Greyhound37
Super Anarchist
My newly issued club certificate predicted speeds are 15%+ faster than my designers polars (which are tough to reach). Is this common?
ORC Certificate speeds vs Polars
- Thread starter Greyhound37
- Start date
Left Shift
Super Anarchist
ORC and ORR prepare polars for special conditions and assumptions for specific races or locales. Is that the case with your certificate? They can be wildly different from what designer's assumptions for polars show.
EastCoastHustle
Member
Yes, common. They use different VPP's and make different assumptions in how the boat is sailed.
Greyhound37
Super Anarchist
- Thread starter
- #4
I thought your polars speed was as good as it gets. Polars show 12.6 kts at 135 degrees in 20 knots. ORC says 14.7 in those conditions. How do you find 2 knots?
MauiPunter
Will sail for food
Just ask Scotty for more power. The Warp Core can definitely take it.
There is a significant discrepancy in ORC accuracy of polars. ORC uses an assumed stability computation that favors boats with high initial stability and penalizes older style boats that do not have the same degree of initial stability. So if you have a boat that does not have a lot of initial stability, like an older narrower boat with a shallower keel, you are at a real disadvantage compared to the ORC rule. The new breed of racers with very low vcg and wide beam have a huge advantage racing under ORC.
The ORR vpp uses actual stability of the boat in its speed prediction and can be more accurate than ORC.
The ORR vpp uses actual stability of the boat in its speed prediction and can be more accurate than ORC.
Itsabimmerthing
Anarchist
ORCi polars/targets seem to be pretty accurate for C/R type boats. My old boat sailed pretty easily to 100% polars.
It would help to know what boat you have? and if you have you ORCi-cert?
Greyhound37
Super Anarchist
- Thread starter
- #10
So I voiced my concern to ORC, asking if this is just the way it is. They asked for a few clarifications, and I pointed out a ballast tank error... they sent a revised "test" certificate faster in every way. I think I will just leave it alone.
