Petrol vs diesel

[chippie]

Re:Wankel

Oddly enough , my old trimaran had a Sachs wankel that came with the boat but I decided against re fitting it on the grounds that the anti petrol brigade have mentioned.They also had a poor reputation for fuel economy. It is air cooled and very smooth running but would be noisy installed. I currently use an outboard on a bracket but may fit a Kubota diesel in the future.

 

[yoda]

Mike

I leave you alone for a couple of days and look at the post you manage to generate. The arguments are all long and mostly plausable however few are backed up by facts. I'm afraid our pro petrol views will be ignored by the majority. With care and common sense we will continue to have years of happy motoring on petrol without the cost of fitting a new diesel engine. My Dolphin is a great little thing and if it wasn't for a slight lack of power and better battery charging capacity would be most happy to stay with it. In principle I am much happier with petrol than diesel. Strange how the RYA run a couse for Diesels and not petrol outboards yet many owners seem happy to have an outboard as their main engine. Some of the arguments about fuel cost seem to be put forward by those who motor rater than sail. I use about £40 worth of fuel a year and keep the boat 5 miles up a river from the sea. I couldn't justify a new diesel on those grounds alone. I must admit I have a big Yanmar diesel sitting in the garage ready for the winter however if it won't fit then it will be sold on to one of the many diesel loving people out there. I'm still not sure about it .................. Regretably in this country there is a lack of a good petrol inboard at a sensible price due to lack of demand, perhaps I'll surf the net and see what turns up elsewhere. Keep the Dolphin going, your reasoning is sound and principles right. PS I have fitted quick conections so I can remove electrics quickly in the winter without large wiring nightmare, a well worth evolution. I also have dedicated engine batteries and run domestics from another bank with a solar panel to charge them. This has also been a great sucess.

 

[ArthurWood]

In past 3 yrs there have been 3 boat fires in our marina, 2 diesels, but fires caused by electrical probs; petrol fire happened after refueling - most common time for this to occur according to BoatUS stats - fuel spillage in bilge. After refueling I always run blowers for at least 4 min and lift engine hatch and have a sniff before starting.
Only ever had one electrical prob on my Merc 7.4l in 1130hr, whereas others in our marina, many w/$1M+ boats, are always having probs w/diesel, eg diesel bug, turbo probs, jet probs. I would have diesel if I could justify $40-50K price diff, because of lower fuel price and better economy, but not on basis of safety and reliability. I can buy a lot of petrol and maintenance for $40K! I guess I'll find out a lot about diesels during July as we shall be cruising Lake Michigan and Georgian Bay for 4 weeks on friends' 60ft Hatteras.

 

[chippie]

Hi Arthur, what is the current price for petrol where you are?
I can see that it makes sense for you to retain petrols. Would you consider diesel if you were buying a new boat?

 

[ArthurWood]

Hi Chippie - on the water it's $1.89/US gal ($2.36/Imp gal). Diesel is $1.19/US gal. Yes, I would have diesels if I changed boats, but for running cost reasons as described earlier, although it does not make economic sense unless I do about 300hr/yr and keep the boat >5yr and that's being optimistic. (I seem to remember seing a calculation in a mag sometime ago). It's just painful having to fill up after every 120 mi or so, but being retired, I think it better to preserve capital rather than go out and buy a new boat and think I'm saving money!! However, most boats of our size and type(37ft Sport Cruiser) over here have petrol engines. Above 40ft, diesels predominate.

 

[corkonian1]

Anyone know if volkswagen beetle engine was ever fitted to a boat.
This was air cooled, with a large blower attached and the gearbox
was attached below the engine

 

[johmal]

As an aside - I fitted a new gas detector in my boat, and noticed the instructions indicated that the detector would also detect petrol vapour!

A detector would provide thus provide that extra element of safety.

I also wondered how many of the diesel brigade stow small outboards and petrol cans in their boat lockers?

John M

 

[charles_reed]

I'd suggest the safety aspect of petrol vs diesel is a red herring.

More important is the range you can get for your tankage - diesel will give you x3 the distance that you'll get for petrol.

An additional distortion, found only in the UK and Eire, is that marine diesel has a much lower Excise duty than petrol - this doesn't exist elsewhere - and is only significant for power boaters.

On the other hand, petrol gives you a far better power/weight ratio, at the increased likelihood of of ignition problems - though that has been considerably reduced with modern encapsulation techniques.

It's a case surely, of taking your pick, lightweight, better power/weight ratio, lower prime cost against shorter life, smaller range, less reliability.
I'd stick with diesel, but for racing sailboats and high-performance powerboats I'd see petrol as being the more desirable.