If I could make a suggestion regarding lifevest for infants and small children
We sailed and did long passages with our kids
and found that they were miserable in the life jackets. They never fit correctly and are uncomfortable and hot in the tropics.
We also came to the realisation that it is more important to keep them attached to the boat than floating. Additionally as they get a bit older, old enough to take things off, you want them to be comfortable and "buy in" to the concept
We don't put our kids
in life jackets at all, instead we keep them in harnesses and attached to the boat full time. on passages they sleep in their harness as well, it becomes part of them and they are much happier for it.
Thee only time we use life jackets was on dingy rides from the boat to shore.
Floating doesn't help an infant much if the boat is sailing away, staying attached via a harness, that can also be used to limit movement to the cabin
when the parents are busy with the boat, was for us, a much better solution.