TOP Speed Please Take a guess

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ILIKEROSTERTAILS

Seaman
Joined
Jul 14, 2004
Messages
51
Hi,<br />I have a boat just like this one in the picture. I have a 140 3.0 OMC with a prop that has a 16in pitch and a 13in diamiter. It is 16 feet long. I am not sure about the weight. The speedo is busted so I do not know what my top speed is. Can any one give me a guess of how fast it is. It seems really fast.<br /><br />Thanks,<br />Ben
 
Bob_VT

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
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May 19, 2001
Messages
26,022
Re: TOP Speed Please Take a guess

Uhhhh what picture? Look your boat up on NADAGUIDES.Com and look for the retail price of used boats. That will give you the weight then used the theoretical formula posted here on the iboats site.<br /><br />OR<br /><br />Get a friend with a GPS to ride along and you will get an accurate speed.<br /><br />The speed formula uses weight hull type and horsepower... some require prop slip... GPS is the easiest.<br /><br />Bob
 
Z

ZmOz

Captain
Joined
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Messages
3,949
Re: TOP Speed Please Take a guess

Just a rough guess, but you'd be lucky to hit 40. My 16' glastron with 150hp outboard does 50, and inboards are allways slower for a given HP.
 
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ILIKEROSTERTAILS

Seaman
Joined
Jul 14, 2004
Messages
51
Re: TOP Speed Please Take a guess

It is a bayon custom that is why I can't look it up on NADAGUIDES.Com. I think I will order a new speedometer I just wanted a guess of how fast it is. <br />Thanks,<br />Ben
 
Q

quantumleap

Master Chief Petty Officer
Joined
Feb 16, 2004
Messages
813
Re: TOP Speed Please Take a guess

Borrow a hand-held GPS and you'll know exactly how fast.
 
I

ILIKEROSTERTAILS

Seaman
Joined
Jul 14, 2004
Messages
51
Re: TOP Speed Please Take a guess

I will buy a GPS to see how fast if some one can give me a guess so I know if it is even worth finding out lol.
 
C

cobra 3.0

Lieutenant Commander
Joined
Jul 31, 2003
Messages
1,797
Re: TOP Speed Please Take a guess

My 1986 Peterborough bowrider with 3.0 140 hp Cobra goes 38 mph (gps) with a 19" pitch prop. If it's anything like the picture on ebay, that's a very flat, fast hull...probably around low 40 ish...but the 16" pitch is very short?!!! What does it rev at?
 
I

ILIKEROSTERTAILS

Seaman
Joined
Jul 14, 2004
Messages
51
Re: TOP Speed Please Take a guess

Ok I will get a GPS. It seems like I am flying. Also should I get a prop with more pitch?
 
Z

ZmOz

Captain
Joined
Aug 13, 2003
Messages
3,949
Re: TOP Speed Please Take a guess

I don't know what RPMs your motor is supposed to be at WOT, but probably more than 4100. That would mean you need a lower pitch prop...
 
I

ILIKEROSTERTAILS

Seaman
Joined
Jul 14, 2004
Messages
51
Re: TOP Speed Please Take a guess

Oh? I thought 4100 seemed high. I though like 4000 was probley righ. I will look it up.
 
I

ILIKEROSTERTAILS

Seaman
Joined
Jul 14, 2004
Messages
51
Re: TOP Speed Please Take a guess

I have really great acceleration and it levels out in like 3 sec. If you give it WOT. What do I need to do to learn what kind of prop is best?<br />Thanks,<br />Ben
 
Z

ZmOz

Captain
Joined
Aug 13, 2003
Messages
3,949
Re: TOP Speed Please Take a guess

First you need to find out what the WOT RPMs of the motor are supposed to be. If it's higher than what you're getting now, then you need a lower pitch. If it's lower (unlikely) then you need a higher pitch prop. If you're already in the right range, then do nothing. :)
 
Q

quantumleap

Master Chief Petty Officer
Joined
Feb 16, 2004
Messages
813
Re: TOP Speed Please Take a guess

Your motor has a recommended RPM range of 4200-4600 at WOT.
 
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