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Old 02-03-2009, 10:02   #1
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Grapnel or Muchroom Anchor

Can someone recommend a good grapnel for a 34' boat, and a source where I can get one?

Looked on West Marine and Defender, and all they have are the folding kind and only for smaller boats.

FYI - I looking to get one strictly for hooking into wrecks for diving.

Also, someone else suggested using a mushroom instead, saying that it would set just as easily, but be easier to retrieve. Opinions?
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Old 02-03-2009, 10:42   #2
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bad idea from the standpoint of safe diving

Consider, for a moment, the fact that with a grapnel you'll have to physically detach the hook from the wreck prior to ascending. This means that you'll have to ascend holding onto the rode while the boat drifts. Not an ideal way to make a safety stop, and certainly a needless risk should any of the divers become separated from the rode during ascent.
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Old 02-03-2009, 11:25   #3
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I already have. In fact it's common practice around here. This is how it's done.

It's only done with 1 diver, or 1 team still in the water. The exact procedure is dependent on conditions, and discussed beforehand. Unless current is REALLY ripping, you get a little ride when it's first released, but after that it isn't really that big of a deal.

If a diver gets separated, they simply blow a bag. The boat is drifting free at this point, so they can easily move to pick up a diver. Not all that much different than drift diving...probably even safer, because you only have one diver in the water to worry about.
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Old 02-03-2009, 11:41   #4
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Its true most commercal dive boats do this on wrecks- I ran a C-Dive boat for years-but that was something I never did - I prefer to stay up current of the wreck and wait for the divers to surface - we would tie a ball off on the wreck - Here a picture of a nice 24 kg anchor- cheap- around $100 new as I remember- Bought in Greece
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Old 04-03-2009, 16:25   #5
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grunzster,

I have to correct my comment on the mushroom anchor. We really use a modified mushroom that has 4 scallops (~25% of the mat'l) out of the dome. We normally unhook from the surface. Trying to ride the anchor up on a windy day is a recipe for an embolism. Can't control the ascent. Also, many of the dives involve a fair amount of deco. Some of the wrecks are close to the beach so again there is another issue.

After many years of diving we found this to be our favorite solution.
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Old 05-04-2009, 11:06   #6
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But what's a bigger risk:
Going for a little bit of a ride on the line while the boat drifts?
or a boat pulling loose from the wreck, while divers are in the water?

If the boat pulls loose, you're stuck with a bunch of divers doing drifting ascents (possibly at different depths, drifting at different speeds, etc.) Lots of potential for someone to get lost. Or you can try hooking back in with divers on the wreck, also not a good idea.

On the other hand, that would have to be one hell of a windy day to give you a ride all the way to the surface. You have the weight of the anchor and the chain. Not to mention a properly weighted diver, at depth, with with an empty wing is pretty negative. And a smart diver will dump at least some gas before pulling, more if conditions indicate that they're going for a ride.

LakeSuperior, what kind of depths could you possibly be hitting "close to the beach" that your dives require a "fair amount of deco."

Not trying to be a smart ass, but like I said before, that's the way most of the boats have been doing it around here for years. In case you're not familiar with the diving up here, there's 2 little wrecks called the U-869 and the Andrea Doria. Out there, even if a diver who's been out of the water, does a bounce dive, just to pull the hook, they'll need to hang for a good 10 minutes. And that's in 260 feet of water in a spot that tends to have ripping currents.
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Old 14-04-2009, 13:06   #7
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Grunzster,

Every system seems to evolve what is most efficient for the environment. That said, I stand by my earlier comments on safety wrt riding the anchor. How does one do a long safe deco when getting hauled through the water column at 1 to 2 knots on the end of an anchor line with the sea running? This approach may be what is best for the East coast but it is a trade-off in terms of safety and efficiency.

For the Great Lake figure deco times of 15 to 90 minutes (or more) and 1 kt drift rate. There are a number of wrecks we dive within 1 nm of shallow water. For example, the Kamloops (bow at 260') 100 yds to shore, Congdon (stern at 220') 200 ft to reef, etc. It is easy to see from the above examples that "hitting the beach" is a real concern.

Even with the shallow wrecks by the time two divers surface with safety stop on a 100' deep dive, get into the boat, and start the engines a fair amount of ground has been covered. Then what if the boat doesn't start as you converge on the shore, what if the anchor is tangled, etc.

Using the modified mushroom worked best, it hooks into the wreck and can be released from the surface unlike the grapnel. It is just the way things have evolved here in the Great Lakes.

Cheers.
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Old 14-04-2009, 13:33   #8
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WOW! That's a fast drop off. Damn that close to shore, why not just do your deco up the beach, instead of hanging on a line.

Yeah around here the drop off is really gradual, and were usually at least 5 miles out, with many dives within NDL limits not even within view of the shore.

Drifting into the shore isn't a concern.
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