox ratio's for a boat, takes me back many years when we use to drop different diff's into my old rally cars depending on conditions. In reality, I expect in the case of a new boat design, the science will take you so far, perhaps a couple of selections in mind, then you tweak the design on the water. Is that how it works in reality? How much do OEM's invest in this process, are most boats right when they come out of the shed?
 
John100156 said:
How much do OEM's invest in this process, are most boats right when they come out of the shed?
Click to expand...

The correct production process should involve vessel being having sea trials with engine manufacturers representitve on board.

Engine installation is checked to make sure that it complies with guidelines, i.e Plumbing is correct, fuel line, exhaust sizing, adequate filteration and with modern electronic engines that wiring is by the book. Tacho's checked and calibrated whilst alongside. It is 100% vital that commissioning engineer obtains proof in blood of vessels weight before trials.

Trails SHOULD involve running with at least half tanks and representitive vessel loading.

#1 Vessel must make rated speed on trails WITH THE correct margin to allow for some degree of fouling in order that engine does not become overloaded at WOT. Mechanical engines a simple rule is to make RATED speed plus 100 rpm when vessel clean. Unlike a road vehicle you can never have 100% of the power you have paid for.

During trials a decent engine manufacturer will likely check:

* Exhaust back pressure at rated speed.
* EGT at rated speed.
* Raw water flow Delta P.
* Fuel inlet restriction.
* Engine compartment temperature as well as ambient Vs engine compartment Delta T.
* Lube oil pressure.

Dependant on manufacturer there may be a few others. On a production vessel with no engine options, normal that engine manufacturer will allow subsequent vessels to be signed off on the nod. It is at the point of sign off that the engine manufacturers warranty becomes 'live'.

When optional engines are offered still normal and sensible practice for installations to be individually reviewed.

I have issued written warnings to sloppy applications engineers who have failed to follow instructions to the LETTER. In one case poor guy was between a rock and a hard place, builder wanted to wring ever ounce out of the engine as it was going to straight for press testing. Builder complained that the engineer was 'inflexible'.

However not all engine manufacturers are rigerous and in one case here recently poster was left to do his own review when purchasing a new engine for a re-power, just flog em a box.........Simply nuts!
 
Last edited:
John100156 said:
Asteven221: Take a look back at Greg2's post the boat report figures in #16, it seems the most economical speed coincided with peak torque at 1800 RPM. Mind you, my F43 sat quite nicely and trimmed well at 2600/26k which compares well with Bandits
Click to expand...

I am confused.

1800rpm would mean my Sealine F44 is doing about 14 knots (guesstimate) which is right in the hump, pushing lots of water. I would assume that an F43 will be much the same. That's not an economical place to be. I am sure I would use more fuel on a journey of say 20 miles at 1800rpm than I would at either 18 knots or 7 knots covering the same distance. LPH is not really relevant in my book as I don't care how much fuel is burned per hour. I am only interested in the amount of fuel used to cover a specific distance.
 
John100156 said:
Intersting insight, many thanks - so at what stage do they select/tune the selection of the props?
Click to expand...

Prop selection is generally down to the preferred supplier.... For example Clements. As propellers can only work at one point (rated speed), once reduction ratio is agreed all the prop supplier needs to do is work the #'s using resistance curve based on accurate displacement and LWL. Prop people know all about whacko spec sheets, dodgy fuel density or should. As I mantioned nice match for mechanical engines as I said is 100 rpm over rated, half tanks and clean. Production boats should have two specs, Northern European and Med.

Selection of three four or five blades down to hull shape, tunnels etc, noise, some science and a lot of experience and a bit of SWAG.
 
You must log in or register to reply here.

Share this page

Top