Kate Chastain is ready to sail-ebrate Ben Robinson on his greatest adventure yet.

Amid speculation that her Below Deck co-star possibly fathered her newborn son Sullivan Cay, Kate poked fun at the paternity rumors while fêting Ben and his fiancée Kiara Cabral on their recent engagement.

"Congratulations!" Kate wrote on her Instagram Stories May 11, alongside a screenshot of a news article about the couple's engagement, "she's going to be the best stepmom ever."

Along with Kate's cheeky post, Ben took to his own social media to share the news of his and Kiara's engagement.

"After a wonderful 4 year relationship with my love Kiara I decided to take the next step and propose," Ben captioned engagement photos of the couple. "I feel like the luckiest man alive! Thank you to my friends and family for all of your support."

The 42-year-old continued, "I couldn't have done it without you, and obviously thank you to Kiara for saying yes and making an honest man out of me, I love you."

News of Ben's engagement comes three days after Kate addressed online claims that Ben is the father of her baby boy. On May 8, the 40-year-old tweeted alongside a photo of her son, "For the record, the only thing this handsome guy has in common with any chef is the tendency to get emotional around meal times."

The former chief stew and Ben first sparked romance rumors between seasons two and three of Below Deck, with Kate later confirming in a July 2019 taping of Watch What Happens Live that they did hook up once off-air.

Though their fling fizzled out, Ben and Kate have remained friends. In April, Ben posted a sweet snap with a then-pregnant Kate, joking in the caption: "Who knew that Kate Chastain and I would be the same weight one day… But to be fair I have been hitting the gym! Please wish my great friend @kate_chastain an easy delivery and a healthy beautiful baby! I am so proud of who you have become and the mother you will soon be."

The chef—who appeared on the Below Deck from 2013 to 2016—revealed he was dating someone during the Bravo show's 100th episode special in Jan. 2020. However, he kept tight-lipped about Kiara's identity at the time. 

"There is a girl that I like at the moment. We're trying to take it slowly. So, we'll see what becomes of it," Ben told host Andy Cohen. "But she's a friend, and we're having a good time together."