Re: Numbers (back to the polar thing)

Archives
1

Posted by Dave_Benjamin (dave_benjamin@…>)

Here’s an example of a polar plot for a J-30

http://www.sailingsource.com/j30/splash/images/j30polars.jpeg

Now explain exactly how you plan to derive true wind (not indicated
wind as shown on your anenomter) with your current set of instruments.
In order to do it you’ll need to correct your indicated wind for the
following parameters.

Influence of boat movement taking into account both velocity,
direction, sideslip, and effect of local currents.

Now this can be readily done provided you have the proper
instrumentation. Remember you’ve got to interface a GPS into this
system to provide the most critical indication which is the movement
of the boat over the bottom. Once the precise movement vector is known
then the computer can remove the effect of boat movement from
indicated wind velocity and direction so that the true wind component
can be used to consult the polars.

How many Freedom owners have the appropriate instruments and
electronics to derive true wind speed and direction? With the
exception of some race boats I haven’t seen that capability on a boat.
I’m sure there are a few cruisers with the money to outfit the boat
with that electronic suite. Unless you have the electronics those
polars are pretty much worthless. I’m sure if they were printed on
some nice paper and framed they would make a wonderful decoration.
Might be fun to mount that framed document in the head so you’d have
something to peruse while seated.

A good sailor can combine his or her sensory perception of the boats
movement, feel/position of the helm, and the position of telltales to
tell if the boat is moving efficiently or not.



— In freedomyachts2003@yahoogroups.com, “Frank Maier” <PVMaro@…>
wrote:

“jerry_magic1” <jerry_magic1@> wrote:

— “Dave_Benjamin” wrote:

You shouldn’t need polars to figure out that the sails need
tweaking
or trimming. (snip) I’m sorry but a cruising
sailor needs polars about as much as a fish needs an umbrella.
(snip}

Yea, Yea, Yea, Yea - It’s beginning to sound like an issue on
rec.boats.
You sure your name isn’t Capt Neal? :slight_smile:
…snip…

Ack! If that idiot starts posting here, along with the recent spate of
spam from tessa_whoever, I’m gonna stop lurking!

Frank

2

Posted by Skip Turpin (skipperf33@…>)

Thanks Dave,

You did it again! Ya know you save me untold amounts of time at the
keyboard? I just sit back and wait for you to say what is on my
mind. Keep up the good work!

Look folks, a Polar Plot is 100% theoretical information. Think of
them in the same category as the EPA sticker on a new car. They are
good for comparative use. When you walk up to a new car and see that
the EPA sticker sais this vehicle gets 42 mpg on the highway, do you
really expect to ever see that mileage NO! Why? Because that number
did not come out of the real world! It is all done in a laboratory
using fuel that you will never put in your tank. Did you know that
they don’t even look at the mpg when they do the test? They look at
only the amount of a specific chemical as it comes out of the
tailpipe. It is all done on a dynamometer(tread mill for cars)!
There are no hills, there is no wind, there are no passengers. The
car doesn’t even move! That is theoretical information!

Does that mean that the EPA sticker is useless? NO! If you walk up
to say a Honda Civic and see that the EPA is say 40 mpg and then you
walk up to a Hummer as see say 10 mpg. Does that surprise you?
Probably not. Was that information very helpful? Not really.
However, if your next stop is at the side of say a nice shinny new
Ford F350 4x4 crew cab, long bed, duelly with a big fat 10 cylinder
diesel purring under the hood. Well now the EPA sticker will mean
something! That is if you are COMPARING it to the Hummer!

Even though the Polar Plot is theoretical info, it can be used to
compare one boats supposed performance to that of another under
theoretical conditions. Still even here you need to be careful. If
the plot sais that at X angle to a wind of Y speed, you should get
your best speed through the water, in the words of a great old
song “It aint necessarily so”! The Plot did not take into
consideration, sea conditions, nor a myriad of other variables, like
added weight, added windage, age and condition of the sails, how
about the condition of your bottom paint, or the number of crew on
deck or their location on the boat . And if you are cruising…
well there is stuff tied in, under, around and on top of the boat
everywhere!

