Firstly, let me liken my experience utilizing a swim coach to what I know best: cycling.
Each time I spend quality time with a swimming expert and mentor I feel as if I had just been riding my bike for the last 3000 miles with the break rubbing. Yes, huge wattage for a fraction of the potential speed. Yeah, that sucks. You may feel the same way in your swim.
My whole career has been spent hammering the swim to come out in the middle of the pack and then chasing down guys who swam much better, seemingly, on much less effort. As I become more and more efficient swimmer I'm learning one thing: yes, they did swim much faster and they used half the energy shed by my completely non-hydrodynamiclly inclined body.
2010, enter Melissa Grosenstein. Find her on Facebook or track her down at the Randolph, NJ YMCA or hit me up for her info. Or, now, maybe find her on a tri course, being that she just started racing, and, by the way, was the fastest Newbie AND an AG podium in her very first tri. She won't mind me telling you it was mostly on pure fitness and swimming domination because experience sure didn't play into it :) Being first out of the water must be nice! (One day, with her help, I'll see how that feels.)
Working with her a day or two a week means one thing: drills, drills, and drills. She's on the money with this. I'm going to paraphrase the epic triathlete Don Fink. If you can bike 112 miles and run 26.2, you have the aerobic capacity to swim 2.4. Period. How efficiently and fast you do so has to do with your swimming form. Thus, treat swimming like golf. It's all about form during the majority of practice.
So now I've been in the water 5 days a week. But only one of those days is focused on distance. Once a week I get out in the open water and hammer for 2+ miles. Here is where I build swimming endurance and work on sighting skills.
Otherwise, yes, I'm in chlorinated water staring at a black line on the bottom of the pool trying desperately to figure out how to roll my hips properly. (Yes, ladies, my inability to dance even cuts into my triathlon performance). Would seem boring, but each time I swim a new PR it gets easier and easier. In the Randolph Triathlon I only had to bike by 9 guys to be third on the bike course.
For those of you down towards the Princeton area please check out Erica Smith, a great swim coach I have worked with previously. She's an OPEN WATER BEAST. Find her on face book or hit me up for her number. A collegiate all-american she'll get you in top form for sure