How Far Can I Go Fuel Problem

[Daniel TD5]

I have a Vailant Vanguard 450 with a nice new mariner 40hp two stroke
i have been out on a few sub 5m outings now the most was about 75 miles
by gps. most last about five hours when returning to the slip i have checked the fuel and found i would not fill a pint glass with whats left in the tank. so i started to take a 5L fuel can with me as a spare. i went to the dealers to day
and picked up a new seat as my one had come apart it was replaced under the warrenty
i asked the mechanic about the fuel he said just fit a new tank next to the existing 25 litre one he show me were to cut the seat box and the tank
handel so it would fit i now just have to swop the fuel line over when i run out and fit a strap before i go out i now have 50 litre under the seat so how long can i stay out or how far can i go

dan

[Louise]

Originally Posted by Daniel TD5

i have been out on a few sub 5m outings now the most was about 75 miles by gps. most last about five hours ... i asked the mechanic about the fuel he said just fit a new tank next to the existing 25 litre ... i now have 50 litre under the seat so how long can i stay out or how far can i go

Well, you went 75 miles with 25l of fuel. You are now able to carry 2 x 25l of fuel so surely you can go 2 x as far!

2 x 75 = 150 miles.

The advice given above is not to be used for navigational purposes. In other words, please don't sue me if you run out of fuel next time you go out!!

[Tim M]

Well. They say 1l per mile. I'm not sure that totally relates to the Mariner 40hp. I have the same engine as you, and I have to say, I my fuel consumption is pretty poor. Whilst I have no way of measuring distance other than on a chart (not very accurate) I would say that there's no way I could do 75 miles on a 25l tank. I carry a 13l spare just in case, and often end up using it!

[Biggles]

I have a Tohatsu 40 HP 2 Stroke and reckon on average I can get 2 miles to the Litre.

Last week I got caught out in heavy seas and was stuck at about 5 mph. My fuel consumption increased considerably.

I have a 40 litre tank, carry 5 litres spare, and usually cruise for 3 - 4 hours on a trip and cover about 45 miles during that time.

I have a fuel gauge which is always showing low (Thank God), and when I top up I usually need under 25 Litres. Last week I needed 32 Litres. I think mainly due to the bad weather, bad sea state. And also I had a new prop on with a bigger pitch and we had two fatties in the boat.

By the way Daniel where do you go on these jaunts?

Is it down the Thames and if so where do you launch from, is it easy to launch and what is parking like for security etc.

I must admit I fancy a trip down the Thames out to sea sometime.

I take it you can get some good speed up with little to worry about in the way of waves.

[Daniel TD5]

louise

what about when i only do say forty miles but stay out four five hours and still use a full tank going fast the mechanc said ten litre should last one hour
of runing time


i will say it must be about 2 litres a mile give or take in good weather so that good for a small rib over 100 miles

biggles

we go just about all places we can bradwell levington hernebay and poplar
for our thames trips

dan

[Jono]

2 litres/Mile? S**t, I thought my engine was thirsty at 1.8 litres/Mile....

[Biggles]

Thats 2 Miles per Litre
Not 2 Litres per Mile

[swginn]

Daniel, I presume you mean 2 miles/litre and not 2 litres/mile- yep Biggles got there b4 me. On our last valiant, we had the same setup as you (fuel wise) with 2 x 25l tanks under the jockey console with a 75 mercury(2 stroke). We also carried a small 5l tank under the bench. The one thing about the older tech (non-direct injection) 2-stroke engines is that they can be quite unpredictable as regards fuel consumption. What we did once to check our range was to drive as far as possible, varying the engine speed on one tank and then swapped to the second tank for the way back, we ended up running out of fuel with about 2miles to go (hence the 5l spare!!). We didn't account for tide in our test and this caught us out!! .

You could always beef up the transom and fit a 75hp optimax. You'd get your fuel flow in litres/hour and also how many miles you're getting to the litre and your range taking into account how much fuel you have left. Oh and I almost forgot, plenty of off-boat excursions!!

[Biggles]

At the end of the day what we all have to realise is that we are using two strokes.

We have very high revving and large engines with no gearing running flat out all day.

For instance I have a 500cc engine with no gearing running flat out for 3 hours.

I use about 8 litres per hour.

Nearly 2 gallons in old money.

Or £6.40 per hour.

Cheap if you compare it to any sort of other high fun factor experience, but bloody expensive when you realise that 80% of it, or over £ 5.00 every hour is going to the Government to waste on their stupid policies.

Even for 4 stroke engines its all very expensive. None of the engines have gearing and so will never be very fuel efficient.

For my little two pennies worth I am looking at going for a diesel engine next. I spoke to a guy at East Cowes Marina last week and he was paying 26 pence per litre. He was running a 7 metre Humber with a 1.7 Litre Turbocharged Mercruiser with 160 BHP. Thats got to be the way to go.

Mind you his rig cost £32000 at one year old or £48000 new.

Nick R

Its not a cheap sport.

Basically when you buy a boat (Of any sort) Its something you buy and then just throw money at.

[Hightower]

Yeh but don't forget to factor in the 2 Stroke oil as well!

One advantage of 2 strokes though is to smoke out the 4's and that in it's self is worth the extra money

[Biggles]

And its dead noisy as well. That is guaranteed to annoy everybody and sound dead hard in the process.

Seriously.

I bought my two stroke for simplicity, size and reliability.

That was the two main overriding factors. Fuel costs were a secondary factor.

[roohairy]

Got this from somewhere, have used compared it to several boats and it seems pretty accurate - for a rough guide! It's not new so the 2 stroke figures are for the good old carburetted premix models.

Fuel consumption

2 stroke outboard motor 0.5 to 0.6 litres per hour per horsepower
4 stroke petrol motor 0.3 to 0.4 litres per hour per horsepower
4 stroke diesel inboard around 0.2 litres per hour per horsepower

[Biggles]

I make that 20 Litres per hour for my Tohatsu 2 Stroke.

Sorry but that is way out.

I stick by my average of 2 Miles per Litre.

I am usually out for three hours and use 23 Litres.

About 8 Litres per hour.

And I boot it whenever I can.

[Cookee]

The race boat generally uses at least 1.5 litres per mile - thats a V6 200hp 2 litre Mercury XR2 on the 7.3 metre BananaShark race boat with a stepped hull weighing in at the new heavier weight of 950 kg dry to make it the correct weight for Formula 2 RIB racing regulations.

[timboli]

I was out the other weekend on the bournemouth power boats cruise and used 46.6 litres for 68 miles(72 on gps).0.68 l/m,cruising speed was about 24 knots,4100-4300 revs,hourmeter showed running time of about 5 hours,about 2 galls per hr,engine is fairly new with 35 hours on it now.
I/ll go get my anorak

[roohairy]

Biggles,
Remember that these are only for WOT and engine developing max power. I would guess that you don't run like that all the time, so your consumption would seem to be better, especially if you're running a lighter pitch prop for carrying a load.
I used to have a 5.5m dory with 85Hp yamaha, cruised at 21 kts but the engine's only developing about 40Hp, (Same boat did same speed or slightly more with 2x25Hp WOT) 1.1L / Nm. WOT was 30kts, and burnt a 25L tank in just under 30 mins. 1.7L / Nm. Current boat's a diesel and uses so little I can't be bothered working it out!