Polar / Velocity Prediction

[b393capt]

What are my options for getting polar information for my Beneteau
393 ? Is there software where I can supply information about my B
and have it produce this information ?

[Ted Weitz]

Here are the polars form the Beneteau USA website.

Ted Weitz
S/V Gossamer Wings
B323
East Hampton, NY

--
Ted Weitz
tm...@columbia.edu

[b393capt]

These are the one's I have been using this season, and have found to
be unachievable.

My 393 cannot sail nearly so close to the wind as the true angles
represented as "Up.bt" without a severe drop in speed, and/or
otherwise achieve the performance listed in the diagram.

My thoughts as to why not are varied, but I expect that perhaps my 393
does not meet the version modeled here. E.g. 393's come with three
different types of keels, classic (I have) or furling mains, sails
from different manufacturers depending where your 393 is built, etc.
Also, different prop's can be purchased (I have an autoprop), and the
weight of my 393 might be very different.

I would like to know if there is a program I can enter this stuff
into, and obtain a polar more specific to my 393 configuration.

Thanks !
Dan

On Oct 19, 8:31 am, "Ted Weitz" <ted.we...@gmail.com> wrote:
> Here are the polars form the Beneteau USA website.
>
> Ted Weitz
> S/V Gossamer Wings
> B323
> East Hampton, NY
>

> On 10/19/07, b393capt <danielwcorco...@hotmail.com> wrote:
>
>
>
> > What are my options for getting polar information for my Beneteau
> > 393 ? Is there software where I can supply information about my B
> > and have it produce this information ?
>
> --
> Ted Weitz
> tm...@columbia.edu
>

> 393 polars.pdf
> 104KDownload

[Rick Donovan]

Dan

Others on this list may be able to speak on this in more detail than I, but as far as I know, the Velocity Prediction Program used to come up with the finished numbers in the polar predictions are from a very sophisticated piece of software used by the designers of the boats. US Sailing may be another possible source but I would expect them to come up with about the same values. As for the predictions you have now, the info used to get the final VPP numbers, i.e. what keel, rig, etc should be on that sheet somewhere. 

Our VPP sheet is for a deep draft standard furling rig. We have the shoal version of the Classic rig so the numbers don't match completely but it is a close estimate. From my experience racing over the years, the deep keels will out point a shallow keel on the same boat model by 3-5 degree's in most conditions when all else is equal . Predictions for other wind angles would be a little closer, especially in lower wind speeds, as when you can sail slightly off the wind or down wind. 

We use the VPP predictions on our 473 as a target not for a definitive speed. At certain angles and wind speeds we will get quite close to the numbers and at other times we might be frustratingly off the mark. It is all part of the process. I get the most value from those numbers in choosing what angle to sail in what wind speed. The final boat speed you see on your instruments could be off from the predictions for so many reasons. 

There are so many things that can affect the final speed and wind angles you want to sail that the list is almost unending and if any one of those are out of whack even a little bit it could provide bad information that can be magnified as that value is used for other calculations. To begin with, the bottom needs to be in perfect condition, the sails in like new condition and a proper design for YOUR rig as well as properly trimmed for the present conditions and wind angle, mast tuning must be correct, the instruments need to be properly aligned and adjusted, the boat should not be weighted down with lots of extra gear and what is onboard should be as close to the center of gravity as possible for best results, even the guy driving will have a major result in the target vs actual speed thru the water. If all of the above issues were perfect, you are still left with crew work as a possible big reason for "slowitiis" of the boat and we haven't even started talking about proper tactics out on the race course and how much that contributes to your finishing results. There are many more but you get the idea. 

I would recommend that if possible, sail against another 393 to use them as a gauge for what you are doing on your boat. If they are faster, ask yourself what they are doing differently than you and try to learn from that to get up to speed. If you are faster, help get them up to speed so that you can benefit from things they learn they were doing wrong. If another 393 is not available, find someone with the same PHRF rating and see how you stack up against that boat. Although probably not as reliable for testing as using the same model would be, it may also help you with the learning curve.

Ivars or Max may be able to help clear this up for you some more with their racing experience but I gave it a shot to try to explain all the little things that can contribute to your end boat speed and wind angle. It is just not as simple as "my boat is slow". The more time you spend on the race course, the more obvious that will become if you pay attention to what is happening around you. 

