As I mentioned previously I did 2 miles in the open water without a wetsuit on Saturday. And to be fair I was quite pleased with that.
However, one thing I wasn’t pleased about was my speed as I swam at exactly a 40-minute mile pace.
The reason this is concerning me is that as you extend the distance, the time takes on a much greater significance. I was always working on the assumption that I was a 35-minute mile swimmer, but over a mile the five minutes is neither here nor there. However as I swim the 10 ½ mile Windermere it makes quite a big difference. 10 ½ miles at 35 minutes per mile means I’d be in the water for less than 6 ¼ hours, yet at 40 minutes per mile it’s exactly 7 hours (at 30 minutes per mile it’s “only” 5 ¼ hours).
Now I know that as I swim I’m likely to slow down my pace and that these figures aren’t accurate for that reason – but if anything that makes it more important.
Then on Sunday evening I did my usual mile in the pool. As the whole time thing was preying on my mind I timed it. I actually did it in 31 minutes and 19 seconds, so more than eight minutes faster than in the lake.
So what’s the reason for this? I was tired on Saturday morning, but then no more tired on Sunday evening as I’d had a very active weekend (we did the excellent Tonya’s Challenge as a family on Sunday morning – for anyone local I’d strongly recommend it for next year). I swam hard on Sunday night, but I wasn’t hanging about on Saturday either.
The main difference was the lake versus the pool. Some of that was the fact that I wasn’t always that straight in the lake (military swimming – left, right, left, right), but of course the biggest difference was the cold.
However, the more I’ve thought about it since the weekend the more I’ve decided to not worry about it – for now.
The whole 1,000kms concept is important to me this year, so I’m going to use this year as a way to get my body used to the effort required by putting as many miles in as possible (and doing as much on the bike as I can, and maybe even running too). But I’ve decided that I won’t give myself the 1,000kms challenge next year and instead I’ll plan some sessions that are more specifically designed to trying to speed up a bit, while also building up for the effort of Windermere.
1000kmstowindermere 
Interesting stuff. I was pleased to see on a personal note that my mile pace isn’t too dissimilar to yours.
I think you are right about the cold, the other aspects that might need considering is turbulence.
When there are lots of swimmers there is lots of turbulence and messy water is difficult to get purchase in. In pools this is often constrained by the lane ropes and sometimes funnelled to help you. I know where I swim, if there is aqua aerobics on its like swimming up and downhill!
Another consideration might also be the effect of wind (not your bottom) on the flow of the water, plus the drag effect on you.
Hi Barry, thanks for that. I agree that there are a lot of factors involved. I think my main disappointment with the time in the lake was the fact that it was quite a still day – so not too much wind or turbulence. I’m sure in many other swims it’ll be worse and I’ll be even slower. Anyway, as I mentioned that’s something I’m going to work on much more next year. I’ll try to do another 2.5 miles this evening and see how I get on.
Well I’m no hydrodynamic expert, though I do have some interests in the topic. I would also suspect some differences due to the nature of the bottom also (again not yours). How deep is the lake and how flat is the bottom. I would also suspect lake water to be a little more dense due to the flora/fauna that is within, thus more resistance.
Don’t get me wrong, I’ll take all the excuses I can get 😉
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