After testing that our engine reaches full RPM (over 3K) in neutral,
but in gear only reaches 2K, we've decided that the most likely cause
is too much prop. We currently have a 13RH10 2-blade prop. Any
recommendations for what is "standard" prop for Catalina 27? I would
guess a 13x8 tops? Also, any ideas for which particular prop to buy?
Don't want to shell out big bucks for Maxprop, so thinking of going
with campbell 3 prop? Thoughts?

Thanks.

First be sure that you're not 'chewing up' a lot of HP with too tight a
stuffing box. Consider Gore GFO PTFE packing for the most friction
free packing.

Most boats of that 'era' were over 'overpropped'.
Go to the "Michigan Wheel" website: http://www.miwheel.com/ and size
yourself a new prop (based on you typical / normal rpm at present vs.
the engine's power curve).
For best 'sailing' performance consider a folding prop such a Martec.
(but I dont think that you'll find a folding prop with small enough
pitch/diameter for your application.).
If your engine is an A4 go to the CDI website for an "exact match" prop
for this direct drive engine.
:-)


In article , Sebastian
wrote:

After testing that our engine reaches full RPM (over 3K) in neutral,
but in gear only reaches 2K, we've decided that the most likely cause
is too much prop. We currently have a 13RH10 2-blade prop. Any
recommendations for what is "standard" prop for Catalina 27? I would
guess a 13x8 tops? Also, any ideas for which particular prop to buy?
Don't want to shell out big bucks for Maxprop, so thinking of going
with campbell 3 prop? Thoughts?

Thanks.

First be sure that you're not 'chewing up' a lot of HP with too tight a
stuffing box. Consider Gore GFO PTFE packing for the most friction
free packing.

Most boats of that 'era' were over 'overpropped'.
Go to the "Michigan Wheel" website: http://www.miwheel.com/ and size
yourself a new prop (based on you typical / normal rpm at present vs.
the engine's power curve).
For best 'sailing' performance consider a folding prop such a Martec.
(but I dont think that you'll find a folding prop with small enough
pitch/diameter for your application.).
If your engine is an A4 go to the CDI website for an "exact match" prop
for this direct drive engine.
:-)


In article , Sebastian
wrote:

After testing that our engine reaches full RPM (over 3K) in neutral,
but in gear only reaches 2K, we've decided that the most likely cause
is too much prop. We currently have a 13RH10 2-blade prop. Any
recommendations for what is "standard" prop for Catalina 27? I would
guess a 13x8 tops? Also, any ideas for which particular prop to buy?
Don't want to shell out big bucks for Maxprop, so thinking of going
with campbell 3 prop? Thoughts?

Thanks.

"Rich Hampel" wrote in message
...
First be sure that you're not 'chewing up' a lot of HP with too tight a
stuffing box. Consider Gore GFO PTFE packing for the most friction
free packing.

Most boats of that 'era' were over 'overpropped'.
Go to the "Michigan Wheel" website: http://www.miwheel.com/ and size
yourself a new prop (based on you typical / normal rpm at present vs.
the engine's power curve).
For best 'sailing' performance consider a folding prop such a Martec.
(but I dont think that you'll find a folding prop with small enough
pitch/diameter for your application.).
If your engine is an A4 go to the CDI website for an "exact match" prop
for this direct drive engine.
:-)


In article , Sebastian
wrote:

After testing that our engine reaches full RPM (over 3K) in neutral,
but in gear only reaches 2K, we've decided that the most likely cause
is too much prop. We currently have a 13RH10 2-blade prop. Any
recommendations for what is "standard" prop for Catalina 27? I would
guess a 13x8 tops? Also, any ideas for which particular prop to buy?
Don't want to shell out big bucks for Maxprop, so thinking of going
with campbell 3 prop? Thoughts?

Thanks.

Just gone through the experience of changing the prop. Apart form a lot of
time with catalogues and marine engineers try the following link
http://www.castlemarine.co.uk/pitch.htm
evntually after a wide range of solutions from the experts the chosen prop
matched that recommended by the engine manufacturer. 12"x9" RH3 driven by a
beta 13.5hp diesel 2:1 reduction on a 26' fairey atalanta. I get within
200rpm of max and pull about 6.2kts

Grahame

"Rich Hampel" wrote in message
...
First be sure that you're not 'chewing up' a lot of HP with too tight a
stuffing box. Consider Gore GFO PTFE packing for the most friction
free packing.

