Question about props
 

I have a 20' Bayliner, a 1990 with a 5.0L Merc and (I think) Alpha 1
outdrive. The engine has been modified with a 4BBL carb (now a marine one,
for those who followed my earlier travails!) which should give it about 230
HP (as comared with 200HP with the original 2BBL).

After getting the engine fixed up with the right kind of carb, I took it out
on the lake last week and while the engine seems to run well, there's
absolutely no way the boat could have gotten an adult out of the water on
skis. Top speed is pretty good (nearly 40 mph, and this is at an elevation
of over 5000 feet) but the boat is really slow to dig its way up onto
plane. As you might guess from the subject line, I suspect the prop.

This boat apparently came with, and was pretty much always run with, a
three-bladed 17 pitch prop. This spring, however, the former owner trashed
the prop on a sand bar. Before he sold it, he purchased a new four-bladed,
19 pitch aluminum prop (don't know what the diameter is, but it looks about
the same as the previous 17-pitch prop, which he left in the boat). My
suspicion is that this prop is just too much for my engine to turn, but I
don't really know if 2 inches of pitch make that much difference.

At plane, with a wide-open throttle (assuming the throttle cable is adjusted
correctly), the engine peaks out at 3500 rpm. According to a Mercruiser
manual I have, it should run to about 4200 WOT.

So, before I go buy a prop, what do you all think? Should this engine be
able to handle a 19 pitch? Actually, I'll buy a prop anyway, because it's
cheaper than looking into deeper engine problems, and if it gets me
acceptable performance, I'll stick with it. However, if the current
performance indicates that there might be other problems, I'd rather know
sooner rather than later, even if I decide not to do anything.

Thanks for any help,

Shawn

Question about props
 

At 5000ft I would be surprised if you have more than about 175-180 horses.
MY guess to get the RPM where it should be figure on buying a 15p prop. I
would think your RPM range should be 4200-4600.


"Shawn Willden" wrote in message
...
I have a 20' Bayliner, a 1990 with a 5.0L Merc and (I think) Alpha 1
outdrive. The engine has been modified with a 4BBL carb (now a marine
one,
for those who followed my earlier travails!) which should give it about
230
HP (as comared with 200HP with the original 2BBL).

After getting the engine fixed up with the right kind of carb, I took it
out
on the lake last week and while the engine seems to run well, there's
absolutely no way the boat could have gotten an adult out of the water on
skis. Top speed is pretty good (nearly 40 mph, and this is at an
elevation
of over 5000 feet) but the boat is really slow to dig its way up onto
plane. As you might guess from the subject line, I suspect the prop.

This boat apparently came with, and was pretty much always run with, a
three-bladed 17 pitch prop. This spring, however, the former owner
trashed
the prop on a sand bar. Before he sold it, he purchased a new
four-bladed,
19 pitch aluminum prop (don't know what the diameter is, but it looks
about
the same as the previous 17-pitch prop, which he left in the boat). My
suspicion is that this prop is just too much for my engine to turn, but I
don't really know if 2 inches of pitch make that much difference.

At plane, with a wide-open throttle (assuming the throttle cable is
adjusted
correctly), the engine peaks out at 3500 rpm. According to a Mercruiser
manual I have, it should run to about 4200 WOT.

So, before I go buy a prop, what do you all think? Should this engine be
able to handle a 19 pitch? Actually, I'll buy a prop anyway, because it's
cheaper than looking into deeper engine problems, and if it gets me
acceptable performance, I'll stick with it. However, if the current
performance indicates that there might be other problems, I'd rather know
sooner rather than later, even if I decide not to do anything.

Thanks for any help,

Shawn

Question about props
 

I keep telling people, 4 blade props will slow you down, and nobody
listens.....
go back to a 17" three blade, or check with a boat dealer what the original
prop was....
if you want to push a 4 blade, then go to a 250 hp outboard.

"Shawn Willden" wrote in message
...
I have a 20' Bayliner, a 1990 with a 5.0L Merc and (I think) Alpha 1
outdrive. The engine has been modified with a 4BBL carb (now a marine
one,
for those who followed my earlier travails!) which should give it about
230
HP (as comared with 200HP with the original 2BBL).

After getting the engine fixed up with the right kind of carb, I took it
out
on the lake last week and while the engine seems to run well, there's
absolutely no way the boat could have gotten an adult out of the water on
skis. Top speed is pretty good (nearly 40 mph, and this is at an
elevation
of over 5000 feet) but the boat is really slow to dig its way up onto
plane. As you might guess from the subject line, I suspect the prop.

