anchoring an empty dive boat

[jchaplain]

I've been tossing around ideas for anchoring my boat when I leave it at the surface empty. ( 24 foot cabin cruiser, 2 divers.) Of course, the last thing you want is to return to the surface to find the boat drifted away.

My first idea to prevent this was to go to an oversize anchor. This would of course help, but it's still not a positively sure thing.

My new idea is to dive to the anchor to check that it is secure as I always do, but now I have made up a large loop of chain and rope that I intend to have attached to the anchor and throw over some large nearby rock to ensure that even if the anchor does let go the boat will not drift away.
Because of the dive conditions in Boston ( very low vis) I now always dive with a reel to the anchor anyway and return there at the end of the dive, so it would be easy to undo the safety loop before returning to the surface.

My question is....has anyone else ever considered this or used similar techniques for safe anchoring while diving?

John C.

 

[teknitroxdiver]

I'm no expert, but neither of those safeties solves the risk of the line parting or coming unfastened somewhere between the end of the chain and the cleat on the boat.

 

[Charlie99]

As Teknitroxdiver noted, an extra bottom attachment doesn't prevent your anchor rode from parting, or your deck cleat coming off. Meanwhile, since you have run a reel to the achor, if it's dragging you will eventually know it.

I don't see the loop around a rock helping in any significant way.

Hopefully, someone onshore knows exactly where you are, and when you should be calling back them back after safely reboarding the boat.

 

[jchaplain]

I'm no expert, but neither of those safeties solves the risk of the line parting or coming unfastened somewhere between the end of the chain and the cleat on the boat.

Huh? I'm not worried about that risk. Lines are always set secure to the boat and anchor. Lines 'parting' or breaking is not a negligable risk given that they are secured properly. Anchor dragging is the risk in need of overcoming.

John C.

 

[jchaplain]

I don't see the loop around a rock helping in any significant way.

You don't think a loop of chain/rope attached to the anchor and tossed over a 2000 lb rock might prevent the boat from drifting?

Am I missing something? I'm not tryng to be a wiseguy...really!

John C.

 

[SubMariner]

1) the right anchor for the holding conditions. One of the best all-round anchors is a Bruce.
2) the right size anchor for your boat. The usual rule of thumb is 10 pounds per foot, then adding some for good measure. So with a 24' boat you probably should think about a 25-30# anchor.
3) lots of rode with several feet of chain.
4) setting the anchor properly. Once you put it down, drop back to set it.
5) deploying the right amount of scope. THIS, along with the weight of the chain is what actually keeps your anchor at the right angle to stay put. In good conditions, 7:1

Here's a good article about anchoring: http://www.texasgulfcoastfishing.com/anchors.htm

Bonne chance,

 

[H2Andy]

Anchor dragging is the risk in need of overcoming.

probably right

i know two guys who spent two nights in the gulf stream before the Coast
Guard found them

they left Jacksonville, anchored their boat, and both went diving.

soon thereafter, they couldn't find the boat

the Coast Guard did, drifting on its own

their lesson from this accident was: never leave the boat unnatended

just a thought

 

[glbirch]

Though from what I understand laws have changed over the years, I would be worried that someone finding a boat with nobody on board might consider it abandonded and/or salvage and tow it away, regardless of the fact that it is anchored. It's bad enough when someone tries to steal your dive flag while you're tied to it...

 

[Bill51]

Unless I’m diving somewhere that I can easily swim to shore I always set two anchors. I get a good back down on my primary anchor (usually a Bruce depending on the bottom) and then I put out my lunch hook (a smaller Danforth or Fortress) at about a 30 degree angle to the main anchor.

While diving one time a sudden gust front with a wind shift came through and swung the boat 180 degrees and the anchor rode got pinched between the only rock outcropping around and the hull cutting the primary anchor lose. I guess I should add, fortunately the boat was hung up on the rocks when I surfaced but it took 4 divers and 2 jet skis to get off the rocks.

 

[SubMariner]

Unless I’m diving somewhere that I can easily swim to shore I always set two anchors. I get a good back down on my primary anchor (usually a Bruce depending on the bottom) and then I put out my lunch hook (a smaller Danforth or Fortress) at about a 30 degree angle to the main anchor.

We used to use this technique a lot on our sailboat in the Bahamas, where it was called, fittingly enough "a Bahamian Mooring".

It works very well.