Negative split the swim?
Swim the first 300-500M for time and then settle into a pack/pace?
Even pace the whole thing?
Upcoming Oly swim on Sat is rectangular, single loop in nature. 300M, 800M, 400M.
I find it hard to pace the swim because there are so many variables in play – wind, waves, current, poor sighting causing swimming off line, and the course can be less than exact in its set-up.
I swim by effort for the approximate distance of the race – all out in sprints and less effort as the race gets longer. You probably know your level of effort required to swim a decent mile or so; swim like that and look at you watch when you get out of the water.
That almost never happens…
The last time that I swam that race at the “Olympic Club Mile;” I was lucky enought to negative split it going 6 minutes, then 5:50 then 5:40, - kind of freaked out the race director. But I did have some Enervit before. 
I believe that Brian Goodell’s world record swim in the 76 Olympics was negative split, at least a portion of it…
It’s a real challenge to watch everyone take off at the beginning and not try to run with the big dogs. Or take off then slow down a touch after the first couple of 100s, and then maintain pace.
Last year, I was swimming a lot of 4000 meter swims straight, concentrating on going faster at the end. That didn’t happen all of the time, but after one gets in better shape, - one is able to do it. There’s a certain point where you achieve diminishing returns by doing “over-distance” workouts, - but I do it in both cycling and swimming. I also did a fair number of 4000 meter swims where’d I go the first 2000 without paddles, then stop for 10 seconds, get my time, put on hand paddles and make sure that I went faster for the second 2000 meters.
On my masters team, every two days we would swim 14 X 150s with 10 seconds rest trying to maintain the exact same time, every 150.
Now, that’s the pool… Get out in the open water?? Currents? Swimmers? Waves? Navigating? Goodness, - holding a pace, much less negative splitting, is a real challenge
Just don’t fall asleep in there…
Based on your times from Cali - you would rate as a decently strong tri swimmer (not an uber fish, but probably top 1/4) - so if you can handle the crowds/excitiments etc - go out full pace from the beginning. If on the other hand you have some level of race anxiety/hyperventilation problems at the start - hold back and negative split - definitely by the first turn you should be hammering your swim.
Basically for a 1500 there is no reason to do anything but go your pace, other than your ability to handle the race start and general open water - I would guess you don’t have a problem with those issues.
Thanks for the insight. I have quite a bit of confidence in my abilities in the open water - just need to channel that fitness and skill in the right direction at the right time.
In an OW swim at the beginning of a tri, I don’t think the question is so much pace as as to do as well as possible under the conditions you find, which includes where you are relative to the rest of the field. Since I’m usually one of the faster swimmers in my wave, I try to go out fast enough to get clear of the traffic so I can then swim as straight as possible. If I can catch faster feet, great, but otherwise once clear of traffic (about 200 yards) I just get into about the same pace that I could for an hour long swim and then try to avoid running over too many people from slower waves and stay on a straight line between buoys. Lots of other potential strategies depending upon how you are going to end up relative to the rest of the field.
a 1500m in open water?
I would:
swim the first 300 AFAYCG (as fast as you can go!!!) to get away from everyone.
and then I would sight the next waves and swim as fast as I could, to try to catch them,
repeat.
I heart swim racing. though I’m not sure why I’m in such a hurry to get to my bike 
if we were talking about a pool 1500m I’d tell you something different.