Fuel consumption from a 225 - 250 hp 4 stroke outboard

Brian Dinsley · 28 May 2007, 10:42

I am planning to buy a RIB later this year, probably during the winter months. I have priced up a new 6.3 metre outfit with a Honda BF150. With electronics and trailer, I'm looking at around the 30 grand mark. However, I've spotted a few nice used RIB in the 6.8 metre+ range, usually fitted with 225 to 250 HP 4 stroke outboards. Buying one of these would initially be a substantial saving over a new 6.3 metre outfit and would come with other equipment, such as anchors etc, which makes me wonder whether I wouldn't be better off buying a bigger (and better???) used boat. Problem is, I need to know just how bad is the fuel consumption going to be?

I'll be using the boat for family cruising, fishing and diving with mates. Could anyone advise whether a day out with a 6.8m & 250 hp motor is likely to be a hugely costly affair, and what sort of fuel consumption I could realistically expect to see.

Thanks

Brian

Milo72 · 28 May 2007, 16:07

I run a suzuki 250 on a ribcraft 7.5m when estimating fuel I worked on 8-9g/h at full ahead and 4-5 g/h as an average just gently running about [cruising/skiing etc] I now have a FLOSCAN meter fitted which is excellent, very accurate. at full ahead it uses 44 L/H, but at 45kts you can cover a lot of ground!

codprawn · 28 May 2007, 17:21

Quote:

Originally Posted by Milo72

I run a suzuki 250 on a ribcraft 7.5m when estimating fuel I worked on 8-9g/h at full ahead and 4-5 g/h as an average just gently running about [cruising/skiing etc] I now have a FLOSCAN meter fitted which is excellent, very accurate. at full ahead it uses 44 L/H, but at 45kts you can cover a lot of ground!

How accurate is that? Someone on here has just reported 85l/h with a Suzuki 300hp - it can't be THAT much different for 250 can it???

If so you could have 2x 250 for the same consumption as a single 300 - doesn't make sense to me!!!

Brian Dinsley · 29 May 2007, 13:53

Quote:

Originally Posted by Milo72

I run a suzuki 250 on a ribcraft 7.5m when estimating fuel I worked on 8-9g/h at full ahead and 4-5 g/h as an average just gently running about [cruising/skiing etc] I now have a FLOSCAN meter fitted which is excellent, very accurate. at full ahead it uses 44 L/H, but at 45kts you can cover a lot of ground!

Hi Milo72

I've seen your boat and it does look nice. I've checked other threads, and there seems that different users get a broad range of fuel consumption on a boat/ engine combo of this size. As Codprawn quotes, it seems that some engines typically burn 85 ish lites per hour

I'd like a boat of that size, but this sort of consumption could mean that a days boating could cost 300 quid!!! I would be running at cruising speed most of the time, so hopefully consumption wouldn't be up in the dizzy 80's, but even at 50 litres per hour, a day out could be more than 200 quid. Last RIB I owned was a 5.1 metre Tornado with 60 HP Yamaha 2 stroker. A different animal.... I think.

Anyone else have typical fuel consumption figures for a 6.8 M+ rib with 225 to 250 hp 4 stroke??

Thanks everyone...

Milo72 · 31 May 2007, 20:13

It's not that bad... don't fear the 250...! If I'm out all day [5-6hrs] and working the throttle hard, I reckon on using no more than 130lts.
taking into consideration that it's not 5-6hrs constantly flat out of course, but most of the time she's running at above 4krpm
last summer I was out for 4hrs skiing with a family, the kids wanted to blast about, 6 skied, just a family day on the water. 45lts.

I honestly don't think you'll be disappointed.

behavin · 01 June 2007, 08:34

i have the df250 (now fixed..!! see electrics) and i get 25-30 litres/hour on the flowscan at 28 knots which i think is pretty good.

when you crack the laughing stick though the needle reads 75-80 litre/hour which gives 48 knots on a 6.8 ribcraft.

I had loads of ribbing about getting such a large engine with ref to fuel consumption but this one is better than my old delta with twin 65's.

simmons0 · 01 June 2007, 12:43

Milo I can't help but think your figures are optimistic.
You can't spend 4 hours water skiing on 45 litres of fuel. I'd expect ours to use more than that, skiing drinks it.

I've been on a lot of boats with 200hp+ outboards and they all seem to use more like 70l/h WOT and about 30l/h at a 30knt cruise.
H

codprawn · 01 June 2007, 12:59

Seeing these figures makes me realise my "old" 2 stroke efi isn't so bad after all. I use about 85lh flat out and about 25-30 crusing. The fuel injection and twin spark must be helping quite a bit.

