Water Temperature

[ChillyWaters]

Water Temperature

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Well, I got a little thermometer in my stocking this x-mas. I now have a question regarding the usual water temperature around here.


The thermometer reported 39F (3.9C) on Saturday. Is this abnormally cold, or does it get colder? And how cold does it get in the Inlet, especially if there's some run-off?


We were just enjoying a very relaxing shallow dive at Saxe point. I'm kinda glad we didn't go deep and cold somewhere. I don't want to get toooo much cooler in my wetsuit.

OFF TOPIC: Anybody know what those small "brittle star"-like creatures are at Saxe? They look like a very small brittle star or baby starfish, but they get sucked into the sand if you disturb them.

- ChillyWaters
P.S. Random info: Someone told me that the gravitational pull is so strong today that you can balance an egg, and it should stay on its end nearly all day. I forgot to try it...

 

[Lightning Fish]

Water Temperature

The thermometer reported 39F (3.9C) on Saturday. Is this abnormally cold, or does it get colder? And how cold does it get in the Inlet, especially if there's some run-off?
...

I was out at Whytecliff a couple weeks ago and the water temperature was 8C. Is it normal for the water temperature to change that much in a couple of weeks? Or is run-off or other effects causing the water temperature to drop that much lower where you are?

P.S. Random info: Someone told me that the gravitational pull is so strong today that you can balance an egg, and it should stay on its end nearly all day. I forgot to try it...

Gravitational pull from what? Your leg perhaps?

Cheers,
Bill.

 

[SeanQ]

My bottom timer was reading 50F (10C) in the inlet a few days ago. I'm not sure if that is accurate though because I had to send the unit back after it got stuck in dive mode.

If we're thinking of the same creature, I always thought they looked like the bottom of a mushroom cap. IIRC, they're a type of Polychaete (bristle worms) belonging to same class as tube worms. I'll try to find some species or genus names; I know I've seen them in one of the local guide books.

 

[ChillyWaters]

My bottom timer was reading 50F (10C) in the inlet a few days ago. I'm not sure if that is accurate though because I had to send the unit back after it got stuck in dive mode.

Is this normal, is this a low, etc?

If we're thinking of the same creature, I always thought they looked like the bottom of a mushroom cap. IIRC, they're a type of Polychaete (bristle worms) belonging to same class as tube worms. I'll try to find some species or genus names; I know I've seen them in one of the local guide books.

http://www.iopan.gda.pl/~trapper/www.underwater photos Trapper/Ceriantus spp and polychaete.jpg

I did a google image search and this is the closest thing I could find. They looked kinda like the smaller little stars in the sand, in the picture. Except there were fewer arms on the things I was looking at. I saw them last year when I dove there too -- they are everywhere.

- ChillyWaters

 

[ChillyWaters]

Ihttp://www.iopan.gda.pl/~trapper/www.underwater photos Trapper/Ceriantus spp and polychaete.jpg

I did a google image search and this is the closest thing I could find. They looked kinda like the smaller little stars in the sand, in the picture. Except there were fewer arms on the things I was looking at. I saw them last year when I dove there too -- they are everywhere.

- ChillyWaters

Actually, they did basically look like the medium-sized one in the top left of the picture... interesting.

- Steven

 

[nessum]

If water seems particularly colder from one dive to another within a short period of time, you may want to consider if run-off is a factor. Is the colder site you're diving exposed to much more fresh water run-off than the warmer site? If it's the same site has there been more run-off recently?

Because fresh water coming off of snowy mountains is freaking cold (did a safety stop on the weekend in some chilly waters, myself).

 

[AtomicWalrus]

I've been keeping track of bottom temperatures from my dive computer on a spreadsheet for a few years now, and water temperatures have typically been at their coldest at this time of year. Water temp is usually about 50°F (10°C) throughout the summer at depth, getting down to 48°F (9°C) in November/December, and bottom out at around 46°F (7°C) in January. It starts warming up again around March.

It's also important to distinguish between surface temperature at temperature at depth: temperature at depth (40 ft and below) doesn't vary much, but the surface temperature (down through 20-30 ft) changes a lot depending on air temperature & run-off from streams, rain, etc. I really notice this when doing my safety stop at the end of a dive in about 15 ft of water, or when I've been sitting on the surface for an extended period on a course while students demonstrate their skills.

 

[MarkH]

The Strait of Juan De Fuca (Saxe Point) is very different from the Strait of Georgia (Vancouver, Nanaimo, etc.) We don't really have a thermocline here. Temps are more or less the same at the surface and at depth (same with visibility). Fresh water runoff isn't much of an issue here. Saanich Inlet is alot more like the Strait of Georgia with regards to stratification, fresh water, etc. (but without the silting).