Speed Polars

PDQ issues applicable across all PDQ Yachts (or if you can't find a place for something, it probably belongs here for now)
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thinwater
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Speed Polars

Post by thinwater »

I've refined the polars I developed for my boat (PDQ 32 standard rig, inside jib leads, stretched to 34) and posted them for your amusement. They were constructed in average Chesapeake bay conditions over a period of years, with average loads (full tanks, dingy, solar panels, some crew, average sails, but pretty light on junk and with a pretty clean bottom).

I was cleaning out the basement and ran across an old Multihulls Mag with a review of the "new" PDQ 36. I massaged the data (some of the wind speeds were the same (10 knots and 20 knots) and some were different (5 and 15 knots had to be interpolated). The data is supposedly based on real testing, but...
* I'm sure they filled in gaps too.
* No tender
* I'm betting EVERTHING was empty.
* Clean bottom...
So I'm guessing the numbers are about 0.3-1 knot optimistic. Also, carrying a full sail hard on the wind at 20 knots or a chute at 90 degrees true in 20 knots is asking for capsize and sail damage. In both plots I clipped the data in ranges that I think are folly for cruisers.

http://sail-delmarva.blogspot.com/2014/ ... -3234.html

Enjoy. If you have any data to add, let me know. I'm not a racer, but I enjoy understanding what I'm doing. I know I've gained some speed over the years.

For example, take a look at how fast wing-and-wing is in terms of down wind VMG compared to reaching with plain sail. You need both a preventer and a jib sheet down haul to get it stable. On the Bay, for example, the fastest way to go 160 degrees is wing and wing, and then jibe one sail and reach at 130. Also, wing and wing is good in stronger winds where flying the chute gets scary. I've smoked down the Bay in 25-30 knots with deep reefs, wing and wing, and it was so smooth, the boat going just about wave speed (the stronger the wind the more stable it becomes).
Writing full time since 2014.
"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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