Yamaha 150 - what speed?

[johnboym3]

Hey guys just bought a RIB with a 4 stroke 150 yamaha outboard on it... i was expecting to get around 50mph at sea with it but i am getting around 34 mph flat

what do you reckon?

[Nos4r2]

Originally Posted by johnboym3

Hey guys just bought a RIB with a 4 stroke 150 yamaha outboard on it... i was expecting to get around 50mph at sea with it but i am getting around 34 mph flat

what do you reckon?

What revs is it making, how much green stuff is growing on the bottom and is the hull full of water?

[neilda]

Others are more qualified than I (actually everyone is at the moment), but a 150, depending on the size of RIB, should be in the 45+ area I would have thought. At least that's what the sales people say!

What RIB and size is it?

[Heart-trouble]

is it trimmed right?

[Trevor G]

Hi Neilda. I've a 2004 Yamaha F150AET on the back of my Ballistic 6.5 and I get a top speed of about 39 knots (Satnav speed) - this is 4-up with a pretty full tank but I'm not sure it will go much faster!
Trevor

[johnboym3]

Originally Posted by Nos4r2

What revs is it making, how much green stuff is growing on the bottom and is the hull full of water?

it is revving to 4400rpm. dont think there is much on the bottom as it has been anti fouled.

no water in the hull

[johnboym3]

Originally Posted by neilda

Others are more qualified than I (actually everyone is at the moment), but a 150, depending on the size of RIB, should be in the 45+ area I would have thought. At least that's what the sales people say!

What RIB and size is it?

its a ribeye 650 sport and it 6.5 meters

yeah i have moved the trim to all areas

[Heart-trouble]

if yr on your own you should easily get 45-50mph @ 5600rpm, i think you have the wrong size prop

[codprawn]

Have you experimented with the trim?

If so then it is the wrong prop or a damaged one - the hub could even be slipping.

It doesn't take much slime or other growth to rob you of a lot of speed either.

[Nos4r2]

Originally Posted by johnboym3

it is revving to 4400rpm. dont think there is much on the bottom as it has been anti fouled.

no water in the hull

Your prop hub isn't slipping if you're only making 4400 rpm.

Physically check for slime buildup. You'd be surprised how much difference a small layer makes. More importantly find out what pitch and diameter propeller you've got. You should be doing between 5000 and 6000 rpm at wide open throttle depending on how much load is onboard so either
a) You're overpropped
b)Your hull is filthy (or worse but unlikely , damaged somewhere out of sight)
c)You've got an engine problem.