Buoy: (noun):  float 2; especially, nautical: a floating object moored to the bottom to mark a channel or something (such as a shoal) lying under the water.

https://www.merriam-webster.com/dictionary/buoy

The word is from, Bio Lowe: I Always Write About My Mother When I Start To Write.

“I wanted to lay them, breathtaking, at her feet, and by doing to bind her heart to mine, ever after to be buoyed up like a raft on a calmed ocean.”

In this sentence the author is trying to expalin how he/she wanted to feel their mother close to her/his heart by thinking of the love towards the mother in the calm ocean.