Outdrive torque...
 

I've already admitted that I don't have a lot of experience with
outdrives, but I ran into something this morning with the Pro Line
that was fixed that may, or may not, be imagination.

I took the boat up to Webster Lake this morning to run it up for a
prospective buyer. Everything seems to work ok - boat is running
fine,nothing seems amiss, but I noticed something odd - or at least I
think it's odd.

When you cram the throttle for a hole shot, the boat rotates slightly
to starboard along it's bow/stern axis - almost like the torgue roll
you get with a high horsepower car. At least it feels like that to me
- it's not a violent movement by any means, but it feels funky.

It that normal? Just asking - I've never "felt" this before on other
outdrive boats I've tested or driven.

Outdrive torque...
 

On Fri, 25 Sep 2009 08:18:30 -0400, Tom Francis - SWSports
wrote:

I've already admitted that I don't have a lot of experience with
outdrives, but I ran into something this morning with the Pro Line
that was fixed that may, or may not, be imagination.

I took the boat up to Webster Lake this morning to run it up for a
prospective buyer. Everything seems to work ok - boat is running
fine,nothing seems amiss, but I noticed something odd - or at least I
think it's odd.

When you cram the throttle for a hole shot, the boat rotates slightly
to starboard along it's bow/stern axis - almost like the torgue roll
you get with a high horsepower car. At least it feels like that to me
- it's not a violent movement by any means, but it feels funky.

It that normal? Just asking - I've never "felt" this before on other
outdrive boats I've tested or driven.

What year is this Pro LIne? Mine was a 1997 model 211 cuddy. I don't
recall anything like you're mentioning, but I don't recall ever
cramming the throttle either. Did you try this with different trim
settings?
--

John H

Outdrive torque...
 

"Tom Francis - SWSports" wrote in
message ...
I've already admitted that I don't have a lot of experience with
outdrives, but I ran into something this morning with the Pro Line
that was fixed that may, or may not, be imagination.

I took the boat up to Webster Lake this morning to run it up for a
prospective buyer. Everything seems to work ok - boat is running
fine,nothing seems amiss, but I noticed something odd - or at least I
think it's odd.

When you cram the throttle for a hole shot, the boat rotates slightly
to starboard along it's bow/stern axis - almost like the torgue roll
you get with a high horsepower car. At least it feels like that to me
- it's not a violent movement by any means, but it feels funky.

It that normal? Just asking - I've never "felt" this before on other
outdrive boats I've tested or driven.

Newton's Third Law of Motion. Your analogy to a torque roll in a high
horsepower car is applicable. In this case, since the boat is resting in
water versus the car on land, the boat is naturally more tender and will
exhibit Newton's Third Law by way of a reaction to torque being applied to
the longitudinal axis with less input (torque) than was required for the
car. This phenomena is one of the reasons counter-rotating propellers were
invented for torpedoes and ultimately for outdrives. If that boat had a
Bravo 3 drive instead of an Alpha drive, you couldn't get it to rotate on
the longitudinal no matter how hard you stuffed the go stick.

Outdrive torque...
 

Tom Francis - SWSports wrote:
I've already admitted that I don't have a lot of experience with
outdrives, but I ran into something this morning with the Pro Line
that was fixed that may, or may not, be imagination.

I took the boat up to Webster Lake this morning to run it up for a
prospective buyer. Everything seems to work ok - boat is running
fine,nothing seems amiss, but I noticed something odd - or at least I
think it's odd.

When you cram the throttle for a hole shot, the boat rotates slightly
to starboard along it's bow/stern axis - almost like the torgue roll
you get with a high horsepower car. At least it feels like that to me
- it's not a violent movement by any means, but it feels funky.

It that normal? Just asking - I've never "felt" this before on other
outdrive boats I've tested or driven.

It's called torque steer. In the olden days there was an fin anode above
the prop that could be adjusted to minimize that effect. More modern
setups use a flat plate anode in place of the fin. I couldn't tell you why.

Outdrive torque...
 

