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Fuel Consumption


Hockham Admiral

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I thought it might be appropriate to write about how I plan a holiday, or indeed just a trip from Brundall to Beccles or Oulton Broad.

My first task is to check the tide tables (http://www.norfolk-broads.org/tides/tide_report.asp?StartDate=18/06/2013 14:12:06).

I then plan to go through Reedham (on the South Broads) at slack water, about an hour after low water, whichever way I am going. I then get pushed up the Yare or the Waveney, either way.

Going Norrh or returning South I aim for slack water at Great Yarmouth Yacht Station, about 1.30 after low water. This also gives me a good push up the Yare or Waveney and if I'm going North I may well stay at the yacht Station for an hour or so in order to get the full benefit of the flood up the Bure.

It's not rockert science and doesn't take long to work out!

But "Why bother?" I hear.... Fuel Consumption is the answer.

Let's look at the Fuel Consumption graph for our Nanni 50bhp diesel... a common Broads Cruiser engine.

 

post-146-0-99052300-1371561906_thumb.jpg

 

If I select 1400 rpm then my FC is just on 1 L/hr and this will give me just short of 6mph with a +1.5 mph tide behind me.

If I go head to tide and want to maintain the same speed then I'll need between 1700 and 1800 rpm. That will up my FC to either 2 or 2.4 L/hr.

If I was daft and went along with the throttle to the wall, as some do, them I'm up to 5 L/hr..... I rest my case!

 

 

 

 

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Good advice indeed. I also tend to stick to around 1300/1400 revs and go with the tide where possible. Over the last 2 weeks we covered the whole of the network making the limit of navigation on every river. We used 102 litres in total so I was very happy with that. When you see folks ploughing around at full throttle I dread to think what their fuel consumption must be! :shocked 

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I was really aiming this at newbies to the Broads and new hirers in particular. With diesel at around £1.30/L it seems like just common sense to keep that usage down as far as possible. :clap

 

I do understand that with limited time one sometimes has little option. But to see the flotillas "heading for home" on a Saturday morning at wave-generating speeds does little for the pocket! :Stinky

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It is hard to use manufacturers data for an engine to determine what your fuel consumption will be – just as cars will not get what the manufacturers claim they will – but even more in a boat where the boat the engine is in makes a lot of difference – how heavy it is, hull type, prop – even how much growth might be on the hull hidden below the waterline.

 

As a rough idea to cover all the above I calculate a rate of 2 litres per hour which means on a weeks cruise my £150.00 fuel deposit will get around 53 hours of cruising or roughly 107 litres of fuel. That does not include heater use, and is based on £1.40 per litre.

 

Anything to aid the above is always helpful – it is better to try and have nature as your friend pushing you along with the tide, than your enemy going against it.  It really can make a huge difference in RPM (and noise).  Every boat is as I said to being, different some will have 38HP engines, some 40HP and some 50hp – I always have a look to see what engine is installed and it is always nice when one finds a Nanni for the smoothness, though I was impressed with the old BMC fitted in Distant Horizon 2 – it seemed better on fuel.

 

Something I have seen with regard to the ‘big rush home’ is not limited to hire boats. Last year at the beginning of September on the Ant, it was as if someone had dropped the flag mid Sunday afternoon when it was not hire boats heading for Stalham but the privateers – and many seemed in a great rush to get to the marina, unload and get in the car and off home if their speeds were anything to go by.

 

So far I have not used all of a fuel deposit up – I’ve come close though on longer outings but I always go wit the expectation I might and then there is money in the kitty to pay if that was to be the case.  As far as fuel goes, I really think the Broads could do a lot more with alternative means of getting a boat along.

 

The electric posts (so I believe) were put in to begin for the charging of electric craft – Quiet Light from Herbert Woods when launched was all electric – hence her name – but that did not last long and though in recent years more posts have gone in, it is to fuel the need of electrical items on board than charging of batteries for propulsion.  Faircraft Loynes have a Hybrid boat – but not much has ever been said about this, how good it is, is it viable – does it work and save fuel etc. The fact other yards have not followed and indeed Faricraft Loynes themselves have only the one says it may not be working out as well as hoped.

