View Full Version : calculating open water swim distances

May 2nd, 2005, 11:15 AM
I was wondering how people calculated open water distances? I started to swim in Long Beach, CA and was wondering if there was something that can help me figure out distances, for example, if there was a standard distance between life guard stations or beach bathrooms (I tried talking to the lifeguards but no one knew :confused: )

Rob Copeland
May 2nd, 2005, 01:51 PM
Personally, the actual distance in open water training is irrelevant. The important factors are time in the water and level of effort.

There are so many factors that impact point to point measurements/time (wind, waves, currents, chop, navigation skills…) that using them to figure your distance swum becomes secondary to how hard you are swimming for how long. For example, when I was training of the Jersey shore a few years ago, we would start from one beach shelter and head down the coast past another shelter 1 mile away. We would hit the 1-mile shelter anywhere from 10 to 45 minutes into the swim, depending on the current, wind, etc. A mile swum was not always a mile of swimming.

But, if you must know the distance, I’d suggest if there is a road parallel to the shore you could drive the route and note the landmarks. Another option is to check out distances on Mapquest. Or if you know someone with a GPS, you could walk it off and check your way points. Or the old fashion approach and pace it off (approximately 1760 adult male strides per mile)

May 2nd, 2005, 02:19 PM
Well, maybe I don't need distance measured like you said. I'm trying to train for an international distance triathlon (1000m ocean swim) and not sure how far I need to swim in the ocean. Are you saying all I need to really do is swim for a specific amount of time, like 30 minutes or so) and it should suffice in my training?

I can swim a long time and I can make the 1000m with no problem, but I just didn't know the level of effort I needed to expend for the 1000m. So for example, I was thinking that if I knew the distance, maybe I could sprint 200m, rest the 500m in between, and sprint the last 300m. Any suggestions on how I should train using time instead of distance?

Thanks in advance.

Rob Copeland
May 2nd, 2005, 05:21 PM
Don’t get me started on triathletes propensity to sprint the first 200 meters of the swim. How many marathon runners sprint the first mile, before settling into their pace?

But back to your questions; The first thing I recommend is to find your stroke rate, this way you won’t need to be checking the clock as much in training. After a 5 minute warm-up swim, time yourself for a 100 stroke swim (right arm + left arm = 2 strokes) at a moderate pace. The time for this should be somewhere between 1 minute (fast turnover) and 2 minutes (slow turnover).

For the sake of this post let’s assume your stroke rate is 60 strokes per minute (1:40 on your test swim) and your goal time for the swim is 20 minutes.

One possible training swim could be:
• 5 minute warm-up swim
• 100 strokes moderate pace (60%), 100 at 70%, 100 at 80%, 100 at 95%, 100 at 80% and 100 strokes easy (a 10 minute swim)
• 200 strokes at 70%, 200 at 80% and 200 at 90% (another 10 minute swim)
• easy 2 – minute swim
• 300 strokes all out (5 minute swim)
• 10-20 minute body surfing warm-down, practicing riding the waves on the way in (the greatest way to finish an ocean swim is catching a wave) and not getting thrashed by the waves on your way out

May 3rd, 2005, 12:53 PM
Your method sounds good. I'll try it this saturday. If you feel up to it, I'm all ears as to your take on the all out sprint in triathlon starts. The 1000m swim triathlon will only be my second one, so i'm not stuck on any specific strategy just yet.

Kevin in MD
May 4th, 2005, 09:15 AM
Originally posted by Rob Copeland
Don’t get me started on triathletes propensity to sprint the first 200 meters of the swim. How many marathon runners sprint the first mile, before settling into their pace?

How many marathoners go out too fast? Lots of them.

But the alternate question is, how many marathoners draft when running?

It also drives me quite nuts but I have adjusted to it.

Rob Copeland
May 4th, 2005, 01:02 PM
Didn’t I ask “Don’t get me started”?

How many marathoners go out too fast? Lots of them. – Yes, you will find marathon runners who take it out too fast, but I’d guess very few finish who sprint as fast as they can for the first mile, while bashing the brains out of anyone near then.

But the alternate question is how many marathoners draft when running? – The good ones do. Have you ever run into a head wind? Drafting in running does not provide nearly the benefit of drafting in swimming, but every little bit helps.

And for me there is a huge difference between sprinting the first 200 M and taking it out at a fast pace to get in a favorable position to draft. The typical Cuisinart-esque start at a triathlon makes it real difficult for most people to swim efficiently. And if you’re in an Olympic distance tri or longer you don’t want to be burning energy fruitlessly.

My basic advice is to take an outside position (away from the center of the melee) and at the gun take off at a strong steady pace (for a 1K or 1.5Kmile swim, I recommend starting out at your 400Meter race pace, find some feet by the 200M mark and settle in .

Why start away from the center of the pack, the straight line to the first turn? Basic math. First 300 people standing shoulder to shoulder 30 across and 10 deep will occupy about 600 sq.feet. Soon after the gun sounds those 300 people go from vertical to horizontal and now take up closer to 3600 sq.feet. Additionally the outside ranks of those 300 people are trying to squeeze onto that straight line to the turn buoy, with everyone sprinting. Instant Mix-Master. In a race with a 200Meter straightaway at the start, before the first turn, if you start 25Meters left or right of the center of the pack you will end up swimming an extra 2Meters. 40Meters left/right makes that an extra 4Meters you swim.

May 6th, 2005, 12:11 AM
Thanks Rob for the info. I will have to experiment a little since it will be my longest distance yet for tris but your analysis makes sense regarding square footage of starting behind a couple of rows vs. just starting on the far right or left.

May 8th, 2005, 11:01 AM
Go to www.topozone.com and find your starting location and click on that exact point on the map.

Switch the "coordinate format" to d/m/s and copy and paste it into this website:


Do the same for your ending point.

Click on "calculate" and you should have the distance.

May 10th, 2005, 10:46 AM
An international distance triathlon usually has the swim distance listed as 1500 yards.

May 15th, 2005, 10:27 AM
Well, unless the description is wrong, the international distance is 1000m for the tri I will do. Here's the link. http://www.kozenterprises.com/exec/koz/inter.cfm?publicationID=177

Originally posted by BriRunner
An international distance triathlon usually has the swim distance listed as 1500 yards.

May 15th, 2005, 12:29 PM
I looked at the website, and I'm sure they have it listed correctly, as 1K swim, 30K bike, 10K run. However, most of them are 1.5K swim, 40K bike, 10K run. I guess there is a range of what can be listed as "International Distance." Good luck!

May 15th, 2005, 07:09 PM
Have seen tri races of varied distances it just depends who is running them. Swimming distances are varied so I would train to maximize speed. Lots of 100s, 200s and 400s with short rests.

How do you determine how far you swim, count strokes per minute. I found that I could swim one mile in about 21 minutes at 64 strokes per minute. Herman Willamese took 75 strokes a minute to swim the same time for one mile. Current controls your time I have gone as fast as a half mile in 7 min with the current and 14 min and up against the current. Find a place where you can measure out a quarter or half mile course and do a two way swim. I used my car and plotted it out as close as possible (not a trig guy) Once you establish a swim count per minute to give you the time you want, you will take the time you swim and you will be able to tell your approx speed. You only have to have your strokes counted occasionally once you are used to pacing yourself by strokes.