RPM & WOT question
 

I just re-proped my boat -- my range is supposed to be 4200-4600

is this under "best case" conditions? (flat water, no wind, light load, trim
optimised, etc)

Or "no mater what, when you're "WOT" your engine should be between 4200-4600?

Thanks
Davie

RPM & WOT question
 

"Dave Jones" wrote in message
...
I just re-proped my boat -- my range is supposed to be 4200-4600

is this under "best case" conditions? (flat water, no wind, light load,
trim
optimised, etc)

Or "no mater what, when you're "WOT" your engine should be between
4200-4600?

Thanks
Davie

It should be optimized for your normal loading and usage and depends a lot
on the size of your boat. That RPM range indicates a likely I/O setup and I
assume it's a single engine. You may find out, as I did years ago, that you
will have two props ... one for normal use with 2 or 3 people aboard and a
second, lower pitched prop for when the whole gang shows up for a boat ride.

RCE

www.eisboch.com

RPM & WOT question
 

That's why it's a range..... 4600 lean and mean 4200 with the whole fam
damily.

But assume 4600 is max at leanest config, so if you prop it lighter, watch
the tach and don't exceed.

-W

"Dave Jones" wrote in message
...
I just re-proped my boat -- my range is supposed to be 4200-4600

is this under "best case" conditions? (flat water, no wind, light load,
trim
optimised, etc)

Or "no mater what, when you're "WOT" your engine should be between
4200-4600?

Thanks
Davie

RPM & WOT question
 

Someone should invent an easily adjustable, variable-pitch prop. Maybe
I will. I just hate pulling the prop off my OMC.

Jeff



Dave Jones wrote:
I just re-proped my boat -- my range is supposed to be 4200-4600

is this under "best case" conditions? (flat water, no wind, light load, trim
optimised, etc)

Or "no mater what, when you're "WOT" your engine should be between 4200-4600?

Thanks
Davie

RPM & WOT question
 

"Chehalis Jeff" wrote in message
ps.com...
Someone should invent an easily adjustable, variable-pitch prop. Maybe
I will. I just hate pulling the prop off my OMC.

Jeff




I think one of the outboard manufacturers (Mercury?) tried to introduce an
"automatic" variable pitch prop many years ago that had two pitch positions.
It was costly, problem prone and it's performance wasn't any better than a
properly sized fixed pitch prop. The prop was a flop.

RCE

www.eisboch.com

RPM & WOT question
 

RCE wrote:
"Dave Jones" wrote in message
...

I just re-proped my boat -- my range is supposed to be 4200-4600

is this under "best case" conditions? (flat water, no wind, light load,
trim
optimised, etc)

Or "no mater what, when you're "WOT" your engine should be between
4200-4600?

Thanks
Davie


It should be optimized for your normal loading and usage and depends a lot
on the size of your boat. That RPM range indicates a likely I/O setup and I
assume it's a single engine. You may find out, as I did years ago, that you
will have two props ... one for normal use with 2 or 3 people aboard and a
second, lower pitched prop for when the whole gang shows up for a boat ride.

RCE

www.eisboch.com



Excellent advice. For my Evinrude 115(16' Glastron), I have a SS 19"
prop that is good for overall use, a SS 17" prop for heavy loads w/
watersports & gear for a day away from the dock, and a large surface
area AL 15" prop for power on demand (we sometimes pull 5 skiers with
this prop) but even with 5 skiers in tow, the engine will over-rev at
full throttle once they are up.

Our old inboard is getting tired, I have 2 14", a 15", a 10" & a 9"
NiBrAl (or brass) props for it, it likes the 14" cupped Michigan the
best at 4600-4800 rpm(engine is rated 220hp at 4400) . It over revs
with the 14" Stannus, to almost 5000 rpm, this we do only for short
bursts with a good load in the boat.

I/O & inboard engines(& most outboards - some Mercs are VERY sensitive
to this) really should not be run for any duration over recommended WOT max.

Target the middle of the range with your usual load.

Rob

RPM & WOT question
 

I just put a 21" pitch on my boat (same range) and WHAT A DIFFERENCE! 10mph
improvement and still w/in range (supposed to use a 19)

That was iwth me - tonight I'll take my wife to work (two people) and bring
friends back (5 people total). We'll see how it runs then.

As I understand it; the WOT rpm range is under "ideal" situations.

On Thu, 15 Jun 2006 13:11:43 -0700, Dave Jones wrote:

I just re-proped my boat -- my range is supposed to be 4200-4600

is this under "best case" conditions? (flat water, no wind, light load, trim
optimised, etc)

Or "no mater what, when you're "WOT" your engine should be between 4200-4600?

Thanks
Davie


--- AntiSpam/harvest ---
Remove X's to send email to me.

RPM & WOT question
 

That's why it's a range..... 4600 lean and mean 4200 with the whole fam
damily.

But assume 4600 is max at leanest config, so if you prop it lighter, watch
the tach and don't exceed.

So my new 21" pitch -- me alone, WOT , semi-flat water trimed right, 4300 RPM --
the prop is no good? Too much strain on the engine?

(I may have 14.5x21" prop for sale soon)


--- AntiSpam/harvest ---
Remove X's to send email to me.

RPM & WOT question
 

"RCE" wrote in message
...

"Dave Jones" wrote in message
...
I just re-proped my boat -- my range is supposed to be 4200-4600

is this under "best case" conditions? (flat water, no wind, light load,
trim
optimised, etc)

Or "no mater what, when you're "WOT" your engine should be between
4200-4600?

Thanks
Davie

It should be optimized for your normal loading and usage and depends a lot
on the size of your boat. That RPM range indicates a likely I/O setup and
I assume it's a single engine. You may find out, as I did years ago, that
you will have two props ... one for normal use with 2 or 3 people aboard
and a second, lower pitched prop for when the whole gang shows up for a
boat ride.

RCE

www.eisboch.com


Are you telling us that you actually changed props each time your guest list
changed?

RPM & WOT question
 

Josh Assing wrote:

That's why it's a range..... 4600 lean and mean 4200 with the whole fam
damily.

But assume 4600 is max at leanest config, so if you prop it lighter, watch
the tach and don't exceed.


So my new 21" pitch -- me alone, WOT , semi-flat water trimed right, 4300 RPM --
the prop is no good? Too much strain on the engine?

Looks good from here...

Rob


(I may have 14.5x21" prop for sale soon)


--- AntiSpam/harvest ---
Remove X's to send email to me.