Twin diesel vs twin petrol conundrum...

rbcoomer

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Ok, this will seem like an insane proposition to many, but a dilemma I suspect quite a few have faced at some stage!

I'm looking to move up in the next 12 months to a twin engined 30' sports cruiser (something specific in mind, but probably immaterial at this stage and don't want to reveal too much yet - although some will guess.). Likely budget will be £20-25K and a clean, twin diesel example of this particular vessel is typically around £30-35K vs a twin petrol around £20K. Our use would likely be mixed, but typically we anticipate a couple of dozen local trips each season (<40-50nm) and one or two longer trips (200nm). The diesel variants are probably going to be twin AQAD41 and the petrols 5L V8. Servicing etc will be done myself, with some probable VP trained assistance as and when required...

I have found a clean example within budget, repowered with twin GXI petrols and later drives - low hours and less than 10 years old... Bearing in mind I'm likely to get perhaps 1.8mpg with these at cruise, I'm starting to think the unthinkable and consider twin petrols! :ambivalence: Am I right in thinking that the AQAD41's are only going to deliver around 3mpg at best anyway? I also have a small personal pension that matures in 6 years and as I'm very unlikely to ever fully retire, I'm thinking that might fund a pair of D4's further down the line! :cool:

Has anyone else opted for a petrol over a diesel due to lower capital outlay, or even better switched like-for-like either way and if so, how have they stacked up?

All things being equal and if the petrols were the same age as the diesels (i.e. close to 30 years old!), I probably wouldn't consider for a third less outlay, but as the petrols are less than 10 years old I am... I should add that there's also a performance difference in that the diesel boat (400hp less whatever has skipped the coral in the last 25+ years) will achieve 27~30kts and cruise around 20kts. The petrol boat (550hp) will cruise mid-20's and reach over 40kts! Finally, the later drives are also likely to be less troublesome than the earlier variants.

I've kept an eye on market over the last 18m or so and noted a couple of older twin petrol examples that have sold and another that's 'under offer' - so I'm clearly not the only idiot considering such things - which makes any future resale slightly less concerning too.

Any thoughts...?
 
I take it you are entirely comfortable with the significant dangers of bulk petrol stowage when compared to diesel fuel?
 
From your figures I would say you are planning to travel 1300 Nm in the year. At the mpg figures you give an allowing £1.50 a litre for petrol and £1 per litre for diesel the fuel for the petrol boat will cost almost £2.7 k a year more.
 
Petrol is fine but please, not in the form of inboard sterndrives. I know your budget is tight but outboards are far better, even a single outboard will probably do better than twin inboards. What's wrong with a single diesel?
 
Sounds to me you know exactly why you should not buy a petrol boat with anything larger than a seagull hanging on the stern.
No amount of pleading on here for some (any ) reason to go against your better judgement and buy a twin engined petrol will make you less aware of that nagging doubt when you sign the cheque and watch the broker/seller desperately trying to conceal their glee at having unloaded the unsellable. ?
 
The other major factor is availability of petrol, both at your home port, and where you want to cruise to,

Lack of availability of fuel was precisely the reason my friend sold his otherwise nice and reliable petrol engined boat.
 
Can only echo what others have said really. It all rather hinges on how much you are prepared to pay for your fuel and the availability of it in the areas you intend to cruise.

We discounted petrol as the availability where we are located is pretty poor. We didn't fancy lugging jerry cans around everywhere we went.
 
Can only echo what others have said really. It all rather hinges on how much you are prepared to pay for your fuel and the availability of it in the areas you intend to cruise.

We discounted petrol as the availability where we are located is pretty poor. We didn't fancy lugging jerry cans around everywhere we went.

how many smelly inflamable jerry cans can you fit in your car ?
 
Our Portofino 31 averaged about 2.5mpg with AD41s.
The price differential between Petrol and 60/40 diesel in Poole at the end of last year was about 35p per liter.
I easily spent more than the difference between petrol and diesel fuel use each year on maintenance and repairs to the AD41s and their drives over the five years of ownership. I even asked my VP mechanic if I had been unlucky, and he said for their age, no I hadn't.
I am now 12 months into owning a 17 year old Mercruiser V8 petrol engine boat. The difference to the balance of my 'boat' account is staggering!!!!
 
how many smelly inflamable jerry cans can you fit in your car ?