Most boats of that 'era' were over 'overpropped'.
Go to the "Michigan Wheel" website: http://www.miwheel.com/ and size
yourself a new prop (based on you typical / normal rpm at present vs.
the engine's power curve).
For best 'sailing' performance consider a folding prop such a Martec.
(but I dont think that you'll find a folding prop with small enough
pitch/diameter for your application.).
If your engine is an A4 go to the CDI website for an "exact match" prop
for this direct drive engine.
:-)


In article , Sebastian
wrote:

After testing that our engine reaches full RPM (over 3K) in neutral,
but in gear only reaches 2K, we've decided that the most likely cause
is too much prop. We currently have a 13RH10 2-blade prop. Any
recommendations for what is "standard" prop for Catalina 27? I would
guess a 13x8 tops? Also, any ideas for which particular prop to buy?
Don't want to shell out big bucks for Maxprop, so thinking of going
with campbell 3 prop? Thoughts?

Thanks.

Just gone through the experience of changing the prop. Apart form a lot of
time with catalogues and marine engineers try the following link
http://www.castlemarine.co.uk/pitch.htm
evntually after a wide range of solutions from the experts the chosen prop
matched that recommended by the engine manufacturer. 12"x9" RH3 driven by a
beta 13.5hp diesel 2:1 reduction on a 26' fairey atalanta. I get within
200rpm of max and pull about 6.2kts

Grahame

In article ,
(Sebastian) wrote:

After testing that our engine reaches full RPM (over 3K) in neutral,
but in gear only reaches 2K, we've decided that the most likely cause
is too much prop. We currently have a 13RH10 2-blade prop. Any
recommendations for what is "standard" prop for Catalina 27? I would
guess a 13x8 tops? Also, any ideas for which particular prop to buy?
Don't want to shell out big bucks for Maxprop, so thinking of going
with campbell 3 prop? Thoughts?

Thanks.

I agree with others that you should check the prop manufacturers -- and
that there may be something else going on here. 13x10x2 seems to be in
the right range and you should be pulling within 2-400 rpm of maximum.

Perhaps the engine isn't putting out rated power? Remember, you have to
be moving to pull full revs (and power). I doubt we can pull much more
than 2500 at the dock, but achieve the target 3400 (and 7 knots) on the
water.

A fixed three-blade prop creates a LOT of drag under sail and doesn't
help much while motoring. If you're not getting harmonic vibration near
max power (as we had), a 2 blade is more efficient and will drive the
boat faster.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

In article ,
(Sebastian) wrote:

After testing that our engine reaches full RPM (over 3K) in neutral,
but in gear only reaches 2K, we've decided that the most likely cause
is too much prop. We currently have a 13RH10 2-blade prop. Any
recommendations for what is "standard" prop for Catalina 27? I would
guess a 13x8 tops? Also, any ideas for which particular prop to buy?
Don't want to shell out big bucks for Maxprop, so thinking of going
with campbell 3 prop? Thoughts?

Thanks.

I agree with others that you should check the prop manufacturers -- and
that there may be something else going on here. 13x10x2 seems to be in
the right range and you should be pulling within 2-400 rpm of maximum.

Perhaps the engine isn't putting out rated power? Remember, you have to
be moving to pull full revs (and power). I doubt we can pull much more
than 2500 at the dock, but achieve the target 3400 (and 7 knots) on the
water.

A fixed three-blade prop creates a LOT of drag under sail and doesn't
help much while motoring. If you're not getting harmonic vibration near
max power (as we had), a 2 blade is more efficient and will drive the
boat faster.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

"Sebastian" wrote in message
om...
After testing that our engine reaches full RPM (over 3K) in neutral,
but in gear only reaches 2K, we've decided that the most likely cause
is too much prop. We currently have a 13RH10 2-blade prop. Any
recommendations for what is "standard" prop for Catalina 27? I would
guess a 13x8 tops? Also, any ideas for which particular prop to buy?
Don't want to shell out big bucks for Maxprop, so thinking of going
with campbell 3 prop? Thoughts?

Thanks.

If you're a long distance cruiser a maxprop might be a good idea, for you
though it sounds like a waste of $$$$. You might try this instead-
http://www.gori-propeller.dk/Index.asp?IDS=1196
$750 for my Catalina 28, better performance in reverse, 1/2 kt. of
additional speed under sail, when the wind dies you can still sail rather
than motor. Folders actually have less drag than feathering props. You
contact the distributor with your boat model and engine and they tell you
what size you need. You can also get a 3 blade folder if you have to have 3
blades.
John Cairns