Need advice on diving virgin wreck

sensor330

I've discovered the location of a uncharted wreck in my area and would like some advice while the planning for the dives are still in it infancy.

Details:

-After some research I discovered that its probably a WWII Flower Class Corvette approx 65m long.

-depth is 250'

-current can reach up to 2 knots but they are reasonable during slack tide

-the wreck may or may not be covered in fishing nets.

The only thing I'm really worried about is the 2 knot current. I would like to stay away from drifting deco as the wreck is really close to shipping lanes and I'm sure that using a jon line is feasible but will be very uncomfortable. Are there any other options I can consider?

Scott

divelermentov

well done sounds exciting,
would love to join in, but i am down under (no the water is not running down th esink the other way aroun d:-) )

If you are close to a shipping lane, it might pay informing coast guard and harbour master with regards to what you are planing to do,
drifting deco is certainly not a good option I agree, I would try to stay with the travel line,
but just in case that you have to drift i would arrange a couple of chase boats (2 or 3), At least they cans stay with your deco bouy and mark teh position, furthermore I would make sure that they display the correct flags to mark them as not able to maneuvre - this might keep the big pots away,

however the harbour master should be able to tell you at least when a big pot is expected to come past and you might want to avoid these times.


What is your planed runtime ?

Cheers
christian

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May The Sorb Be With You

Drmike

Id stick with a Jon line, but you can also have a deco platform under your boat (if its a big enough size) and drift with the boat. That will give you a better radar signiature and higher visibility (modern cargo ships have virtually no crew these days that would ever see a surface marker/chase boat let alone have time to react to one once in visible range, the radar is your best bet)

Spend some time setting up lines to make it easy for you to get from the downline to the ladder ! Can be fun in strong currents

Pic the best time to End your dive based on slack, take a hacksaw - go straight for bell!

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Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you

sensor330

We're doing our work up dives before we proceed with the planned dive. Last weekend we attempted to locate a wreck that rests in 165' water and has similar current to the planned dive. We'll we couldn't locate the wreck on the sounder and we missed our tide window but we dove anyway. We got as close to the GPS co-ordinates as possible and went now with a small hand held sonar with hope of pinging off it on the bottom. Needless to say it didn't work and we ended up doing a circle search for 23 mins in 165' of water.

The next time we will be a little more patient and locate the wreck on the sounder and drop a anchor of some sort before we dive.

BTW it is not as close to shipping lanes as I though so driftind deco could be a possiblity.

Scott

sensor330

Well diverrob and I managed a successful dive to a wreck called the Black Dragon which sank while it was being towed in the Straight of Juan de ***a, and rests in about 160 fsw.

Things we learned:

-drop the anchor/shot close as possible and then drag it in closer.

-just because the chart says it will be slack don't assume it will be.

-if your using your own boat and there is a lot of current have a buddy sit in your boat and drink beer while you dive.

-use bolt snaps instead of gate snaps on bailout cylinders as I found out today they come off too easy. Ended up losing a bailout bottle and reg when I rolled off the boat. That's OK though I didn't like yellow anyway.

-we used a anchor with 200' of rope and a float with what we thought was a substantial enough to keep the line a float but we we're very close to losing the anchor and the rope because the current was running hard. Lucky when the current slowed down the float came back up. Next time if we think the float is big enough we'll get the next one bigger.

A couple more dives on this wreck and we'll be ready for the Corvette.

Scott

divelermentov

good luck for your dive

What a great oportunity
Doesn't happen too often - well done

cheers form DownUnder
Christian

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May The Sorb Be With You

needlebender

The beauty of going where no one has been before is that no one knows how to do it.
You have to invent your own system, try it out, modify it, practice till you're slick, then do it.
Beware of experts, especially on this list.

Jim Brown

Greetings:

Consider just bouncing it first, drifting descent, short stay, maybe with video, then drifting ascent. Lets you assess hazards and conditions without incurring big deco obligation.

Jon line will be very comfortable, even in currents harder than you can swim against. When tethered to anchored boat in current, you will notice jaw fatigue from current water pressure against Rebreather hoses, greather than felt with O/C gear; consider a neck strap to help support DSV in your mouth. However, beware that even though you will be able to relax your jaw, you must still maintain lip seal to prevent water ingress. You must also be able to close and remove DSV to switch to O/C bailout or alternate gasses. I noticed in a great deal of current, water pressure exercised against counterlung (MK15.5) sometimes caused unintentional venting. Body attitude counted to keep CL sheltered on downstream side of body.

Here are a bunch of random thoughts. This has worked with strong tides and short slacks. Like other activities with many moving parts, the devil is often in the details. I probably put more info than you want or need, but others may read this. There is a bunch more info, this is just a summary; we can expand subtopical discussion if you like, just ask. Others will surely contribute. There are so many ways to skin this cat and two or more heads are better than one, until you're out there executing and something goes wrong. Then there has to be one person calling the shots. Call it a dive supervisor or whatever, once Murphy steps in, that guy's in charge. No second guessing, no diver/ topside slate conversations. Just do it. In many ways, it doesn't matter so much what you do, as long as you do it well. You and everyone on your team, most importantly topside crew, should rehearse drifting deco procedures in a 'no-D' environment. Get it wired tight. Talk it through before every dive, even if you just did it yesterday. Rehearse it in a benign environment first.

You mentioned ship channel or traffic lane. The ebb and flood should be reciprocal, so could you time things to drift away instead of towards?

