Question: Use of dive light at surface in the day - for emergency signaling.

[oldschool45]

Good to think about. Wife & I both started carrying flashlights to look under "stuff." Great idea to have an alternative use for the flashlight. Also keep a good polish on at least one side of your dive knife and that can be used as an alternative to a mirror. < that works. Many years ago it got me a helicopter ride out of Everglades Park.

 

[Chris-Wood]

I made a navigation error a couple of weeks ago on a fairly easy dive at St Abbs in Scotland. There were 4 boats in the area, with a mild fog. I was diving solo and foolishly switiching between my wrist mounted compass and my dive computer integrated compass. Iended up surfacing after an hour dive BEHIND all 4 dive boats.

My dive boat was only just visible to me, after around 5 minutes there was no sign it was coming to pick me up. At this point I decided to try signalling with my torch, and one of the boats at the other side of my boat saw the light and alerted my boat via radio after another 5 minutes.

I learnt three lessons that day, don't use two compasses, calibrate your computer integrated compass, and always carry multiple signalling devices (my canister torch never leaves my set up, and my back up torch is also a narrow beam LED). I also have stobes for wreck diving when it's return to shot. I now carry these in my pocket, even on non wreck/RTS dives, and can be clipped to the top of my SMB.

 

[johndiver999]

How far is "useful"?

That is kinda what I am asking. Basically the way I look at it, if you are close enough that you can yell and/or the smb is very clearly visible to the boat, then a light is probably not useful or advantageous. If the light is MORE visibile than the smb, then it is useful.

As for the actual linear distance, that would depend on sea state, light intensity, ambient light levels etc. I'm hoping somebody takes this idea and runs with it and does some empirical testing, something I have NOT done. Cool experiment for a high school science project, I would think.

 

[johndiver999]

Hi @johndiver999

Interesting story.

I do quite a bit of drift diving in SE FL. In Boynton Beach, whether diving solo or with others, I generally have the dive flag and do not use my SMB. In Palm Beach and Jupiter, there is a guide in the water carrying a flag. Sometimes I ascend with the guide, other times I ascend by myself on my SMB. Usually, the pickup is relatively prompt but occasionally it takes longer. Often, when it takes longer, the boat is not visible to me when I ascend, and I would not have an idea of where to point a light. I do carry a relatively powerful light with me at all times and may consider using it if I can spot the boat and think that they may not see me. I wonder what might be more visible, constant light or the SOS flashing mode.

Out of curiosity, where were you diving when you used your light to get the attention of your boat? What is their drift diving policy regarding flags and/or SMBs?

We were diving from a private boat, under calm conditions, slight currents, far out in the Gulf of Mex... america, LOL We were not towing any floats and our SOP was: deploy an smb from the safety stop so as to reduce the chance of being run over and killed. The boat was dropping multiple solo divers at different reef locations that had separations of maybe 750 feet (and 5 minutes of time) or a little more.

If the boat is so far away that the diver can not see it, then (I assume) under those conditions, the smb is not going to be visible from the boat. I suppose you could spin around and shine a light in a circular manner, but I have no idea if that would work or is practical.

I am envisioning the use in applications where the diver can see the boat, but the smb may not be easily discernable from the boat. As you know, often an smb is visible at considerable distance, once someone ELSE has pointed it out to you. I think the light might do a better job of "catching your eye"?

 

[johndiver999]

I routinely use my flashlight for the boat to find me, infect I always bring and use a flashlight, and I always dive in the day.

Well maybe I am late to the party, but I have only come upon this idea recently.

 

[scubadada]

We were diving from a private boat, under calm conditions, slight currents, far out in the Gulf of Mex... america, LOL We were not towing any floats and our SOP was: deploy an smb from the safety stop so as to reduce the chance of being run over and killed. The boat was dropping multiple solo divers at different reef locations that had separations of maybe 750 feet (and 5 minutes of time) or a little more.

If the boat is so far away that the diver can not see it, then (I assume) under those conditions, the smb is not going to be visible from the boat. I suppose you could spin around and shine a light in a circular manner, but I have no idea if that would work or is practical.

I am envisioning the use in applications where the diver can see the boat, but the smb may not be easily discernable from the boat. As you know, often an smb is visible at considerable distance, once someone ELSE has pointed it out to you. I think the light might do a better job of "catching your eye"?

My SMB is a couple of feet taller than yours

 

[dmaziuk]

I'm hoping somebody takes this idea and runs with it and does some empirical testing, something I have NOT done. Cool experiment for a high school science project, I would think.

Too many variables I expect. At a guess, I wouldn't expect my $20 lights to be more visible than the mirror. They pump out quite a lot of lumens, but the beam is not particularly narrow and you can't focus it.

 

[Still Kicking]

Too many variables I expect. At a guess, I wouldn't expect my $20 lights to be more visible than the mirror. They pump out quite a lot of lumens, but the beam is not particularly narrow and you can't focus it.

I was using a $100 1,000 lumen light. An active light source flicked back and forth is apparently quite eye-catching.

 

[BoltSnap]

don't use two compasses, calibrate your computer integrated compass,

How so? Why? What did you find wrong with using two compasses, a computer compass, and a regular compass? I am curious about your experience.

The computer compass, when calibrated and the declination is set, will have an offset from the analog compass pointing North. You can play with the declination until the computer compass is pointing North in the same direction as the analog compass. (Not good for long distance or working from a map navigation)

 

[Mike_4635]

I was in Palau and a pretty good rain storm came in during the dive. The boat couldn’t see us but I had my dive light that has a strobe function. The boat saw the strobe and picked us. Tried a whisle first, the mirror I carried was of no use as was the SMB. I now also have scuba alert the connects to my BC inflator hose that came in handy during a Red Sea trip.