So let’s keep it real here folks, the plots may be fun to play around
with and do some comparing, but there is no place for them at see.
Well, other than Dave’s idea, in the head. Hay make multiple copies
and use them as educational “ticker tape”!

That’s my take! What’s yours?

Skip

3

Posted by Alfred Roberts (lab2doodle@…>)
Is 52 degrees the closest Freedoms can sail to windward?? We’ve beem looking at some F35s and may be interested.Dave_Benjamin <dave_benjamin@…> wrote: Here’s an example of a polar plot for a J-30http://www.sailingsource.com/j30/splash/images/j30polars.jpegNow explain exactly how you plan to derive true wind (not indicatedwind as shown on your anenomter) with your current set of instruments.In order to do it you’ll need to correct your indicated wind for thefollowing parameters.Influence of boat movement taking into account both velocity,direction, sideslip, and effect of local currents.Now this can be readily done provided you have the properinstrumentation. Remember you’ve got to interface a GPS into
thissystem to provide the most critical indication which is the movementof the boat over the bottom. Once the precise movement vector is knownthen the computer can remove the effect of boat movement fromindicated wind velocity and direction so that the true wind componentcan be used to consult the polars.How many Freedom owners have the appropriate instruments andelectronics to derive true wind speed and direction? With theexception of some race boats I haven’t seen that capability on a boat.I’m sure there are a few cruisers with the money to outfit the boatwith that electronic suite. Unless you have the electronics thosepolars are pretty much worthless. I’m sure if they were printed onsome nice paper and framed they would make a wonderful decoration.Might be fun to mount that framed document in the head so you’d havesomething to peruse while seated.A good sailor can combine his or her sensory perception of the
boatsmovement, feel/position of the helm, and the position of telltales totell if the boat is moving efficiently or not. — In freedomyachts2003@yahoogroups.com, “Frank Maier” <PVMaro@…>wrote:>> “jerry_magic1” <jerry_magic1@> wrote:> > — “Dave_Benjamin” wrote:> > > You shouldn’t need polars to figure out that the sails need > tweaking > > > or trimming. (snip) I’m sorry but a cruising > > > sailor needs polars about as much as a fish needs an umbrella. > (snip}> > > > Yea, Yea, Yea, Yea - It’s beginning to sound like an issue on > rec.boats.> > You sure your name isn’t Capt Neal? :-)> …snip…> > Ack! If that idiot starts posting here, along with the recent spate of > spam from tessa_whoever, I’m gonna stop lurking! > >
Frank>
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4

Posted by Fred Molden (fredmolden@…>)

The Pedrick designed F35 is a bit different than other Freedom designs. I’ve been told that the mast has been placed a bit further aft to better allow for the optional 150 Genoa. Of course a Genoa would not be self tending or have a camberspar but it does provide more power and better pointing. I sail my F35 with a self tending roller furling jib to 35 degrees apparent in flat water. I don’t know the design speeds or angles but have seen articles rating the F35 with Genoa on equal or better ground with a Beneteau 35s7 and Catalina 320. See Cruising World February 1995 “Freedom 35” and Sailing World January 1994 “Sizing Up Three Club Racers”. I have also seen an article in Yachting Monthly November 1994 that talks to “…80 odd degrees between tacks, she loses virtually no way…”. That was with the standard camberspar and working jib.