 

If there was a network of electric posts though – you could then have more boats being electric – cruise in the day – moor up, plug in and charge batteries at the same time as using residual power for the telly etc before leaving the next morning and heading for the next place – knowing points would be there. You would have near silent cruising, the posts could be supplied from electricity generated through carbon neutral suppliers and hey presto you’ve done something for the environment and kissed goodbye to worries about diesel spills and the like. Problem is it would cost a lot of money for infrastructure and fitting such ‘electric engines’ to boats.

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The Peace & quiet would soon be broken, not by the engines by the arguements that would no doubt break out when an electric boat needed the post to charge up & a diesel gin palace refused to move cause they needed the electric post to run the TV Playstation microwave & hair dryer simultaneously.

If we are to ever see a wider usage of electric boats then there needs to be a clearly define set of rules on their usage by BA i.e, electrically propelled craft have priority or a seperate set of charging only posts which are locked with only electric boats having keys.

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The Peace & quiet would soon be broken, not by the engines by the arguements that would no doubt break out when an electric boat needed the post to charge up & a diesel gin palace refused to move cause they needed the electric post to run the TV Playstation microwave & hair dryer simultaneously.

If we are to ever see a wider usage of electric boats then there needs to be a clearly define set of rules on their usage by BA i.e, electrically propelled craft have priority or a seperate set of charging only posts which are locked with only electric boats having keys.

 

I quite agree Minor.

 

Even though electric propulsion has many other practical drawbacks at this time, the usage of the electric charging posts needs to be better controlled.

 

The BA did in fact try to ensure some demarcation by providing 16 amp and 32 amp sockets on the posts. The 32 amp being intended to be exclusive to electric boat charging.

 

Even that was circumvented by many hook-up power users by the use of 32 amp to 16 amp line adapters and splitters. Most of which are even dangerous and illegal, since they enable 16 amp leads to be backed by 32 amp supply breakers.

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The newly installed addition posts installed at Brammerton & Reedham are clearly not intended for battery driven craft.

I agree that craft that need battery charge facilities should be given priority but when did you last see such a craft? I saw some electric day boats a few years ago at Herbert Woods but have not seen any since. I thought they had sold these or were trying to do so.

More could be done in this field of hybrid craft but it would take a complete rethink with regards to the construction of the said craft.

I have seen articals on hybrid canal narrow boats these are constructed of aluminium and have huge banks of the latest cells.

All in all very expensive way to go.

Regards

Alan

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It is hard to use manufacturers data for an engine to determine what your fuel consumption will be – just as cars will not get what the manufacturers claim they will – but even more in a boat where the boat the engine is in makes a lot of difference – how heavy it is, hull type, prop – even how much growth might be on the hull hidden below the waterline.

 

 

Quite right, Robin.

That curve is at the flywheel and doesn't take any account of friction/propeller losses or any of the other factors you mention. But all those are constant and you could probably just double the figures I showed to get a more appropriate consumption.

It certainly does give an idea of what it costs to "put the throttle to the firewall", as we used to say in propeller-driven aeroplane days.   :smile:

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The Peace & quiet would soon be broken, not by the engines by the arguements that would no doubt break out when an electric boat needed the post to charge up & a diesel gin palace refused to move cause they needed the electric post to run the TV Playstation microwave & hair dryer simultaneously.

If we are to ever see a wider usage of electric boats then there needs to be a clearly define set of rules on their usage by BA i.e, electrically propelled craft have priority or a seperate set of charging only posts which are locked with only electric boats having keys.

I have to be careful what I say but I must point out that some boats (and notably Barnes Brinkcraft ex-hire boats like ours) don't have gas... which means if you want a late night or early morning cuppa you either have to be plugged in or run your generator.

The second option will not be favoured by many. (Even though BB designed an underwater exhaust system which is relatively quiet). You often hear boats running their propulsion engines to heat water late at night and early in the mornings, to the detriment of your sleep!

By "Gin Palace" I take that to mean a very large 'pointy', high speed boat which usually sits in its yard, occasionally ventures out down the river and back and never goes to sea? 

