60 Hp mecrury

[boris]

hi guys and girls,
im looking at buying a new mercury 60 hp 'bigfoot' oil injected two stroke engine.
(the one with the higher ratio gearbox)...
I am repowering my 4.5m bream aluminium tournament craft.
Wondering what your thoughts are about this package and any reports good or bad about this engine.
cheers
Jason
p.s. i would go to a four stroke but it isn't viable for me as im only 17 and don't have really stable work, so that option is ruled out. But the four stroke is a great engine, thats what was on it and i couldn't fault it in anyway.

[Mandurah Marine]

Bigfoot setups are for high load (pontoon boats, displacement boats etc) - your boat will go slow and you won't like it!

[boris]

i wanted the bigfoot motor so i could drop back the revs and do the same speed in theory as the normal 60 would at the higher rpm thus saving on fuel and it will also get on the plane faster.
in time it will have a stainless high speed prop and will regain the speed that way.

[jorn]

do you mind me asking how mucht hey cost?

i was tinkering with the idea of repowering my boat (50hp mercury)

but 10k for a 4stroke doesnt seem viable to me...

[Justin Boyle]

What motor will you be replacing and what is the current performance of the rig?

[boris]

ok i'll tell you the story. im replacing a 60hp mercury four stroke as my motor filled up with water due to a boating mistake (bungs were stolen).
The engine filled with water and therefore is now ruined, so the insurance company is giving me $7800 to buy a new engine.
My current choice is a big foot 60hp 2 stroke as i can't afford the difference between what im getting from insurance and the $10k for a new 60hp 4 stroke.
Current performance on this rig was 74km/h top speed with one up, gear and a full tank of fuel (70L).
Not bad when you think the hull and motor weight is about 750 kg

[boris]

I can get a 60hp 4 stroke mercury for $9800 fitted but atm i can get a 60hp mercury bigfoot or small foot (standard size) for $7100 fitted.
Also worth noting that mercury Australia has no 60hp four strokes in stock but if your on the east coast Graham Barclay marine can do one for $8600 plus fitting.
Just give mark a call if you want to know more.
Im trying to get out of this for as little as possible so the 2 stroke is my best option.
P.s. im the one at the back of the boat in the water holding it up

[Timmah]

Hey dude,

That must of sucked when that happened. I remember putting the boat in the water for the second time and i left the bungs out. Lucky i had a bilge pump setup for auto, that saved the day and i was able to get the bungs in fairly soon. Is there any reason why your only looking a Mercury? How much would a yammie set you back?

Cheers
Tim

[Justin Boyle]

I don't know where you are located but have a look at this

http://www.aquasportsmarine.com.au/l...=misc&de=51457

Not sure if it is still there as it was on their website 3 months ago. Just goes to show there are some cheaper motors out there. A lot of people would argue also that 2 strokes are just as good now as the 4's anyway.

[shaynes_god]

I have a mercury 60hp four stroke big foot with a stainless vengence prop and it is pushes my 475 trailcraft profish at about 23kts WOT and it is slow getting out of the hole but you will be doing well to find a motor that uses less fuel. I do wish it was a bit faster but speed = more fuel its a preference thing i guess.
hth
shayne

[Justin Boyle]

must be a heavy boat. I know they are different designs but my boat is 3 cylinder 40hp merc 4str and it does 26knots 1 up with gear and livewell.

[Mandurah Marine]

The std gearbox runs at 1.64:1 ratio with 11 to 12" diameter props
The bigfoot runs at 2.33:1 with 13 to 14" diameter props (it is simply the gearbox from the larger horsepower engines - 75 to 130 odd hp)

Thus you will need more rpm.
Pitch is relative to speed, diameter is relative to load.

The bigfoot has a larger gearcase so for you it will be at the detriment of speed as you are dragging more negative area through the water with the same HP. Although you should have better holeshot.

Prop rpm x pitch = inches per minute (assuming zero prop slip)
1000 inches per minute = 1 knot

Therefore your BF swinging a 17p prop at 5500 engine rpm gives a theoretical speed of 40 knots

STD box swinging a 15p prop at 5500 engine rpm gives 50 knots - less pitch, more speed, less drag in the water and less wasted blade area ratio (BAR) will add to the theoretical speed.

A larger BAR requires more horsepower.

Use the above calculation to do some sums for yourself to determine what you want, but you can see that the std box for same speed will give you less engine rpm thus less fuel consumption. Dragging more negative area thru the water will also give you poorer fuel consumption. You will also be paying 2-300 $$ more for the stainless prop to suit the BF.
Remember: You cannot prop an engine out of it's manufacturer's Wide Open Throttle (WOT) specifications (5000 - 5500 for the Merc 60) or you will void warranty, anyways, you don't get the performance or fuel consumption if it isn't within.

I urge you to look into this further as you will be dissapointed - more fuel consumption and less speed!

[Justin Boyle]

Was ur original 4st engine a bigfoot? I think most are and if that is the case shouldn't the top speed be similar but with a better hole shot than old engine because of 2 stroke?

[boris]

first think is first i didn't forget the bungs they went missing
The original was the small foot version. and it wen't great...
thanks for the info on the bigfoot gearing... i'll look into it and let you know what i choose

[boris]

a yammy is about $10,300 plus fitting where i can get a merc for $9,100 fully fitted.
the reason i wanted a merc is cause i had a yammy and the merc suited the boat better...