Swimming

Before Christmas I did some arms-only drills with a float held (oh so glamourously between my legs), and found that I didn't run out of breath then.

This led me to the possibly false conclusion that it is powering my legs that is costing me more oxygen than I have on board- therefore I need to simply swim more and become more efficient.

Also, all my other training (well, running and cycling) does not involve holding my breath, so my body simply isn't used to having to deal with things as-is for three strokes.

I have this exact problem - just wondered if you'd got anywhere with it, Dammit, or if anyone else had any advice? Essentially, can swim crawl relatively ok with a float between my legs, but when I have to kick I get out of breath and panicky within a length, pretty much. Am a capable swimming generally and can happily swim 2k of reasonably bs, but something is going badly with the crawl...