@Convert that graph is bollox!

from a deep-water oceanography point of view it isn’t.

generally lakes don’t stratify much but they can if you get very little wind to mix them and a lot of solar input.

like last week.

Convert, your graph represents open ocean in the tropics. A couple of clicks further on from that Wiki page would have got you to Dimitic Lakes

https://en.wikipedia.org/wiki/Dimictic_lake

your point about getting to 4 degrees by jumping off a pier probably still stands, though!

from a deep-water oceanography point of view it isn’t.

true dat!

Incidentally, if you want a real surreal experience, you take a youngish lad who’s only really ever swam outdoors in the sea and get him to jump in off a research boat in the middle of Lake Ontario. Of course I new that fresh water is less dense than the sea and that I wouldn’t float as well, but when you can’t see the shore your brain tells you you are in the sea. Very weird!

Cold water shock can happen at almost any temp.
I always find that the biggest effect is when there is a large difference between air and water temperature.
I had a few involuntary gasps a c couple of weeks ago when the water temp was 20, considering the lowest we got down to over the winter was 1.9.
The biggest difference for me was that the air temp was over 30 on the recent swim where in the winter the temp difference was about 2 degrees.
You can get cold in most temps of water if you are not swimming

The narrow (around 1 meter deep) thermal layer between the top and bottom layers is called the thermocline, and here the temperature drops rapidly from around 18 to 7℃. It’s worth knowing about this layer because if you do jump in you might encounter colder water rather suddenly.

I knew my PhD in Large Lake Phytoplankton dynamics would come in useful on here one day 🙂

OK – all good stuff. But still not the 20 difference in your first post it is 😉

This layering I suppose is relevant if you had been paddling (or seen other people paddling) and made an assumption that it would be the same when you jumped in unprepared AND the water had been sufficiently still for sufficiently long not to be mixed the relatively shallow depth a dive/jump will go down to.

All those ‘hidden currents’ we keep getting warned about will ensure the water is nicely mixed anyway 😉

My standard approach is just to stick my head down and do 10 or so strokes without breathing (or half that for breaststroke) Your body and mind get over the shock, and when you breathe, you breathe more normally, rather than gasping, so you don’t get the the additional panic of thinking you can’t breathe. Also minimises the chances of yelping and screeching!

Listening to the interview on the link to the Loch Lomond incident is enlightening – it seems they all thought that the water would be shallow enough to step into as the end of the jetty was so close to shore. 3 or 4 of the people involved made the same mistake – stepping off the jetty into the water. If I followed correctly, the only adult able to swim was drowned.

There’s a big difference between lack of appreciation and the frank negligence of not bothering to teach your kids how to swim.

Wow, by what age should your children have been taught to swim so that you are not labelled as negligent? The kids were 7 and 9. Neither of the parents of the older child could swim themselves.

I dont understand why adults would allow children who cant swim to play on a pier.

If its where I think it was, then its not actually a pier at all – its a mix of shonky reporting and a distressed father who just lost his wife and son (who almost certainly doesn’t speak English as his first language) – its actually a sort of narrow sand/gravel “spit” that runs from the out into the water. And the water suddenly gets deep on either side of it – so if you were just paddling at the side you could very suddenly end up out your depth.

I’ve actually been quite impressed with the moderate response from police and fire service providing advice. I kind of expected a more dramatic – keep out the water message but they seemed to have a more realistic, pragmatic message about being sensible, planning ahead and knowing what to do if it goes wrong. I was less impressed by Swim Scotland and the RLSS statements which seemed to be living in a bubble.

I suspect not many people know who to call if someone is in trouble on inland water? I suspect it’s even more confusing on Loch Lomond (or Loch Ness)! On most inland water in Scotland the fire brigade will be the people that rescue you, and so calling them is recommended; on Loch Lomond there is a rescue boat which is requested to Launch by the police so you are better calling the police; on Loch Ness the rescue boat is an RNLI one which seems to be requested to launch by the coastguard. That’s a really messy picture. The situation on L. Lomond may be even messier because on a busy hot weekend the rangers would almost certainly have been out in their rib and there is a good chance the police were too. Additionally, there would have been dozens of fast boats not that far away who would all have gone to help if only there was a joined-up system for sharing distress messages like there is at sea. I’ve no idea if it would have helped with either Friday night, or Saturday’s incidents but trouble on such a large loch is hardly unusual. For non-swimmers it probably doesn’t make much difference – no rescuer could get to you in time if they weren’t standing nearby. There are signs in car parks around the national park about safe approaches to wild swimming – but I suspect if you are just going for a paddle to cool down on the road from Skye to Glasgow you are not likely to think they apply to you. I can’t think of having seen a lifering or throw line anywhere other than purpose made piers/jetties around the loch. If they can afford a £100k rib (and its ongoing upkeep), I’d have to question if the park should be looking to provide some basic equipment at roadside car parks?

Poly, spot on, I think it’s the wee concrete structure at a layby just south of ardlui station?.

Poor reporting, and knowalls assumptions ain’t a great mix.

There was a call out / rescue reported the other day that ended well (bloke climbed out or was pulled out by his mates) where he was branded as a drunken fool or similar (https://www.theguardian.com/uk-news/2021/jul/25/drunk-swimming-a-growing-danger-in-the-lake-district) but in the event if a fatality such reporting doesn’t occur. Makes me think (tangentially) of the reporting guidelines for road incidents involving people riding bikes where it needs to be a little bit more objective.

@matt_outandabout Ta👍

@trailrat you’d think given that’s a ten minute walk from ours we’d have got in the water there. Will give it a go (when the rain stops).

@Nobeerinthefridge

Poly, spot on, I think it’s the wee concrete structure at a layby just south of ardlui station?.

mmm…, do you mean at Ardlui marina? I don’t think so. The rescue boat described it as Rhuba Ban near I Vow – they’d have said Ardlui if it was there. The police described it as “near pulpit rock”. Rhuba Ban is the name of the “spit” that sticks out of the west shore between I Vow and Pulpit Rock.

Naw, I mean the wee spit, never stopped at it, just thought it looked concrete.