MerCruiser D1.7L TDI

sasa · 01 July 2001, 10:40

What is your opinion on this new small diesel from MerCruiser?

Our next RIB is going to be in 6.5m - 7m range and until now we only looked at outboards as we considered inboards (especially diesel) to be too expensive.
But, that has changed as this new diesel inboard is less expensive than some of the outboards we were considering!

It weighs some 300 kg including Alpha sterndrive, so it is somewhat heavier than a single outboard. Still, this shouldn't be too much for a 6.5m RIB.

I read a test of Askeladden 645 Beetle powered by this engine. The boat weighs some 1500 kg with this engine and tops 32 knots. More interesting is the fuel consumption at cruise speed of 23 knots - only 0.65 l/nautical mile.

Do you think this engine could be installed in Ribcraft 6.5 or Ribtec 655? What kind of performance could I expect in that case? I'm not interested in racing so top speed is of no concern. However, cruising speed of around 30 knots is desirable.

Regards,

Sasa

LamacqS · 02 July 2001, 15:02

I think that 30knot cruising speed would be a bit optimistic. They recommend 230hp on the 6.8m if you want to cruise at 30knots.

Some of the earlier comments I have heard about the MerCruiser does make it sound an attractive option.

For those lucker soles who have the cash, could these engines provide a viable twin installation option on the 7.8m?

Prehaps Jace could comment??

John Kennett · 02 July 2001, 18:59

Sasa

Get in touch with Lee Fairweather at Fairweather Marine. They had a demo boat with this engine at RIBEX, and he reckons that it had a top speed of 50 mile per hour!

Fairweather Marine
43 Old Gosport Road
Fareham
Hants, PO16 OXH
Phone: 01329 823927
Fax: 01329 232459
E-mail: info@fairweathermarine.co.uk

John

------------------
John Kennett
RIBnet

nickfarmer · 06 July 2001, 17:04

I am pleased to say that I have just bought a 7.0 metre Ocean Extreme with this engine. On sea trials a couple of weeks ago it managed 42 knots and reportedly drank just 1.5 gallons/hour during the entire test. I've just got it in the water and hope to be doing great things with it on the south coast later this month.
Nick

nickfarmer · 06 July 2001, 17:15

Sasa,

In fact I have just seen on your photo page that you include a picture of my boat..the black Humber inboard.

I've had extra jockey seats put in, changed the design of the seat backs and a couple of other goodies as well.

Nick

sasa · 08 July 2001, 10:21

Thanks for your comments, guys. This engine is definitely interesting, and worth further investigation. I'll contact Lee Fairweather to hear his opinion.

Nick, keep us informed about your boat and what you think about the combination engine/boat. Send us a picture if you have.

I'll let you know when I find out more.

Sasa

nickfarmer · 14 July 2001, 08:55

I'll let you know how it goes...and I would be very interested to hear coverage on the engine that you might get.
Nick

sasa · 26 August 2001, 19:13

A bit more info on this engine. I still haven't spoken with Lee Fairweather, but I found another test in the Swedish magazine Båtnytt. They compared the MerCruiser D1.7L TDI with MerCruiser 3.0L (gasoline, 135 hk, 296 kg including Alpha 1 stern drive). The test boat was an Örnvik 610 MC (image enclosed). The boat is 6.1 x 2.25 m, weighs 800 kg without engine. The tests werre conducted with 2 persons and 100 l of fuel, resulting in total boat weight of 1500 kg.

The results are (D1.7L in green).

Speed [knots]:
WOT: 30.0 34.0
WOT - 300 RPM: 27.8 31.8
WOT - 600 RPM: 25.2 28.0
WOT - 900 RPM: 22.7 24.8
WOT - 1200 RPM: 20.0 22.0

Fuel consumption [litres/nautical mile]:
WOT: 1.31 0.93
WOT - 300 RPM: 1.14 0.79
WOT - 600 RPM: 1.12 0.73
WOT - 900 RPM: 1.11 0.72
WOT - 1200 RPM: 1.14 0.70

These are just the most interesting numbers. If you are interesed in more details let me know and I'll post them. The magazine concluded that the diesel beats the gasoline overall, despite the higher price (SEK 134900.00 against SEK 72500.00).

I guess that a similar performance could be expected from a 6.5 m RIB.

