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Newer Or Mid Range Boats Don't Use Much Diesel


Andrewcook

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No. It is mostly dependant on how you use the boat. There's not a great deal of fuel efficiency difference between a new Nanni 35hp engine and an old BMC 1.5. It's down to how its used. Against the tide all the time will not help. Hell for leather will guzzle fuel like no tomorrow. Strong headwind will help swallow it too. 

Hydraulic drive boats usually use more fuel too as there's up to 30% efficiency loss in the drive train. 

 

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6 minutes ago, Oddfellow said:

Hydraulic drive boats usually use more fuel too as there's up to 30% efficiency loss in the drive train.

Sorry, can't agree with that.  Peachments hydraulic drive hardly loses any power in the drive.  The old Dowty or Dennison systems lost about 10% but that was over 50 years ago!  There are other enormous advantages to hydraulic drive especially on a waterway which has a lot of locks, such as the Thames.

I did a lot of research into fuel consumption as all our boats in France were fitted with hour meters.

You can expect a Nanni 4220 to use just over 2 litres per hour at moderate speeds - depending on the size of the prop of course.  Consumption of any diesel goes up sharply when you go fast.  The Nanni 5 cylinder was using about 3 litres an hour when the speed was limited.  Take the limiter off and go up to 2500 revs and you start using over 7 litres an hour.

The most economical was the good old Perkins 4108.  Consistent consumption of 1.6 litres per hour on a 4 berth boat.

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I've hired suncharm a fair few times from her first season up until two years ago. She's a very economical boat, I've always had a refund on my fuel deposit. I've travelled from Stalham to Norwich, Loddon and back and still got money back. Number 2 has a real pain in the but throttle lever that after 1000 rpm you have to physically hold down. But a very nice boat IMHO 

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We were on  one of Richardson's older bathtubs in May, and of the £125 fuel deposit got just over £72 refunded. We travelled south to Cantley and to Oulton Broad, kept to the speed limits, and had the heating on a few times. We were very happy with our fuel refund. 

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6 minutes ago, twowrights said:

We were on  one of Richardson's older bathtubs in May, and of the £125 fuel deposit got just over £72 refunded. We travelled south to Cantley and to Oulton Broad, kept to the speed limits, and had the heating on a few times. We were very happy with our fuel refund. 

Typically, it was the short break hirers that used more fuel because they just hammered the boats: had to get everywhere because their time was limited. Often a 3 day hire would use more fuel than a week hire on the same boat. 

2 hours ago, Vaughan said:

Sorry, can't agree with that.  Peachments hydraulic drive hardly loses any power in the drive.  The old Dowty or Dennison systems lost about 10% but that was over 50 years ago!  

There are LOTS of those still in use... 

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water rail with her 21 hp 3 cylinder Nanni is lucky if her tank is 45 litres, however she does use less than a litre an hour, so a gallon every 4.5-5 hours cruising, I used a lot last time when I had her out for 11 days, I must have bought £70 of fuel while aboard, of course she was nearly empty when I picked her up, and near full when I left.

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Engine load most likely has the largest contributing factor to fuel consumption, then tides depending where you are, followed by hull design. There are those that will say most broads boats are all displacement hulls and this makes little difference, however I would beg to differ. There are some boats that would appear to glide and cut through the water much better than others, where at the end of a long trip, 3 boats with almost the same BMC engines, two used a lot more fuel than the “pacemaker” we were following. Also depends if your towing a water break.... 🚣‍♂️ 

Cheers

Paul

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Once some years ago H.W's couldn't provide us with three Jewels so we had a large different type with hydraulic drive.  As well as being noisier it was also less efficient by some margin using a full 50% more fuel than the two Jewels, despite being a similar hull design, the same size and visiting exactly the same venues whist maintaining the same speed.

When hiring we always do our best to avoid hydraulic drive at all costs

Griff

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Hi Most engines are at there most economical at 1200 to 1500 rev's over that and consumption goes up proportionally with higher rev's and running while moored up to heat water dosn't help. John

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  • 2 weeks later...

As a matter of interest I have just come across a paper from Nanni whilst sorting out old stuff after our move.

In 2000, We needed to know the exact shaft horsepower (SHP) before sending boats to Italy, where engine size is limited on hire boats.

According to them there is a difference on the Nanni 4220, between a PRM gearbox on 2:1 reduction and a Dowty hydraulic drive, of 7,5 HP, which is 15% of the gross HP.  These figures are quoted at 2800 RPM but the difference will be a lot less at normal Broads speeds below 2000RPM.

When you consider that fitting a second alternator to power the inverter batteries for a microwave, will take 5 HP off the engine, I don't think that's too bad.

Incidentally the power rating for the PRM version was 29.44 kilowatts.  An electric powered cabin cruiser would need a motor of that sort of power, the batteries to run it for at least 4 hours per day and the means of putting back that amount of charge overnight, every night.

In reply to Griff, I am afraid I have to say that whenever customers hire a group of boats together, they will always, always, complain that one of them used more fuel than the others!  It's par for the course in our business.

Seriously though, although one of them may have been swinging a different size prop, a difference of 50% consumption cannot be put down to hydraulic drive alone.  It would sound to me as though one of the boats had not been full of diesel before departure.  These things can sometimes happen and I imagine you complained about it at the time?

 

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Seeing how well we know H.W's and in turn they us, not so much an outright complaint but expressing our disappointment.

They refunded us the difference.

I have to say each and every time I have hired a hydraulic drive boat , I have been disappointed with both the noise and the increased fuel consumption, not surprised, just a resigned disappointment.

You can probably tell I'm not a fan of them

Griff

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Hi My Beta supplied hydraulic drive unit with pod shaft is silent both inside and out but with a Axium prop and higher spec insulation perhaps not surprising, cant comment on fuel consumption but with two alternators i get 1 1/2 to 2 lts per hour average on a 44ft boat. John

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