Ah, but, Bear, my thing is, I know I can do a mile of pure breast stroke fairly easily, it's the crawl that's the major problem. (In fact, if I have time, I can happily breast stroke for 1.5 or 2 miles without knackering myself. Not very fast, mind, but I can keep going.) Even a very slow crawl leaves me so much more tired than breast stroke. It's like 7 minute miling compared to 11 minute miling! I'm sure it's poor technique mixed with feeble arm muscles, and I am getting better with practice, but I still have a way to go.