Anybody have any experience with the segmented composite props like the
4-blade Pirahana?
Pros and cons from the real world? As always the ads look good.
Most of the use will be for wakeboarding and cruising. I am looking at an
18P x 4 blade for an '86 20' Chapparal with 305 Alpha 1. Currently using a
17P alum 3 blade which will over-rev up to ~5100. 19P x 3 blade alum yeilds
top rev of 3800 and no pull.
Not keen on SS due to cost and potential damage to lower drive if I hit
something in the water.
Thanks in advance.
jbrown

Something doesn't add up, going from a 17p to 19p should only drop your RPM
300-400rpm. Comp props work well.

"Jeff Brown" wrote in message
...
Anybody have any experience with the segmented composite props like the
4-blade Pirahana?
Pros and cons from the real world? As always the ads look good.
Most of the use will be for wakeboarding and cruising. I am looking at an
18P x 4 blade for an '86 20' Chapparal with 305 Alpha 1. Currently using a
17P alum 3 blade which will over-rev up to ~5100. 19P x 3 blade alum
yeilds
top rev of 3800 and no pull.
Not keen on SS due to cost and potential damage to lower drive if I hit
something in the water.
Thanks in advance.
jbrown

Remember, you pay for what you get.
First - something is wrong. No way going from a 17 to a 19 is going to drop
the rpms by 1300. 300 would be right.
Second - That is a heavy boat and w/ the 305 you really need a good SS prop
to get this boat to perform. A good 4 blade SS prop used should be
available in an 18 pitch.
Third - the pirahana prop will flex under this load and will not hold it
shape or be very good out of the hole for your load.
Fourth - I don't know why people think a SS prop is going to tear up stuff.
They obviously don't have much boating experience. The hub is the weak link
in the prop/drivetrain. What will peal the ear off an aluminum or composite
prop will not even scratch the SS prop or the outdrive. If you hit
something hard enough to tear up your drive w/ a SS prop - you will tear it
up w/ the aluminum one also as you are going to hit the drive on the object
and not just the prop.

Bottom line - Get a 4 blade SS 18pitch and find out how your boat is
supposed to perform.


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

"Jeff Brown" wrote in message
...
Anybody have any experience with the segmented composite props like the
4-blade Pirahana?
Pros and cons from the real world? As always the ads look good.
Most of the use will be for wakeboarding and cruising. I am looking at an
18P x 4 blade for an '86 20' Chapparal with 305 Alpha 1. Currently using a
17P alum 3 blade which will over-rev up to ~5100. 19P x 3 blade alum
yeilds
top rev of 3800 and no pull.
Not keen on SS due to cost and potential damage to lower drive if I hit
something in the water.
Thanks in advance.
jbrown

Yes.

Your engine config is marginal with this prop.

I had one on a V6 170HP Volvo sterndrive a few years ago. I lost TWO blades
in relatively rapid succession with no impact, not running over anything,
nothing.

Both blade failures occurred while attempting a deep-water ski start.
That's maximum load, of course. Both incidents required an in-water removal
and repair of the prop, which is not hard to do, but a royal PITA when it
occurs due to no reason at all.

If you had less power, it'd probably be ok. However, load 'em heavily and
the blades will break on it in my experience.

I gave up on the prop after the second failure. I still have it in my
garage, but it sits unused.

While it stayed together performance was good.

--
--
Karl Denninger ) Internet Consultant & Kids Rights Activist
http://www.denninger.net My home on the net
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In article ,
Jeff Brown wrote:


Anybody have any experience with the segmented composite props like the
4-blade Pirahana?
Pros and cons from the real world? As always the ads look good.
Most of the use will be for wakeboarding and cruising. I am looking at an
18P x 4 blade for an '86 20' Chapparal with 305 Alpha 1. Currently using a
17P alum 3 blade which will over-rev up to ~5100. 19P x 3 blade alum yeilds
top rev of 3800 and no pull.
Not keen on SS due to cost and potential damage to lower drive if I hit
something in the water.
Thanks in advance.
jbrown

"Jeff Brown" wrote in message
...
Anybody have any experience with the segmented composite props like the
4-blade Pirahana?
Pros and cons from the real world? As always the ads look good.
Most of the use will be for wakeboarding and cruising. I am looking at an
18P x 4 blade for an '86 20' Chapparal with 305 Alpha 1. Currently using a
17P alum 3 blade which will over-rev up to ~5100. 19P x 3 blade alum
yeilds
top rev of 3800 and no pull.
Not keen on SS due to cost and potential damage to lower drive if I hit
something in the water.
Thanks in advance.
jbrown


Thanks for the input. The loss of rpm on the 19p is probably due to the
fact that it is a VERY old prop. A very rough beater that was stowed up in
the bilge of the boat when I bought it. It appears to have no cupping and
the exhaust dia. may be constricted as well. I have used a newer 19p prop
with fair results. I have a chance to buy a used 17P ss for a reasonable $.
Will the 4th blade be that much of an improvement? Sounds like the
composite will have significant flex under the heavy load.
Thanks again for the help.
best regards
jbrown

The 4 blade will make a difference in acceleration but the 3 blade will be
faster on top end. I assume the 17 you found is a performance polished SS
and not just a black SS prop.
You will probably be happy with it until you get a chance to try a good 4
blade.

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

"Jeff Brown" wrote in message
...
"Jeff Brown" wrote in message
...
Anybody have any experience with the segmented composite props like the
4-blade Pirahana?
Pros and cons from the real world? As always the ads look good.
Most of the use will be for wakeboarding and cruising. I am looking at
an
18P x 4 blade for an '86 20' Chapparal with 305 Alpha 1. Currently using
a
17P alum 3 blade which will over-rev up to ~5100. 19P x 3 blade alum
yeilds
top rev of 3800 and no pull.
Not keen on SS due to cost and potential damage to lower drive if I hit
something in the water.
Thanks in advance.
jbrown


Thanks for the input. The loss of rpm on the 19p is probably due to the
fact that it is a VERY old prop. A very rough beater that was stowed up in
the bilge of the boat when I bought it. It appears to have no cupping and
the exhaust dia. may be constricted as well. I have used a newer 19p prop
with fair results. I have a chance to buy a used 17P ss for a reasonable
$.
Will the 4th blade be that much of an improvement? Sounds like the
composite will have significant flex under the heavy load.
Thanks again for the help.
best regards
jbrown