I'm trying to understand propellers
 

On Tue, 28 Feb 2006 14:28:01 -0500, Harry Krause
wrote:


You work as a systems specialist in housing, food services and event
center facilities, and you were recently advertising for an assistant to
hang network wire for yo

And lets not forget the original thread were you demonstrated you know
nothing about props, and even the basic fundamental differences
between HP and torque...something I learned in high school.

Thank you.

Bye.
__

"It's just about going fast...that's all..."

http://home.columbus.rr.com/ckg/

I'm trying to understand propellers
 

On Thu, 02 Mar 2006 06:33:43 -0500, Harry Krause
wrote:


Yep. You're a tech support worker at Ohio State University. Hey, it's a
perfect job for an incompetent little geek like you. Be happy. In a few
years, you might graduate to the "Geek Squad" at Best Buy.

The 6th grade called.

They want their childish, immature, name-calling, lying insults back.
__

"It's just about going fast...that's all..."

http://home.columbus.rr.com/ckg/

I'm trying to understand propellers
 

Shortwave Sportfishing wrote:
On Sun, 26 Feb 2006 20:57:58 GMT, "Injam"
wrote:

If I'm screwing a wood screw into a piece of wood and my friend Charley is
doing the same thing. The wood is the same and the pitch on the screws are
the same. Screws are identical, but Charley is a lot stronger than I am. We
turn the screws at the same RPM. Will Charley screw his screw in before me?

If he's bigger and stronger, I'd bet on Charley. Even with the same
revolutions per minute, the depth of the stroke would be longer
because of Charley's available strength.

Nope, the screws are the same pitch. Therefore, if both turn one turn,
without slipping (seeing how this is a theoretical discussion) the
distance travelled will be exactly the same.

I'm trying to understand propellers
 

- Both boats would be the same fast in Theory.

The same fast. Yes boats go same fast, Tarzan.

a. The 200 HP motor could not rev up to 6000 rpm IF its a prop for the
250

In my scenario the 200hp is turning at 6000 RPM.
b. If the prop is for the 200 HP motor the 250 would rev at 6000 not be
able to put more power in the water.

I don't even know what you are saying.

c. The 250 would accelerate faster until it has reached 6000 rpm and
there have the same speed as the 200 (if it can swing the prop).

The 200hp can (swing the prop), but because of it's lighter weight the 200hp
would pass the 250hp on are about the five mile mark. At the ten
thousand-mile mark the 200hp would be approximately five thousand miles
ahead of the 250hp.

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Just having a little fun. Thanks for the post. I did figure it out and I did
post my conclusion. It is in this NG somewhere.

Sincerely,

Injam

"M" wrote in message
ups.com...

Injam wrote:
If we use a 24" pitch propeller and there was no slippage, both boats
would
travel 12,000 feet every minute at 6000 RPM.

With the same propeller on each boat the 250 hp boat would over rev at
WOT.
So the helmsman would have to back off to keep it at 6000. The difference
in
weight of the motors is about 30 lbs. Probably not going to be much of a
factor. The 250 might get to 6000 more quickly, but once at 6000 I think
both boats would be traveling at the same speed.

Thanks again,
Injam

"Injam" wrote in message
ink.net...
Hello,

I'm trying to understand propellers.

If you have two identical boats, but the outboard horsepower ratings
are
different. One boat has a 200 hp and the other a 250 hp. Both motors
have
the same Gear Ratio. If the propellers are identical and the RPM of the
outboard is the same on each boat. Say 6000 RPM. Because of the weight
advantage will the 200-hp boat be faster than the 250 hp? I'm thinking
less weight less slippage otherwise they would be going the same speed.

Depending on what brand motor you have they will even weigh the same...
even if not the little difference in weight will not make a difference.

Here is how it goes:

- Both boats would be the same fast in Theory.

- In reality one of these will happen:

a. The 200 HP motor could not rev up to 6000 rpm IF its a prop for the
250

b. If the prop is for the 200 HP motor the 250 would rev at 6000 not be
able to put more power in the water.

c. The 250 would accelerate faster until it has reached 6000 rpm and
there have the same speed as the 200 (if it can swing the prop).


A similar question is:

"Is a 250 HP 2 stroke or 250 HP 4 stroke faster?"

answer is: They will reach the same top speed but the 2 stroke will
likely accelerate faster.

In reality acceleration and top speed may be different as both will be
propped and geared differently and have different torque curves. But
for top speed its peak HP that matters.

Matt

I'm trying to understand propellers
 

"Injam" wrote in message
ink.net...


Just having a little fun. Thanks for the post. I did figure it out and I
did post my conclusion. It is in this NG somewhere.

Sincerely,

Injam



Admit it. It was the clocks that did it, huh?
Maybe now you can explain it to Shortwave if he can take a break from taking
pictures of bugs.

RCE

I'm trying to understand propellers
 

Injam wrote:
- Both boats would be the same fast in Theory.

