Not sure why you say this Rob. A 21 double cupped will definetly help on
the hole shot but will overrev by about 250 rpms. The double cupping adds
bite and creates extra drag which reduces the rpms without adding pitch. It
will also slow the boat down considerable due to the fact that your now
turning a 21 instead of a 23. Expect about 5 mph drop in top end if you
keep the rpms at 4600 (don't overrev).

As for the Torque Shift prop - I don't care for the maintenance of the prop
springs and the cracked hubs and the stress on the lower unit. They do work
but are not worth the money and maintenance costs.

--
Tony
my boats at http://t.thomas.home.mchsi.com

"trainfan1" wrote in message
...
Steve wrote:
I'm looking for help in selecting a new prop. I'm currently running a 14
1/4x 23p
3 blade that came on the boat from the factory. The boat is a 2003
Larson
SEI 190 (open bow runabout) with a 4.3 volvo sx sterndrive. It will turn
this prop 4600 rpms (4200-4600 reccomended by volvo at WOT) and 49 mph
according to speedometer at WOT.

This summer we have started doing alot of slalom skiing. Needless to say
it
is a bit lacking on power to pull up a 200# plus skier . I have been
looking
at 4 and 5 blade props but am at a loss as to what size should work best
for
me. Also is there a big trade off for power to loss of top end? I need
something that will be a good all around prop as we do alot of tubing
and
wakeboarding as well as just cruising around the lake.

I do not have a local dealer that will let me try out different sizes.
I'm
not afraid to spend some $ on a good prop, but dont want to experiment
with
sizes at the prices of these props.

Thanks for any help Steve




I would go for a 3 blade stainless 21" double cupped. It should give
you improved holeshot with superior water-holding & comparable top end
speed & rpm's... maybe just a little higher rpm's. For a wild set-up,
go for the Land & Sea Torque-Shift variable pitch prop... holeshot out
at 13"-14" and top end speed at 23"-24". Your boat will "jump" out of
the water!

Rob

On Thu, 09 Sep 2004 01:00:54 GMT, "Tony Thomas"
wrote:

Not sure why you say this Rob. A 21 double cupped will definetly help on
the hole shot but will overrev by about 250 rpms. The double cupping adds
bite and creates extra drag which reduces the rpms without adding pitch. It
will also slow the boat down considerable due to the fact that your now
turning a 21 instead of a 23. Expect about 5 mph drop in top end if you
keep the rpms at 4600 (don't overrev).

As for the Torque Shift prop - I don't care for the maintenance of the prop
springs and the cracked hubs and the stress on the lower unit. They do work
but are not worth the money and maintenance costs.

I have a question for you.

My friend who has the engine problems also has a prop problem. He is
currently swinging a 14 1/2 x 23 on an Evinrude 200 FICHTand gets
about 38 mph at 5400 rpm WOT fully trimmed out. He can change pitch
which changes RPM but no relative increase in speed - in fact with a
21, he got 5700 RPM and lost four mph. The engine is properly
installed, etc.

Any idea why?

Later,

Tom

You are exactly right. Dropping to a 21 will increase rpms by about 300 and
drop your speed. You would have to increase rpms by 500 to maintain the
same speed w/ a 2" drop in pitch.

However, something does not add up based on the numbers.
23 x 5400 / 1056 / 1.86 = 63 mph. That means you have a 60% efficiency.
Even if you had a 2:1 gearcase you still have a theoritical speed of 58 mph
which gives a 65% efficiency.



--
Tony
my boats at http://t.thomas.home.mchsi.com

"Short Wave Sportfishing" wrote in message
...
On Thu, 09 Sep 2004 01:00:54 GMT, "Tony Thomas"
wrote:

Not sure why you say this Rob. A 21 double cupped will definetly help on
the hole shot but will overrev by about 250 rpms. The double cupping
adds
bite and creates extra drag which reduces the rpms without adding pitch.
It
will also slow the boat down considerable due to the fact that your now
turning a 21 instead of a 23. Expect about 5 mph drop in top end if you
keep the rpms at 4600 (don't overrev).

As for the Torque Shift prop - I don't care for the maintenance of the
prop
springs and the cracked hubs and the stress on the lower unit. They do
work
but are not worth the money and maintenance costs.

I have a question for you.

My friend who has the engine problems also has a prop problem. He is
currently swinging a 14 1/2 x 23 on an Evinrude 200 FICHTand gets
about 38 mph at 5400 rpm WOT fully trimmed out. He can change pitch
which changes RPM but no relative increase in speed - in fact with a
21, he got 5700 RPM and lost four mph. The engine is properly
installed, etc.

Any idea why?

Later,

Tom

On Fri, 10 Sep 2004 03:02:03 GMT, "Tony Thomas"
wrote:

You are exactly right. Dropping to a 21 will increase rpms by about 300 and
drop your speed. You would have to increase rpms by 500 to maintain the
same speed w/ a 2" drop in pitch.

However, something does not add up based on the numbers.
23 x 5400 / 1056 / 1.86 = 63 mph. That means you have a 60% efficiency.
Even if you had a 2:1 gearcase you still have a theoritical speed of 58 mph
which gives a 65% efficiency.

You 'da man!!!!

I never thought of the gear case.

I'll let him know.

Take care.

Tom

"The beatings will stop when morale improves."
E. Teach, 1717

Tony Thomas wrote:
Not sure why you say this Rob. A 21 double cupped will definetly help on
the hole shot but will overrev by about 250 rpms. The double cupping adds
bite and creates extra drag which reduces the rpms without adding pitch.

You almost answer your own question here...

It
will also slow the boat down considerable due to the fact that your now
turning a 21 instead of a 23. Expect about 5 mph drop in top end if you
keep the rpms at 4600 (don't overrev).

This should be somewhat offset by the switch to a precision SS prop from
a cast aluminum wheel - typically minimal loss of top end...

As for the Torque Shift prop - I don't care for the maintenance of the prop
springs and the cracked hubs and the stress on the lower unit. They do work
but are not worth the money and maintenance costs.


For a Mercruiser Alpha, you are correct, but a Volvo SX should be able
to handle it... esp. with the V-6.

Rob