For a change I entered the pool with just the pull buoy and no other aids. Notably there was someone else with fins so there is a bit of a trend developing.
Today's session was 7x300m juts trying to keep a regular relaxed pace. As time went on they became harder and I found I was struggling with waves. Whether the pool really was getting rougher or I was just finding it harder to cope is unclear. It was evident however that my pace slackened across the sets from around 2:30min/100m to over 2:40min/100m. That's perhaps not too surprising as it is over 2km and that's quite a bit for me still.
I've found that the watch has missed a few lengths in the last couple of sessions and assume this must be where I turn very promptly, without a pause but don't manage a decent push off. That tends to happen when there's congestion at the end of the pool. It is good though that I'm not pausing; although in general I'm not finding the arms-only approach aerobically intense.