MPG 150 HP Evinrude and 6 m Rib

[Jon H]

Very general question but if I was messing around for say 4 hours in a 6 M rib with 150 HP stroke how much fuel woudl you think was reasonable to use

For me Messing around woudl mean a a lot of speed and some towing

I am about to buy a new boat and I am keen to ensure I dont have to refuel every day so want to get something like the right sized tank

I know this is a bit like "how long is a piece of string" but I am thinking circa 100 litres

Also would a 4 stroke be better from a consumption view point

[Poly]

Originally Posted by Jon H

I am thinking circa 100 litres

sounds more like 4 hours cruising than 4 hours at top speed.

[Mollers]

a 100 litre tank is a bit small. Cruising you'll be using roughly 1ltr per Nm, that''ll give you a workable cruising range of 80-90 miles which is surprisingly little. A good run up the coast and back could put you on the limits of your range. My 6.5 Osprey had a 180ltr tank, my current boat 220.

[RichardB]

Originally Posted by Polwart

sounds more like 4 hours cruising than 4 hours at top speed.

Agreed, my 150hp could easily get through 100l in under 2 hrs at wide open as I'm sure everyone else's would. I get about 25 l/h at 'economy' cruising of around 25-6 kts. So that's 4hrs. Mind you, that's quite a bit of range; 100+nm for a day out.

My own tank is 150l and I'd personally think that is a sensible minimum for a 150hp. Using the usual safety guide of 1/3 out, 1/3 return and 1/3 spare it's really a 100l usable before eating into the 'reserve' margin. However, if you are just bombing around the Solent you probably don't need to be quite so generous on the reserve.

[Hightower]

I doubt you'll get any better than 1lt per mile from an average outboard, more realistic is 1.2 lt per miles at cruising speed. My DI sucks up fuel at the rate of 65 lt per hour at WOT! With my Tank which is 200lt this gives me a workable range of 150 Nmiles to include a 10% margin.

Get the tank size wrong now and you'll regret it forever, so go for the biggest tank you can, you don't have to fill it to the brim every time, but the capacity is there if you need it.

[BogMonster]

I'd second going for the largest tank you can fit. The in console tank on my Humber probably holds about 80L though the fuel gauge is not very accurate (it shows less than there actually is I think/hope!) but the range is really quite restrictive. I carry about 60L of fuel in cans on the boat, but refuelling at sea is a PITA unless it is absolutely flat calm, and I'd much rather have a 150L tank and forget about the cans... mind you my old clunker burns about 1.2L/nm (oh for an Etec ) so that doesn't help. If I ever replace it with something of a similar size I wouldn't go for less than a 150L tank. You can always run a 150L tank with 100L in if you need to cut down on weight, but its hard to do it the other way round

[Tim M]

Originally Posted by Hightower

I doubt you'll get any better than 1lt per mile from an average outboard, more realistic is 1.2 lt per miles at cruising speed. My DI sucks up fuel at the rate of 65 lt per hour at WOT! With my Tank which is 200lt this gives me a workable range of 150 Nmiles to include a 10% margin.

Get the tank size wrong now and you'll regret it forever, so go for the biggest tank you can, you don't have to fill it to the brim every time, but the capacity is there if you need it.

Agreed about the tank size. You don't have to use it, but at least you know its there if you need it.

Consumption depends hugly on how you drive. Used 122l on Revo yesterday(6.5m, 175 Evinrude). Did roughly the same day again today and used about half (drove like a nutcase yesterday and very conservatively today)

[Jon H]

Thats to all of you for the replies

So without doubt I am hearing... get as big as you can

What says you on 4 stoke or 2 stroke in terms of MPG or indeed any other view?

[Chris]

Jon,

I am running a 150HP Etec (2stroke) on the back of a 6.5 I get about .9 litres per mile when crusing at 20-25 knots then at WOT about 54 litres per hour.

If you buy a modern 2 stroke or 4 stroke and ensure it is propped right then you should be able to achieve the same.

[Tim M]

I wouldn't buy another large 2 stroke, simply because buying and filling oil is such a pain.

[Hightower]

I hear Optimax's are good on Fuel, however so is the Suzuki too. I bet the Opti's are cheaper to buy and are lighter too. However don't forget to factor 2 stroke oil into the equation.

[Jon H]

Originally Posted by Chris

Jon,

I am running a 150HP Etec (2stroke) on the back of a 6.5 I get about .9 litres per mile when crusing at 20-25 knots then at WOT about 54 litres per hour.

If you buy a modern 2 stroke or 4 stroke and ensure it is propped right then you should be able to achieve the same.

showing my ignorance but what is WOT ?

[Poly]

Originally Posted by Jon H

showing my ignorance but what is WOT ?

WOT=Wide Open Throttle.

[brucehawsker]

we blast around the Solent and kill 1.1L per NM. I think of 20L per hour. Typical trips in the Solent (including stops) means with a 150L tank I fill up every other 2nd or 3rd trip.

I love the Opti grunt especially in the rough and do not find the oil a pain. Just chuck in a bottle every few weeks. No sweat.

[Ferdi]

Originally Posted by Tim M

I wouldn't buy another large 2 stroke, simply because buying and filling oil is such a pain.

my pain would be the lot more weight on transom of a 4-stroke ;-)

[GED]

Originally Posted by Tim M

I wouldn't buy another large 2 stroke, simply because buying and filling oil is such a pain.

Not as much of a pain in taking your 4 stroke to the dealers every time for an overpriced service

[GED]

On a trip to the Isle Of Man.......


175 etec 6.7 rib
5 and 1/2 hours round trip
sea state 3/4
126 lts used

you can do the maths

[Mollers]

Originally Posted by GED

On a trip to the Isle Of Man.......


175 etec 6.7 rib
5 and 1/2 hours round trip
sea state 3/4
126 lts used

you can do the maths

Can we conclude that Etec's are economical? I've not managed to get my fuel management dialled in and don't really know WTF it's getting through. According to Chris, I need more electronic gizmos.

[bedajim]

Originally Posted by Mollers

Can we conclude that Etec's are economical? I've not managed to get my fuel management dialled in and don't really know WTF it's getting through. According to Chris, I need more electronic gizmos.

You must of got a Friday afternoon one

[Ferdi]

if you look on my website ( www.hobbycaptain.at ) you can see my boat (ZAR53) which is comparable from hull length to a normal 6m RIB which has tubes also behind the transom like most UK Ribs.

I owned a Johnson 140 4-stroke (= Suzuki 140) and changed to an E-TEC 150HO.
I am using almost the same fuel with the E-TEC as I used with the Johnson.

Johnson was about 0,4-0,45 l/km , E-TEC is about 0,45-0,5 l/km at normal cruisiung speed between 3000 and 4000 rpm .
Top Speed improved from 75 km/h to 89 km/h (from 40 to 48 kn) and with E-TEC in average at the same rpm I am always 10 km/h faster than with Johnson. This is the major reason for using a bit little more fuel. At the same speed they consume the same amount of fuel.

I never would change back to a 4-stroke any more, I like jumping into plane :-) .


PS: fuel usage is minimum 0,4 l/km with just planing and 2700 rpm (still stratified load) , about 0,5 l/km between 3500 and 4000 rpm (normal cruising speed at about 50 - 60 km/h (27-32 kn) and 0,70 l/km at WOT (89 km/h = 48 kn at 5600 rpm) .
All data recorded with Lowrance 7200C and NMEA2000 engine kit and Navman Powerfuel3100.