New Yamaha 4 stroke numbers
 

Was it cold...yes, was the rain pelting me...yes, was trying out a new motor awesome...absolutely! My old 1986 merc 2 stroke must have been more tired than I thought, because the new 4 stroke, which isn't supposed to be so quick out of the hole, is a real rocket. The tide and wind were pretty strong but I think these numbers are good. I arrived at the speeds by comparing the GPS speed to the depthfinder speed and taking into account the direction of the current.

Motor: 2005 Yamaha 150 4 stroke 25 " leg (extended transom)
Boat: 1986 SeaCraft 20 ft CC (20'6")
Carrying: One person, 40 gals fuel
Prop: 14x19
2000 rpm 9 mph
2500 rpm 12 mph
3000 rpm 23 mph
I haven't gone above 3200 rpm as I am still breaking her in. Between 2500 rpm and 3000 rpm she leaps up on plane.

Re: New Yamaha 4 stroke numbers
 

When you have a chance, I'd be interested to hear what you get at 4000rpm - both speed and gph burn (flat water, no tide calculation: straight GPS numbers).

Re: New Yamaha 4 stroke numbers
 

I didn't buy the fuel management gauges so I won't be able to nail down gph but the speed info will be no problem.

Re: New Yamaha 4 stroke numbers
 

Mark - The Prop calculator should give you a pretty good idea.

http://www.rbbi.com/folders/prop/propcalc.htm

Yamaha 150 gear ratio = 2.0
Prop Pitch = 19
With a prop slip of = .149

3000 = 23.0 mph
4000 = 30.6 mph (prop slip 14.9%)
4000 = 32.4 mph (prop slip 10%)
----------------------------------

Re: New Yamaha 4 stroke numbers
 

Whoa! [img]/images/graemlins/shocked.gif[/img] That prop calc says that my slip is only 9%.

20' Seafari, '91 Mercury XR4 w/ large gearcase, 1.68 gear ratio & nosecone, 6150 rpm, 16.5"P PowerTech prop, at 52 mph on the GPS. [img]/images/graemlins/grin.gif[/img]

Re: New Yamaha 4 stroke numbers
 

FRFrank.

What size motor is that? 200hp?

Abe's Rocket

Re: New Yamaha 4 stroke numbers
 

Hat Trick,I have the same boat as yours that I just put a new Evinrude 25" 175 Ficht on last year.I get about 35 knots according to the GPS wide open with a lite load(fuel, people).Not sure the prop numbers offhand.

Re: New Yamaha 4 stroke numbers
 

Bottomline,
My old motor was a 1986 Merc 150 black Max with a 15x17 aluminum prop and I would get 32 mph (gps) at 4500 - 5000 rpm with a 1/2 tank of fuel and two people on board. I don't know what I'll see at those rpm's with the new motor, but I'll let you know when the break in period is over. All I know is that the new motor is peppier at low rpm's.

Re: New Yamaha 4 stroke numbers
 

14.5X19 ss rapter
4100rpm
35mph gps
2 people 70 gals fuel

Re: New Yamaha 4 stroke numbers
 

I went out yesterday to do some more break in on the new motor. Here are some more numbers:

Motor: 2005 Yamaha 150 4 stroke 25 " leg (extended transom)
Boat: 1986 SeaCraft 20 ft CC (20'6")
Carrying: One person, 40 gals fuel
Prop: 14x19
2000 rpm 9 mph
2500 rpm 12 mph
3000 rpm 23 mph
4000 rpm 32 mph

I was only able to get the motor to 4700 rpms at full throttle. That doesn't seem like I'm getting what I should. Do I have the right prop?