Ferdi · 01 June 2007, 13:34

Quote:

Originally Posted by Milo72

I run a suzuki 250 on a ribcraft 7.5m when estimating fuel I worked on 8-9g/h at full ahead and 4-5 g/h as an average just gently running about [cruising/skiing etc] I now have a FLOSCAN meter fitted which is excellent, very accurate. at full ahead it uses 44 L/H, but at 45kts you can cover a lot of ground!

let me doubt a little about the 44 l/h with a 250 HP engine.
my Johnson 140 ( = Suzuki 140) 4-Stroke uses 45 l/h at WOT and high revs.

Mollers · 01 June 2007, 13:47

Quote:

Originally Posted by behavin

i have the df250 (now fixed..!! see electrics) and i get 25-30 litres/hour on the flowscan at 28 knots which i think is pretty good.

when you crack the laughing stick though the needle reads 75-80 litre/hour which gives 48 knots on a 6.8 ribcraft.

I had loads of ribbing about getting such a large engine with ref to fuel consumption but this one is better than my old delta with twin 65's.

Bearing in mind the cost of 'go go juice' over there it's an important factor. I've short-listed the DF250 for next time. Let's hope the 'lecky' problems aren't going to be an issue. Roy's DF140 has recently been re-loomed.

Roy Smith · 02 June 2007, 00:01

I have had Yamaha 225 & 250 F/Strokes and if you abuse the throttle its
2 lts a n/mile taking thing a bit less frantic will get you about 1-1/4 to 1-1/2
lts a N/mile i have checked it loads of time. Big engine big fuel bill no way round it. Its all relevant

Milo72 · 03 June 2007, 00:03

Quote:

Originally Posted by simmons0

Milo I can't help but think your figures are optimistic.
You can't spend 4 hours water skiing on 45 litres of fuel. I'd expect ours to use more than that, skiing drinks it.

I've been on a lot of boats with 200hp+ outboards and they all seem to use more like 70l/h WOT and about 30l/h at a 30knt cruise.
H

Don't doubt me... doubt the Floscan and Mr Morrisons delivery pumps! both of which I find rather accurate.

I was a general days skiing and boating. Some resting, some WOT, some gentle running. Not all of the 4hrs was spent at 30kts.

The trick to an economical days skiing is not to get heavy with the throttle between pulls. Towing at a steady 25kts and returning steadily to the skier rather that leaning on the stick makes a HUGE difference to the days fuel consumpion.

I now have the Suzuki COMMANDER gauges, made by Faria, it will be intersting to see how accurate they are.

codprawn · 03 June 2007, 01:10

I am not doubting your crusing figures but the WOT figures are pretty hard to believe. What sort of speed and revs are you doing???

Milo72 · 05 June 2007, 07:02

On the Floscan, the immediate 'needle' reading at WOT would show 70l/h however, the 'fuel used' counter and on re filling at the pumps, it would equate to 45l/h.

Have to admit I'm strugging with the Commander gauges at the mo.... I can get the flo/used/trip fuel reading to say ANYTHING at all! must find the distruction booklet....

codprawn · 05 June 2007, 12:06

Quote:

Originally Posted by Milo72

On the Floscan, the immediate 'needle' reading at WOT would show 70l/h however, the 'fuel used' counter and on re filling at the pumps, it would equate to 45l/h.

Have to admit I'm strugging with the Commander gauges at the mo.... I can get the flo/used/trip fuel reading to say ANYTHING at all! must find the distruction booklet....

70lh it is then - makes much more sense - obviously fuel used when you refill is for the whole trip unless you go straight to WOT after launch!!!

Brian Dinsley · 07 June 2007, 12:43

Thanks for the input guys.... I think I'd have real difficulty refraining from pushing that "laughing stick" and so I guess 300 quid boating days would be a distinct possibility!!

I think I need to put my sensible hat back on and take another look at the humble 6.3metre/ 150 HP family outfit....

All the best.....

Brian

Hugh Jardon · 07 June 2007, 13:48

Quote:

Originally Posted by Brian Dinsley

Thanks for the input guys.... I think I'd have real difficulty refraining from pushing that "laughing stick" and so I guess 300 quid boating days would be a distinct possibility!!

I think I need to put my sensible hat back on and take another look at the humble 6.3metre/ 150 HP family outfit....

All the best.....

Brian

dont get too hung up on the wot fuel consumption figures, i have a 6.5 with a 200 opti and that returns on average around 1litre/mile, and that is a mixture of slow and fast and mucking about.

when i first looked at engines and the fuel they can use a wot i scared myself but in reality you use far less fuel as you can spend much less time at wot.

i would be surprised if you are spending 300 a day on fuel.

we can go out for the day, round a few places, round the iow and still use far less than £100 for the day