Kate Chastain on Why Motherhood Is Way Harder Than 'Below Deck' Life and Her Next Bravo Chapter (Exclusive)

The Bravo favorite's next chapter is already looking full, with a new baby, a 'Project Runway' guest stint and new series 'Couch Talk.'

Kate Chastain is learning a lot in her first few months as a mom. Namely, she despises "tummy time."

"You have to teach them literally everything," the former Below Deck star remarks to ET, chatting from her home in Fort Lauderdale, Florida, over video call. She welcomed her first child, a son named Sullivan Cay, in May.

"I didn't know about 'tummy time,'" she rattles off. "You have to teach them to just lay on their tummy! Everything has to be taught. I thought they would kind of get it themselves." 

Being a mom is "a lot more" than Kate expected, but she's soaking up every minute of it. While she assumed her time as a chief stewardess aboard super yachts would serve as training for handling a baby, she now owns that she was very wrong. 

"It is so much different than I expected, so much more difficult, so I think that was healthy for me," she confesses. "I love a challenge. But a lot of moms would DM me on social media over the years and be like, 'I'm the chief stew in my house! I'm chief stew at my home! I've got three kids, I cook dinner, I've got to do their laundry and all their rooms and, you know, picnics...' I said, yeah, I guess it's kind of similar. Good for you, but now I'm like, I wish I could tell all of those moms you had it so much harder!"

"I was the mom of the boat," she says. "They were not the chief stew their home."

While Kate has kept details about Sullivan's dad a secret (she previously told ET it will be Sullivan's decision, once he's old enough, whether he wants to share that story), she did recently take to Twitter (aka X?) to dispel one rampant rumor among the Below Deck fandom: that her one-time co-star and close friend, Chef Ben Robinson, is the father. 

"This is an ET exclusive," she jokes of her reasoning behind the post. "Actually, when I was nine months pregnant, I went over to visit Ben. He's like, 'Let's take a photo together, and I was like, 'Ben. I am nine months pregnant. I don't want to. Don't post this on the internet.' He's like, 'We're friends. I just want to keep it for myself.' I go, 'OK, fine. Don't post this on the internet...' So he took the photo, guess what you did? He posted it on the internet! And the caption was, 'I can't believe it. Kate Chastain weighs more than I do.' Not my favorite caption."

For the record, Ben's caption was actually as follows: "Who knew that Kate Chastain and I would be the same weight one day… But to be fair I have been hitting the gym!" He also included well wishes as she stepped into this next chapter. Nevertheless, Kate needed a little bit of social media revenge. 

"That photo of me nine months pregnant with him started a lot of, like, 'baby daddy' rumors," she notes. "So I was very upset with him that he posted a photo of me when I was not looking my cutest. So, really, I knew that BravoTV.com had his baby photo where he was not looking his cutest. So that's really why I did it." 

That said, Kate admits to being "tired of people comparing" Sullivan to Ben, pointing out that the two really don't share much of a resemblance. She calls Ben Sullivan the "fun-cle," as in fun uncle. He's also got a surrogate grandfather in the form of Captain Lee Rosbach.

"Captain Lee is the type of grandfather figure to Sullivan that you would expect to say, 'I don't do diapers,'" Kate cracks. "I think, you know, he loves him from afar."

Stephanie Diani / Bravo

Sullivan and Lee are getting a little extra quality times these days, as Kate and Lee film their new series, Couch Talk. It's sort of a reboot of Bravo fan-favorite The People's Couch, mixed in with elements borrowed from Kate's other shows, Galley Talk and Chat Room. Each week, Kate and Lee sit down to watch the best of Bravo's current lineup, reacting to the most meme-able moments. 

"How lucky am I that I get to watch Bravo -- which I already do -- talk about Bravo with Captain Lee -- which I already do -- and do it in Fort Lauderdale, which is so convenient for me, which I already do," she quips. "It's been so much fun, and Captain Lee, it's nice to see him where he's, this is not his wheelhouse -- literally! You know, I'm explaining to him like, 'No, no, that's Marysol..."

Kate and Lee will react to pretty much everything currently airing on the network: Below Deck Down UnderThe Real Housewives Ultimate Girls Trip: ThailandLuann and Sonja: Welcome to Crappie Lake and, of course, all things Real Housewives: Orange County, New York City, Miami and Atlanta.

"It was so fun for me to describe to him the new cast of Real Housewives of New York, and his response is one of my favorite moments with him ever!" Kate teases.

Turns out, that moment was trailer-worthy! Check out the first look at the new series here:

"He really likes Crappie Lake," Kate shares. "A lot of people would be surprised to know, actually, though, that Captain Lee is a Bravo fanatic. He loved Don't Be Tardy." 

The pair will also be tuning into Project Runway, and -- in a meta moment -- will be watching back the episode they filmed for the show's current All Stars season. The remaining designers each took on the challenge of redesigning the formal uniforms the crews of the Below Deck universe wear every season. 

"I think it's a great idea to have them design new uniforms, because I was saying for years, I think we could use cuter uniforms," Kate notes. "Alas, it was always a polo shirt and a skort, so it was so fun to see what the designers came up with."

Kate believes she "manifested" her guest judging stint alongside Crappie Lake star Luann de Lesseps (Lee serves as inspiration/a model), having been a longtime fan of the fashion competition. Her "life goals," OG judge Nina Garcia, paying her a compliment ("She likes my hair!") only made the situation sweeter. 

"I love judging things," she says. "Like, I do that naturally from my couch when I watch this show, so to have the opportunity to sit in that chair and do it was amazing."

Zach Dilgard / Bravo

With multiple shows on her plate and two little men depending on her (she's also mom to dog Halo), Kate says her love tank feels quite full at the moment. However, she's not ruling anything out... especially whenever she takes her first weekend away as a mom.

"I am really loving being a mom, and Sullivan is the new love of my life as is Halo -- getting less attention -- so really, I got two living things really demanding a lot of my attention, but I think ... my first time away from the baby, mommy is out, mommy's first trip out? ... I am looking forward to that trip."

Should that trip be BravoCon in November, Kate isn't ruling out dipping into the pond of available Bravo-leb men, though she's not so sure available equals eligible

"I think that I am looking for less drama in my life, so while there are lovely gentlemen, lovely men on Bravo, I think we will just see what happens," she muses. "I don't know. I mean there is a lot, there is a lot that I would consider... at least for once."

Kate's guest stint on Project Runway airs this Thursday, Aug. 3, at 9 p.m. ET/PT on Bravo. Couch Talk With Captain Lee and Kate premieres on Monday, Aug. 14, at 10 p.m. ET/PT.