Diesel vs Petrol vs LPG

What nobody seems to take account of in calculating break even points is that you'll get most if not all of the extra cost of the diesel powered boat back when you sell. The petrol version maybe cheaper but it will depreciate faster. For me its a no brainer. I started my boating life with a petrol V8 powered SeaRay and the pain of putting £300 of petrol (that was a lot of money 16yrs ago) in the tank every weekend soon made me forget about the cheaper price of the boat
Even if red diesel goes, I still think diesel boats will depreciate slower than petrol ones because of the better fuel economy, safety and availability of diesel
 
Only 50 hours per year???? seems a shortfull to me. Only had our boat a month and clocked over 70 hours, and still not using it to the full.
 
I dont know what everybody elses savings will be, and no doubt if you have a cruiser (as I have) you will do more hours, especially if you have enough berths for a couple of mates. My cost calculations look like this.

100 hours use a year @ 10 gallons per hour = 1000 gallons
1000 gallon = 4540 litres.
Petrol at 97 pence per litre = .97x4540 = £4403.80 per year in fuel costs. I intend (though dont we all) to keep the boat at least 5 years.
So, total ownership petrol costs = £22019.00

The same sums on Gas look like this: We expect the boat to be as efficient of gas, but for caution, I have assumed efficiency will drop by 15%. So, boat on gas uses 11.5 gallons per hour.

100 hours use a year @ 11.5 gallons per hour = 1150 gallons
1150 gallon = 5221 litres.
Gas at 37 pence per litre = .37x5221 = £1931.77 per year in fuel costs. I intend (though dont we all) to keep the boat at least 5 years.
So, total ownership Gas costs = £9658.85
Add to this the £3000.00 for the istallation and the gas costs are £12658.85.

This is pessimistic because actually most reports show boats are as efficient on Gas as on petrol, but I like to play safe.

In real terms, even with the conversion cost, and accepting that the boat will be worth the same in 5 years as a normal petrol boat, I will still save nearly £10000! Thats £2000 per year.

I think this makes it a viable option, especially if Red diesel increases, even by 15 pence per litre!
 
Just a point on running costs.

One of the veterans on this forum often recommends that people estimate 10% of the purchase price per year for running costs. I don't think that's too far off the mark.
 
Thats another thing... 10% of the boats cost per year.

It is something i have heard and as a guide use 10-15% for the sums, but what i dont understand is this.

I buy a new pocket cruiser for 60k, yearly costs will be 6k.
If i buy a 2nd hand, lets say 10 years old for 25k, it will cost me 2.5k a year to run.

I dont beleive a newer boat of similar size will cost more to run?!?! Puzzled!!
 
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err, no-one has mentioned yet that petrol is highly volatile and dangerous but you can drop a lighted match into diesel....

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I seem to remember figures quoted on this forum that petrol-fuelled boats account for 2/3rds of fires on boats......leaving diesel engines as the other 1/3rd.

Wouldn't suggest dropping lighted matches into anything - you could always set fires to the more volatile additives..... /forums/images/graemlins/frown.gif

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And in the US, at least, most boat fires are started by electrical faults, not by waving around lighted matches in petrol vapour. /forums/images/graemlins/smile.gif
 
Jez

I have been there and done it. I can assure you that Gas is around 20% less efficient than petrol. Ie you use around 20% more for a given trip.

Before I converted I also did the figures in the same way that you have, and thought that I couldn't lose. Unfortunatley after just 30 hours running on gas, my engine died. In that 30 hours I had probably saved a few hundred quid in fuel but it had cost me £4k. I am now converting to diesel at significant cost and my biggest regret is that I didn't keep that £4k and put it towards a diesel back then.

I wouldn't recommend anyone converts a boat, not least because getting hold of the fuel is a nightmare.

Neale
 
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This is pessimistic because actually most reports show boats are as efficient on Gas as on petrol

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I'd be surprised - LPG has a lower octane rating than unleaded, this means two things:

Firstly a gallon of LPG produces 15-20% less energy than petrol, this is why you will need 15-20% more volume of LPG to travel each Nm compared to petrol, any boat test taht doesn't find this either would seem not to be testing very well or finding a way around the science.

Secondly, due to the lower octane the engine requires more ignition advance to burn LPG correctly, a lot of conversions don't take account of this and have to run with a single ignition setting for LPG and petrol, as you can't run on petrol with too much advance (you get detonation = damage), conversions such as this run with the ignition too retarded on LPG - this means the engines run hotter temps (and less efficiently than it could on LPG). If you get a conversion check these areas before you patr with hard-earned AND run the risk of engine damage.
 
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Jez

I have been there and done it. I can assure you that Gas is around 20% less efficient than petrol. Ie you use around 20% more for a given trip.

Before I converted I also did the figures in the same way that you have, and thought that I couldn't lose. Unfortunatley after just 30 hours running on gas, my engine died. In that 30 hours I had probably saved a few hundred quid in fuel but it had cost me £4k. I am now converting to diesel at significant cost and my biggest regret is that I didn't keep that £4k and put it towards a diesel back then.

I wouldn't recommend anyone converts a boat, not least because getting hold of the fuel is a nightmare.

Neale

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Sorry to re quote the whole post, but I could have written the same - Neal as you know, I did convert to diesel, and not looked back! You and I had the same problem. I wished I'd kept my money and gone for diesel conversion in the first place. Hindsite is a very rich man! I have a friend who also did an LPG conversion - he's now just converted with a Yanmar 240 diesel - threw the LPG kit away!
 
/forums/images/graemlins/cool.gif Nah, that's myhi speed turn after fitting a diesel engine and getting rid of all that weight - by that I mean LPG tanks that cocked up the balance of the boat as well!! /forums/images/graemlins/frown.gif
 
LPG is actually higher octane than petrol circa 115 compared to 95, hence why it needs more advance to be economic. The more advanced (sic) petrol conversions are using dual ignition mapping to take advantage of this in that when you switch to LPG you switch in different ignition map. This to a certain extent takes care of the lower calorific value.
Go to http://www.v8engines.com/homepage.htm Chris Crane has done a lot of development on LPG powered RRs and writes on his site.
 
Whoops, wrong way around /forums/images/graemlins/blush.gif still right answer for wrong reason eh?

Agree with everything else you say - but last time I looked the marine conversions appeared to be about 3yrs behind current vehicle technology.

Fraid I still don't trust the fuel and wouldn't put up with the refuelling location restrictions and the need to (probably) put the tanks in a less than ideal place relative to the cg of the boat.....
 
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