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Ice Diving Shelter
Minnesota style

Michael J. Knorr

Fall is a beautiful time of year in Minnesota. With the changing of the season, there comes brisk, cool nights and the leaves take on a full palette of gorgeous colors. Our Minnesota waters start their slow cooling and with that comes increased visibility and a last chance for divers to enjoy a few dives before their equipment is put away for the winter season.

Minnesota winters can be quite harsh. For a few divers, winter offers an opportunity to brave the elements and enjoy unprecedented visibility under the calmest of conditions, and a layer of ice. Micks's Scuba, Inc. has for years run a popular ice diving course. This class has always been offered in March. By then, winter has started to let up on its headlock of subzero temperatures and there is still adequate ice cover to stage an ice operation. Temperatures can predictably get to 20 to 40 degrees and there is still 2 to 3 feet of ice cover. Why couldn't we offer these programs throughout of long winter? We often encounter 20 to 30 degree below zero temperatures for weeks on end during these times. What we offer is a recreational ice diving program. We had to take control of the weather, hence the development of the 'N'Ice Dive Inn'.

Plans for a workable design were developed with the help of Ardin and Dale Niemi of S-M Enterprises of Moorhead (a metal fabricating company). We needed a light weight, portable, stable, comfortable, dry, warm and (of course) good looking shelter! Let me describe the new Minnesota weather environment we were able to fabricate.

We started with the floor. The floor consists of six panels of treated lumber that when assembled covers an area about 200 square feet. The floor panels resemble dock sections in that the top is slotted so that any water will run down to the ice. Each panel has rope handles to make transportation easier. In one corner of the assembled floor there is an opening approximately 4 by 5 feet. This is the diving entrance. A cover drops into this hole to provide security during setup, breakdown, and when diving activities are halted.

The sides of the structure are assembled from 14 panels of insulated aluminum. The roof consists of five expandable bows over which we stretch white canvas (for light penetration). We are integrating a bubble insulation sheet under the canvas that will lessen the heat loss. This design can easily be enlarge by adding additional panels and extensions.

We use a free standing propane heater for heat. The 50,000 BTU heater can take the temperature from subzero to 70 degrees in a matter of minutes. We have found that from door traffic and air circulating under the floor, we get adequate ventilation for fresh air.

The inside design keeps everything off the floor. All attachments are of aluminum and hook over the wall panels. For example the 150 foot diver lines, are coiled onto standard garden hose holders that are mounted on aluminum sheets. The safety lines are anchored to the floor through bolted pad eyes with locking carabiners. We also have a variety of hooks and shelves for various items.

One of our lines used during our training is a hardwire communication line. The instructor who is monitoring the divers uses this line. At the shelter's communication station, the dive supervisor can either communicate directly with the diver via head set and microphone or the shelter's speakers. The speakers allow the diver to talk directly to the tenders, giving instructions and suggestions based on their observations underwater.

At the far end of the shelter (away from the hole) there is a designated dry area where people can dress down in comfort at the end of the dive.

Divers use an aluminum ladder to get in and out of the dive hole. Divers exit the water no differently than boarding a Caribbean dive boat! This ladder swings up and out of the water while divers are down to prevent problems with the lines.

How does our dive operation work? First, we clear an area of snow about 25 by 50 feet. This gives us easy movement around the shelter once it is up. We use two groups, one prepares the hole while the others shovel orientation lines in the snow (providing we have snow). The lines run out on the cardinal directions to a distance of 150 feet. These orientation lines have arrows shoveled into them giving direction back to the hole. The hole cutting is done totally by use of handsaws. We use the hole cover to trace out the hole size. Then, using a 10 inch ice auger, we cut a series of holes around the perimeter of that tracing and in the middle. The handsaws that we use are made locally and look very much like a very large jackknife. The blades are about 4 feet long with very course teeth. We have two of these saws and have found that the hole can be cut in about 20 minutes with 30 plus inches of ice. Once we have completed the hole, the ice chunks are pulled from the hole with large ice tongs and slid off to the side. We tip each up and insert a small block of wood to prevent them from freezing to the ice. The shelter is then assembled over this site.

Our trailer is positioned closely outside as a changing facility and equipment assembly location. The trailer is heated and has a large air cascade system for onsite tank fills.

We set up a rotation with divers. Typically, we have a number of certified ice divers just diving as well as a number of students. We alternate between divers and students. We are on a strict 20 minute dive rotation. This allows us to have the next team of divers start suiting up as one group goes in. We give them a 10 minute, 5 minute, 1 minute heads up and when one group of divers comes out of the water, the next team, with their tenders, are standing ready to lock into the lines and go. One thing we do that is different from many, is that we run separate safety lines for each diver. Hence, each diver has their own tender. I have found this to be advantageous in that both divers are communicating with the surface independently, they can better work through problems without affecting the other diver adversely and, in the event of a more severe problem, the diver is able to independently return to the hole. This does not mean that each diver is diving independently by themselves. Divers continue to stay together during the dive, communicate with each other and follow general safe diving practices. The down side is the crossing and entangling of the two lines. Divers are taught to be aware of their position as they swim about. They must be aware of how all their movements affect their line position. In the event lines do get crossed, we have found this does not affect communications with either diver nor does it affect their ability to freely move, swim, and return to the hole.

Ice diving Minnesota style allows us to start programs in early December as soon as the ice cover allows safe staging of the shelter. We can teach 6 to 7 classes rather then the usual 1 or 2. We are not concerned about the weather nearly as much…we have conquered the cold. Our equipment related problems are just about gone. As most ice divers know, equipment problems are typically a result of improper handling of gear prior to the start of the dive and are related to the cold conditions. We are able to keep equipment warm right up to the dive. Other surprising facts…about 70 percent of our divers are diving wet! We have a large insulted Igloo cooler with hot water, which is replenished with water heated on our furnace. As the divers complete their final check, their tenders flush their gloves, boots and suit with this water. All seams are then duct taped to minimize circulation. We have had small women comfortably complete a 20 minute dive and return with a warm smile! Night ice diving has become a popular activity among the certified crowd. We often start diving at 8:00 a.m. and do not stop until 11:00 p.m. We may rotate through 30 or 40 divers a day. Of course with this number of dives, everyone has to be very aware of their buoyancy control because we use this same site all day.

In the Midwest, when many divers usually are putting their equipment away for the long cold winter, we are excitedly getting ours ready for a full winter of diving. Even though the water might be 39 degrees, we happily except the 60 to 100 foot visibility and the now warm topside conditions!



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P.O. Box 593
Hurley, NY 12443
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