+1 to the NO clock watching. Go by feel, and if you come in over the time, you know that you swim feel pace is slower than you want so go harder. If it is under the time, enjoy the faster time, but know you can go harder.

As for pacing. I do my research on who in my age group from previous races is at the pace I am looking to swim at, then seek them out before the start and hit their feet.

Works most of the time, except when they are having an off day, then you need to decide if you want to stay there or make you own waves.

If you're comfortable enough with your swimming, you might be able to manage your Heart Rate by feel. I did a workout last week where I tried to keep my HR between 130 and 140, which is something that I can do by feel in the water but not as easily on land.

Failing that, I suggest taking your Cruise Interval and then do a 1000-yard timer where you make an effort to hold steady at about your CI the whole way through. I think you'll find that if you can properly pace the early part of the swim, the rest will fall naturally into place. But that involves watching the clock, especially early on.

For me, my CI is about 1:15. And I find that when I'm swimming at about 75-80% of my MHR, I'm usually going somewhere between my 1:15 and 1:18. Which is kind of the point of finding your CI.

My favorite pacing workout is descending sets. Descending in this case refers to the time (as in getting faster). That means you take a distance and break it into smaller chunks, set an interval pace, then set your goal on swimming each chunk faster.

So, training for a 500 yard sprint triathlon swim, I would suggest:

6 x 100 Descend by 3

What this means is that you'll pick an interval time. Let's say you normally swim an average of 1:45 per 100 yards at your comfortable distance pace. So your interval will be 2:00. You will aim to swim your first 100 on a 1:50 average pace, your second 100 on a 1:45 pace, and your 3rd at a 1:40 pace. That means you'll get 10 seconds rest after the 1st 100 (leaving on the 2:00), 15 seconds rest on the 2nd, and 20 seconds rest on the third. Then you start over with the next set of 3, swimming them again at a slow, medium, and fast pace. Once you get comfortable with doing these, you can aim to make your 2nd set slightly faster than the first. You can also start backing the interval down to get less rest.

Keep a good eye on the clock and make sure you are actually hitting the times you set out. The first one should feel very easy, the last one should feel tough. Doing these sets will help you become very proficient at knowing your paces and setting them accordingly. So you can look at a distance and know exactly what pace you want to start out at, and hit that pace exactly, finishing strong.

BTW, this workout can be scaled up to any distance. For an Oly triathlon, you could use 200s or 300s. My favorite IM swim workout is a good warmup then 6 x 500 descending by 3s, 2nd set faster.