Reminds me of Tom Neale's "An Island to Oneself" - https://harpercollins.com.au/products/9781775492979
Luckily you can read the entire book on his daughters site, or at least you could in the past.
Unrelated but similarly enjoyable is: Shrimpy: A Record Round-the-World Voyage - https://en.wikipedia.org/wiki/Shane_Acton