I had to get a bigger half/partial prosthesis because my replacement implant is much smaller & still a work in progress .....blah blah & so on. When I went to get the new one I asked if I could swim with it & was told I could as long as I washed it gently each day. Which is what I did. I went home & started sewing triangle pockets in my tank tops. It worked well I am happy to report, because we were basically spending all day in our swimmers I wasn't fussing with it &to keep it secure I used little plastic press studs to close the pocket. Even though it was a bit smaller I had a sarong tied around me if I was walking anywhere & something was better than nothing.
I am about a D/DD & the partial is an Amoena Balance Delta & if you have a look on the internet it is a weighted one & I found it great, didn't have any issues with using it this way.
Carmel