This boat apparently came with, and was pretty much always run with, a
three-bladed 17 pitch prop. This spring, however, the former owner
trashed
the prop on a sand bar. Before he sold it, he purchased a new
four-bladed,
19 pitch aluminum prop (don't know what the diameter is, but it looks
about
the same as the previous 17-pitch prop, which he left in the boat). My
suspicion is that this prop is just too much for my engine to turn, but I
don't really know if 2 inches of pitch make that much difference.

At plane, with a wide-open throttle (assuming the throttle cable is
adjusted
correctly), the engine peaks out at 3500 rpm. According to a Mercruiser
manual I have, it should run to about 4200 WOT.

So, before I go buy a prop, what do you all think? Should this engine be
able to handle a 19 pitch? Actually, I'll buy a prop anyway, because it's
cheaper than looking into deeper engine problems, and if it gets me
acceptable performance, I'll stick with it. However, if the current
performance indicates that there might be other problems, I'd rather know
sooner rather than later, even if I decide not to do anything.

Thanks for any help,

Shawn

Question about props
 

Okay, based on a couple of responses, it sounds likely that the prop is
probably just too much for the engine (especially at altitude).

Any recommendations about where I can buy good quality props cheaply? I'll
hit Google and e-bay, obviously, but if there are any particularly good
on-line shops, I'd appreciate pointers. OTOH, since props are bulky and
heavy, the shipping costs may be heavy.

I also have to figure out the exact specs of the prop I need. I'll look at
my Merc manual and the props I have, but again, any pointers would be
greatly appreciated.

Thanks again,

Shawn.

Question about props
 

In article ,
says...
I keep telling people, 4 blade props will slow you down, and nobody
listens.....
go back to a 17" three blade, or check with a boat dealer what the original
prop was....
if you want to push a 4 blade, then go to a 250 hp outboard.

"Shawn Willden" wrote in message
...
I have a 20' Bayliner, a 1990 with a 5.0L Merc and (I think) Alpha 1
outdrive. The engine has been modified with a 4BBL carb (now a marine
one,
for those who followed my earlier travails!) which should give it about
230
HP (as comared with 200HP with the original 2BBL).

After getting the engine fixed up with the right kind of carb, I took it
out
on the lake last week and while the engine seems to run well, there's
absolutely no way the boat could have gotten an adult out of the water on
skis. Top speed is pretty good (nearly 40 mph, and this is at an
elevation
of over 5000 feet) but the boat is really slow to dig its way up onto
plane. As you might guess from the subject line, I suspect the prop.

This boat apparently came with, and was pretty much always run with, a
three-bladed 17 pitch prop. This spring, however, the former owner
trashed
the prop on a sand bar. Before he sold it, he purchased a new
four-bladed,
19 pitch aluminum prop (don't know what the diameter is, but it looks
about
the same as the previous 17-pitch prop, which he left in the boat). My
suspicion is that this prop is just too much for my engine to turn, but I
don't really know if 2 inches of pitch make that much difference.

At plane, with a wide-open throttle (assuming the throttle cable is
adjusted
correctly), the engine peaks out at 3500 rpm. According to a Mercruiser
manual I have, it should run to about 4200 WOT.

So, before I go buy a prop, what do you all think? Should this engine be
able to handle a 19 pitch? Actually, I'll buy a prop anyway, because it's
cheaper than looking into deeper engine problems, and if it gets me
acceptable performance, I'll stick with it. However, if the current
performance indicates that there might be other problems, I'd rather know
sooner rather than later, even if I decide not to do anything.

Thanks for any help,

Shawn


Ok, I'm new here and it's been a long time since I had anything to do
with small boats and even then the prop wasn't my concern. Now it will
be, Why will a four bladed prop slow you down?

Thanks.
--
MikeG
Heirloom Woods
www.heirloom-woods.net

Question about props
 

A 19 pitch 4 blade prop is equivalent to a 21 pitch 3 bladed prop. If you go
back to a 17 pitch 3 bladed. you should increase your rpms by 6-800.

--
Bill
Chesapeake, Va


"Shawn Willden" wrote in message
...
I have a 20' Bayliner, a 1990 with a 5.0L Merc and (I think) Alpha 1
outdrive. The engine has been modified with a 4BBL carb (now a marine
one,
for those who followed my earlier travails!) which should give it about
230
HP (as comared with 200HP with the original 2BBL).

After getting the engine fixed up with the right kind of carb, I took it
out
on the lake last week and while the engine seems to run well, there's
absolutely no way the boat could have gotten an adult out of the water on
skis. Top speed is pretty good (nearly 40 mph, and this is at an
elevation
of over 5000 feet) but the boat is really slow to dig its way up onto
plane. As you might guess from the subject line, I suspect the prop.

