26 November 2004

A Bob spiel!!!

Today we split into two teams and dove at different sites. I think we have described the diving enough so I thought I would give another nuts and bolts version of some of the supporting tasks involved in the dives.


towing the polar haven.JPG (2429472 bytes)

The first thing we do is to drive over to where our PolarHaven portable dive shelter is parked and hook it up to the Pisten Bully. It's a nice light weight tent type of shelter on a light but sturdy sled frame. It tows real smoothly and has lots of room.

Our dive holes are scattered all over the place and can often be detected only by the black flags we leave marking them. If it's been more then a day or two since the hole has been dove, there will be a thick layer of ice covering the hole. We have chipper bars and dip nets that take care of the ice. It's easier to do this before the dive hut is pulled over the hole

Dipping.JPG (2813884 bytes)
Bingo dive hole.JPG (2523986 bytes)

If you're a good driver you can bulls eye the dive hole directly under the hatch in the floor of the dive hut. This hole has a current meter hanging around 60 feet down. It measures the water currents and the tide over several days.

Parking the Pisten Bully so that the wind won't blow the big doors off and aligning the the cargo door near the hut front door makes the job of unloading much easier. It may take as much as 700 lbs of gear to put 4 divers in the water. Minimizing the distance the weight belts and air tanks have to travel is a good idea.

Bully and haven.JPG (2396550 bytes)
lowering the line in to the hole.JPG (2714935 bytes)

Next is rigging the down line. This line dangles down the hole all the way to the bottom. It  is very important as it contains many of the cues that we may use to find the hole again. It's length is less then our maximum allowed diving depth of 130ft. We often ascend near this line to help us judge our ascent rate. 

One of the first things to go down the line are often things we need when we get to the bottom. Here is the video camera and light, the film camera and its strobe, and the big square thing is call a quadrat. The quadrat is used for counting densities of critters. The diver randomly sets it on the sea floor then counts everything inside the square.

cameras and quadrat.JPG (2623902 bytes)
flashers.JPG (2392145 bytes)

Flashers are very important and spaced out about every 20 feet on the down line. This year's ice being 15 feet thick and mostly covered by snow has caused most of our dive sites to be just like night diving. The flashers can sometimes be the only way to see where the down line is and their constant flashing in the corner of your eye is not only a comfort but a good aid in staying oriented.

It still amazes me how well the checkered flags work. There are usually 3 or 4 of these on every line. We might be able to see the flashers farther and in lower light but the flag size gives you a reference to judge your distance from the hole. They will flap in the current to warn us if it's too strong for a dive. But mostly they are the easiest thing on the down line to see.

line flag.JPG (2795905 bytes)
Pony bottle.JPG (2616035 bytes) The last thing to go on the down line is the pony bottle. This small bottle of air is a comforting item indeed. We haven't needed it this year and I sort of hope we don't ever need it but it's just a few minutes of extra air at 20 feet. We halt our ascents at 20 feet for 3 to 10 minutes depending on the maximum depth and bottom time of our dive. At this 20ft. depth we still have enough pressure on us that we don't decompress too fast but it's shallow enough to allow us to offgas gradually. It simply allows us to slowly readjust to the pressure at the surface. The pony bottle insures that we have some extra air available for this safety stop.

Lets see the next day!