Polar Diagram/VPP Resources

[sandycohen]

Does anyone know of a good resource of polar diagrams for older boats? I am trying to find one for my Pearson 32, without shelling out $300 to USSA.

Thanks!

[barnakiel]

What do you need it for? If for a real life situation, then just go out on the bay one sunny day and make yours.

For most practical purposes I found that similar boats make similar diagrams. In real life the choice of fore sails / kites will make most difference.

In Pearson you will have a super short WL and light displacement with relatively fine foils. Probably easy to get her up to speed in light conditions provided she gets good canvas, but not easy to keep her pointing high nor going fast in any good chop.

b.

[bob perry]

Call US Sailing in RI. I'll bet they have the data on file already for your boat.

[Bash]

Unlike Barnaiel, I find polars to provide useful data in conditions where I'm unable to achieve hull speed.

If you have a GPS system that measures VMG, velocity made good, you can use this as a substitute for polars. The way it works is quite simple: once you're close hauled, set a waypoint directly to weather and note your compass course and the VMG. Now, pinch up a few degrees, and determine how this effected VMG. If it went up, come up a few more degrees until the point where it no longer rises. If it went down, bear away a few degrees at a time until it comes up.

The advantage of using VMG on a GPS, rather than using polars, is that the VMG system will automatically compensate for such factors as surface chop, a dirty bottom, or less-than-new sails. The disadvantage is that you won't know whether you're getting the absolute best speed through the water you should be getting for a given amount of wind pressure.

[hellosailor]

Sandy, there used to be at least one freeware VPP calculator available online but I suspect the one you can buy from USAA will be better. Your other alternate sources are to try other owners, owner groups, etc. to see if anyone will give you a copy. VPPs are not easy to come by, in general.