Can't be right... can it?

[richrich123]

Can\'t be right... can it?

I have just contacted a chap who is selling a 2003 Regal 1800 lsr which has a 1.7dti turbo diesel mercruiser engine, mercruiser alpha 1 outdrive.

Regal LSR

I asked what the fuel economy was like and was told:

"Simply amazing, I used just £10 going from Brighton to the Isle of Wight, around it then back! Due to red diesel only costing 39p per litre and the unbelievable economy, I would think that the 3L Mercruise petrol would cost 10x that for the same trip!!"

From other information I have been told on this site about engines and fuel usage, this can't be right, can it? Even using red diesel at 39p a litre.

Brighton to the IOW is about 40 miles each way and I think the IOW is about 60 miles to go right round so this would be about 140 miles in all..

If red diesel is 39p a litre then £10.00 would buy 25 litres/5.5 gallons. From what other users on here have told me, a diesel engine uses about 2-3 gallons per hour (at 20 mph) so even going carefully at 20 mph, 5.5 gallons is only going to last for 2 hours which 2 hours at 20mph is only going to carry you 40 miles...

Does it appear this guy is lying blatently about what this boat will do?

 

[landlockedpirate]

Re: Can\'t be right... can it?

This combination is good, but not that good! /forums/images/graemlins/laugh.gif


Theres a couple of formites with that engine, I'm sure they will be along soon to give you real figures.

 

[TRH]

Re: Can\'t be right... can it?

He should do well telling bed time stories, /forums/images/graemlins/laugh.gif

 

[DoubleVision]

Re: Can\'t be right... can it?

I would say that is a somewhat optimistic estimate of the fuel consumption of this engine. The 1.7 dti is no doubt a very economical unit but if thats all they use i`m going to install 4 of them in mine this winter /forums/images/graemlins/laugh.gif

 

[Ifraser]

Re: Can\'t be right... can it?

The 1.7 dti is reputedly very economical...which is good cos I'm just fitting 2 of them!! but I feel your seller is stretching the point a little too far on those figures. The fuel consumption curves that I have ( and you can find on the mercruiser web site ) gives it at 14.4 litres / hour at 3600rpm which would probably be close to 20 knots giving under 2 hours at that rate so less than 40 miles.
Having said all that at 2200 rpm which appears to be max torque it is 6.1 litres / hour so if his boat is quite light and he can cruise at 2200 rpm then maybe....would be nice to know what RPM he reckons he runs at... I would still suspect that at the very least he's stretching a point to sell his boat. However I really hope he's right cos then I'll be spending a lot less on fuel than I thought when I finally get the boat back in the water.... hope the ramble above helps a little cheers Iain

 

[BrendanS]

Re: Can\'t be right... can it?

I don't have personal experience, but the 1800LSR has a very efficient stepped hull, which does reduce fuel consumption.

 

[DAVIDO]

Re: Can\'t be right... can it?

He might not be lying intentionally he might be assuming a boat fuel guage is accurate.

 

[Andrew_Fanner]

Re: Can\'t be right... can it?

Blow the rest of it, where is he getting red at 39ppl?

 

[richrich123]

Re: Can\'t be right... can it?

Thanks Ifraser, that is really helpful. Maybe he is stretching it a little but I guess if you can make progress at 2200 rpm and get 6.1 litres an hour and the boat is light and has an efficient hull then maybe he is not miles out.

I would really appreciate any one who has this engine to let me know what kind of economy it can produce.

Many thanks

 

[alt]

Re: Can\'t be right... can it?

I had one of these fitted to a Panther 19SC (Weighed in at 1200KG all in)

At 3800RPM, 25-27MPH I was using about 23 liters on a 25 mile trip.

Hope this helps. I ended up selling the boat as the many issues associated with this engine worried me (Mainly wastegate failure - Though in theory the wastegate shouldnt ever need to be used if engine is never laboured)

 

[richrich123]

Re: Can\'t be right... can it?

Now I am really confused...

