Ideal temps & times

NZL1NZL1 AucklandNew Member

I’m contemplating a long (for me) ocean swim which will be around 22km and probably take 7-8hrs depending on conditions and tides.

Assuming I start early eg 7am, I’m hoping to finish by mid-afternoon.

My normal eating habits are eating nothing all day and then starting to graze on fruit, nuts & cheese around 3-4pm followed by one evening main meal around 6-7pm. And that’s it until the same time next day. In other words my body is used to eating no breakfast or lunch and only eating during a 4-5hr window starting mid-late afternoon.

This is true even if I do an hour of swimming in the morning - I still don’t feel hungry until my normal time of around 3pm.

BUT. Will this change on the day I start swimming at 7am and try to keep going? Do you think I’ll run out of juice and need to eat at various intervals?

I presume I’ll need to takes breaks to drink water but not so sure about food if I can finish swimming before my usual ‘hunger window’ starts.

Final question, what’s the ideal water temp to do a 7-8hr swim (no wetsuit or hat or goggles just swimmers).

I was thinking to wait until we reach about 21C which will likely be early / mid summer here in NZ.


  • BillyChambersBillyChambers OhioNew Member

    Have you done some longer swims before? Knowing your history would be helpful to know! Hopping right to a 22km open water swim can be a big jump for some people I'd imagine. Ramping it up a little might be a better move beforehand.

    And in my opinion, you definitely should be eating during your swim with that duration (as a good place to start, every 30 ish minutes is generally recommended from what I've read. Plus or minus 15min depending on the person).

    I can burn pretty close to 800-900 calories an hour of open water swimming, so replenishing is very much needed. You die pretty quickly if you are not gaining back those calories you are burning, especially for that long of a swim! There are some really good threads on here with nutrition and what other people take. It's a little different for everyone so experimenting during practice is helpful.

  • NZL1NZL1 AucklandNew Member
    edited September 2023

    Thanks. I’ll search for nutrition-specific threads in that case.

    My longest non-stop swim to date has been 90 mins / 4.5km so I’m planning on slowing building over the next few months to increase that steadily to hopefully be ready in time for NZ summer in about 6 months from now.

    And by then the water temp will probably be around 21-22C which feels about right for a longer swim?

  • BillyChambersBillyChambers OhioNew Member

    If you are acclimated that kind of temperature I'd be cautious but it should be ok.

    For your training I would definitely look at this thread for your training. Like I said before, that distance can still be quite a bit for some people, especially for their first big swim.

  • LakeBaggerLakeBagger Central OregonSenior Member

    I agree with @BillyChambers— swimming = burning calories. Some of those can be from fat stores, but you need some sugar to act as a spark to get those going.

    You don’t really need to “eat” per se, just drink something with carbs on the go every 30 mins or so. Here’s the nutrition thread:

    Hypoglycemia is one of the most likely causes of hypothermia. Even well acclimated swimmers can get very cold in warm water if they are under-caloried. Plus, you will have a lot more fun if you are adequately fueled!

  • NZL1NZL1 AucklandNew Member

    It’s now 20C+ (~68-70F) here around Auckland and it’s fine for longer durations. Yesterday I swam 10.2km (took 3:30hrs in open water due to headwind coming up for second half of swim).

    I wasn’t cold or exhausted at the end and had more in the tank. But 10km within 3:30hrs was my goal so I was happy to finish and get out.

  • abeabe australiaMember

    great work kiwi

  • NZL1NZL1 AucklandNew Member

    Sorry I meant to add that I stopped 3x times for 750ml of electrolyte drink. I wasn’t feeling thirsty or hungry but it was more to prevent problems especially cramps. Which affected me quite a bit on my previous 6km swim a week earlier.

  • abeabe australiaMember

    i am about to do 34km in 7 weeks so distance/fitness is great but nutrition the key getting enough calories in - i dont like eating/drinking but realise i am no chance without it

  • abeabe australiaMember

    swimming speed about 3.6km an hour

  • NZL1NZL1 AucklandNew Member

    3.6km/h is a fast average (assuming that’s no tidal stream). I don’t think I’ll ever improve on my average of 3km/h. Personally, all I want to do is improve my endurance / distance ability rather than speed.

  • abeabe australiaMember

    3km an hour good most marathon swims cook strait look at that speed to get you across

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