Do UV rash vests work if they are a bit big?

[BornToFolk]

Sorry if this isn't the right place for this, I had no idea where to put it!

Anyway, I've just ordered DS a UV rash vest for holiday. I got a size up to be on the safe side but it really is quite big.

Do they have to be skin tight in order to protect from the sun? It's like a baggy t-shirt on him.

dc are skinny so they are rarely a tight fit and work fine. Less comfy when wet though.

You only need them tight if your using it under a wetsuit.