Oh no ... another Diesel vs. Petrol thread – Fuel Burn?

ari said:
At 18 minutes there is a cost comparison between two identical twin engine boats, one twin diesel, one twin petrol.

It's about 3x the cost in fuel at planing speeds for the petrol.
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Yeah thats probably about right, taking into account the differecne in the fuel price. It will get closer once red goes, but still be significantly more for petrol when comparing twin installations.
 
Hot Property said:
Compare that to the numerous service items on an inboard engine of either fuel type and the pendulum swings towards outboards again.

Just down the road is a brand new sports cruiser of probably 35 ft with twin 400 Verados on the back. The trend is for bigger boats to be outboard powered.......
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You are gonna need to save on servicing to feed those bad boys. Think under 1mpg at cruising speed and you are looking at very big fuel bills to go anywhere.

To be honest, the only real servicing item you are saving on with outboards is the rubber bellows on the sterndrive and maybe a belt or two less on the engine. If you have an E-tec, out of production now of course, you can also cut out the oil change, but overall its not a huge difference. Then there is the security issues with outboards. Just because they weigh quarter of a ton each, don't think someone won't come along and cut them off. I have never heard of an inboard being stolen.
 
CLB said:
You are gonna need to save on servicing to feed those bad boys. Think under 1mpg at cruising speed and you are looking at very big fuel bills to go anywhere.

To be honest, the only real servicing item you are saving on with outboards is the rubber bellows on the sterndrive and maybe a belt or two less on the engine. If you have an E-tec, out of production now of course, you can also cut out the oil change, but overall its not a huge difference. Then there is the security issues with outboards. Just because they weigh quarter of a ton each, don't think someone won't come along and cut them off. I have never heard of an inboard being stolen.
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Yep. One boat was recently hauled off the bottom of the river having sunk as someone was trying to steal the outboard
 
BruceK said:
Yep. One boat was recently hauled off the bottom of the river having sunk as someone was trying to steal the outboard
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Him yes it's a possibility that it may be stolen.

Having said that, I have insurance to cover that eventuality!

2 X 400 hp outboards are indeed gas guzzlers but for boats up to say 28 ft the economics are more positive.
 
Given you will use more petrol than diesel you will need to refuel more often. Where do you get the petrol? A lot of places will have diesel available at a pontoon, few will have petrol. Do you carry half a dozen 25l containers then try to find a taxi that will carry them to and from a petrol station? Except for a few places the logistics of petrol make no sense.
 
The south coast is quite well served for petrol:-

Solent - lots of suppliers
IOW
Portland
Torquay
Dartmouth

I have a range of just over 100 miles with a 25% reserve - that will (did) get me to Brixham from the Hamble.

How far were you thinking of going?
 
“Do you carry half a dozen 25l containers then try to find a taxi that will carry them to and from a petrol station?”

Not exactly… my marina sells petrol.. also I have a safe range of around 125 Nmiles with 25% reserve which suits me fine.
As I am retired and live within a few miles of the boat I can safely carry a couple of 5 litre jerry cans in the boot and top up whenever I feel like it.
Availability wasn’t the issue I was trying to raise .. It was just in the sub 30 foot boats and fuel burn, the argument for diesels is less than convincing … so far.. Yes they are a little more economical but not massively so at cruising speeds and when you factor in servicing and maintenance???
LBRodders video is an excellent example as well as encouraging.
 
moresparks said:
“Do you carry half a dozen 25l containers then try to find a taxi that will carry them to and from a petrol station?”

Not exactly… my marina sells petrol.. also I have a safe range of around 125 Nmiles with 25% reserve which suits me fine.
As I am retired and live within a few miles of the boat I can safely carry a couple of 5 litre jerry cans in the boot and top up whenever I feel like it.
Availability wasn’t the issue I was trying to raise .. It was just in the sub 30 foot boats and fuel burn, the argument for diesels is less than convincing … so far.. Yes they are a little more economical but not massively so at cruising speeds and when you factor in servicing and maintenance???
LBRodders video is an excellent example as well as encouraging.
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That's how I do re-fueling, unless away from my normal stamping grounds.

There seems to be a lot of denial going on regarding the time and costs of maintaining diesels and sterndrives particularly!!!
 
Hot Property said:
The south coast is quite well served for petrol:-

Solent - lots of suppliers
IOW
Portland
Torquay
Dartmouth

I have a range of just over 100 miles with a 25% reserve - that will (did) get me to Brixham from the Hamble.

How far were you thinking of going?
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Canna, the small isles in general. Diesel at Tobermory and Ulva Ferry. Petrol would be a nightmare even if you could get the range.
 
Hot Property said:
There seems to be a lot of denial going on regarding the time and costs of maintaining diesels and sterndrives particularly!!!
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Not really. This is about petrol V diesel, not outboard V sterndrive. Anyway, sterndrives are not exactly difficult to service. Not much more difficult in fact that dropping the lower unit off an outboard to change the impeller. Diesels, also very easy to service. Much less to look at than a petrol.

The easiest to own would be a single old fashioned diesel on a shaftdrive, but that won't suit the type of boats and boating that many people want.
 
CLB said:
Not really. This is about petrol V diesel, not outboard V sterndrive. Anyway, sterndrives are not exactly difficult to service. Not much more difficult in fact that dropping the lower unit off an outboard to change the impeller. Diesels, also very easy to service. Much less to look at than a petrol.

The easiest to own would be a single old fashioned diesel on a shaftdrive, but that won't suit the type of boats and boating that many people want.
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My point is that a diesel engine with a sterndrive has significant maintenance costs compared to a modern outboard which go quite a way to leveling up the fuel consumption/costs calculation in boats up to say 25ft.
 
moresparks said:
It was just in the sub 30 foot boats and fuel burn, the argument for diesels is less than convincing … so far.. Yes they are a little more economical but not massively so at cruising speeds and when you factor in servicing and maintenance???
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I wouldn't personally call a third of the fuel cost per hour at cruising speeds 'a little more economical', your mileage may vary, as the saying has it! :D
 
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