What I am trying to say is that we're not all "Gin Palace" owners and we own neither PlayStations nor hairdryers.... :bow

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The Peace & quiet would soon be broken, not by the engines by the arguements that would no doubt break out when an electric boat needed the post to charge up & a diesel gin palace refused to move cause they needed the electric post to run the TV Playstation microwave & hair dryer simultaneously.

If we are to ever see a wider usage of electric boats then there needs to be a clearly define set of rules on their usage by BA i.e, electrically propelled craft have priority or a seperate set of charging only posts which are locked with only electric boats having keys.

 

IMHO there is no need for Playstations, microwaves and hair dryers on a boat and to be honest with whats on tv these days we can do without that as well.

We use the electric posts when we can just to keep the batteries topped up or out of season to get some extra heat on the boat.

With regards to Gin it can be used for cleaning electrical/mechanical parts (I used to use it when I was a service engineer whist working in pubs)I prefer a pint rather than any spirit.

Regards

Alan

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I agree that craft that need battery charge facilities should be given priority but when did you last see such a craft?

 

Very true, other than a few day hire boats, I've only seen two in 12 years living on the Broads.

 

The problem is that it is very much a "Chicken and Egg" situation.

 

People aren't going to invest in one for normal cruising until remote charging can be assured with ready established charging posts that can be seen to be available and not in use for other purposes.

 

I doubt they will ever come to anything on the Broads until battery technology improves dramatically.

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That is one of the problems I was on about John... Not your fault as the boat was like that when you bought her but, why are boats being fitted with electric hungry devices when they clearly don't have the power to support them on their own. Being on a boat in a way is like going camping on the water. When have you seen a camper erect a large satellite dish & start breaking out games consoles.

I agree with the chicken & the egg simily, since we have started as a nation putting in more charging points for electric cars we have seen an increase in the range of electric vehicles on our roads. Now, imagine the uproar if a camper van pulled into one & plugged in simply because they wanted to use the microwave.

I used a boat (superior light) which had shore power, but never once felt the need to use it.

On a side note me & my wife recently used an electric day boat on Windermere & have to say it was far more pleasant than using a diesel boat much more quiet with no vibration or smelly exhaust & it provided just as much propulsion as the diesel version that others hired. I couldn't believe some people's reaction when they were offered an electric boat " oh god no we'd rather have a diesel boat please"

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That is one of the problems I was on about John... Not your fault as the boat was like that when you bought her but, why are boats being fitted with electric hungry devices when they clearly don't have the power to support them on their own.

 

In fact ours does have that power, Minor. In the shape of a Beta 1500cc driving a 10 KW (42 amp at 240V) genny. And the electrical shore power hook up is all rated at 32A.....

My point is I'd rather use a hook up for that cuppa and like Alan says, they keep the batteries charged up.

 

(And the dish-washer was straight onto the scrap-heap to be replaced by a drinks cupboard for all that wine and gin) :naughty:  :naughty:  :naughty:

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I let the Mrs. work out any serious tidal streams, we did a trip from wells to hull a few years ago and were 10 minutes out on arrival at hull 11 hours after leaving wells, I would have given up halfway through the working out.....

On a good 2 week run we can easily get through 450 litres of diesel without going over 6 knots, that gets scary.

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It's amazing how much fuel can be saved by using the tides correctly AND by taking it easy.  We had 11 days in May and travelled from Stalham to Beccles, Loddon, Wroxham, Potter, Wayford and place in between and used 56 litres of fuel.

We used  the Satnav  to check our cruising speed and kept to 4mph wherever possible.

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It's amazing how much fuel can be saved by using the tides correctly AND by taking it easy.  We had 11 days in May and travelled from Stalham to Beccles, Loddon, Wroxham, Potter, Wayford and place in between and used 56 litres of fuel.

We used  the Satnav  to check our cruising speed and kept to 4mph wherever possible.

I guess you used the hot air heating as well? (We certainly did in May). If so that is really good going because I'd hazard a guess that lots of peeps would be well over the 100L mark! smiley-eatdrink009.gif
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Yes, we certainly had the heating on in the morning and at night, but we did try not to overdo it.  We found that as we could close-off the saloon (we were on a Major Gem) we didn't need to use the heating as much as we would have done on a boat with a more open-plan design.

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