Things Scuba Instructors teach that are either bad or just wrong.

[BoltSnap]

Fighting a ripping current and with 2 divers we've had it run for 40 minutes on speeds 7 and 8. That is with two 9AH batteries on it. With normal speed (3-4) we can get two+ hours of use with 2 divers on it.

So with the 12AH batteries, you will get much longer time I understand. That's great!!

 

[eponym]

A very lively thread, I must say. Gamon, I think, started the thread. Back to the original question (what did I learn and teach that might be wrong) my most recent discovery is that the "research" into caffeine and dehydration was, to put it mildly, poorly conducted. If you like, here is a link to a very recent Mayo Clinic analysis, which debunks the premise: The myth about caffeine and dehydration.

Thanks, Gamon

Your mileage (and your urinary output) may differ.

 

[boulderjohn]

A very lively thread, I must say. Gamon, I think, started the thread. Back to the original question (what did I learn and teach that might be wrong) my most recent discovery is that the "research" into caffeine and dehydration was, to put it mildly, poorly conducted. If you like, here is a link to a very recent Mayo Clinic analysis, which debunks the premise: The myth about caffeine and dehydration.

Thanks, Gamon

Your mileage (and your urinary output) may differ.

Avid readers of ScubaBoard should know the truth about this myth. It is debunked on a regular basis.

 

[Nick_Radov]

There are many reasons why this isn't efficient for swimming a direct line to target and would make you have to correct your direction and wasting air and power. I have done this for many decades and have experimented in pool and took videos and analyzed the swim postures, effort, distances, etc. over a very long time and came to the conclusion that swimming on back isn't an option and isn't ideal at all. If I get tired swimming with snorkel on surface, I just stop and not move at all looking at the bottom with all muscles are relaxed and just chill until I am rested and my pulse goes back to normal, not a second sooner.

You have not done the correct analysis. Swimming on your back works fine and is efficient. Maybe you have the wrong fins, or an inefficient technique. It's easy to stay on course, just watch a landmark or check your compass occasionally.

 

[Nick_Radov]

In contrast, I teach snorkeling/skin diving along with scuba and emphasize good skin diving skills throughout the course. I don't have students confuse or struggle with snorkels by the middle of the course at all. When students drop underwater, they learn to push back the snorkel keeper on the mask strap (it is usually pushed back for optimum location while snorkeling on surface anyways). If anyone confuses using the BC inflator or anything else with the snorkel, they will go through exercises switching between all without confusion. I don't have any issues afterwards with snorkel confusion.

Teaching some skin diving skills along with scuba is absolutely a good idea and helps build comfort in the water. Kudos to you for putting extra teaching effort into that area.

But as for using snorkels during scuba dives, you are giving your students bad advice and teaching them poor skills which will not work well when diving in other areas. There's nothing wrong with bringing a snorkel in your pocket if you might need it to mess around on the surface. But it absolutely should never be attached to a mask strap while scuba diving underwater. It presents an entanglement hazard (especially when diving in kelp forests or in overhead environments) and in a ripping current it can pull your mask right off your head. You've got to think this stuff though and figure out approaches that work everywhere instead of just in one specific circumstance.

 

[Pressurehead]

Do some you old guys remember in the past when we had a large knife strapped to our leg [mine was on inside of the left leg] and we had our snorkel [basic tube with mouthpiece] pushed down the straps beside the knife ?
Only on dives we may require it, that is.
Did not notice it when flutter kicking [which we did].
This was taught to me by some 'old salt' divers 50+ years ago.
Entanglement you say, we had "Excalibur" and often a small knife on the harness as well [I did].
I have a rolled one when required now.
Only had a snorkel on mask when I was teaching [as required and is a law here].

 

[Bob DBF]

But as for using snorkels during scuba dives, you are giving your students bad advice and teaching them poor skills which will not work well when diving in other areas.

I would think one would teach for the conditions the students are diving. That does not preclude advising of different configurations depending on other conditions.

But it absolutely should never be attached to a mask strap while scuba diving underwater. It presents an entanglement hazard (especially when diving in kelp forests...

I have been diving kelp forests of NorCal, since I arrived in the '70's, and SoCal trips in the 2000's, with an attached snorkel. I have been entangled in kelp several times, the f'n boa kelp being the worst, but never by my snorkel. It's only one data point, but I have not heard complaints about snorkel entanglements, by fellow divers who use the snorkel on long surface swims to the dive sites.

The best advice to give, is for a diver in a new area to find out the local dive configuration and why they use it.

 

[Bob DBF]

Do some you old guys remember in the past when we had a large knife strapped to our leg [mine was on inside of the left leg] and we had our snorkel [basic tube with mouthpiece] pushed down the straps beside the knife ?

What do you mean, in the past. If I took the BFK off I'd probably swim in circles for lack of weight on my inside right calf. Since I use the snorkel, I only tuck it in the knife straps occasionally depending on the dive plan.

 

[Pressurehead]

If I took the BFK

I only gave up the BFK, funny that is, about 10 years ago, only have 2 left, bottom photos
I only use a small serrated knife [still on the leg] and a line cutter on the harness now.

 

[Bob DBF]

I now also carry a line cutter, shears, and a small sharp knife as well. I started carrying all the hardware after I got tangled in an illegal trot line off the NorCal coast. F'n monofilament so I didn't see it, maybe 5' viz, until I was hooked a number of times, glad I was wearing 7mm farmer John, so the hooks were mostly in the suit. Obviously I got out OK, but trying to cut myself loose and untangled with the BFK was more work than I liked, so I started looking for more effective tools for the problem.

Since then I've run into mono in lakes I dive, but nothing like the first mess, and the line cutter makes short work of it. Since I mostly dive alone, I feel much better now.