Winther was unable to comment on her appeal while it goes through the official channels, but confirmed she planned to lodge proceedings with the Tribunal.
She later posted a statement on her Facebook page.
"YNZ's decision has come as a huge disappointment to me and I will be appealing...I have been reminded by YNZ that I am still bound by my Athlete's Agreement and can't comment on this issue."
YNZ high performance director Jez Fanstone said he had not been notified of any appeals from the athletes. Asked if he expected there to be any, Fanstone responded:
"That's up to the individuals. We've taken a lot of flak recently from certain individuals around supporting or not supporting some of the classes. We've supported all the classes in this Olympic cycle but when it comes to selections we have a high bar," he said.
While Winther offered no details on the basis of her appeal, it is understood it will centre around a lack of clarity and transparency in Yachting New Zealand's selection process.
Winther qualified New Zealand a berth in the Laser Radial class at the August Games with a 11th place finish at the 2014 world championships in Santander, but was dropped from the NZL Sailing Team the following year due to inconsistent form after a battle with injury.
Since then, Winther's campaign has been entirely self-funded. In a last ditch bid for selection, Winther sold one of her boats to compete in key regattas in South America and Europe last month, finishing 11th at both the world championships in Mexico, and a World Cup event in Hyeres.
Her 11th placing in Mexico met the published benchmark for selection in the NZL Sailing Team, being one of "New Zealand's top Olympic campaigners who have made the top 12 in their most recent (respective) class World Championships ... and have shown consistency of performance over the years".
There is no new NZL Sailing Team selected this year, with the team being the actual Olympic team.
Kosinska may have a tough task convincing the Tribunal of her case for inclusion, having finished 24th at last month's key selection regatta in Hyeres.