None. We don't need too!

The diesel at our marina is cheap at 75ppl.

As a comparison our marina does sell petrol but the last time we looked it was £1.50pl.

That's a massive difference in price.
 
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I take it you are entirely comfortable with the significant dangers of bulk petrol stowage when compared to diesel fuel?


What 'significant dangers' are these?

There are literally tens of thousands of petrol engined boats up and down the south coast and elsewhere. When was the last time you saw one spontaneously combust?

I'd be more concerned about the pressurised gas systems that so many 'safer' diesel boats are fitted with.
 
What 'significant dangers' are these?

There are literally tens of thousands of petrol engined boats up and down the south coast and elsewhere. When was the last time you saw one spontaneously combust?

I'd be more concerned about the pressurised gas systems that so many 'safer' diesel boats are fitted with.

http://www.pbo.co.uk/news/warning-after-boat-fire-explosion-caused-by-petrol-spillage-23519

https://www.thesun.co.uk/news/14999...a-marina-sending-victims-flying-into-the-sea/

http://www.stuff.co.nz/national/65667228/man-burned-in-petrol-pump-boat-explosion
 

Precisely, thank you!

You've broadened your search to the entire world and several years and come up with just three.

Two of which were clearly down to carelessness, not storage (one tried to fill his boat through a rod holder instead of the filler cap FFS) and one we don't even know if it was a petrol boat! Could easily have been a diesel boat and the gas system went up.

I'll apply a modicum of care and common sense and take those odds.
 
I went through exactly your scenario last year Rob, upgrading from a 21' Merry Fisher with petrol outboard to a 30' twin sports cruiser. I spent ages trying to justify petrol, as all I have ever known is petrol outboards. I failed miserably on both cost and availability.

We have now purchased our 30' sports cruiser with twin D3's, she will hopefully be home in Torquay next month, you are welcome to come round and have a look and natter over beer.
 
They were the first three stories that came up when searching boat fires.

All petrol related. I'm sure if I did a more thorough, i.e more then 2 second, search there would be plenty more.

Careless or not they all ended in boats setting alight.

Accidentally pouring diesel in the wrong place won't lead to a fire. It will make a mess though.
 
I found range is a big factor, that extra 1mpg takes you a lot further, and of course the range anxiety is reduced if you know you can always get fuel at the other end.
Paying the extra only hurts once with a diesel boat and it usually stays in the value of the boat, but petrol hurts every time you fill up and does rather ruin the enjoyment and stop you using the boat as often.

You know the answer really, just find the money :encouragement:
 
Our Portofino 31 averaged about 2.5mpg with AD41s.
The price differential between Petrol and 60/40 diesel in Poole at the end of last year was about 35p per liter.
I easily spent more than the difference between petrol and diesel fuel use each year on maintenance and repairs to the AD41s and their drives over the five years of ownership. I even asked my VP mechanic if I had been unlucky, and he said for their age, no I hadn't.
I am now 12 months into owning a 17 year old Mercruiser V8 petrol engine boat. The difference to the balance of my 'boat' account is staggering!!!!

Single Merc V8?

Petrols make some sort of sense on smaller boats, one engine per boat.
But a twin engined V8 will sound amazing whilst shrinking your wallet every time you go out.
At least with diesels, more of the investment is up-front, which means you have an incentive to go out more.
 
They were the first three stories that came up when searching boat fires.

All petrol related. I'm sure if I did a more thorough, i.e more then 2 second, search there would be plenty more.

Careless or not they all ended in boats setting alight.

Accidentally pouring diesel in the wrong place won't lead to a fire. It will make a mess though.

Did you get in a car this week? Over 20,000 people are killed in car crashes across the globe every week!

Been on a flight recently? Try searching for plane crashes.

Walked down stairs? A thousand people a year die falling down stairs!

http://news.bbc.co.uk/1/hi/health/790609.stm

Meanwhile, hundreds of thousands, millions probably, of petrol boats carry on year after year, quite happily managing not to go pop.

In the grand scheme of things, running a petrol boat with a modicum of care really is not taking your life in your hands.
 

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