Just like in cycling and car racing, following closely behind another swimmer is called drafting.
For the Triathlete this can be a huge advantage, a time saver and definitely something you should start to practice and do when you are racing.
The best part about it is that it's legal.
I cannot stress the benefits to you enough, they are tenfold and something you really need to start to do.
Firstly, you are getting pulled along by the swimmer in front which alone saves about ten percent (about 10%) of your energy output.
This means that you will be able to swim faster and get a better time if you pick the right person to draft off.
Another benefit is that you will not have to look up as much, however, you must still sight while you are swimming.
Never place full confidence in the swimmer in front of you.
Going off course, by not sighting will cause you to spend unnecessary energy.
You should practice drafting in the pool.
It is not a competitive environment and you can perfect your style of drafting there.
Although Mark Allen used to tap Dave Scott's feet during an Ironman this is not suggested.
It can really annoy the person in front of you.
Therefore, you want to be almost doing so, almost touching their feet and to be able to maintain this distance for the whole race.
Don't be afraid of the open water.
If you are a little nervous about it, do it with friends as a practice or where the water is supervised by lifeguards.
Think of it as a positive.
Open water swimming can add some much needed variety to your training:-)