Expedition Navigation Software 
1 of 1
- i2b
- Expert
Offline - Registered: 2/04/2018
- Posts: 11
Route Optimization and Polar Correction for sea state
The boat I am racing on has relatively low displacement (7000lbs), her downwind performance is greatly affected by sea state. The polars are very accurate for flat water but offshore depending on sea state the optimal TWA that the boat can sail to can be 10+ degrees higher than the polar optimal TWA. How can we account for that? Correcting the polars themselves does not produce desired results, very likely due to the interpolation algorithm in Expediton and the optimal route still has angles which the boat can't sail to. Can someone share some for reference?
- Ernie M
- Moderator
Offline
- Registered: 11/05/2015
- Posts: 412
Re: Route Optimization and Polar Correction for sea state
I think your solution might be more practical rather than technical. I would develop at least a couple separate polars; maybe called "OffshoreModSeas" and OffshoreHeavySeas" and develop them using observed data. That way you keep your 'very accurate' polar for inshore events without degrading them.
Cheers
- i2b
- Expert
Offline
- Registered: 2/04/2018
- Posts: 11
Re: Route Optimization and Polar Correction for sea state
Ernie - any suggestions how to update the polars? Just putting "0" in the polar doesn't force the routing algorithm to cut off downwind angles.
- •
Thread Starter- Ernie M
- Moderator
Offline
- Registered: 11/05/2015
- Posts: 412
Re: Route Optimization and Polar Correction for sea state
You can just make the curve drop off steeply like you would if you were trying to avoid deep angles with an asym. I'm not sure if zero's work or if the program considers it a null value and ignors it.
Send me a PM and I'll try one for your type of boat and email it to you.
1 of 1