Rick Donovan

2002 Beneteau 473 #29

Turn the Page

Falmouth, Maine

richard....@verizon.net

[Ivars]

No.

You can use the VPP that you have ....even if they were generated for
another 393 configured differently.

VPP are the carrot at the end of the "stick" They are computer generated
values for an imperfect enviornment. They always come with a disclaimer
that the values represented may not be achieved. For your configuartion
make your own, record your best values as they will be lower than those
generated by computer. See how close you can get, pay attention to optimum
sailing angles, stability curve etc, there is a lot of information
available other than raw speed that will help you optimize the performance
of your boat. Error creeps in rather quickly. Instrument callibration
errors, dirty bottoms, less than perfect rig tune,
less than perfect sails etc.

My primary VPP is one I generate myself with a clean bottom. The next you
clean your bottom make a couple of mid and high RPM runs. Record the RPM
and speed for future reference. You will see your ref numbers drop as your
bottom becomes fouled. How much speed drop can you stand before you clean
again ? A dirty bottom slows the boat, the foils become less efficient
with loss of speed and pointing goes into the toilet. Many variables to
keep track of. Record your best and you will have what you need and use
the VPP for a reference ( wish list )

> [Original Message]
> From: b393capt <danielw...@hotmail.com>
> To: Beneteau Owners <Benetea...@googlegroups.com>
> Date: 10/21/2007 9:20:01 PM
> Subject: {Beneteau Owners} Re: Polar / Velocity Prediction

[Max Lynn]

Rick and Ivars have given you a lot of good input.  As Ivars said, you can essentially generate your own polars by simply recording boat speed, wind speed and wind angle (preferably true wind angle) when you have a clean bottom and all sails are the same.  If you have a laptop on board connected to your instrument system, and you have a lot of extra money, you can purchase any of several programs which will gather the data for boat-specific polars for you.  Nobeltec has an add-on module which works with their Visual Navigator program.  There is another family of programs marketed by Furuno called MaxSea which also has a sailing performance data module which will generate polars for your boat.  B&G markets another similar program called Deckman.  Then there is the apparent champion among the performance prediction and routing software systems called Expedition.  These cost a minimum of several hundred dollars, and require a very well calibrated instrument system connected to a laptop.  Very few of us have need for such a set-up, but some of these systems are part of excellent laptop charting programs, so you might want to invest in them as an add-on to such a program. 

 

Max Lynn

----- Original Message -----

From: b393capt

To: Beneteau Owners

Sent: Sunday, October 21, 2007 6:20 PM

Subject: {Beneteau Owners} Re: Polar / Velocity Prediction

[b393capt]

Ideally I would have a few 393 to race against locally, but do not.

Thank you everyone for your advice to live with the polar's I have and
augment it with collecting my own data, given "so many things that can

affect the final speed and wind

angles you want to sail that the list is almost unending " vs. looking
at getting VPP software. Following your advise seems the best tool
for knowing something is wrong before, rather then during a race
against boats of various PHRF ratings that I had been giving up a 1/4
knot or more by missing a sail trim adjustment.

[Rick Donovan]

Dan

.25 Knots doesnt seem like much to folks that are not familiar with the racing crowd but it will definitely make the difference between winning and losing a race. it kills me to see a race lost when the crew works their tail off and just can't seem to keep up with the boats that they think they should no matter what they try. there is no better helper around the race course than boat speed because it can pull you back into contention and/or give tactical options not available to a slower boat.

The good news is that you don't seem to have all that far to go to be competitive with your fleet. Pay attention to the little details because that is often the biggest difference between the fast boats and the rest of the fleet. A steady core group of crew is key on the boats I have raced on over the years. They don't make the mistakes that the others do and they make gains each time a mistake is made by the other boats. It can be very frustrating if you are the boat losing ground to them and you won't really know why. I would also suggest trying to sail on a couple of the fast boats to learn how they deal with the race as it unfolds, I think you might find a lot of things that could be improved on with your boat, boat handling and crew work. Start by finding the common settings for sail trim upwind and downwind then keep refining them as you learn what the boat responds well to, make sure the bottom is properly done in the spring and maintained thru the season, keep working at the trim settings and you will find your self improving I bet. 

Good Luck

Rick Donovan

2002 Beneteau 473 #29

Turn the Page

Falmouth, Maine

richard....@verizon.net

[b393capt]

I didn't mean to give the impression I am doing well.