As Ifraser points out, the mercruiser websites official figures for the 1.7 dti say that it uses 14.4 litres / hour at 3600rpm which would be about 25-30mph

If Niall has got 25 miles (at 25 mph) and used 23 litres that means he has burnt 23 litres an hour - I can't believe an economical engince being driven sensibly could possibly burn 23 litres of fuel in only 1 hour and having only covered 25 miles.

Nial, could your engine have been having some issues ??

 

[gerbil]

Re: Can\'t be right... can it?

No experience of this engine and too tired to do the maths but......

I think Dave_Simmons on this forum has a Regal 18ft with that engine so try PM him and see what his experience has been blatting round Poole / Studland etc

Also there is a Yahoo group for this engine that might have info :
http://groups.yahoo.com/group/cummins_mercruiser_120hp_DTI/

and here is a link to some info on taking care of the turbo on this engine ! :

http://rib.net/forum/showthread.php?t=19433

Cheers

Dave

 

[BrendanS]

Re: Can\'t be right... can it?

If it helps any, I have a 2150LSR with 4.3 litre mercruiser petrol. I cruise at 28knts and use 1 litre per nautical mile

 

[richrich123]

Re: Can\'t be right... can it?

thanks gerbil, that is really helpfull, will have a look through them. Thanks

 

[Renegade_Master]

Re: Can\'t be right... can it?

think you'll find from my memory anyways (someone may correct me) IOW is a bit further than 40nm from Brighton?

 

[lovezoo]

Re: Can\'t be right... can it?

On my Fletcher 19GTS with a petrol 4.3V6 I am getting around 1 mile per litre, so Niall's experience with his diesel doesn't sound right. Also I've had a look at the ad for the Regal and the vendor is claiming a top speed of 40MPH, which is high for a 120HP boat. So unless he has some very efficient prop on the boat which gives him such good performance, I would take his claims with a pinch of salt.

Maybe ask him what prop he has on the boat (type, number of blades and pitch)?

 

[Chas25]

Re: Can\'t be right... can it?

A few years ago I actually sea trialed this combination.

From memory it did actaully hit 40 although more than likely on the speedo rather than GPS.

I suspect the reason would be it could handle a larger prop compared to say the 3.0l petrol reason being the increased torque of the diesel, by comparison I actually bought a Searay 18ft BR with 3.0l petrol and (again on the speedo) it would top out around 43 I also have a feeling the speedo's are in MPH...

I have also owned a boat (albeit a bit bigger) with that engine, it is extreamly frugle although I have to say £10 for what has to be at the very least 5 hours of cruising is pushing it somewhat! At current fuel prices I would assuming around £5-£10 per hour depending on usage.

 

[duncan]

Re: Can\'t be right... can it?

agreed - Niall's figures are no more realistic than the original quoted!

at the most optomistic, flat sea, wind behind and running light on that hull with that engine you might scrape 2 miles per litre but that's the absolute max.

however in context that is bloody brilliant for a planning boat! anyone managing a mile a litre is usually happy enough once you get over about 18ft.

 

[Fire99]

Re: Can\'t be right... can it?

oh how i dream of figures like that.
My 23ft shetland with an old 5 litre Petrol does more gallons than that does litres. /forums/images/graemlins/frown.gif

 

[alt]

Re: Can\'t be right... can it?

I had my engine under-propped so as to not labour the engine, so less economy there (It beat's a bust turbo)

Also, my boat almost always had full fuel/water and about 4 crew on board, so less economy there again

That may be why I was getting less economy. I actually need to make a correction, the boat was using about 23litres on the 25mile trip at WOT which was 30knots, so that was over 4000RPM. Sorry about that

[ QUOTE ]
Now I am really confused...

As Ifraser points out, the mercruiser websites official figures for the 1.7 dti say that it uses 14.4 litres / hour at 3600rpm which would be about 25-30mph

If Niall has got 25 miles (at 25 mph) and used 23 litres that means he has burnt 23 litres an hour - I can't believe an economical engince being driven sensibly could possibly burn 23 litres of fuel in only 1 hour and having only covered 25 miles.

Nial, could your engine have been having some issues ??

[/ QUOTE ]