4.8 brumby 90hp would be great

[maddognt]

I have a 4.8 cubby cab with a 70hp goes like a boat 20hp under powered, 27 knots WOT.
It not much good water skiing “too slow”, can't buy a new 80hp in an brand anyway. 75 and 90 e-tec are the same weight 145kg, hell 115 e-tec is 170kg, max motor legal weight is 175kg! 35 knots would be great.

My old boat was a 4.5 half cabin (fibre glass!) 70hp would do 33 knots WOT.

How to I sand far as rules and legal?

Has anyone put a bigger motor on a 4.8 and how did it go? Thanks

[Dave]

Hi MDNT..

The rules and legals are pretty simple really... if you put a motor on exceeding the manufacturers standards then you would not be able to buy insurance.
If you already have insurance and you dont tell them, then make a claim, they will refuse due to lack of disclosure on modifications and also exceeding the manufacturers standards.
If you have an accident, the company would not honour your policy, you would not have insurance and may be liable if the motor is too big. If someone is injured or killed, you may be liable for criminal proceedings.

The big question with your boat is the setup
Height of motor?
Angle of trim (user knowledge)?
Propellor matched to boat / motor setup?
Weight of load on board?
WOT RPM?

There are many factors that affect the boat performance.

Could you provide some more information and the guys should be able to help you out

[bushbeachboy]

Mad Dog which 70 are you running? ie Zook, Yam 2 stroke etc? There is at least one 4.8 on here running a 75 Merc 2 stroke (carby) and report it as being fine with plenty of power. Of course if you are already running a four stroke, that would be a backward step. A 75 Optimax could be a choice, or the Etec. If you are running a 2 stroke 70 Yamaha, it has a much smaller displacement than the other motors and that will affect its ability to 'get up and go'.

[chin]

The wrong prop can make any boat a real dog, I'd be looking at that first.

P.S. I thought Yammy and Zuke both had an 80 in their range?

[bingo]

I have a honda 75 on my Brumby and I can't fault it.

[maddognt]

I have a honda 75 on my Brumby and I can't fault it.

what speed you geting at WOT?

[sweeden]

I have a brand new 80 4 stroke suzuki on my brumby with a #15 alloy prop, and get about 30 knots WOT. I spoke to someone with similar configuration and #17 prop, and they get about 33 knots.

[bingo]

I don't work in knots but I have had the Brumby to 58kmh with only myself in it, and at 4000 revs it sits on 40kmh.

[Pirate Pete]

58Km = 31.31749Kt

[Keithy P]

That sounds good to me! My 2 banger, 50 horse dinger only does 30kt at full noise with me in it.... though I am a little chunky 'round the midriff...

I cant wait for my Brumby!!!

[Doug]

'Zat what you call it, Keithy? "Chunky", eh? Isn't that a dog food?

[Keithy P]

We dont know anything about dogs up here in the far far north thanks Doug.
http://www.cairns.com.au/article/2010/02/23/95425_local-news.html

[Threadie]

'Zat what you call it, Keithy? "Chunky", eh? Isn't that a dog food?

Tastes like crap ...but your hair is nice n shiny

[RATFish]

put a 115hp on it and to hell with liability!

[maddognt]

put a 115hp on it and to hell with liability!

I’m with you mate; 115hp would pull a skier up good and go fast enough.

What would happen if I was pulled up by the waterways authority, with a 115 or 90 and a 80hp max power on the boat plate? Anything or is the plate the manufactures guide lines?

[Doug]

My own experience is that the various state authorities couldn't find their own arse with both hands and a hunting dog. However, when the insurance people get involved, with their overwhelming urge to get out of paying a (potentially huge) claim, you're playing with the big boys, and inevitably you'll end up with your head in your hands, and a huge liability bill. 'Course that doesn't mean you wouldn't get away with it for a lifetime or more, but if you didn't......................it's hello poorhouse.

[bushbeachboy]

My own experience is that the various state authorities couldn't find their own arse with both hands and a hunting dog.

laugh1

That just made me think about state authorities and their equipment. What would happen if you farted at the same instant you got tasered?shock Would you just explode?:eek:

[maddognt]

polycraft have up'd hp ratings on 4.8m to 90hp, 5.3m to 140hp "150hp why not". have had 90hp on 4.8 for a year or so.

[Inschy23]

I have a 70 suzuki on my 4.8 and i get 32knots with the whole family on board. Seems fine to me :)

[Wilco]

Hi Keith,

Weve got a 4.8 cuddy with a 75hp merc. We get 34-35 knots WOT. We tested a similar 4.8 cuddy with a 90 and it handle it well. We got 37knots WOT.

Cheers Wilko

[Giffo]

Hey Keith,I hope he wined and dined the dog beforehandlaugh1.