Fred

----- Original Message -----
From: Alfred Roberts
To: freedomyachts2003@yahoogroups.com
Sent: Monday, March 20, 2006 7:21 PM
Subject: Re: [freedomyachts2003] Re: Numbers (back to the polar thing)
Is 52 degrees the closest Freedoms can sail to windward?? We’ve beem looking at some F35s and may be interested.Dave_Benjamin <dave_benjamin@…> wrote: Here’s an example of a polar plot for a J-30http://www.sailingsource.com/j30/splash/images/j30polars.jpegNow explain exactly how you plan to derive true wind (not indicatedwind as shown on your anenomter) with your current set of instruments.In order to do it you’ll need to correct your indicated wind for thefollowing parameters.Influence of boat movement taking into account both velocity,direction, sideslip, and effect of local currents.Now this can be readily done provided you have the properinstrumentation. Remember you’ve got to interface a GPS into thissystem to provide the most critical indication which is the movementof the boat over the bottom. Once the precise movement vector is knownthen the computer can remove the effect of boat movement fromindicated wind velocity and direction so that the true wind componentcan be used to consult the polars.How many Freedom owners have the appropriate instruments andelectronics to derive true wind speed and direction? With theexception of some race boats I haven’t seen that capability on a boat.I’m sure there are a few cruisers with the money to outfit the boatwith that electronic suite. Unless you have the electronics thosepolars are pretty much worthless. I’m sure if they were printed onsome nice paper and framed they would make a wonderful decoration.Might be fun to mount that framed document in the head so you’d havesomething to peruse while seated.A good sailor can combine his or her sensory perception of the boatsmovement, feel/position of the helm, and the position of telltales totell if the boat is moving efficiently or not. — In freedomyachts2003@yahoogroups.com, “Frank Maier” <PVMaro@…>wrote:>> “jerry_magic1” <jerry_magic1@> wrote:> > — “Dave_Benjamin” wrote:> > > You shouldn’t need polars to figure out that the sails need > tweaking > > > or trimming. (snip) I’m sorry but a cruising > > > sailor needs polars about as much as a fish needs an umbrella. > (snip}> > > > Yea, Yea, Yea, Yea - It’s beginning to sound like an issue on > rec.boats.> > You sure your name isn’t Capt Neal? :-)> …snip…> > Ack! If that idiot starts posting here, along with the recent spate of > spam from tessa_whoever, I’m gonna stop lurking! > > Frank>


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5

Posted by lance_ryley (lance_ryley@…>)

52 degrees is about how close a Freedom Cat Ketch sails to windward
before it just starts sliding sideways. The Cat Sloops and Sloop
rigs point higher. How much higher depends on the model, but a 35
points pretty well.

Lance

— In freedomyachts2003@yahoogroups.com, Alfred Roberts
<lab2doodle@…> wrote:

Is 52 degrees the closest Freedoms can sail to windward?? We’ve
beem looking at some F35s and may be interested.

Dave_Benjamin <dave_benjamin@…> wrote:
Here’s an example of a polar plot for a J-30

http://www.sailingsource.com/j30/splash/images/j30polars.jpeg

Now explain exactly how you plan to derive true wind (not
indicated
wind as shown on your anenomter) with your current set of
instruments.
In order to do it you’ll need to correct your indicated wind for
the
following parameters.

Influence of boat movement taking into account both velocity,
direction, sideslip, and effect of local currents.

Now this can be readily done provided you have the proper
instrumentation. Remember you’ve got to interface a GPS into this
system to provide the most critical indication which is the
movement
of the boat over the bottom. Once the precise movement vector is
known
then the computer can remove the effect of boat movement from
indicated wind velocity and direction so that the true wind
component
can be used to consult the polars.

How many Freedom owners have the appropriate instruments and
electronics to derive true wind speed and direction? With the
exception of some race boats I haven’t seen that capability on a
boat.
I’m sure there are a few cruisers with the money to outfit the boat
with that electronic suite. Unless you have the electronics those
polars are pretty much worthless. I’m sure if they were printed on
some nice paper and framed they would make a wonderful decoration.
Might be fun to mount that framed document in the head so you’d
have
something to peruse while seated.

A good sailor can combine his or her sensory perception of the
boats
movement, feel/position of the helm, and the position of telltales
to
tell if the boat is moving efficiently or not.

— In freedomyachts2003@yahoogroups.com, “Frank Maier” <PVMaro@>
wrote:

“jerry_magic1” <jerry_magic1@> wrote:

— “Dave_Benjamin” wrote:

You shouldn’t need polars to figure out that the sails need
tweaking
or trimming. (snip) I’m sorry but a cruising
sailor needs polars about as much as a fish needs an
umbrella.
(snip}

Yea, Yea, Yea, Yea - It’s beginning to sound like an issue on
rec.boats.
You sure your name isn’t Capt Neal? :slight_smile:
…snip…

Ack! If that idiot starts posting here, along with the recent
spate of
spam from tessa_whoever, I’m gonna stop lurking!

Frank

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