This new Windows only update has improved graphics performance (for some machines) and a slight modification to the 'add user' screen. To try the Beta:
1) In your Steam client, right click on eSail Sailing Simulator (in the list on the left). Or control click in Mac.
2) A list of options should appear. Click on 'Properties' at the bottom of the list.
3) Click on the 'BETAS' tab and select 'beta -' from the dropdown list.
4) That will download the Windows Beta as appropriate. Mac version is unchanged.
Please report any issues or thoughts in 'eSail Beta' discussion group.