Havent got a direct comparison for you Darryl but I changed from an 18ft ally with a 115 jonno 2 banger which was only 2 years old to a 20ft glass boat with a 140 4 stroke and my fuel usage has dropped by at least a third over the same trip.

Felt it was a great improvement for a bigger boat and motor.

Hopefully someone has some direct comparison figures for you.

** Rockingham Offshore Fishing Club **

same, not really same comparison but i have a quite a few boats, 9 in fact, and all types of motors, one thing i will tell u  is,

right now i have the biggest boat i have ever had 650 walkaround, 7metre hull, shes a heavy 6mm aly rig, and i have a 150hp 4 stroke yammy on her.

 she moves and is a dream on fuel.. i have driven all day sounding ground out from nats reefs way right out past the c.lumps in one day,n reefs are around 25nm out, then another 3o +to the c lumps from there.. even down towarrds cowaramup, i have never used more than 80litres of fuel in one day.

this thing is that quiet , sometimes i,ve thought it was on, and tried restarting after a drift..the prop on this boat makes a big diff also, on my last 620 quinny, i had a stainless prop, could never get the same torque,nor the revs needed to power in when needed.. the aly prop seems to handle alot better on the heavier rig..

i,ve had a 115 also equally good, 

i,m already thinking of getting an upgrade of benj,s boat..

8.5 walkaround with twin 150hp 4 strokes..

prob next year sometime.. normal running this uses anything between 7.5 and 11.5 litres of fuel an hr depending on conditions etc..

I have a Yamy 200,direct fuel injection on a grady white that is solid gpr,at 4,000 to 4300 doing around 30K I got approx 50lts an hour with 5 men on board,I think the thing you must weigh up is the added cost of a four as the 2 stroke,debending on the use you get it may take a long time to recover the extra cost from fuel,but ,personally ,I would love a 4 for my next but 3 or 4 grand buys a bit of fuel,just think it through,two are reliable as are the 4 but I think the Yamy hpdi is more technical to do the the pressure injection,desienged for racing so just do the mathsjesrey

I have a 90 yammy 2001 model, 90litre fuel tank,

25 nautical & I am at the half a tank mark,

Is this normal for such a beast?

It seems i will have to carry jerry cans to get out after the grey band cod and other species to feed my family after the Ban,

What do these boats run like with a 100 or 80 four stroke on the back? will a 90 E Tec do just as good? any other suggestions?

e tec or 4 stroke?

Recently put a new 200hp Suzuki on the boat, saving around 40% on fuel comparing to the old 175hp Two stroke. Done around 25 hours so far and very happy with the change. Using between .7 to .8 of a litre per 1km,  so to do 100km we use between 70lt and 80lt. The Seafarer 6.2m is a heavy boat so you could even get better on a lighter Glas boat or a Ally? @ 4000rpm we are doing around 30knots, @ WOT 5800rpm we are doing around 45 knots.

recently swaped from 2 to a 4 stroke 60hp yammie. saving good 40% but the killer for me is cleaner environment.....and oh so quiet...

wrassmaster, not sure about your figures!!! 25 Nmiles is 47km = 45litre (half tank)which is roughly 1 lt per km. mine 60 2 stroke would do that on average.... I thought those southwinds were designed to take a smalll engine with good economy....no expert on the boats though just what I've read.

my 4 stroke 60hp yammie should get me on average 4.02km per litre at 3500rpm. i have a 100 litre tank so long range. one thing with my dig dials is the last fuel bar flashes but easy 30 litres left, must be where float is located.....

eTec or 4stroke......well i went 4stroke because it was an old yammie and the conversion saved me heaps of $$ cuase same gauges etc otherwise i would go Etec and next boat will be Etec.....they wanted to charge an extra $1000 for the Etec but the best quote i got was on a 4stroke yammie period. but yammies are good.  

got the same 90 yam 40km to 25ltr of fuel at 3500

G'day BQ

To be honest I would have thought that a 115hp on a 20' glass hull would be underpowered. What sort of hull is it? What sort of speed does it get up with beer and gear on board? Personally I would be looking at a larger engine. It will be working a lot less under the same conditions and load and using a hell of a lot less fuel.

Cheers mick

2 boats

1st in a 6.1 Razorline with a 135 honda 4stk
Uses around just over 1 litre per mile at the moment

2nd boat is a 25 blackwatch (Mates boat) has 2 x 200hp optimax engines 2 stk

Uses 2 litres per mile exactly.

In comparison, i would say optimax's are better on fuel, but a power to weight ratio does play a part.

very interesting fiqures... I think if the economic downturn recovers a bit I will look at 4 stroke and maybe go up to a 140.

cheers

I took a 70 HP 2 stroke merc off my 5.2 m and put a 60hp 4 stroke Yammy on it and get 3 times the fuel econmy than the old 2 stroke. I get around 30 to 35 NM from a 25 l tank.

I love my Yammy .

________________________________________________________________________

OFW Agent 88 , the Scarecrow.

And I get better speed from the 60 4stroke  than the 70 2stroke ever did, and trolling is a dream .

________________________________________________________________________

OFW Agent 88 , the Scarecrow.

I've got a 5.0 metre ali,all 4mm plate,with a 60 etec on it.Normally use 35-40litres on a trip to the islands[30nm]and running around,usually 80nm for a trip sitting on 2500-2700 giving 22-24knots.