hrm for swimming?
I'm a bit new to this but can you use a heart rate monitor for swimming,,, and what stops the chest strap ending up around your waist ,, apart from the fact that my waist is bigger than my chest
You can most definitely use an HRM whilst swimming, but they're not always 100% effective: it's not a matter of conductivity between the chest strap and your chest, but of the connection between the chest strap and the monitor itself. Some manufacturers offer a memory belt that records HR data during the swim, for review at a later date, which is useful for some applications but won't give you the immediacy you may be looking for.
That being said, have you tried swimming whilst reading a watch before? It's not easy, in fact you're probably better off just going on 'rate of perceived exertion' to determine the training effect your swim is having on you.
Oh, and there's nothing to stop the belt from end up around your waist - it happens quite a lot to me, especially right at the start of a swim-phase when I'm pushing off from the side of a pool (which is obviously always the least convenient moment!). Tightening the strap helps, most of the time, but not always!