This boat apparently came with, and was pretty much always run with, a
three-bladed 17 pitch prop. This spring, however, the former owner
trashed
the prop on a sand bar. Before he sold it, he purchased a new
four-bladed,
19 pitch aluminum prop (don't know what the diameter is, but it looks
about
the same as the previous 17-pitch prop, which he left in the boat). My
suspicion is that this prop is just too much for my engine to turn, but I
don't really know if 2 inches of pitch make that much difference.

At plane, with a wide-open throttle (assuming the throttle cable is
adjusted
correctly), the engine peaks out at 3500 rpm. According to a Mercruiser
manual I have, it should run to about 4200 WOT.

So, before I go buy a prop, what do you all think? Should this engine be
able to handle a 19 pitch? Actually, I'll buy a prop anyway, because it's
cheaper than looking into deeper engine problems, and if it gets me
acceptable performance, I'll stick with it. However, if the current
performance indicates that there might be other problems, I'd rather know
sooner rather than later, even if I decide not to do anything.

Thanks for any help,

Shawn

Question about props
 

A 4 blade prop of the same pitch will be slower on top end due to the extra
blade surface (althought a 4 blade will usually be smaller in diameter to
help compensate - it still will be slower on top end).
A 4 blade prop of the same pitch will be faster out of the hole due to less
slippage. A 4 blade is more efficient at lower rpms.

If your not comparing same pitch then all bets are off.

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

"MikeG" wrote in message
ws.com...
In article ,
says...
I keep telling people, 4 blade props will slow you down, and nobody
listens.....
go back to a 17" three blade, or check with a boat dealer what the
original
prop was....
if you want to push a 4 blade, then go to a 250 hp outboard.

"Shawn Willden" wrote in message
...
I have a 20' Bayliner, a 1990 with a 5.0L Merc and (I think) Alpha 1
outdrive. The engine has been modified with a 4BBL carb (now a marine
one,
for those who followed my earlier travails!) which should give it
about
230
HP (as comared with 200HP with the original 2BBL).

After getting the engine fixed up with the right kind of carb, I took
it
out
on the lake last week and while the engine seems to run well, there's
absolutely no way the boat could have gotten an adult out of the water
on
skis. Top speed is pretty good (nearly 40 mph, and this is at an
elevation
of over 5000 feet) but the boat is really slow to dig its way up onto
plane. As you might guess from the subject line, I suspect the prop.

This boat apparently came with, and was pretty much always run with, a
three-bladed 17 pitch prop. This spring, however, the former owner
trashed
the prop on a sand bar. Before he sold it, he purchased a new
four-bladed,
19 pitch aluminum prop (don't know what the diameter is, but it looks
about
the same as the previous 17-pitch prop, which he left in the boat).
My
suspicion is that this prop is just too much for my engine to turn,
but I
don't really know if 2 inches of pitch make that much difference.

At plane, with a wide-open throttle (assuming the throttle cable is
adjusted
correctly), the engine peaks out at 3500 rpm. According to a
Mercruiser
manual I have, it should run to about 4200 WOT.

So, before I go buy a prop, what do you all think? Should this engine
be
able to handle a 19 pitch? Actually, I'll buy a prop anyway, because
it's
cheaper than looking into deeper engine problems, and if it gets me
acceptable performance, I'll stick with it. However, if the current
performance indicates that there might be other problems, I'd rather
know
sooner rather than later, even if I decide not to do anything.

Thanks for any help,

Shawn


Ok, I'm new here and it's been a long time since I had anything to do
with small boats and even then the prop wasn't my concern. Now it will
be, Why will a four bladed prop slow you down?

Thanks.
--
MikeG
Heirloom Woods
www.heirloom-woods.net

Question about props
 

Not true at all. A 19 pitch 4 blade will produce better hole shot than a 21
pitch 3 blade any day. It will also turn more rpms than a 21 3 blade on the
same boat.
No way you will increase by 600 rpms (unless other factors are involved) by
going to a 17 3 blade. You will see 300 to 400.

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

"IBNFSHN" wrote in message
news:6BeQc.13182$Jo1.6803@lakeread01...
A 19 pitch 4 blade prop is equivalent to a 21 pitch 3 bladed prop. If you
go
back to a 17 pitch 3 bladed. you should increase your rpms by 6-800.

--
Bill
Chesapeake, Va


"Shawn Willden" wrote in message
...
I have a 20' Bayliner, a 1990 with a 5.0L Merc and (I think) Alpha 1
outdrive. The engine has been modified with a 4BBL carb (now a marine
one,
for those who followed my earlier travails!) which should give it about
230
HP (as comared with 200HP with the original 2BBL).

