Petrol vs Diesel

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chucklebus

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I'm looking to buy a single engine sports cruiser around 22-27ft and there's obviously a significant difference between the price of petrol vs diesel engine powered boats. I'd like to know roughly what the mpg difference is, and if it's worth spending the extra to get a diesel and running/service costs.
 
It'd be worth mentioning where and how you plan to use the boat. Availability of petrol can be an issue in some areas.
 
Very roughly you'll use something like ~50 litres an hour at cruising speed in the petrol Vs ~30 litres per hour in the diesel. Obviously there are loads of variables that would affect this, but this is my experience of a single petrol Vs diesel in the type and size of boat you mention.

However you shouldnt just take into account fuel consumption. There is purchase cost,servicing costs,cost of parts( parts for mercruiser petrols tend to be much cheaperthan parts for Volvo penta diesels for example) availability of fuel ,resale cost ,how many hours you expect to run per year and range of boat to also take into account.

I've had similar boats with both fuel types,and for my use and where I boat I'd choose petrol over diesel, but if I was doing hundreds of hours and/or boating in an area where I couldn't get petrol easily then diesel would be the winner
 
There's a lot more to this than 'MPG', you also need to consider the cost of dockside fuel (way more than road prices) plus (as has been said above) availability.

Also you need to consider that the extra money to buy a diesel boat over petrol is not 'spent', it's invested in the boat and you'll get most, or maybe all, back on resale.

There is a really good breakdown of running costs of a 26ft diesel boat , which includes a direct comparison of petrol versus diesel running costs, in this video.

 
Before I bought my first boat the option of petrol was quickly ruled out on the basis that petrol was scarcely available at the waterside.

Some people we got to be friends with had a petrol boat. On a couple of cruises in company the quest for petrol became a pain while we passed plenty of refuelling opportunities but did not need them all. Ultimately we set our sights on wider travel which was simply not possibly for them to follow.
 
To very much over-simplify......

At the 22' end of that spectrum, if I was trailing the boat and could pick up petrol from a forecourt in the usual way - petrol outboard is the way to go.

At the 27' end of the spectrum the fuel cost will become eye watering (I had a 26' cruiser with a 5.7 v8 - that burned 20 GALLONS (90 litres) an hour flat out - 16gal an hr at cruise - so at £2 a litre - that's £180 per hr to run - that's crippling.... so then diesel all the way to my mind.

There may be exceptions to this - a modern MPi petrol will be more economical (a bit) and if the boat is exceptionally light it will also use less fuel...... but the principle is sound.

Also, if you want to fill quayside, then petrol is a little harder to come by on the south coast and MUCH harder to come by in some less well frequented locations......

Then there is range - if you want to cruise to France for example either petrol or diesel is ok if you're doing it at Calais - but if you are doing it from the West Country with 4 hour cruises to France, you are needing significant range - and then diesel is also the way to go.....


Give us a bit more info and we'll make some better recommendations - what type of boat are you looking at - low slung sportsboat, big heavy high sided cruisers?
 
QUOTE="ari, post: 8084987, member: 48"]
Does it? Are you absolutely sure.
[/QUOTE]
Not absolutely as I've not seen any facts or figures so I'm just making it up as I go along . :D
I have watched a fair amount of "miami haulover" vids and similar and it seems usa "sport boats"up to 60ft are mainly outboard powered as stern drives have fallen out of favour.
In the last decade, maximum outboard horsepower size has gone up dramatically and some boat designers have redesigned some models for outboard use in the USA market.
Would that not suggest the lighter, quieter, easier to live with ,smoother running outboards are replacing inboards because they are more desirable ?
So no, im not absolutely sure.
 
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I reckon if the boat lives on a trailer it’s a no brainer - go with a petrol outboard.

If the boat is moored somewhere where petrol is easily available dock side - it’s a bit of a wash. The increased servicing costs of a diesel inboard will probably cancel out any fuel savings with a diesel.

If the boat is moored somewhere where petrol is hard to come by dock side - go with diesel; lugging cans out quickly becomes a pita.

If the boat is moored somewhere where you have to take cans to it either way, go with petrol (less messy when you spill some).
 
It’s going to depend on where you are based...here in the Med petrol and diesel are equally available dockside...in the UK the history of red diesel meant that petrol was squeezed out of the market and isn’t readily available. You can of course fetch and decant your own petrol (if this is legal, it’s not in parts of the Med) but it is a pain (literally and figuratively) to do.
The price differential between an inboard petrol and inboard diesel will mean that what you save to buy you lose when you sell. Outboards are a different matter and as long as nobody steals them are a far superior beast...especially manœuvring for a newbie.
You will use more petrol (but you will also go faster so swings and roundabouts) and while red diesel is not what it once was, there still might be the old heating calculation that means diesel can be cheaper (I apologize if this loophole has been closed).
So it is not a straightforward question and better to start with your ideal boat..then worry about propulsion
 
Rappey said:
Not absolutely as I've not seen any facts or figures so I'm just making it up as I go along . :D
I have watched a fair amount of "miami haulover" vids and similar and it seems usa "sport boats"up to 60ft are mainly outboard powered as stern drives have fallen out of favour.
In the last decade, maximum outboard horsepower size has gone up dramatically and some boat designers have redesigned some models for outboard use in the USA market.
Would that not suggest the lighter, quieter, easier to live with ,smoother running outboards are replacing inboards because they are more desirable ?
So no, im not absolutely sure.
Click to expand...

Well, that's an interesting basis for making statements like 'An outboard driven boat has many advantages over an inboard and holds a far better resale value'
 
Bouba said:
The price differential between an inboard petrol and inboard diesel will mean that what you save to buy you lose when you sell. Outboards are a different matter and as long as nobody steals them are a far superior beast...especially manœuvring for a newbie.
Click to expand...

I can't say that's something I've noticed over an outdrive which directs thrust in exactly the same way.
 
May I ask if this is your first boat purchase ?

If so most first timers will want to change within 1 or 2 seasons, so ability to sell on should be a significant consideration. Petrol inboard boats are also cheaper because they are difficult to sell on.

Good luck with your search for a suitable boat and please come back here and tell us what you bought.
 
Rappey said:
QUOTE="ari, post: 8084987, member: 48"]
Does it? Are you absolutely sure.
Click to expand...
Not absolutely as I've not seen any facts or figures so I'm just making it up as I go along . :D
I have watched a fair amount of "miami haulover" vids and similar and it seems usa "sport boats"up to 60ft are mainly outboard powered as stern drives have fallen out of favour.
In the last decade, maximum outboard horsepower size has gone up dramatically and some boat designers have redesigned some models for outboard use in the USA market.
Would that not suggest the lighter, quieter, easier to live with ,smoother running outboards are replacing inboards because they are more desirable ?
So no, im not absolutely sure.
[/QUOTE]

No, it's that Petrol is available everywhere at about $1 a litre or so......
 
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