I am being slaughtered on the race course. This last race I was
creamed by everything from light weight catalina 22's crewed by a dad
and two 10 year olds,thru heavy displacement boats with huge handicaps
that finished well before me. If I can get just another .25 knots, I
can move one up from last position on boat speed alone.

I don't have the common settings for sail trim figured out yet, but
have started marking the lines and deck so I can repeat them.

On Oct 22, 4:39 pm, Rick Donovan <richard.donova...@verizon.net>
wrote:

> richard.donova...@verizon.net

>
> On Oct 22, 2007, at 4:16 PM, b393capt wrote:
>
>
>
>
>
> > Ideally I would have a few 393 to race against locally, but do not.
>
> > Thank you everyone for your advice to live with the polar's I have and
> > augment it with collecting my own data, given "so many things that can
> > affect the final speed and wind
> > angles you want to sail that the list is almost unending " vs. looking
> > at getting VPP software. Following your advise seems the best tool
> > for knowing something is wrong before, rather then during a race
> > against boats of various PHRF ratings that I had been giving up a 1/4

> > knot or more by missing a sail trim adjustment.- Hide quoted text -
>
> - Show quoted text -

[Bruce Bates]

Screw the polars, keep sailing your boat. Better yet, find a guy that knows
how to race and take him sailing with you. Read some books on racing and
tactics. Crew on a race boat that knows what their doing.There is no magic
bullet to racing success just practice.Do you have a feathering or folding
prop?
I'm willing to bet you start way at the back of the fleet , (hoping that
your boat's size will allow you to catch up)because you are afraid to mix it
up with the guys that know what they are doing.
Bruce Allez 430

----- Original Message -----
From: "b393capt" <danielw...@hotmail.com>
To: "Beneteau Owners" <Benetea...@googlegroups.com>

Sent: Tuesday, October 23, 2007 7:43 AM
Subject: {Beneteau Owners} Re: Polar / Velocity Prediction

>

> --
> No virus found in this incoming message.
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> Version: 7.5.488 / Virus Database: 269.15.5/1085 - Release Date:
10/22/2007 10:35 AM
>
>

[Noble, Milner E.]

What are the usual wind velocities where you race -- and where do you
race? I guess missed that earlier. With a 393, I'm thinking about our
experience on a Pearson 32 that I race on in Lake Champlain. Because of
its displacement, and the fact that we use "newish" Dacron-type sails
(only a couple of years old) and not a "hi-tech" fabric, we have to rely
on people making more errors than we do to finish well in consistent
winds under 10 knots. That "dad and the 10-year-olds" do real well
against us then.

BUT, get the winds above 15 --- more towards 20, please, and look out --
that Pearson becomes one screaming machine and we're fighting with the
"big boys" in our division for the lead. I never thought I'd pray for
20 knots and above, but now I do -- every Wednesday afternoon in the
summer. Those winds propelled us into 2nd overall in our division this
year.

So, in addition to thinking that having a heavier boat do well in a
mixed fleet is partly a function of overall wind velocity, the good
suggestions made by Rick earlier on this tread ring true with our
experience over the past couple of seasons: crewing on another good boat
to see what they do if you can, have a consistent core of crew who know
the boat and where thing are and how they work, getting a good start,
improving "course management," and s-l-o-w-l-y learning how to tweak all
the little things for performance. I wouldn't focus so much on polars -
the rest of the fleet will be your indicator of performance. A polite
way of saying "screw the polars." :-)

Even if you don't crew on that other boat, focus on all the details on
your boat. This Pearson sails very differently than my boat and it has
taken us two long years to figure out how to make it perform. In some
instances our set-up can be contrary to popular wisdom to get this boat
to go fast, but now we know how to set up this particular boat for
various conditions and legs of a course. Our downwind performance
improved by double simply by experimenting and learning all the "tweaks"
for that leg -- we, too, were getting creamed on that leg, and it made
no sense to us, but finally, by getting all the little things right over
time, we're competing and not wondering why we're not. We are looking
back at most of the fleet in our division now. It took a lot of work,
thought, commitment and experimenting to get there. And this year we
even had a "guest" on our boat late in the season to see how to get his
boat to go faster... the ultimate compliment.
--Milner
P.S Next year we also race my boat again and I can't wait. :-)

-----Original Message-----
From: Benetea...@googlegroups.com
[mailto:Benetea...@googlegroups.com] On Behalf Of b393capt
Sent: Tuesday, October 23, 2007 7:44 AM
To: Beneteau Owners
Subject: {Beneteau Owners} Re: Polar / Velocity Prediction

Confidentiality Notice:
This message, and any attachments, may contain information that is confidential, privileged, and/or protected from disclosure under state and federal laws that deal with the privacy and security of medical information. If you received this message in error or through inappropriate means, please reply to this message to notify the Sender that the message was received by you in error, and then permanently delete this message from all storage media, without forwarding or retaining a copy.