After getting the engine fixed up with the right kind of carb, I took it
out
on the lake last week and while the engine seems to run well, there's
absolutely no way the boat could have gotten an adult out of the water
on
skis. Top speed is pretty good (nearly 40 mph, and this is at an
elevation
of over 5000 feet) but the boat is really slow to dig its way up onto
plane. As you might guess from the subject line, I suspect the prop.

This boat apparently came with, and was pretty much always run with, a
three-bladed 17 pitch prop. This spring, however, the former owner
trashed
the prop on a sand bar. Before he sold it, he purchased a new
four-bladed,
19 pitch aluminum prop (don't know what the diameter is, but it looks
about
the same as the previous 17-pitch prop, which he left in the boat). My
suspicion is that this prop is just too much for my engine to turn, but
I
don't really know if 2 inches of pitch make that much difference.

At plane, with a wide-open throttle (assuming the throttle cable is
adjusted
correctly), the engine peaks out at 3500 rpm. According to a Mercruiser
manual I have, it should run to about 4200 WOT.

So, before I go buy a prop, what do you all think? Should this engine
be
able to handle a 19 pitch? Actually, I'll buy a prop anyway, because
it's
cheaper than looking into deeper engine problems, and if it gets me
acceptable performance, I'll stick with it. However, if the current
performance indicates that there might be other problems, I'd rather
know
sooner rather than later, even if I decide not to do anything.

Thanks for any help,

Shawn

Question about props
 

In article xcgQc.246823$XM6.7643@attbi_s53, says...
A 4 blade prop of the same pitch will be slower on top end due to the extra
blade surface (althought a 4 blade will usually be smaller in diameter to
help compensate - it still will be slower on top end).
A 4 blade prop of the same pitch will be faster out of the hole due to less
slippage. A 4 blade is more efficient at lower rpms.

If your not comparing same pitch then all bets are off.




Ok then, if I understand this properly, if my main interest is strictly
fishing and towing a joy rider is only the faintest of possibilities and
assuming the same pith I'd be better served by a three bladed prop since
good hole shots are not a necessity but getting from one spot to another
in the fastest most efficient way would be?

Thanks again for the info.
--
MikeG
Heirloom Woods
www.heirloom-woods.net

Question about props
 

That must be a pretty heavy boat. Try going back to the 17. You might even
want to try a 15. Personally I prefer to run the wot rpm a little high to
improve the hole shot. After all you can control how long you run it wide
open. I let my 5.7 turn about 5200 but seldom keep it there for more that 4
or 5 minutes.

"Joseph Stachyra" wrote in message
...
I keep telling people, 4 blade props will slow you down, and nobody
listens.....
go back to a 17" three blade, or check with a boat dealer what the
original
prop was....
if you want to push a 4 blade, then go to a 250 hp outboard.

"Shawn Willden" wrote in message
...
I have a 20' Bayliner, a 1990 with a 5.0L Merc and (I think) Alpha 1
outdrive. The engine has been modified with a 4BBL carb (now a marine
one,
for those who followed my earlier travails!) which should give it about
230
HP (as comared with 200HP with the original 2BBL).

After getting the engine fixed up with the right kind of carb, I took it
out
on the lake last week and while the engine seems to run well, there's
absolutely no way the boat could have gotten an adult out of the water
on
skis. Top speed is pretty good (nearly 40 mph, and this is at an
elevation
of over 5000 feet) but the boat is really slow to dig its way up onto
plane. As you might guess from the subject line, I suspect the prop.

This boat apparently came with, and was pretty much always run with, a
three-bladed 17 pitch prop. This spring, however, the former owner
trashed
the prop on a sand bar. Before he sold it, he purchased a new
four-bladed,
19 pitch aluminum prop (don't know what the diameter is, but it looks
about
the same as the previous 17-pitch prop, which he left in the boat). My
suspicion is that this prop is just too much for my engine to turn, but
I
don't really know if 2 inches of pitch make that much difference.

At plane, with a wide-open throttle (assuming the throttle cable is
adjusted
correctly), the engine peaks out at 3500 rpm. According to a Mercruiser
manual I have, it should run to about 4200 WOT.

So, before I go buy a prop, what do you all think? Should this engine
be
able to handle a 19 pitch? Actually, I'll buy a prop anyway, because
it's
cheaper than looking into deeper engine problems, and if it gets me
acceptable performance, I'll stick with it. However, if the current
performance indicates that there might be other problems, I'd rather
know
sooner rather than later, even if I decide not to do anything.

Thanks for any help,

Shawn