Night Diving

[Foxfish]

How do you stay orientated while night diving? I've been doing a few dives along jetties including a ship loading jetty. Visibility is poor at say 3-4 m. I suspect the steel pylons are also affecting the magnet. It has amazed me how quickly I can become completely disorientated.

I've got a console mounted compass which is not great but don't believe this is going to make a drastic difference. It has got to the stage where I'm thinking a line may be the only other way to stay orientated.

 

[Bubbletrubble]

In low vis and night dives, I use a mix of "natural" landmarks (depth contours, rocks, cracks in the wall, etc.) and compass headings to ensure that I know where I am. On a dive, I always try to keep an updated mental picture/map in my mind of where I've been, where I am at present, and where I'm going to go. Here in SoCal we do a lot of shore dives. Typically, we'll select our initial descent point using a few landmarks on shore (two sets of line-ups separated by a good distance on shore) to make sure that we drop in at the desired site. With familiar dive sites, I rarely even look at my compass underwater.

I'd recommend doing whatever you think is necessary to maintain orientation. If that means running a line, so be it.

 

[Mr Carcharodon]

How oriented to you want to be? If I know I am swimming to shore, or out to the ocean that is enough. A compass works great for that. Beyond that you can use natural navigation. Note the slope of the sea floor, the ripples in the sand and the direction the marine organisms are pointed (they often orient themselves to maximize current on one side of their bodies). Night diving is just diving with a light. There is nothing to worry about and there is a whole new world of animals to look at. Have fun, it is wonderful out there.

 

[Foxfish]

How oriented to you want to be? If I know I am swimming to shore, or out to the ocean that is enough. A compass works great for that. Beyond that you can use natural navigation. Note the slope of the sea floor, the ripples in the sand and the direction the marine organisms are pointed (they often orient themselves to maximize current on one side of their bodies). Night diving is just diving with a light. There is nothing to worry about and there is a whole new world of animals to look at. Have fun, it is wonderful out there.

I'd like to be able to follow the jetty! :depressed: We were in only about 4 m of water so kept popping up to the surface every now and then to get a bearing. The jetty is about 500 m long at a guess. The bottom is sandy except close to the pylons. Pylons are spaced about every 10 m. I can get completely lost swimming from one pylon to the next! It's a bit embarrassing I know. My only consolation is that most of the other divers seem to have the same problem. I've dived this location before a number of times during the day.

 

[Foxfish]

In low vis and night dives, I use a mix of "natural" landmarks (depth contours, rocks, cracks in the wall, etc.) and compass headings to ensure that I know where I am. On a dive, I always try to keep an updated mental picture/map in my mind of where I've been, where I am at present, and where I'm going to go. Here in SoCal we do a lot of shore dives. Typically, we'll select our initial descent point using a few landmarks on shore (two sets of line-ups separated by a good distance on shore) to make sure that we drop in at the desired site. With familiar dive sites, I rarely even look at my compass underwater.

I'd recommend doing whatever you think is necessary to maintain orientation. If that means running a line, so be it.

I try to do the same thing except my mental map seems to get lost very quickly.

 

[gcbryan]

I understand the problem. If the steel pilings are affecting the compass it could be a real problem. Check that out during the day to verify that the compass is being affected (or not).

We used to have a long jetty (dock) here (since torn down) that was sandy, with a rather flat shallow bottom until you got to the end. Without a compass and with a little current moving you around considering the flat featureless bottom it was easy to get turned around. One piling looked like all the rest. I had to just trust the compass but the pilings here were wooden. Maybe you can just move away from the piling enough to not affect the compass and then just trust the compass.

If there is a slight increase in depth as you move along the jetty your depth gauge can give you some clues of course.

 

[g1138]

Swimming along a jetty with pylons is a real pain. Even in the day time, the local wharf here is a dark nightmare. If it's not the night type visibility once you're under, it's the black wall of loose detritus and sea grass blowing across your face.

The fact that you have metal pylons to contend with makes me feel extremely sorry for you. Are you absolutely sure it affects your compass?
Without a compass, the best way to maintain orientation in that environment (where "natural" landmarks all look alike), is to be extremely OCD.
Descend at a pylon and remember where you turn and orient with respect to that.
You're going to have to remember specific features on one side of each pylon such as the cluster pattern of barnacles, tunicates, and sea stars OR the damage marks on a pylon (easier if they're made of wood *cough* dive knife *cough*). You do this for each pylon you leave and arrive to. Stay at a constant depth when traversing between pylons. Once you're ready to turn around, it's a memory game.

With a compass this is easier, as you'll just rely on that.

Even following this type of strategy, it's near impossible in my mind, especially when your compass isn't working. Heck even with a working compass I still feel completely lost. I'll see the light coming into the wharf from the wrong heading at the end of my dive and completely stall in confusion.
Usually my buddy and I will just exit from under the wharf and surface to get our bearings before heading in. We're lucky in that our wharf site has an open beach on either side.

I wouldn't recommend diving a wharf at night unless you're planning on staying in a real localized area (The fun-feel to dodgy-feel factor is too lopsided IMO; I get creeped out a bit).
Having a line will definitely help but you should be aware that line in the water can pose an entanglement hazard.

A safer suggestion would be to buy a 50m or 100m meter tape instead. Bulky yes, but less chance of entanglement. Tie a bolt snap to it and loop it around a pylon and you're set to go.
I only suggest this because I've had more experience with meter tapes than reels. It's more in my equipment comfort zone. xD

 

[WetBoy101]

If you'd have gotten one compass heading during one of your day dives (pylon to pylon) you would be a hero on your night dive!!!

 

[Foxfish]

I understand the problem. If the steel pilings are affecting the compass it could be a real problem. Check that out during the day to verify that the compass is being affected (or not).

We used to have a long jetty (dock) here (since torn down) that was sandy, with a rather flat shallow bottom until you got to the end. Without a compass and with a little current moving you around considering the flat featureless bottom it was easy to get turned around. One piling looked like all the rest. I had to just trust the compass but the pilings here were wooden. Maybe you can just move away from the piling enough to not affect the compass and then just trust the compass.

If there is a slight increase in depth as you move along the jetty your depth gauge can give you some clues of course.

Good idea. I'll try it out during the day to verify if the compass is being affected.

 

[Foxfish]

g1138, good to hear others have similar difficulties. This is a jetty so while relatively safe you tend to wander out into no mans land on either side. We dove on another jetty an few weeks back and had similar problems.

Hadn't thought of a tape measure. Can't see how you'd progress far with it though.