Sasa

Alan Mckewan · 26 August 2001, 21:50

I've been wondereing about this engine for my next RIB. What does it cost in sterling? Can it be bought for home installation or do Mercruiser insist on "their" installers for warranty cover? 300Kg is still a fair weight for a smaller rib, does anyone sell a much lighter inboard rig?

nickfarmer · 29 August 2001, 09:29

Alan,

The Mercruiser is about £9986 (I think that's including VAT) + of course you get all the other extras added on for fixing it in the boat, unless you were going to do it yourself?

I think that my boat weighs in at around the 1 1/2 tonne mark and that's a 7.0 metre with 4 jockeys and a bench seat in front of the console.

The torque on this engine is just incredible. I haven't timed it getting up onto the plane, but it knocks you back into your seat.

I've done quite a few miles in the boat now and the fuel gauge has barely moved! I just can't speak too highly of it.

If you want to speak to a boat builder try Andy Roffee at Humber Inflatable Boats. tel: 01482 226 100. He's the guy that I did the business with and he thinks the engine is the business too.

Best wishes,
Nick

sasa · 29 August 2001, 19:26

Hi Nick,

Good to hear that you are happy with the engine! Your RIB is rather large and it's encouraging to see that the small MerCruiser diesel is capable of pushing it!

Alan, I don't think you'll find any lighter inboard. This is as light as it gets, gasoline engines weighing roughly the same.

Staying with inboards, what is the general opinion on diesel vs. gasoline? Say that I can't afford a diesel, so I have to choose between a gasoline inboard and an outboard. Is the inboard a better choice? Seaworthiness and safety are of main concern here. Still assuming we are talking about a 6.5 m - 7m RIB.
Sasa

nickfarmer · 30 August 2001, 10:15

Hi Sasa,

I just love filling up with red diesel at 34 pence per litre (minus marina discount) and then seeing a simialr size RIB fill up with petrol at something like 90 pence per litre.

I'm not sure that I would enjoy going out quite so much if I had to pay such a high price for fuel.

I saw a guy fill up his 'gin palace' the other day and he looked like he was almost in tears at the bill. He was only going around the Isle of Wight and it was going to cost him £100's to do it.

Yep I love my diesel....

nickfarmer · 01 September 2001, 08:36

Sasa and Alan.

Just to prove how good this engine is.........I filled up yesterday and put a total of 16 1/2 gallons of red diesel in at a cost of about £23.

That equated to just over 17 hours of boating.

This was a combination of slow (4-8 knot and about 4 miles or so) through harbour restrictions and anything up to 30 knots out on the big stuff. Weather has generally been 3-5 with some big stuff over the Chichester Bar.

If I had filled up with petrol that would have cost about £71

Even with the extra cost of purchasing a diesel over a petrol engine, when you look at these figures it would pay for itself in no time at all.

Nick

batfalcon · 04 September 2001, 18:24

In Greece even though we are in the same EC petrol has similar price as diesel. It is a little more expensive but no way like in UK.
Even worse, only proffesional boats are allowed to use diesel. In other words NO ribs.

Michael

Charles · 04 September 2001, 18:56

The big drawback obviously is performance! You simply do not get the same low-end torque with diesel when attempting to pull someone' out the hole' - particularly with mono-skiing!
Comments??

batfalcon · 04 September 2001, 19:04

I think that the low end torque has nothing to do with the skier pulling. What you need there isn't torque. You need immediate response to the throtle. That's what you haven't got with diesel.

Michael

nickfarmer · 05 September 2001, 07:50

Well all I can say is that I think my boat would pull your arms right out of their sockets if you wanted immediate acceleration chaps.

It may not be quite as quick as a petrol outboard but it will do the same job, longer and more cheaply.

batfalcon · 05 September 2001, 08:27

I can't agree more with you. And more reliable too !!

Michael

Charles · 06 September 2001, 18:04

Thanks guys ...... I am totally confused now!
A 8.1m - 8.5 m RIB used for long and short range (fast) cruising, water-skiing and general pottering - what sort of diesel engine and set-up would you recommend?
We were going to hang an Optimax 225 off the back!
Please advise!

John Kennett · 06 September 2001, 19:09

I reckon that an outboard would be better for waterskiing. It was your comment about torque that got people arguing!

Diesels have bags of torque, and will pull like a train once they get going, but as Michael said it's the immediate response that only an outboard will give you.

I suspect that with petrol cheaper than water where you are you'll go for the outboard in the end, but a Yamaha 240 or Yanmar 300 would both do well in a boat the size you are looking at.

John