What's the longest butterfly race you could swim?

I put 50, but it wouldn't be much of a race. I just started swimming fly a few months ago, and have just gotten to the point where I can swim it decently with fins. Just barely at the point where I actually do the last 100 of our 400 Reverse IM warmup, instead of making it a 300. The most I've tried so far without fins is a 50, and the last 10 or 15 yards were pretty ugly.

I put 50, but it wouldn't be much of a race. I just started swimming fly a few months ago, and have just gotten to the point where I can swim it decently with fins. Just barely at the point where I actually do the last 100 of our 400 Reverse IM warmup, instead of making it a 300. The most I've tried so far without fins is a 50, and the last 10 or 15 yards were pretty ugly.