[Uwe Mewes]

That's why winning is so rewarding. It's so hard to get there.
We started doing a lot better when we began to sail our own races.
Develop your own strategy. Have a game plan - stick to it - execute. Our
most memorable race this season was from the Delaware Bay up this winding
Cohansey River which meanders with 200+ degree bends through the saltmarsh
of South Jersey. The wind was around 5 to 8 knots from the south. My wife
decided the free fly the spinnaker. A friend helped a little jibing the
chute around the forestay following those tight bends but no pole. We won
the race with such a lead that some spectators thought a second race was in
progress :-).

Uwe Mewes
F305
Heaven Can Wait

----- Original Message -----
From: "b393capt" <danielw...@hotmail.com>
To: "Beneteau Owners" <Benetea...@googlegroups.com>

Sent: Tuesday, October 23, 2007 7:43 AM
Subject: {Beneteau Owners} Re: Polar / Velocity Prediction

>

[Noble, Milner E.]

Very good, Uwe!
--Milner

Confidentiality Notice:

[Brian Mikiten]

I don't know what level of experience you have but have you taken
another skipper on board for a race? When I used to campaign Solings,
I was getting whipped, bought new sails and everything else you can
imagine only to find that it was the guy behind the wheel and the sail
trimming that was killing the races. <G> I brought on a local J-24
expert who gave me more tips in a 3 hour race than any books, polar
plots, etc. could have given in years. I started moving up quickly
right after that experience.

Brian

[Michael]

I'm considering the purchase of a 1996 First 36s7. When we hauled the boat
for the survey we found about 30 blisters in the 1.5" to 2.75" size range.
On my current 1986 First 305 we have only had 4 or 5 dime sized blisters. I
thought that by the mid-1990's Beneteau was doing all the right stuff to
prevent blisters. Are my findings on the 36s7 unusual for that vintage
Beneteau? Should I be concerned enough about these blisters to stop the
transaction? Or should I just go ahead and then locally grind, fair, barrier
coat, and bottom paint the blisters?

Thanks, Michael

[Max Lynn]

Beneteau applies a very thin vinyl coating just beneath the gel coat as the hull is constructed.  Its purpose is to provide protection from blistering.  If the yard which does the initial bottom prep is not careful, it is easy to penetrate this coating by rough sanding.  Then, if the yard does not apply any additional barrier coating, the stage is set for blistering.  In the case of the boat you are considering, you have a bargaining chip in the blisters.  I would deduct the cost of a good barrier coat from the price, plus a little extra for the time required and your trouble, and not let that detract from the boat's purchase (all else being equal).

 

Max Lynn

[Max Lynn]

I should have been a little clearer.  To be safe, you need a complete barrier coat over the entire bottom.  That would entail stripping the old bottom paint down to the gel coat, allowing some drying time for the blisters, then applying an overall barrier coat to the specifications of the barrier coat manufacturer.  The cost of that sort of treatment is what you need to deduct from the price of the boat.

At least that's what I would do.

 

Max Lynn

----- Original Message -----

From: Michael

To: Benetea...@googlegroups.com

Sent: Saturday, November 03, 2007 8:55 AM

Subject: {Beneteau Owners} Hull Blisters

[Ivars]

deduct the cost of the blister repair / barrier coat from purchase price.
When buying a boat one expects the bottom to be serviceable.....that is no
blisters...... I would not worrry about that there are a few blisters,
normal for any boat easy enough to correct. If you like the boat make
price adjustment for blister repair and continue with the transaction
Annual or semi annual haul out by the current owner should have cured the
blisters as he owned the boat....but no worry...have him catch up now.

> [Original Message]
> From: Michael <mar4...@pacbell.net>
> To: <Benetea...@googlegroups.com>
> Date: 11/3/2007 11:56:01 AM