Swim the race distance (practice)

I'd definitely recommend being able to swim your race distance non-stop in practice prior to attempting the race. 
If nothing else it's good psychologically knowing that you can comfortably complete the distance, plus you get a feel for the pacing.

Assuming your logs are accurate, I'd say you are woefully underprepared for your swim.  You haven't been swimming much more than 1500m/month, let alone continuously.  The longest set I saw was only 500m.

An old rule of thumb is that you should be swimming a total of three times your race distance per week in training.

Could you do it on less?  Sure, but I don't think it's a very good idea. 

Mark

Yup!  Or at the very least, be able to do this much at peak before race day.

if your swim is in open water, there is a good chance you will have to swim a good bit more than the distance --- currents, sighting issues, getting around crowds.  i know i like to swim outside to create an empty lane, which i also know gives me a longer swim course.

and like pointed out before, that swim is followed up by a lot more work!

I agree with both the above.  The "standard" session that I shoot to have my athletes doing prior to an oly is a main set of 20 x 100's at an interval of their T1000 pace + 5 seconds.  For example, if they swim a 1,000 TT in 17:30, that's 1:45 per 100, so their main set would be 20 x 100 @ 1:50.  Combined with the warmup, drills, and cool down, the entire training session will be about 3,000 yds.  Of course, this is in addition to adequate ows training.

x2 on this. Its a phychological necessity for me to know that I can comfortably to this. But I only do it once. For subsequent races at that distance I rarely swim more than 1000m in any set.

That seems kind of extreme for shorter distances like a 500M swim race O_o

If so, by the same logic, would someone training for an Ironman stick in 16 hours of swimming as part of their regular workout? (I don't know, I haven't done an Ironman, is that something you do for training? O_o  You're freaking me out here...)

I'm not saying I can't actually have a combo workout for an hour or two to train for a sprint, and really for the bike and the run it's not a problem, but having regular workouts that load the entire estimated time of finish on just just the swim as a cutoff to even start considering to sign up for an sprint still seems overkill on the safe side to me.  

No, not to sign up. 

But swimming for an hour by the time you get to the race is a very good idea.  Way too many people think they did 25 yards they are good to go for a race.

I'm not an advocate of any sort of mandatory swim check.  But if you come to BT and ask if you should have ever swum the distance before the race then the answer Shane gave is right on.

Shane,

Just to be clear, you are saying the swim workout duration for an Oly should regularly be in the 2500-3000 meter range.   You are not saying that someone doing an Oly should regularly swim 2500-3000 meters continuous, right?  

Don

What type of rest are you doing on the above set?

The 1:50 is a send-off interval, so the "rest period" is whatever is left over from swimming the 100. If he swims it in 1:45, then 5 sec rest. 1:49 means 1 sec.

I started swimming a few months ago and after I became somewhat comfortable with my understanding of "how" to swim (still far from perfect/expert) I started the 0-1650 program.  One thing I learned is that whatever your initial pace is when you start swimming (you usually try to go faster because you think you need to in order to stay afloat) you need to slow it down.  Once I slowed my pace down my endurance and form improved dramatically.  

To directly answer your question and from the perspective of someone who was in your shoes I would recommend definitely being able to swim the distance and add a margin for error to it.  The psychological benefits are huge, in addition to the physical.  

Everyone listen to Shane, not me.  But, as an anecdote, before my last sprint (750m swim), my Masters coach had the people doing the race put in a 15 min continuous swim as part of the 1 hour workout.  Her logic was to get us reassociated with the boredom from the continuous OWS and to focus on holding form for that amount to time.  While we never do that sort of swim otherwise, I really liked it a few days before the race for the reasons she stated.

ETA: This group could swim the distance no problem, so it was unrelated to that sort of test.

I always start my workout with a 1,000 yard warmup swim. It seems to me that if you can't focus on swimming that period of time already, you should stick to 50 sprints (and even those swimmers do a warmup nearly that long)