Plan and rehearse. At a minimum, rehearse actions at the dive site. Hook-up, actions during the dive, deco, recovery, and contingencies. A dry erase board can work well for this. Of course, you will do most of your planning and rehearsals ashore, but take the time to make final briefing between hook-up and putting divers in the water. Allows pause to gauge local weather, sea state, diver state, and brief wind and current conditions. This short pause will allow a diver who is not up to the dive to make the call. It will also allow observation of quality of anchor connection.

What should you plan for? Plan to have divers blow off the wreck or line any time. If one goes, all go. It's easier to support a group of drifting divers from a maneuverable boat than a drifting diver from an anchored boat with tethered divers. Divers always carry enough gas to complete deco alone and surface healthy. You can maneuver and gently gather the drifting divers to a deco station under the boat. Now it's even easier to support and recover. Keep the engines running, and make sure everyone knows where the intakes and discharges are. Always have the safety diver visually clear the screws before engaging drive, or better yet, cage the props if you're going to support alot of drifting deco.

Keep someone on the boat who can operate it in the complex way that drifting deco support demands, knows the radios, and can use the nav systems. Must know how to contact and transport to nearest recompression chamber or EMS. Use a safety/ support diver. This person rigs lines, meets divers at first gas switch (if rebreather, 1st planned O/C gas switch if on bailout gas) with extra deco bottles he can pass off to a diver if lost or malfunctioned gas. Meets divers somewhere between 130' and 100', but must stay in "no D". Can be on nitrox, wears dive computer to track multi-level and repetitive profile. Breathes some O2 on surface supplied system between supporting divers. Recovers lines, including liftbag to recover clump/ deco line (unless boat has winch).

Binoculars, 7 or 10 power. More power are harder to hold steady and see fine details when searching for sausage, lift bag, bubble trail, etc.

200 styrofoam cups. As soon as a diver is missing or blown off wreck or lines, start tossing one cup each minute overboard. The cups will serve like a breadcrumb trail while other divers are recovered or told to break free, or boat is unhooked. Note that wind will act on the cups so there is a bit of an art to vectoring between cups and drifting divers.

3 marker buoys. There is an oblong kind of lobster buoy that's like a bullet, has a hole thru the center, about 24" (63cm) long by 8" (20cm) diameter. Spraypaint them bright orange traffic paint. Tie one end of 1000' (304m) light poly line (about diameter of shoelaces) to buoy and wrap around the buoy like a spool. Weight the free end. When you toss this in the water, it will quickly unreel. You can mark the line at 250' intervals, tie off any amount you like to create the needed scope. Throw the buoy upcurrent of the wreck. It will drift some as the weight descends. If the buoy is pulled under by current, hold off on diving until it surfaces. If you haven’t located a wreck, but have general numbers, hit the numbers, throw a buoy, and use it as center for circle or other search pattern aided by track plotting GPS.

If you're doing this a lot, even visiting the same wreck and don't have good ranges off shore, plotting GPS and (preferably color CRT) depth sounder. Some models can wire GPS to the sounder to put increased functionality on one screen. The color isn't essential but can give more information at a glance. Learn what diver's bubble trails look like on the sounder. CRT is nice because it's so much brighter than even backlit LCD (at least the one's I've seen). If you do many searches, and value your time, $1000 is not too much to spend to lessen predive stress and increase chances of successful hook-up.

If you haven't found the wreck and don't know where it is to your boat and anchor, don't bother getting in the water. Train yourself to locate the wreck, determine the current, and determine the lie of the wreck to know downcurrent and upcurrent side. Intentionally leave the dive gear at home during primary search days. This will allow you to focus on developing an essential topside skill absent the distraction of all that dive gear just waiting to get in the water.

Throw a buoy in the water and let it drift. Practice maneuvering your boat all around it without running it over. Become expert at how the wind and current move your boat when you are at bare steerageway (around divers in the water).

Good anchor line, strong enough and long enough to allow you to stay connected. You should be the one to decide when to disconnect, not your anchor line, or conditions if not enough scope. Use a stout hook at the end of 15' (4.5m) of chain to lessen chafing. Safety wire all clevises. Reinforce all loops with eyes. Try not to use rope directly against steel. There are several breakaway methods using sisal. Can elaborate if you want. Chain hook into wreck while you are there, unchain when you leave. Idea is to avoid boat breaking free while you are on wreck. Don't want to return to hook site and find boat gone.

Have some bulk O2 on the boat and if possible, surface supply it to 20' (6m). A K-cylinder (strapped down), 30' (9m) synflex HP line, yoke block, high-flow 1st stage (Poseidon), and 15' (4.5m) LP whips to second stages. Lets divers breathe pure O2 at 20' (6m) and 15' (4.5m) stops. Gives bulk gas if in-water deco necessary.
Slate to pass between divers and topside.

Divers carry a closed-end sausage (write their name on it) with reflective tape that will remain inflated on surface, and a reel with line equivalent at least to greatest depth. If diver gets blown off, shoot bag as soon as possible. Divers have to keep some tension on line to stand sausage vertically on surface. Whistle, smoke and flares (triple vacuum pack to keep dry), strobe, EPIRB. Divers carry a backup lift bag (can be bag they would use to recover artifacts) and backup reel (can weld two stainless washers to ends of 1.5" (3.8cm) long stainless tube), with 150' line.

There’s a bunch more, but it’s time to fire up the grill.

Happy diving from Jim Brown in Stuttgart, Germany

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