Your prop hub is slipping. Get the prop rebuilt.
JR
BTDT got the T-shirt, too

Mike Slater wrote:

I was cruising along in my 24ft pontoon boat when I got a real surprise.
Somebody please tell me how and why I could be running wide open
throttle at my normal 5500 rpm and then suddenly the boat took off like
a bat out of hell running at 8000 rpms and 25mph??? I never touched the
throttle. It has never run that fast ever. After about 2 minutes it
went back down to 5500 and never did 8000 again. Its a 60hp mercury
Bigfoot outboard. It has never done this before and I don't even know
how it could rev that high and go 25mph. Normal is 5500 and 17mph.
What happened??

Mike

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Home Page: http://www.seanet.com/~jasonrnorth

"JR North" wrote in message
diainc...
Your prop hub is slipping. Get the prop rebuilt.
JR
BTDT got the T-shirt, too

Mike Slater wrote:

I was cruising along in my 24ft pontoon boat when I got a real surprise.
Somebody please tell me how and why I could be running wide open throttle
at my normal 5500 rpm and then suddenly the boat took off like a bat out
of hell running at 8000 rpms and 25mph??? I never touched the throttle.
It has never run that fast ever. After about 2 minutes it went back down
to 5500 and never did 8000 again. Its a 60hp mercury Bigfoot outboard.
It has never done this before and I don't even know how it could rev that
high and go 25mph. Normal is 5500 and 17mph. What happened??

Mike


Nope. The boat went from its normal 17mph WOT cruising speed up to 25mph in
an instant.

Mike

NO WAY is the prop hub slipping. That would be 8000 rpms and ducks
swimming by you.
I vote for leaning out. BIG bubble in the fuel line, or the kid hooked
up a nitro bottle!
Den
48YF EAGLE

Nope. *The boat went from its normal 17mph WOT cruising speed up to 25mph in
an instant.

Mike

On Mon, 15 Jun 2009 02:27:29 -0700 (PDT), den wrote:

NO WAY is the prop hub slipping. That would be 8000 rpms and ducks
swimming by you.
I vote for leaning out. BIG bubble in the fuel line, or the kid hooked
up a nitro bottle!
Den
48YF EAGLE

Nope. *The boat went from its normal 17mph WOT cruising speed up to 25mph in
an instant.

Very interesting. Unusual motor to say the least. Power required to
overcome viscous drag varies with the cube of the speed. So this
engine tripled the power while going from five grand to eight. All you
can get from nitrous oxide is double. If you supercharge and burn
methanol, in an engine designed for it, you might triple the power
going from five to eight.

It is would be more usual for power to drop going five grand to eight.
Matter of insufficient time for the cylinders to get a full charge of
air.

Casady

"den" wrote in message
...
NO WAY is the prop hub slipping. That would be 8000 rpms and ducks
swimming by you.
I vote for leaning out. BIG bubble in the fuel line, or the kid hooked
up a nitro bottle!
Den
48YF EAGLE

Nope. The boat went from its normal 17mph WOT cruising speed up to 25mph
in
an instant.

Mike

Oh yeah... I did kick the nitrous in when it happened.... kidding!
Anyway, I did get the clear message not to let it run that fast if I want
to have a motor when I get back to the dock. Thanks.

On Jun 14, 9:05*pm, "Mike Slater" wrote:
"JR North" wrote in message

diainc...





Your prop hub is slipping. Get the prop rebuilt.
JR
BTDT got the T-shirt, too

Mike Slater wrote:

I was cruising along in my 24ft pontoon boat when I got a real surprise.
Somebody please tell me how and why I could be running wide open throttle
at my normal 5500 rpm and then suddenly the boat took off like a bat out
of hell running at 8000 rpms and 25mph??? *I never touched the throttle.
It has never run that fast ever. *After about 2 minutes it went back down
to 5500 and never did 8000 again. *Its a 60hp mercury Bigfoot outboard.
It has never done this before and I don't even know how it could rev that
high and go 25mph. *Normal is 5500 and 17mph. *What happened??

Mike

Nope. *The boat went from its normal 17mph WOT cruising speed up to 25mph in
an instant.

Mike-

The anchor you've been dragging around finally broke free. :-)

On Jun 14, 9:01*pm, JR North wrote:
Your prop hub is slipping. Get the prop rebuilt.
JR
BTDT got the T-shirt, too

If the prop was slipping it wouldn't go from the normal 17mph @ 5500
RPM to the 25mph at 8k.

Didn't read the post right. The 'normal' speed was ambiguously unclear
and out of place in the text.
JR


Loogypicker wrote:

On Jun 14, 9:01 pm, JR North wrote:

Your prop hub is slipping. Get the prop rebuilt.
JR
BTDT got the T-shirt, too


If the prop was slipping it wouldn't go from the normal 17mph @ 5500
RPM to the 25mph at 8k.

--
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Home Page: http://www.seanet.com/~jasonrnorth

JR North wrote:
Didn't read the post right. The 'normal' speed was ambiguously unclear
and out of place in the text.
JR


Loogypicker wrote:

On Jun 14, 9:01 pm, JR North wrote:

Your prop hub is slipping. Get the prop rebuilt.
JR
BTDT got the T-shirt, too


If the prop was slipping it wouldn't go from the normal 17mph @ 5500
RPM to the 25mph at 8k.


Can you imagine if he top posted? Everyone else might have come to the
same conclusion as you.

On Jun 15, 5:22*pm, JR North wrote:
Didn't read the post right. The 'normal' speed was ambiguously unclear
and out of place in the text.
JR

10-4!

Loogypicker wrote:
On Jun 14, 9:01 pm, JR North wrote:

Your prop hub is slipping. Get the prop rebuilt.
JR
BTDT got the T-shirt, too

If the prop was slipping it wouldn't go from the normal 17mph @ 5500
RPM to the 25mph at 8k.

--
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* * * * Home Page:http://www.seanet.com/~jasonrnorth