Speed Polar Plot for PDQ 32

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thinwater
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Speed Polar Plot for PDQ 32

Post by thinwater »

I couldn't find one, so I assembled my own data, borrowed some methodology from another plot (PDQ 36), and built a real-world plot based on my expereince. It is not a projection of what is possible, it is a compilation of what I have seen, though waves and loading varied enough that I wouldn't call it science. Goals for cruisers, perhaps. Racers should be able to stomp these numbers.

Still, it gives food for thought. If you have data points of your own you would like to insert, I would love to.

http://sail-delmarva.blogspot.com/2010/ ... olars.html
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Re: Speed Polar Plot for PDQ 32

Post by doubledutch »

Well Done!
I found your numbers to be fairly consistent with my own experience.
When shopping for my boat I was disappointed with the information I found on the internet that suggested rather modest performance expectations. Once I spent some time with the boat I was happy to find that my experiences with performance were generally better what I had been lead to expect. An aquaintance who bought a Gemini at about the same time has made a point of entering into an impromptu race whenever we encounter each other. In spite of some suggestions that the Gemini would be a faster boat I have in every case been able to easily overtake or pass him - including to windward where although I had a few more tacks I was still able to overtake.
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Re: Speed Polar Plot for PDQ 32

Post by mikemak777 »

hey drew -

thanks again for more great info -

is your boat the classic or altair with the taller mast?

mike
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Re: Speed Polar Plot for PDQ 32

Post by thinwater »

It is the Altair with the 45'-foot mast height.

I've found I could walk away from a couple of local Gemini's too, but that could be a reflection of many things and they did not appear to be well sailed, so I can't make a statement. I dare say, there are probably some well-sailed Geminis that would sail away from me. From what I have heard of race results, it is a close match.
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Re: Speed Polar Plot for PDQ 32

Post by mikemak777 »

drew -

it is my understanding that the classic (1996 and earlier) have the 45 foot mast
and the altair has the 49 foot mast.

what year is your boat?

thanks,

mike.
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Re: Speed Polar Plot for PDQ 32

Post by thinwater »

1997. There are stickers that say Altair and Classic.

I thought the "classic" label was specifically to differentiate it from the LRC. Who knows. I measured the mast I never believe the book on that!
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Re: Speed Polar Plot for PDQ 32

Post by mikemak777 »

thanks, drew ... i figured out the error in my thinking .... the mast on the classic is not 45 feet long, but rather 45 feet above the water; whereas the masthead height on the altair is probably 49 feet. as mine is a classic, i have altair "mast envy". hopefully when i get a square top main it will make up most of the difference in the greater sail area of the altair. thanks again.

mike.
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Re: Speed Polar Plot for PDQ 32

Post by HENRY »

You mention 130 genoa. Have you polars for the small self-tacking jib that most of us have. Even here in windy SF BAY I can't get those speeds. I have the tall rig and new dacron sails, cut a bit flat for our conditions.

Henry(Jim)
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Re: Speed Polar Plot for PDQ 32

Post by amytom »

If I can get those numbers out of the DogHouse... I really need to get the Genoa. Anyone have some old winches and a Genoa laying around?


Tom
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Re: Speed Polar Plot for PDQ 32

Post by mikeandrebecca »

I don't know about those numbers but we recently switched the small self-tacking jib to our 150% genoa. Although we know very little about sail trim we have still experienced a HUGE increase in performance.
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Re: Speed Polar Plot for PDQ 32

Post by thinwater »

As Mike and Rebecca pointed out, the genoa is a big kick in the performance, particularly reaching. Hard on the wind in a breeze, the difference is not much, but on a reach in 20 knots it is easily 2-3 knots and over 1 knot in the lighter stuff. Nope, never did a polar, but I will in the fall. I wouldn't need too many data points to fill in the curves.

It is hard to sheet the genoa tight enough as the wind gets up: in part the shrouds are in the way, and in part the load is monster. You can roll-up a bit of jib and sheet inside the shrouds, but it is not much better and it's a hastle.

Yes, these are targets. They are the best I have seen, and I don't see these numbers every day. But I have seen over 12 knots without surfing in 20 knots sustained. It was a little scary and I wouldn't go far from the helm. In those conditions, the sheets are NOT in the self tailers; I mounted cam cleats nearby.
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Re: Speed Polar Plot for PDQ 32

Post by doubledutch »

I just have the regular self tacking jib however my numbers are consistent with those on the plot. I made a point of verifying my speeds with a GPS since they seemed to be better than what others were reporting. I do have the tall mast.
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Re: Speed Polar Plot for PDQ 32

Post by thinwater »

doubledutch wrote:I just have the regular self tacking jib however my numbers are consistent with those on the plot. I made a point of verifying my speeds with a GPS since they seemed to be better than what others were reporting. I do have the tall mast.
Henry
So, trying to stir up tall rig envy? :lol:

In a few years I will need a new main, and I think a square top is in the cards.


Additionally, for what it's worth, those targets were with a load on, old sails, and beer. Cruising numbers.
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Re: Speed Polar Plot for PDQ 32

Post by mikeandrebecca »

Any numbers without an adequate supply of beer on board don't even deserve to be mentioned!
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Re: Speed Polar Plot for PDQ 32

Post by thinwater »

I made a few corrections (Cute down wind) and posted the worksheet to, if anyone cares.

http://sail-delmarva.blogspot.com/2010/ ... olars.html

Go ahead. Beat these numbers. I'm a cruiser - I don't care :wink: . Yeah, I know: any two boats going the same way are always racing.
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"Rigging Modern Anchors,"Seaworthy Press, https://www.amazon.com/Rigging-Modern-A ... 1948494078
Book Store. http://sail-delmarva.blogspot.com/2017/ ... store.html
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