Mercruiser 120 hp 1.7L Sterndrive

Powerboat · 20 June 2003, 15:11

Hi folks ,

Has anyone owned one of these or used one regularly?

I drove one briefly at Southampton two years ago and was quite impressed.

I am thinking of fitting out a new training boat with one as more and more of our cruising and Pro clients are using sterndrives lately.

Best wishes,

Stuart

Jelly · 20 June 2003, 15:23

Stuart
I think Andre and Mike C have them in their respective boats.
I was impressed by their engines on the ribnet Plymouth meet.
Jelly

Andre · 20 June 2003, 15:56

Stuart

Perfect engine for sure

This is the engine I have on my Parker 630 rib. Probably the best inboard engine for a rib of that size. The leg is the Alpha One and the prop which I have is a stainless steel 21" pitch Laser II .

Just to give you an example of fuel consumption from my last cruise.

I left the Nab Tower with a full tank and covered a distance of 66 miles to Cherbourg at a cruising speed of 24/26 knots. ( 2 persons on board, no wind and no waves ideal weather conditions ) This took us 3 hours. Upon arrival to Cherbourg my first priority was to top up with fuel. I put in 46 liters so at say 0.32 pence a liter that is £14.72 (not much petrol you will get for that)
About 15 liters an hour

At lower speeds you will find that the fuel consumption can be about 8/9 liters an hour

The engine is actually the 4 cylinder 1.7L Isuzu which you can find in the new Astra diesel cars. The engine is made in a brand new Isuzu engine plant in Poland and marinized exclusively for Marine Power in Belgium (Mercury). Not many people know that

Andre

Garygee · 20 June 2003, 17:16

Not a 1.7TD but the Yanmar 240HP 4LHZ-STZP and a 7.8M Ribcraft (not the lightest of boats)

Milford Haven to Pwllheli again flat calm, steady 2700RPM and 25Kts. Took only 90L of fuel for the 105 miles trip. Thats less then 1L per mile!!

Know the 120Hp 1.7TD is good on fuel but was suprised that the Yanmar 240 delivered such good fuel economy.

Regards Gary

Andre · 20 June 2003, 19:01

Gary

Twice the HP and nearly twice the fuel consumption. That Yanmar would be too powerful for a 630 rib

My top speed is only about 32/33 knots but I am not complaining

Andre

Garygee · 20 June 2003, 22:22

Andre

You can never have TOO MUCH POWER

Well at least till you have to fill up and pay the fuel bill

.

A lot less then double though
66miles on 46L = 0.696L/mile
105 miles on 90L= 0.857/Mile

However at 2700rpm I was running at well below WOT.

Think the 1.7TD is great for 6 to 6.5M class ribs and at not much more cost then a outboard, just would not push a 7.8 though.
We looked at one when we was considering the 7.0M Humber.

However I have often though if it would be possible to fit two in a 7.8 though, which would be great as a twin instalation and not much more cost then a single 240HP & Bravo drive.

Dont know if it would be possible but a interesting thought.

Regards Gary

Andre · 20 June 2003, 22:50

Gary

your figures are quite correct. I just made a quick guess.

as for twin Mercruiser 1.7L in a 7+ rib then yes interesting .
We have thought about it too

but for single installation then yes you right 6.0 - 6.5 is really the most suitable range

Regards

Andre

Mike C · 21 June 2003, 13:03

Hi all.......

I'll echo the above comments. It's great on fuel consumption; the only drawback is the top speed, which unlike Andre, I would like a bit more of.... but something has to give.

Like Andre, the best top speed I've ever had is 32 knots, (on the GPS - not much tide though!) A nice cruising speed is around 23 knots which with my set up, (23" Ali prop) is about 3,400 revs.

On the fuel side.....

For mixed cruising, (bits of slow harbour and bits of fast) I travel one mile on about 0.65 of a litre. That works out to be about 10 litres per hour (or about 2.2 gallons per hour).

For the constant 'high' speed run to France last weekend it used a bit more fuel. I used 55 litres from Northney Marina to Cherbourg, (75 miles approx).... but we also played around for about half an hour, taking some photos at NAB Tower on the way! Ignoring that and being generous on the 'we actually probably used less side', that works out at 15 litres per hour, (3.3 gallons per hour) or about 0.73 litres per mile.

I know they say it's not worth buying a diesel unless you use it a lot but to put it in perspective, the last time I went to Cherbourg, (from Poole - not quite so far), I used 100 litres of petrol each way, (Twin 60 two strokes on a 5.85 Ribcraft). Return cost for that at road fuel priced petrol, (200 litres x 75p) was £150.
Last weekend, at an over generous 110 litres return, at red diesel prices of 30p = £33

You could even eat at the Restaurant de Fuchsia with that saving!

Mike C

Mike C · 30 June 2003, 11:36

Hi all,

For those fuel consumption addicts around, here is an update on the amount of fuel my Mercruiser 1.7 used on my recent trip to Cherbourg. Whilst in my last post I was sure about the amount of fuel it took to re-fill the tank at Cherbourg, I was estimating the mileage and hours. I have now downloaded my track for that day from the GPS, (Had a software problem before), and now have super accurate figures!

According to the GPS, I left the pontoon at Northney Marina at 09:59:37 and switched off the engine at the Cherbourg fuel pontoon, (where 55 litres filled the tank back to the brim), at 14:41:53. The total mileage recorded on the GPS for the leg, (including about an hour zipping around taking photos at NAB Tower on route) was 82 Nautical miles

So, that alters the figures as follows….

Litres per hour = 55litres / 4.68 hours = 11.75 LPH or (2.59 Gallons per hour)

Litres per Mile = 55litres / 82 miles = 0.67 LPM or (1.49 Miles per litre) or (6.78 Miles per Gallon)

(All Nautical miles and Imperial gallons)

This actually ties in more with my past estimates and is more accurate, so ignore my previous post! Also, remember it was a flat calm day so no 'up hill' travelling - undoubtedly I would have used more had it been rough!

Mike C

Bonnet · 15 December 2007, 00:58

Can't say that I have, but I have worked with a lot of them. My brother is real into it.

nik · 23 December 2007, 17:41

I seemed to have missed this thread till now.
I have a humber 6.5 ocean extreme aka ocean pro, with the 1.7 mercruiser.
I get roughly 0.7 of a litre to a nautical mile.
Nick.

Biggles · 23 December 2007, 22:49

Quote:

Originally Posted by nik

I seemed to have missed this thread till now.
I have a humber 6.5 ocean extreme aka ocean pro, with the 1.7 mercruiser.
I get roughly 0.7 of a litre to a nautical mile.
Nick.

And it goes incredibly fast for a 1.7 diesel.

My 2.2L 140 HP Outboard on a smaller boat is on a par with Niks 1.7 diesel.

nik · 24 December 2007, 09:52

Code:

And it goes incredibly fast for a 1.7 diesel.

Thank you Biggles.
I havnt been out as much as I would like, up to my ears in house renovation. But I should be out over the next couple of weeks.

Nick.

Cookee · 27 December 2007, 11:14

Quote:

Originally Posted by Powerboat

Hi folks ,

Has anyone owned one of these or used one regularly?

I drove one briefly at Southampton two years ago and was quite impressed.

I am thinking of fitting out a new training boat with one as more and more of our cruising and Pro clients are using sterndrives lately.

Best wishes,

Stuart

We have the same unit with a jet drive fitted to one of our 6 metre boats as a demonstrator - it's economical and the jet is a lot of fun - we also offer the stern drive option as well as the new Mercruiser Vazer which is a 100hp inboard petrol