On Fri, 25 Sep 2009 08:18:30 -0400, Tom Francis - SWSports
wrote:

When you cram the throttle for a hole shot, the boat rotates slightly
to starboard along it's bow/stern axis - almost like the torgue roll
you get with a high horsepower car. At least it feels like that to me
- it's not a violent movement by any means, but it feels funky.

It that normal? Just asking - I've never "felt" this before on other
outdrive boats I've tested or driven.

It depends on the weight of the boat, amount of deadrise, trim, etc,
not all that unusual in my also limited experience. It's one of the
reasons for the dual counter-rotating props on the Bravo 3.

Outdrive torque...
 

On Fri, 25 Sep 2009 10:23:47 -0400, Jim wrote:

Tom Francis - SWSports wrote:
I've already admitted that I don't have a lot of experience with
outdrives, but I ran into something this morning with the Pro Line
that was fixed that may, or may not, be imagination.

I took the boat up to Webster Lake this morning to run it up for a
prospective buyer. Everything seems to work ok - boat is running
fine,nothing seems amiss, but I noticed something odd - or at least I
think it's odd.

When you cram the throttle for a hole shot, the boat rotates slightly
to starboard along it's bow/stern axis - almost like the torgue roll
you get with a high horsepower car. At least it feels like that to me
- it's not a violent movement by any means, but it feels funky.

It that normal? Just asking - I've never "felt" this before on other
outdrive boats I've tested or driven.

It's called torque steer. In the olden days there was an fin anode above
the prop that could be adjusted to minimize that effect. More modern
setups use a flat plate anode in place of the fin. I couldn't tell you why.

And this may be why I don't recall the experience with my ProLine.
--

John H

Outdrive torque...
 

On Fri, 25 Sep 2009 08:18:30 -0400, Tom Francis - SWSports
wrote:

Hey - thanks guys - I thought I was imagining it.

Heh - must not be as old as I thought. :)

Outdrive torque...
 

On Sep 25, 4:35*pm, Tom Francis - SWSports
wrote:
On Fri, 25 Sep 2009 08:18:30 -0400, Tom Francis - SWSports

wrote:

Hey - thanks guys - I thought I was imagining it.

Heh - must not be as old as I thought. *:)

No Tom, youre still sane.

My Marquis is a heavy old tub with a 350 GM and Alpha 1, and it takes
a lot of throttle to get it on plane, and yes, it will tip the boat
starboard (not badly) untill the tub gets up a little.

Normal nature of the beast

all is normal.

Outdrive torque...
 

Jim wrote:
Tom Francis - SWSports wrote:
I've already admitted that I don't have a lot of experience with
outdrives, but I ran into something this morning with the Pro Line
that was fixed that may, or may not, be imagination.

I took the boat up to Webster Lake this morning to run it up for a
prospective buyer. Everything seems to work ok - boat is running
fine,nothing seems amiss, but I noticed something odd - or at least I
think it's odd.

When you cram the throttle for a hole shot, the boat rotates slightly
to starboard along it's bow/stern axis - almost like the torgue roll
you get with a high horsepower car. At least it feels like that to me
- it's not a violent movement by any means, but it feels funky.

It that normal? Just asking - I've never "felt" this before on other
outdrive boats I've tested or driven.

It's called torque steer. In the olden days there was an fin anode above
the prop that could be adjusted to minimize that effect. More modern
setups use a flat plate anode in place of the fin. I couldn't tell you why.

Some still do. It must have to do with no-feedback/hydraulic steering
on large OB's.

Outdrive torque...
 

Tim wrote:
On Sep 25, 4:35 pm, Tom Francis - SWSports
wrote:
On Fri, 25 Sep 2009 08:18:30 -0400, Tom Francis - SWSports

wrote:

Hey - thanks guys - I thought I was imagining it.

Heh - must not be as old as I thought. :)

No Tom, youre still sane.

My Marquis is a heavy old tub with a 350 GM and Alpha 1, and it takes
a lot of throttle to get it on plane, and yes, it will tip the boat
starboard (not badly) untill the tub gets up a little.

Normal nature of the beast

all is normal.

Sounds more like weight distribution. I had an I/O that did the same
thing but it depended on where people were seated.