Learning pace, and how to calculate splits immediately comes with practice, so having the pace clock where it can also do some good technically, is a great idea.
I love underwater pace clocks. The ability to learn something, and remind swimmers that they should always have their eyes and mind on the time.
The Pace Pal is a small, and effective underwater pace clock. With a tilting face, you can adjust how far away the swimmers will need to look at the clock. With a tripod mount, you can also attach a camera and get some cool underwater footage during practice.
I personally use the clock with the face pointed more directly up, and either position it close to the wall, or a bit passed the flags.
To get the swimmers to focus keeping the head down coming in to the wall, I place it close to the wall, facing out toward the length of the pool.
To get the swimmers to focus on a longer streamline off the wall, I position the clock with the face aiming back toward the wall.
The swimmers will adjust the time they see based on where the clock is positioned. If it’s going in to the turn, they’ll need to add a second to the time to get a more accurate split time. If the clock is positioned under the flags or further coming off the turn, the swimmer will need to subtract 2-3 seconds from the time they see to get an accurate split.
Keeping your swimmers engaged on the TIME aspects of practice, while also teaching them solid techniques for better walls, is a dream for coaches.