Petrol v. Diesel

[Chris Murray]

I know that diesel is likely to go up to something approaching road prices but my 3 litre diesel car goes a jolly site further on a gallon of diesel than an equivalent car running petrol. Typically, its about 26 mpg diesel and I believe it is something like 17mpg petrol. It weighs about 2.25 tonnes.

With this in mind, has anyone experience of the MPG for a 240hp diesel Yamaha in an 8mtr or 8.5mtr boat? What is the performance like?

I would consider the 315 Yanmar (as opposed to Yamaha) but I understand that the Bravo 3's that they mate them with keep falling apart. Actually, an MPG for this would be good too. Just in case they find a sterndrive that works reliably with it!

Cheers!

Chris.

[craig_c]

Hi, ive got the yamaha 165hp diesal in my 7.4 redbay and it does around 300miles for £60. it weighs 2 tons so i think thats pretty economical

[JIY]

Hi Chris,

I've got the 250hp Yanmar coupled to the Bravo3X leg on my 8.5m Tornado. Fully fuelled (200 litres) and four on board, it weighs in at a little over 2 tonnes. I work my fuel calculations on 1 litre/nautical mile - that allows for rough water and some tacking round larger waves.

My usual consumption in reasonable conditions (wind force 3/4 or less over a large fetch) is about 5.5 gallons/hour cruising at 32 knots (thats at 3000 revs - max revs are 3700 which gives 42 knots, but burns about 7.5 gph).

I chose the 250 Yanmar, because it gave me the smooth 6 cylinder engine (the 240 is 4 cylinder), without going for the 300hp (now 315hp), which anecdotally seemed to be breaking the Bravo3 legs.

Hope this is useful info.

Jim

[Alan]

Louise is clearly sleeping on the job so I will do this on her behalf

Which is best: petrol engine or diesel engine?

[Chris Murray]

Thanks everyone for your input.

One issue I read about somewhere (might have been the RYA site) is that when red diesel eventually goes, whether 31/12/06 or later, there could be a problem getting ordinary diesel alongside.

Worse, until the price changes, diesel engines are being sold at a premium in the UK. This means that I could pay over the odds for an engine, and then a year later find fuel difficult to locate. Mind you, as I shall be towing, I guess that this should not be too much of a problem.

If I knew that I could get red for say 5 more years, then I would have to seriously consider this type of engine. However, there doesn't seem much to choose from at the moment, with Yanmar routinely breaking Bravo 3 legs and no other suitable engine/drive option without buying Volvo, which probably work more reliably but are even more expensive!

Regards,

Chris.

[Richard B]

The bigger problem with the Yanmar 300/315 24-valve engine is not the Bravo leg failures, but the engine block failure where one of the engine mounts is close to an internal oil gallery. Barrus themselves are confused about their own supplied modifications, but all the different "braces" which are supplied are a workaround rather than cure. I'm told that Mark Pascoe had a proper solution which involved re-locating some of the externally mounted components so that the engine mount could be fitted in the same position as the Yamaha 240 12-valve engine, which doesn't suffer from this problem.

If you're interested in a Volvo engined RIB, Paul Lemmer is brokering a superb 2-yr old Ocean 8.5m powered by a 300hp KAD42 duoprop, full electronics, radar, trailer, £45,000

[gavin]

I dont drust diesel outdrives, unless they are Yamaha, Bravo failures are far too common, I respect not to the extent with 240hp, and we all agree its torque not hp, that kill them, but out at sea you must have reliability, ifts not Hydra drive its too risky.

[jwalker]

Originally Posted by Richard B

....If you're interested in a Volvo engined RIB, Paul Lemmer is brokering a superb 2-yr old Ocean 8.5m powered by a 300hp KAD42 duoprop, full electronics, radar, trailer, £45,000

Yeh, I noticed that too. Pity a KAD42 doesn't give anything like 300hp.

[Richard B]

What's their output?

[jwalker]

Originally Posted by gavin

.... ifts not Hydra drive its too risky.

You can't 'arf talk some pish, Gav.