|
DIVE BOATS
By Capt. Dan Berg
Dive boats vary drastically in size, style and design, depending on
what type of conditions they were designed for. For our purposes,
they will fall into two main categories: commercial and private.
When dealing with commercial charter boats, divers should have to
check only to see that the Captain is licensed and that the vessel
is certified for the number of customers on board. Divers can
usually just relax and wait for the Captain to anchor up to the
wreck and then enjoy the dive. Private boats, however, need a little
more discussion. First, the boat, hopefully a good sea worthy craft,
needs to be prepared for diving. Of course, a dive flag is
necessary, but so is a grapple hook, granny line, current line,
oxygen, medical kit, sturdy ladder, radio,
depth recorder,
loran C,
radar, and
compass, as well as the knowledge and seamanship to use
them. As with wreck diving, duplication is the key to a safe and
enjoyable day. Many boats choose to have two lorans, radios, and
depth recorders. Private boats may also have davits to hoist in
heavy artifacts and tank racks or bungie systems to prevent damage
due to tanks rolling in a heavy sea. Since this book is not about
seamanship, rescue or metal shop, let's assume that the boat is
properly fitted and the operator experienced. For new boat owners, I
recommend a course given by the US Power Squadron or Coast Guard
Auxiliary.
Finding the wreck is the next problem. In
Bermuda,
Florida or other
clear water locations, many wrecks are located with the aid of
triangulating land ranges. After aligning these ranges, the skipper
looks for uncharacteristic straight lines on the otherwise barren
sand or coral bottom, which indicate a wreck is underneath. In the
northeast, most wrecks are located with a loran C. Loran, an acronym
for Long Range Aid to Navigation, triangulates land based radio
transmission broad cast from approximate right angles and
interpolates this information into two lines of numbers. A loran
location is usually exact to within 50 feet, which means that each
time you return to the exact number where the wreck is, you are
within 50 feet of the exact spot. Loran numbers for known shipwrecks
are available in a number of shipwreck books as well as on nautical
charts. Boaters should realize that the loran number taken on one
boat may be slightly different from the reading observed on their
boat. This is why it is very important to keep your own list of
loran numbers. When you are doing an initial search for a wreck and
have approximate numbers place a marker buoy over the numbers you
have then do a series of slow grids over the area. The whole time
keep an eye on the depth recorder, watching for the wreck profile.
You can also watch for depth changes because it's common for larger
wrecks to have wash out around them. If the depth drops quickly, it
could be a wash out. Grids can be of circular shape, figure eight or
straight line. Once the wreck is located, another marker buoy can be
tossed over and the exact loran number should be noted.
To anchor with a grapple hook, simply approach the marker buoy from
down-current and toss the hook after the wreck appears on the
recorder. The hook should grab in one or two throws, and divers can
then descend to tie in the hook. The grapple should be tied into the
wreck to prevent it from breaking free. Some divers use a separate
line, while others just wrap the grapple hooks chain around some
solid wreckage. Be very careful when working with an anchor. Any
surge, wave or current can quickly pull the hook upward. Always stay
up-current from the grapple when setting or pulling it. Never get
between or under the anchor line to work on the anchor. Whoever sets
the hook should also make sure that the line cannot chafe on any
overhead wreckage. Before sending divers into the water, the boat
operator should be certain to raise a dive flag, put a current line
with a float off the stern and if there is any current present, he
may setup a granny line. Granny lines are used by divers to assist
themselves up to the anchor line in current situations. The granny
line should be attached to the anchor with a shackle and weighted so
it drops to about 20 feet. The line should also be attached to the
dive boat's stern, so it is within easy grasp after a diver does his
entry. The granny line works well especially when divers are
entering the water using a giant stride entry. This is because the
diver has better control over where he is going to land. Sometimes
divers using entries such as the back roll will get caught in the
floating granny line and have to adopt other techniques. In these
cases, divers can be pulled forward by someone on the boat with a
short line. There should also always be a capable person left in
charge of the boat. Never leave the boat unattended while you go
diving. Whoever is left topside should be instructed not to allow
any other boats to anchor on top of the divers in the water. He
should also know how to operate the vessel, use the loran, have the
correct loran coordinates for the wreck and know how to use the
radio and the proper emergency channels. Let me stress the
importance of this with a little story. Of course, as always I had
to learn the hard way. Kevin Travell, a dive buddy of mine, and I
were diving a small tug boat, the
Fran S. It was a night dive, and
Kevin had brought our friend Phil to sit on the boat. Phil had never
been on my boat before and had absolutely no experience in power
boating at all. Kevin and I anchored, then descended, leaving Phil
in the middle of the ocean on a dark full moon evening. After
catching about six lobsters, Kevin and I checked our air and bottom
time. We headed for the bow, and I started to untie the grapple
anchor that secured the dive boat to the wreck. Kevin tapped me on
the shoulder; he was tangled in some monofilament line. I quickly
hooked the grapple back into the wreck and cut the fishing line off
Kevin's first stage. When we turned around, the grapple was gone. We
came up on an up line, did a safety stop and surfaced to find we
were alone, floating in the middle of the ocean in complete
darkness. As we rose to the top of a wave, we spotted the boat. Phil
was sleeping in the stern while listening to a Sony Walkman. Even if
he had heard our whistle, he would not have been able to bring the
boat back to us or even use the radio to call for help. I had never
taken the time to show him how. Fortunately, everything worked out
fine, I took off my tanks and left them with Kevin who was still
holding his position with the up line. After what seemed like an
eternity I reached the boat and navigated back. We were very lucky,
If the current was stronger or if the waves a little bigger, who
knows what could have happened.
|
The Shipwreck Diving E-Book
Instant Downloadable E-Book
Shipwreck Diving,
by Capt. Dan Berg is a complete how to book about the sport of
wreck diving. This book is packed with information and heavily
illustrated with over 80 sensational color photographs. |
|
 |
|
