How much slower would one expect to swim in a lake IM swim vs. an ocean IM swim, assuming both are wetsuit legal and all other things are equal? Or will the lack of waves or swell negate the lack of buoyancy from the salt?
For reference, I did a 1:06 in the ocean last year, so I’m not appalling but certainly not good, but have a lake swim to contend with this year. I know there’s no one-size-fits-all answer - just a rough figure would be great!
Sounds like you are assuming lack of waves and swell in the lake vs having those things in the ocean, so all other things are NOT equal. If you assume everything except salinity actually IS equal then the increased buoyancy should technically be a benefit but how much will depend on how poor your body position is. Regardless, it’s not really worth worrying about because you can’t do anything about it and swim courses are never exactly comparable anyway.
Hi,
I’m hoping to pick the collective brains of ST:
How much slower would one expect to swim in a lake IM swim vs. an ocean IM swim, assuming both are wetsuit legal and all other things are equal? Or will the lack of waves or swell negate the lack of buoyancy from the salt?
Someone just gave you most of the right answer, all things equal, the only difference is the salt in the water and the temperature. And most people will swim faster in salt water than fresh, as long as they are not overheating in it. Salt water at the same exact temp as fresh water, will feel up to 10 degrees hotter, so an 80 degree lake swim would be quite pleasant in a wetsuit, the equivalent 80 degree ocean would cook you…
Someone just gave you most of the right answer, all things equal, the only difference is the salt in the water and the temperature. And most people will swim faster in salt water than fresh, as long as they are not overheating in it. Salt water at the same exact temp as fresh water, will feel up to 10 degrees hotter, so an 80 degree lake swim would be quite pleasant in a wetsuit, the equivalent 80 degree ocean would cook you…
Really? Why? Not that I doubt your expertise, I’d like to understand the “why”.
The answer is Salt. The more salt in the water, the hotter it is going to fell. You probably have been on vacation somewhere where there was an 80 degree ocean, no wetsuit and hot as hell. Now think to your 80 degree pool, it feels just right, on the cool side even. Same temp, but the salt makes a hell of a difference on what it does to your body, an insulating factor…
FWIW then I swam pretty much the same 1:41/100m pace for a half in the ocean and a full in a lake. However, the ocean swim was in a bay, so slightly sheltered from waves, and the full was in a lake that is 40km across and so had a pretty decent chop. The lake water temp is also much lower than the sea temp.
I swapped between the two a fair bit in training, and to be fair didn’t have any massive differences in feel. Biggest difference is if your’e used to swimming in lake, then you need to get right out the habit of tasting/swallowing water otherwise you’re not going to enjoy the bike run with the stomach cramps.
The answer is Salt. The more salt in the water, the hotter it is going to fell. You probably have been on vacation somewhere where there was an 80 degree ocean, no wetsuit and hot as hell. Now think to your 80 degree pool, it feels just right, on the cool side even. Same temp, but the salt makes a hell of a difference on what it does to your body, an insulating factor…
Thanks. I live and vacation in New England. We’re lucky if the ocean hits 65 degrees :-).
Thanks for the info! I could probably have worded my question more clearly - that’s what happens after a long work day and a swim!
Anyway, I’m not worried about it, just curious. I never worry about things outside my control in races - merely plan for them where possible, but thought it interesting to see how other athletes have fared in that situation.
The answer is Salt. The more salt in the water, the hotter it is going to fell. You probably have been on vacation somewhere where there was an 80 degree ocean, no wetsuit and hot as hell. Now think to your 80 degree pool, it feels just right, on the cool side even. Same temp, but the salt makes a hell of a difference on what it does to your body, an insulating factor…
That really doesn’t make much sense to me.
Dissolved salts will change the specific heat capacity, conductivity, density and boiling point of water. However, I can’t see a reason why any of those would make a huge difference to how you experience a given temperature while swimming. Ambient air temp, solar radiation, wind, and temperature gradient with depth all make a big difference as to how open water feels compared with a lake or pool. All apply to indoor pools, some to outdoor pools and one to lakes. I would expect those to make a much bigger difference than salt with regard to perceived temperature.
Is your assertion about salt based on your experience and observations (I’m certain you have more practical experience than me) or do you also know the mechanism that explains such a big difference?