The same fast. Yes boats go same fast, Tarzan.

whatever you say



a. The 200 HP motor could not rev up to 6000 rpm IF its a prop for the
250

In my scenario the 200hp is turning at 6000 RPM.


read my post ....

b. If the prop is for the 200 HP motor the 250 would rev at 6000 not be
able to put more power in the water.

I don't even know what you are saying.

I imagine

c. The 250 would accelerate faster until it has reached 6000 rpm and
there have the same speed as the 200 (if it can swing the prop).

The 200hp can (swing the prop), but because of it's lighter weight the 200hp
would pass the 250hp on are about the five mile mark. At the ten
thousand-mile mark the 200hp would be approximately five thousand miles
ahead of the 250hp.

Thats just not true. A lot of 200 and 250 HP motors weigh exactly (!)
the same (i.e. Verado) and if one weighed 20lbs more it would hardly
noticably affect top speed.

The 200 HP would be ahead? How that?

If so the 250 would be ahead as it would accelerate up to your 6000 rpm
faster as the 200. Since EVERYTING else is the same. Same boat, same
weight, same prop. They would then continue with lead the 250 has.

Same rpm under same conditions will get the same speed. Duh.


Just having a little fun.

Getting a little insulting with "Tarzan" comments as well?

Matt

I'm trying to understand propellers
 

I have a degree in photography and I like taking photos of bugs.

Yes it was the clock thing that turned the light bulb on.

"RCE" wrote in message
...

"Injam" wrote in message
ink.net...


Just having a little fun. Thanks for the post. I did figure it out and I
did post my conclusion. It is in this NG somewhere.

Sincerely,

Injam



Admit it. It was the clocks that did it, huh?
Maybe now you can explain it to Shortwave if he can take a break from
taking pictures of bugs.

RCE

I'm trying to understand propellers
 

Sorry about that M. I was not trying to be insulting just funny.
But what I say is true. The 200hp boat would be faster.
In my scenario the 200hp boat is lighter.

Sincerely,
Injam

"M" wrote in message
oups.com...

Injam wrote:
- Both boats would be the same fast in Theory.

The same fast. Yes boats go same fast, Tarzan.

whatever you say



a. The 200 HP motor could not rev up to 6000 rpm IF its a prop for the
250

In my scenario the 200hp is turning at 6000 RPM.


read my post ....

b. If the prop is for the 200 HP motor the 250 would rev at 6000 not be
able to put more power in the water.

I don't even know what you are saying.

I imagine

c. The 250 would accelerate faster until it has reached 6000 rpm and
there have the same speed as the 200 (if it can swing the prop).

The 200hp can (swing the prop), but because of it's lighter weight the
200hp
would pass the 250hp on are about the five mile mark. At the ten
thousand-mile mark the 200hp would be approximately five thousand miles
ahead of the 250hp.

Thats just not true. A lot of 200 and 250 HP motors weigh exactly (!)
the same (i.e. Verado) and if one weighed 20lbs more it would hardly
noticably affect top speed.

The 200 HP would be ahead? How that?

If so the 250 would be ahead as it would accelerate up to your 6000 rpm
faster as the 200. Since EVERYTING else is the same. Same boat, same
weight, same prop. They would then continue with lead the 250 has.

Same rpm under same conditions will get the same speed. Duh.


Just having a little fun.

Getting a little insulting with "Tarzan" comments as well?

Matt

I'm trying to understand propellers
 

Yeah. I said in another post that the 250hp boat would have a prop that
would over rev it. The driver would have to ease off the throttle in order
to keep it at 6000 RPM.



"M" wrote in message
oups.com...

Injam wrote:
Sorry about that M. I was not trying to be insulting just funny.
But what I say is true. The 200hp boat would be faster.
In my scenario the 200hp boat is lighter.

Sincerely,
Injam



Ok. lets not worry about the Tarzan then...


Yes. If the 200 HP boat is lighter it will be faster. There you are
right. But rather than the HP the real difference is purely weight.

Matt

I'm trying to understand propellers
 

OMG people...this is so simple, I can't believe it's still going on. Two
boats, identical in every way *except* one has 50 more horses than the
other, turning a prop at 6000 rpm. At 6000 rpm, they will be traveling at
the exact same speed. Forget about the fact that the stronger engine may get
to speed faster...*AT* 6000 rpm they will be moving at the same speed! We're
talking *SPEED* here not *distance* in a given time. Of course if someone in
the 250hp boat raises a skier's spotter flag while underway, that changes
everything g.

--Mike

"M" wrote in message
oups.com...

Injam wrote:
Yeah. I said in another post that the 250hp boat would have a prop that
would over rev it. The driver would have to ease off the throttle in
order
to keep it at 6000 RPM.



"M" wrote in message
oups.com...

Injam wrote:
Sorry about that M. I was not trying to be insulting just funny.
But what I say is true. The 200hp boat would be faster.
In my scenario the 200hp boat is lighter.

yes. same prop the 250 would not go WOT ..

Your example may be simpler if you said same everything , 200 HP but
one boat heavier as the other...

More power would have to be used to push the heavier boat out of the
water thus less power would be available to push it forward...

Matt