Anchoring for Hurricane - Shallow Water, Wing Keel

[Bene505]

Originally Posted by Omatako

If I had a boat in a place where there were "frequent hurricanes" (and even if I didn't have a boat) I'd move to another location.

And that's not a flippant comment - I really would move away.

Having said that, I live in a city surrounded by 24 volcanoes. Go figure. Somehow they're not as scary.

Maybe that's why you have a boat. How scary would they be if you didn't have a boat?

[celenoglu]

It is a better idea to lay three anchors attached to each other and the connection point staying on the sea (water) bed. A line or chain can be attached to this point and the other end goes to the boat. This way any of the one or two anchors will stay completely horizantal to the sea bed. Recovering the anchors migt be real difficult after the storm. But there is always a price to pay.

[NCC320]

As for not living in areas where hurricanes occasionally or regularly visit, it's not always practical to leave, nor desireable to leave. Almost every area has some weather related difficulties, forest fires and mud slides in CA, tornados in middle US, hurricanes in southeastern US and east coast, ice storms in northern areas. So, then the trick is how to successfully deal with the storms. Each locality and boat is a little different. Down on the Gulf Coast, you may have to deal with storm surges of 15-20 feet, but where I live in NC, the record is about 11 feet, with most big storms being about 9 feet, so your defensive measures will be different.

The original question was regarding anchoring in shallow water, with rope rode, for a hurricane where you know you are going to get a 180 degree shift in high storm winds over the course of a hurricane, with a boat having a wing keel, as do many shoal draft boats. The wing will have a tendency to snag the slack rodes in a multiple anchor situation as the storm veers around. If this happens, much greater area is presented to the storm and you are more likely to drag the anchors, and wind up on the shore. Normal storms, not hurricanes, generally come from one direction, more or less. The standard approach here is to put the anchors on a spread 45-60 degrees either side of the bow, when the boat is pointed in the direction of the storm. In this case the rodes never go slack, but in a hurricane with the wind veering over 180 degrees, during much of the storm, one anchor is taking the load and the rode of the other one is slack. So the question was would a very narrow spread of the anchors to minimize amount of slack in the rode as the boat swings be a different, but good way to go. I have seen in a chart, that on a 33 ft. sailboat, the force at 63 kts wind is 1000 lbs. For a 90 kts. hurricane, this force goes to 3000 lbs. So, in the rotation this is what each anchor will have to deal with. With a 1/2" road, the stretch is going to be in the 20% range (I have numbers for my proposal in another place and will post them). If the anchors are close together in a narrow spread, should one drag, the boat doesn't move very far before the second anchor picks up more of the load and they share it together.

The proposal to put anchors (3) in a 120 degree spread or (2) in a 180 degree spread is fine if you have chain, but complicates the snagging by wing keel issue, when the rode is rope. If you have all chain, then you don't get the stretching to releave the shock loads of wave and wind surges.

So the original question regarding the narrow spread still stands as far as I can see. (My first choice and I have done this from 30 years is to stay at the pier with a spider web of lines (~26) and thus far have not had damage, but piers and other hard surfaces can be deadly. The anchoring proposal is an alternate plan in my case, but if I have to do it, at this point, I will use the narrow spread that I proposed.

[NCC320]

Keldee.

What kind of spread did you use on the anchors? Rope or chain rode?

My current boat, a Cat 320, is a "hurricane" boat. Delivery, while boat was in route from CA, was delayed because of Hurricane Dennis, the deal transfering title/paying for boat was done in a flooded out, muddy room at the dealership. Hurricane Floyd, got here before we could launch the boat, and it spent that storm on stands in the yard (yard was flooded in the storm), and came within 1 ft. of floating off the stands. Other boats hauled out for the storm floated off the stands (missed my boat) and crashed into others. A falling large pine tree got some others. Boats at the pier didn't all do so great either, with some banging against pilings as lines failed, or in one case, being speared by a piling as the boat settled down from the falling surge. Anchoring out wasn't too great either. Some boats held, some went ashore, a few wound up docking on their own against marina docks. There are not many mooring bouys, but several of these drug also and boats went ashore with mooring bouy sattached. If the marina is sturdy, with lots of extra lines tied to accommodate the surge, allowing for some chafing (extra lines), tied to take the wind from all directions, and free from adjacent boats that aren't tied properly seems to be the best way to go in my location. But if too many boats stay at the pier, the increased loads due to the additional boats could cause the pier to fail. I am at a fixed pier, and I have a different opinion about floating docks in a hurricane. The surge can float the entire dock over and off the pilings. The pilings, often steel, are bigger, but there are fewer of them and if one fails, then the entire floating pier can go ashore with the boats still attached. Going up a narrow creek and tying off to the trees on the shore is a good way to go, but there are relatively few creeks available that are deep enough to get the boat far enough up the creek and close enough to the shore to tie the lines, so usually the choice here is stay at the pier, haul out in the yard (must pay in advance, even if there is no storm that season), or anchor out, with chance you will drag or someone else will drag down on you. Here, about 1/3 take each of these three options.

[Keldee]

NCC320
Thinking about it again I got the wrong huricane,it was Irene we were anchored out for,Floyd was at a dock in Atlantic City and was downgraded to a tropical storm 2 hrs before it got to us.
Back to the question.The anchor spread was about 45 degrees but you can never be sure by the time you have finished.The boat was a 27ft Tartan and anchors were 1:-35 lb CQR with 50 ft 5/16 chain then 1/2 " rode 2:- 25lb CQR with 30ft5/16 chain and 1/2' rode.I thought we had put out the danforth but hubby says no just the 2 CQR's.
The reason we didn't go to docks was it was our first time down and we didn't know the marinas in the area and what their policy was with huricanes or how good the docks were.We had heard of boats being turned out of a marina in New York just before Denise hit.
Does that help
Ellinor