Is that the combined/both sides usage? Bloody good going, would have to be happy with that.Originally Posted by robothefisho
Is that the combined/both sides usage? Bloody good going, would have to be happy with that.
I agree with others questioning the accuracy of your records Robo.
Your old school 200 carby motor is equal to or slightly better than my 115Etec ? ?
I fished aboard a V17L with a 200hp carby mariner and it sucked fuel down really quick and went really quick, like you're quoted rpm and speeds.
often the urban marketed disparity between old school 2 stroke and modern 4 stroke fuel cons makes me want to puke...well not really that's overacting...possibly just a half hearted dry reach.
marketing works to create belief systems that almost never die, yes 4st are more efficient but really not that much to warrant the extra cost on rec craft but still also that is also personal thing.
I got a 90 yam smoker on a 6m tinny I got 2.1km/L in offshore trim in the past at 42km/h but today I get just 1.8/km because of the front casting deck and the largish aux on the back and a few other things......this 3cyl ob is small cc and low torq so not really well up to the job of the craft it pushes anymore......all outboards will use more or less the same moving average throughout their HP/CC and torque figures...all specific types of engines do.
If I went to a 115/130 yam smoker I expect at least 2.2/3 from that HP grade. The pitch of the prop that can be swung is the key and the only key ie off the shelf diameter and surface area is most often just good money thrown overboard every km travelled.
all medium and above 2 stoke ob if set up well at cruise speed and suited to size boat should see near/around 2.0km/l on average.
That makes sense
Yes mate that's the boats fuel economy. Ie distance/fuel use for both motors.
Lancair you're perfectly entitled to aswell. It's all so variable between boats. Ie this boat uses far less fuel than a 580sf with 140 rude I owned. I've found out of carby 2 strokes that the yamahas are generally the most economical. This is personal experience with merc/johnson/yamaha.
Best figures I get are 1.8km per litre with 90HP 2stk on a long boat which is supposed to be an economical hull so your doing well mate.
My Dad has a 7m x 2.6m wide Bruce Harris shark cat weighs 3ton with 2 x 175hp mercury black max carby jobs tops out @ 45nm/hour if your not holding on while you put the boot into it you will be out the back quicker then you can say jack rabbit.Best economy is @ 25nm/h cruise 1km/litre any less speed it chews juice any more speed you can double if not triple the fuel.Trolling and looking around for fish on the sounder forget it it just pumps the fuel straight out the exhaust pipe.best part of the trip is when coming home and someone trys to drag us off then we say #### the fuel bill see you later sucker.
I had a 560 sportsman podded bruce harris cat with twin 90 yammy 2 stks.
1.2ltr per km loaded.
I find it hard to believe any bigger cats with bigger 2 stks would get any better.
Mmm i think that this last sentence a bit of an exaggeration bud. Just about all boaties i know with 150-175 2 strokes get about 1 km per litre, and i had a yammy 150 on my Yalta 20 footer and thats what it yielded. Went to a Suzy 175 4 stroke and now consistantly average 1.7 - 1.8 km per litreoften the urban marketed disparity between old school 2 stroke and modern 4 stroke fuel cons makes me want to puke...well not really that's overacting...possibly just a half hearted dry reach
marketing works to create belief systems that almost never die, yes 4st are more efficient but really not that much to warrant the extra cost on rec craft but still also that is also personal thing.
I got a 90 yam smoker on a 6m tinny I got 2.1km/L in offshore trim in the past at 42km/h but today I get just 1.8/km because of the front casting deck and the largish aux on the back and a few other things......this 3cyl ob is small cc and low torq so not really well up to the job of the craft it pushes anymore......all outboards will use more or less the same moving average throughout their HP/CC and torque figures...all specific types of engines do.
If I went to a 115/130 yam smoker I expect at least 2.2/3 from that HP grade. The pitch of the prop that can be swung is the key and the only key ie off the shelf diameter and surface area is most often just good money thrown overboard every km travelled.
all medium and above 2 stoke ob if set up well at cruise speed and suited to size boat should see near/around 2.0km/l on average.
"let not he boast who puts his armor on, as he who takes it off"
I can't comment on the shark cats but new ally hulled cat gets around 1.8km/l from 2 yam 60's apparently it will do better but i'm not convinced.
In contrast my 5 meter cruise craft with a 135 blackmax was sitting somewhere around the 1.1km-1.3 per L. Fuel bill was high but dear god did that thing move!
Hi odes 20.
Sorry just checked in and forgot totally I posted here, no not really an exaggeration, dumb props the standard ones we buy off the shelf for straight-line fishing rigs are awesomely over surface area for pitch...if a 4 blade add near 20% to that again. Any traditional modern 2 stroke properly matched to a hull shape and weight should see 2.0KM/L at their most efficient cruise.
People just dont know, I bought a new prop for my smoker a couple months ago when a new to boating decky couldn't judge the shallowness of a bommie when nudging up to a beach on the GBR. My boat should run a standard 13 pitch yam 3 blade to reach it's stated max RPM with load 5500, the prop that was bumped was an old 15p Yam 3 blade (redesigned by me) and could reach 5550rpm in identical situation so I replaced it with same off the shelf.......... a prop that if genuine and unmodified will hold a max wot rpm of 5150 on my boat at best in identical situations.
So the first thing I had to is have at it and redesign the surface area, I now run that brand new prop (now modified) at 5500 wot rpm identical situation from the very first test drive. My consumption with the 13p is about 1.3km/l and at a sloooowwww cruise, with my modified 15p it's 1.6km/l but at a typical 15p faster cruise speed but still the fuel consumption signifies I didn't take enough surface area from it even though cruise speed for RPM is near identical to any brand new identical unmodified genuine yam alum15p.
The weight my boat has grown so the motor is now actually too small....2.0km/l is the correct target but i will be happy enough with 1.7-8 now when propped well (when I get the surface area to best suit the boat/motor/hull/weight combo) and with next to no discernible impact upon typical cruising speeds...no boat with an off the shelf dumb elephant ear'd prop is well propped...none of them they are all dogs...I mean that in a nice way, lots of dogs out there way better than my boat.
Off the shelf props are designed to operate well enough pushing a full oyster barge at displacement speeds, why would any prop with an identical same profile also suit any relatively uber light straight line planing hull fishing rig?...quite simply it cannot, it cannot like a car with square wheels.
cheers
The data is old but an interesting comparison on Roger Hill's website on the Arrowcat.
Almost Identical boats using the same tooling (from memory Diesel boat had more/heavier fitout). One running 2x 150HP optimax the other 2x120HP Mercruiser diesel. Optimax used slightly less fuel across the board.
my last reef trip off Whitsunday's 221 kms for 180 litres with 98 model 175 EFI merc on 19ft fibreglass, no drift, anchor every time. was going to upgrade to 4 stroke but not until this old girl dies. I used the same fuel as my mates 6.5 platey with 225 4 stroke Suzuki, go figure..
Any pics of the modded prop FNQ ??
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