Expedition Navigation Software 
1 of 1- LeeWard Mark
- Expert
Offline - Registered: 12/21/2015
- Posts: 55
Expedition Calculations of TWA and TWS
Howdy --
We use RayMarine instruments :-(. We know enough to have Exp calculate TWS and TWA for the purposes of verifying/updating polars using log file data. We think we are implementing this by going to 'all settings/System/Calculate' and checking the 'Twa&Tws' box. My question is with these settings does Exp calculate TWS and TWA, only using AWA,AWS, and BSP? This, I believe would be the standard definitions of these terms, just need confirmation that this is how Exp does the calculation, please.
Cheers,
Mark
- Nick
- Moderator
Offline
- Registered: 9/16/2015
- Posts: 3,065
Re: Expedition Calculations of TWA and TWS
The Raymarine wind sensor used to be quite good.
If you have them, Exp also uses the heel/roll and leeway values.
Heel is optional as Garmin/Nexus FDX includes an effect in the apparent data.
- LeeWard Mark
- Expert
Offline
- Registered: 12/21/2015
- Posts: 55
Re: Expedition Calculations of TWA and TWS
Hi Nick --Thanks for reply.
Just to clarify, when Exp calculates TWA and TWS it doesn't use SOG (as opposed to BSP). So, when recording a logfile in the presence of current, TWA and TWS are not affected by current.
Unfortunately, I don't think our RayMarine system puts heel/roll on the bus, though I think the fancy solid-state compass has the accelerometers to do that.
Cheers,
Mark
- •
Thread Starter- Nick
- Moderator
Offline
- Registered: 9/16/2015
- Posts: 3,065
Re: Expedition Calculations of TWA and TWS
Yes, it uses BSP.
- LeeWard Mark
- Expert
Offline
- Registered: 12/21/2015
- Posts: 55
Re: Expedition Calculations of TWA and TWS
Great. Thanks much for confirming that.
Cheers,
Mark
- •
Thread Starter