Prop advice for Volvo Penta
 

I have a 1998 17ft Larson 176 SEI bowrider with a Volvo Penta SX Cobra 3.0
Liter with 130HP. I have a 3 blade alum. prop, which is 14 1/4 x 21 pitch.
It is lightly pitted and has very minor damage to it. At WOT my RPM gauge
reads 2300 with a top speed between 33-36 MPH in fresh water. My owners
manual states that the recommended operating range at wide open throttle is
between 4400 - 4600 RPMs. This is a big difference in RPMs. I have
trouble getting skiers up and have played with the trim and weight
distribution to no avail. Should I get a 4 blade, larger diameter, or
lower pitch prop? What else would cause it not to plan or reach the
recommended WOT RPM range? Thanks.

Prop advice for Volvo Penta
 

On Thu, 10 Jul 2003 13:56:06 +0000 (UTC), Joseph
wrote:

I have a 1998 17ft Larson 176 SEI bowrider with a Volvo Penta SX Cobra 3.0
Liter with 130HP. I have a 3 blade alum. prop, which is 14 1/4 x 21 pitch.
It is lightly pitted and has very minor damage to it. At WOT my RPM gauge
reads 2300 with a top speed between 33-36 MPH in fresh water. My owners
manual states that the recommended operating range at wide open throttle is
between 4400 - 4600 RPMs. This is a big difference in RPMs. I have
trouble getting skiers up and have played with the trim and weight
distribution to no avail. Should I get a 4 blade, larger diameter, or
lower pitch prop? What else would cause it not to plan or reach the
recommended WOT RPM range? Thanks.

Wow. That's a *big* drop in WOT. It sounds like someone overpropped
your boat.

The 21" pitch may be a bit much for your boat and 130hp. I think
you'll end up with around a 17" or 19", but do some research. There
are a number of Mfr's sites on the web that will help you with this,
or go to your boat dealer.

*IF* your tach is accurate, you are lugging your engine, and you could
damage it. Don't put off checking this out.
noah

Courtesy of Lee Yeaton,
See the boats of rec.boats
www.TheBayGuide.com/rec.boats

Prop advice for Volvo Penta
 

My guess is your tach is wrong. Boat would not even plain off at 2300 rpms
(chances are).
Also at 2300 rpms w/ a 21 pitch prop your speed would be (assuming a 2:1
gear) would be 20 mph max and probably more like 18.
Buy a cheap automotive tach from the parts store and hook it up. My guess
is your at 4000 rpms if not more.
Having said that, you probably need a 19 pitch prop. 4 blade would be good
for your rig in trying to ski and stuff. SS is always better.

Tony


"Joseph" wrote in message
...
I have a 1998 17ft Larson 176 SEI bowrider with a Volvo Penta SX Cobra 3.0
Liter with 130HP. I have a 3 blade alum. prop, which is 14 1/4 x 21
pitch.
It is lightly pitted and has very minor damage to it. At WOT my RPM
gauge
reads 2300 with a top speed between 33-36 MPH in fresh water. My owners
manual states that the recommended operating range at wide open throttle
is
between 4400 - 4600 RPMs. This is a big difference in RPMs. I have
trouble getting skiers up and have played with the trim and weight
distribution to no avail. Should I get a 4 blade, larger diameter, or
lower pitch prop? What else would cause it not to plan or reach the
recommended WOT RPM range? Thanks.