Sub Zero vs. Sub Tropic, You Decide

Posted on: February 11, 2014

We posed the same questions to an ice diver and a tropical diver, here’s what we got…

1. How do you prep for a dive?

(ICE) First we have to check thickness of ice and make sure it is safe to walk on with our heavy equipment. We require ice that is at least 6 inches thick when teaching the SDI Ice Diver course. In Utah it is typically between 8 and 24 inches thick when we go diving. Besides getting all the gear ready you have to decide who will be surface support, line tender, and safety diver for each dive. Multiple sets of clothing are good since you normally get a little wet cutting the hole whether it is from water or sweat. A warming hut is nice for changing into your diving exposure protection rather than wearing it during all of the prep work prior to diving.

(TROPIC) First we check the weather and the tide charts to see if ocean conditions allow for diving. Depending on the location we’re diving, whether it’s a shore dive or a boat dive, will determine how we prepare for the dive. If it’s a shore dive, we’ll load our gear into a vehicle and drive to the site. If it’s a boat dive, we’ll put our gear on the boat and we will head out to the site that way. If necessary, sea sick medicine and sun screen should be considered, along with snacks for in between dives. You can usually dive in warm water in a swim suit, or rash guard and board shorts, if you tend to get a little cold you might need a 3mm wetsuit for 1-2 dives per day.

2. Equipment considerations for a dive

(ICE) Ice diving requires all of the standard equipment for scuba diving and more with some special considerations. It is helpful if the harness or BC has large D-rings so that you can securely attach the line to you and your buddy.

Because of the temperatures, a drysuit is required. Dry gloves and heated undergarments are recommended and make the dive much more enjoyable. Because of the cold temperatures most divers wear thick, or layer multiple, undergarments. This adds quite a bit of buoyancy so the diver must be sure he has enough weight and sufficient lift in his BC to counteract the additional weight.

The freezing temperatures also require the diver to ensure that the chosen regulator is tested and approved for use in freezing and sub-freezing temperatures. An environmentally sealed regulator is most often preferred due to first stage icing problems.

A great deal of additional equipment is required to cut the hole. An auger is used to cut 3 holes in the ice. Next a chainsaw is needed to cut between the holes making a triangle. If the ice is thicker than the length of your saw you may need to cut out blocks and remove them in pieces. Ice screws are used to secure diver lines to the surface and the divers. Snow shovels are used to shovel snow off in the shape of arrows pointing back to the exit so divers below can see them in an emergency.
Ice divers also need standard cold weather gear and safety equipment including a heated shelter and sleeping bag in case of hypothermia. Don’t forget some sleds to drag your gear out onto the ice.

(TROPIC) Diving in the tropics doesn’t change the fact that you will need all of the standard equipment for scuba diving. You might also consider a full length wetsuit or “skin” in the event you run across a jelly fish.

Even though the water temperature is usually around 26-30C / 80-86F after long in-water durations, getting cold can sneak up on you unexpectedly.

Depending on the location, if you are shore diving, towing a dive flag might be required to let passing boats know your location underwater. Carrying a Surface Marker Buoy (SMB) is highly recommended and often times required if you are diving off a boat to allow you to signal your location on the surface from a far distance if you get lost.

3. How long are your surface intervals and what do you do during your time out of the water?

(ICE) We concentrate on warming up and gearing up for the next dive while keeping the hole from freezing over. During training dives, we must balance the off-gassing during the surface interval with staying warm enough to complete a second dive.

(TROPIC) During our surface intervals we prepare our gear for the next dive, eat snacks, let the hot sun warm us up, and sometimes snorkel on the surface if conditions allow. We talk about what we saw on the previous dive, flip through fish identification books, and every now and then a pod of dolphins will pass by to really brighten up the time spent out of the water.

4. General Hazards

(ICE) The first hazard everyone thinks of is hypothermia. Any time you are exposed to freezing environments hypothermia is a concern. Staying warm is important and necessary for the diver’s safety. žThe diver’s thermal status will affect the rate of inert gas uptake and elimination, and rewarming before a repetitive dive is as important as accounting for residual nitrogen levels.
Any overhead environment can be a hazard. It is necessary to exit in the same place you entered. You can’t always just go straight up. Without a line, finding the hole you entered could be impossible.
More equipment means things are more complicated. The equipment can have more frequent problems such as free flowing regulators, icing over on the surface, etc.

(TROPIC) Because many tropical dive destinations can be fairly remote, make sure to have a first aid kit and oxygen on hand as emergency medical care might be delayed in the event of an accident. Staying hydrated is equally important in this hot humid environment which easily brings on dehydration. In addition, sun screen is usually a must to avoid a painful sun burn keeping you out of the water.

Diving in warm clear water brings on additional set of hazards often times overlooked… It’s important to pay close attention to your depth and time as it’s easy to end up deeper than you originally planned for. Keep an eye on your computer throughout all portions of the dive and if you’re not with a dive guide – make sure your navigation skills in check to ensure you end up back to where you started.

5. How long are you dives?

(ICE) During our ice diving courses, 25-35 minutes would be a typical dive. žBottom time may be limited more by a diver’s intolerance to cold than his exposure to increased oxygen partial pressures or the amount of decompression required.

(TROPIC) Dives in the warm water of the tropics is usually dependent on no-decompression limits or air consumption rates. If you’re doing a shallow reef dive in 6-12M / 20-40FT, you could easily spend over an hour underwater. Deeper dives in the 18-30M / 60-100FT are usually under an hour.

6. What do you see on your dives?

(ICE) Ice diving can be a serene and beautiful aspect of SCUBA diving. As a winter activity, ice diving offers the diver the opportunity to enjoy sport diving year round. In freshwater lakes, we can see everything we would on a normal dive, along with the beauty of the ice itself.

(TROPIC) Tropical diving is famous for its abundance of sea life. From the colorful corals and sponges, to thousands of species of tropical fish, turtles, rays, eels, sharks, dolphins and so much more. Every dive is exciting because you just never know what you might encounter. Along with the amazing critters, the topography of many tropical dive sites is breathtaking in itself. Dramatic walls and deep canyons are commonplace in many tropical destinations and are a spectacular sight.

7. How do you clean your gear?

(ICE) With fresh water dives the gear does not need a lot of cleaning. It doesn’t even get dirty setting it on the snow afterwards. We use a chainsaw with no oil on the chain to prevent contaminating the water and equipment.

(TROPIC) Nothing shortens the life of your scuba equipment more than improper maintenance and salt water. Thoroughly rinsing your scuba gear is absolutely necessary after diving in salt water to avoid the buildup of salt crystals that are extremely abrasive and will destroy dive gear over time.

Your BCD must be rinsed from the inside and out, if you have items in the pockets of your BCD, take them out to thoroughly rinse with fresh water. If you have a cutting device, remove it from its holder while rinsing to avoid rust build up. Wetsuits need to be disinfected every few dives and hung by a hanger to dry. After rinsing your mask, fins, and snorkel let them dry in a cool dry location to avoid mold build up. It’s important to ensure the dust cap on your regulator is in place prior to rinsing it to avoid water entering into the first stage. In addition, try to keep your gear out of direct sunlight for extended periods of time as this will fade and deteriorate your equipment.

Thank you Dive Addicts for helping us with this post.

For assistance preparing and scheduling training for your Team contact ERDI or Omni Divers Underwater Services, L.L.C. directly.

 

Please email omnidive@omnidivers.com or omnidive@gmail.com if you are interested or want additional information.