Anchoring On Wrecks?

Hello I have dove on wrecks before but haven't actually been the boat captain. I have obtained a nice RIB I have dove off of a couple of times and would like to start taking it to wrecks. My question is How do you secure your anchor on a wreck? Nothing like this was covered in my wreck class and I read the book Wreck Diving which gave a couple of ideas on how to anchor. However dragging into the wreck and most of the other way I found in there seemed like there was a good possibility to harm the wreck and if everyone dragged anchor onto the wreck I would think it wouldn't be conducive to the wrecks health. I understand the reasoning to anchoring onto the wreck but is it feasible to anchor right next to the wreck? I know another possibility is to tie off a shot to a buoy. How does everyone else anchor to a wreck that isn't marked?

I drop anchor and try to drag it across the wreck and snag part of it. Sometimes I use a danforth and just anchor next to the wreck if the vis ok. Some dives I basically dive down and physically place the anchor on the wreck. All of these are ways to do it just figure out what way you like to do it and what way works best for a particular situation. Some dives I don't use an anchor if I'm spearing and conditions are ideal.

Most of the nice wrecks in the San Pedro area are 100 feet and deeper. I don't think you will have a choice but to drop the hook when you're over the wreck and hope it lands close enough to find the wreck. Currents, swells and wind can move your boat from the time you drop anchor until it actually grabs hold. I try to anchor just up current from the wreck, then set the hook once I get down there.
BTW, there is a lot of life living just under the sand, so you will cause some damage every time you anchor.

gimewater - When diving in Salt Water, I drop a grappling hook to snag the wreck. The first diver down ties the anchor to the wreck. We like to make sure the boat does not pull out while we are diving. Since visibility is typically poor in the NE, we use tag lines, attached to the anchor to locate the anchor when it is time to leave. In fresh water, I try to anchor near the wreck if visibility permits. We could be damaging the wreck, typically we do not. Most of the wrecks are already in a pile of rubble due to time in the ocean or the cause of placing the wreck on the bottom. The only time I have seen damage from an anchor is in fresh water, on wooden wrecks.

At one of the seminars I attended, One dive op claims they use a 65 lb weight dropped near the wreck, then swim to the wreck. If the current is strong, I'm not sure it will hold. Plus, I can imagine how hard it is to retrieve, especially if it snags something on the bottom.

On dive op sends a diver down with the anchor to tie it in in a safe place. Not practical for me. I would try this in shallow water first.

Your call - Tom

gimewater:

How does everyone else anchor to a wreck that isn't marked?

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We do what divenutny does, drag on using a grappel hook. The first team down the line makes sure the anchor is secure and draws the upline taut. The last team up unties it and takes it with them. In our case we use a small lift bag to carry it up which is also attached to a goodiebag that divers can use to deposit souvenirs in on the bottom so they don't have to manage their ascent carrying stuff with them.

To judge currents we sometimes use a second (smaller) buoy attached to the main one with a length of rope in between them and a weight on a carabiner between them. If there is a lot of surface current the two bouys will be a few metres apart but when the currents are small the weight will drop and pull them together. It just gives you a visual idea of currents without having to get in the water. It also can give divers who are already on the surface and waiting for the boat somewhere to go to get out of the way of divers below them if the currents are strong.

Topside I've seen skippers do different things. Either tie off the boat to the upline (unadvisable if you ask me), anchor nearby (also questionable), freefloat nearby and using GPS guided autopilot to park the boat.

By far the best way is to Park the boat with the autopilot. Anchoring the boat creates delays if problems arise like a diver makes a free ascent and drifts off.

I don't like it when they tie off to the upline because currents and wind will cause the boat to move around (or roll) which causes the upline to change depths as you go. It's a royal pain in the butt if you have any kind of decompression to do.

R..

divenutny:

At one of the seminars I attended, One dive op claims they use a 65 lb weight dropped near the wreck, then swim to the wreck. If the current is strong, I'm not sure it will hold. Plus, I can imagine how hard it is to retrieve, especially if it snags something on the bottom.

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That's our preferred method. Weighted shot line with marker buoy, the heavier the better against currents. Last diver up will check if its free to lift and put some air in an smb tied on the weight which might drag on the bottom but will aid retreival by the captain after all deco is done. Boat is active and not anchored.

If boat must be anchored dragging a grapnel would work best although you would need to physically secure it on the wreck under some conditions and consequently free it when about to ascend.

Diver0001:

To judge currents we sometimes use a second (smaller) buoy attached to the main one with a length of rope in between them and a weight on a carabiner between them. If there is a lot of surface current the two bouys will be a few metres apart but when the currents are small the weight will drop and pull them together. It just gives you a visual idea of currents without having to get in the water. It also can give divers who are already on the surface and waiting for the boat somewhere to go to get out of the way of divers below them if the currents are strong.

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We do the same thing if we're live boating a dive. We use a small weight made from a lead-filled soup can. If we're all diving at the same time we sometimes use a grapnel or anchor. Last week we had a diver from a nearby boat remove our grapnel from the wreck, causing us to drift away. He thought he was doing us a favor.

At one of the seminars I attended, One dive op claims they use a 65 lb weight dropped near the wreck, then swim to the wreck. If the current is strong, I'm not sure it will hold. Plus, I can imagine how hard it is to retrieve, especially if it snags something on the bottom.

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It's a system that works extremely well - only don't tie the boat off, just leave it free and motor over to drop the divers on the shot. We've tried all sorts of shot weights, but seem to have most success with long thin shapes that drop through the water adn drop them just to one side or the other of the wreck so that the line will be over the wreck when it turns. I've used it and seen it used successfully on very tidal wrecks down to about 90m or so - itr helps if the divers are trained not to hang onto the line but to swim up/down it instead and only hold the line on a stop for convenience

I often found that it realy depends alot on the wreck and how it is situated.
There is one wreck that I like to take novice divers from out of town that sits on a little ledge at 80 ft. -past that ledge it drops to 200+. In this instance tying to the wreck is really the only option. As mentioned by walke121 I often use a danforth on most other wrecks and set it when I descend.
If a wreck is well known and frequented alot then talk to a LDC or get agroup of divers together to set a permanent mooring , just make sure that your following the rules of the water - check with local authorities as to the proper protocols in your area. Hope this helps.:thumbs-up

I might experiment with a length of medium chain on the end of a line, no hook. A rib does not weigh much and would not likely move about and when you get to the wreck you can secure it to some thing solid and remove it as you leave with just a shackle, all depends on depth, type of wreck, vis, surrounding material, current etc. but I have seen about 25ft of chain hold a 45ft cat in place, the anchor completely unset.