my best storm anchor technique

[freshalaska]

In a real strong blow the wind picks up the water out of the ocean and sends it sideways. Sort of like smoke coming across the water or in Alaska like a ground blizzard. If it gets bad enough all you can do is hang on or maybe start your engine. At Douglas harbor across from Juneau Alaska they have clocked 150 MPH winds, (Taku winds). In the Philippines last year we had a typhoon come thru with winds stronger than 150 mph. Like I said before you better have your ducks in a row before the wind hits as you don't really get a second chance. I have personally been in winds over 100 knots twice, both times I was on land in Alaska.

 

[Djbangi]

I've written it down, steer clear of Alaska!

 

[freshalaska]

I also like to stay away from other boats in a good blow. Sometimes it's not what you do, it's what others do that can hurt. Lots of big boats don't have proper ground tackle or know how to use it.

 

[Djbangi]

I also like to stay away from other boats in a good blow. Sometimes it's not what you do, it's what others do that can hurt. Lots of big boats don't have proper ground tackle or know how to use it.

+1

I'd have thought this was a positive for Alaska, less boats?

But I'd not limit your comments to big boats - any boats. Many people rely on one, perfect, anchor - they can be quite scary.

 

[Peter B]

Djbangi wrote….

"But I'd not limit your comments to big boats - any boats. Many people rely on one, perfect, anchor - they can be quite scary."

Ok, ok, I give up, I confess. Even though my primary anchor is a Super Sarca, I do have one rather large Danforth in the lazaret, with extra chain and rope road. Never had to dig it out yet and use it, but it's there ok..?

 

[Djbangi]

Nothing like being honest and baring the soul.


As an aside, a propos nothing, - is it a real Danforth (from Danforth) a copy from someone reputable (like Manson? say ,I do not know if they even make them) or just a 'copy'?

 

[markpierce]

I've written it down, steer clear of Alaska!

Why when there are large areas of protected waters in southeastern Alaska?

 

[Djbangi]

Mark,

I would need to go to NW Alaska first, before I could enjoy the SE.

 

[MurrayM]

Why when there are large areas of protected waters in southeastern Alaska?

Mark...that photo reminds me of where I live, and while it may be 'protected' from open ocean wind and waves it can get pretty squirrely with steep, close waves that refract around islands and headlands as well as rebound off steep shorelines resulting in four or more wave sets stacking up into pyramids with exploding tops. Winds also flip 180 degrees from inflow to outflow, and over 20 foot tides also tend to spice things up.

 

[Rogerh]

Some food for thought on using one anchor. In hurricane Opal I watched 120MPH winds go down to nothing clock 180 degrees when the eye went over, and go back up to 100 in less than 5 minutes. 4 of that was dead calm. When the wind started from the other direction it did not start in just went from nothing to full force. This is when many of the boats broke loose. Not sure how a single large anchor would hold in this case. Our anchoring was done before the hurricane, then leave the boat and come back after and hope to not have to pick up the pieces. Fortunately never had to on the boat. With our motor yacht we have arrange to pull it if a hurricane comes.

 

[Delfin]

Some food for thought on using one anchor. In hurricane Opal I watched 120MPH winds go down to nothing clock 180 degrees when the eye went over, and go back up to 100 in less than 5 minutes. 4 of that was dead calm. When the wind started from the other direction it did not start in just went from nothing to full force. This is when many of the boats broke loose. Not sure how a single large anchor would hold in this case. Our anchoring was done before the hurricane, then leave the boat and come back after and hope to not have to pick up the pieces. Fortunately never had to on the boat. With our motor yacht we have arrange to pull it if a hurricane comes.

Roger, that is pretty compelling testimony to why a Bahamian moor with a primary and storm backup makes a lot of sense. That's why I carry a large Guardian (Fortress for cheapskates) as the storm backup. Some anchors will do much better in a quick wind shift than others I suppose but why take the chance.

 

[HiDHo]

Three anchor mooring worked for us when we sailed. As I recall it was described in Chapman's. I used three 22 lb Danforth anchors with 50' 3/8" proof coil chain legs, shackles and a closed double loop style chain swivel and chain up to a float. This held our 28' Cape Dory sloop thru blows up to 65 knots because the boat would always be putting a strain on two legs and anchors. I maintained it as a mooring for about 12 years, one of the good things about it is you can pull up the center and un-shackle each leg for repairs/replacement. That mooring is still in place on the bottom of the St John's river as the Danforth's have buried on the way to China!!

 

[MurrayM]

Mark...that photo reminds me of where I live, and while it may be 'protected' from open ocean wind and waves it can get pretty squirrely with steep, close waves that refract around islands and headlands as well as rebound off steep shorelines resulting in four or more wave sets stacking up into pyramids with exploding tops. Winds also flip 180 degrees from inflow to outflow, and over 20 foot tides also tend to spice things up.

One more jab for Mark

Local 'protected' conditions today are -10C (14F) with 55 knot (100Kmh) Northerly outflow winds with 40 knots being forecasted for the next three days. Southwesterly 'Pineapple Express' storm brewing offshore.

 

[markpierce]

One more jab for Mark ...

 

[MurrayM]

Beautiful. Not the place to be when those avalanche chutes are active though...

 

[Djbangi]

Impossible to compete with scenery like that. Absolutely gorgeous.

 

[eyschulman]

when I lived on the East Coast I thought the Virgin Islands and New England were great visual cruising areas. As soon as I got north of the boarder I was enlightened. With 18 years of PNW cruising I am becoming a frequent flyer(cruiser) amongst the many Islands Fiords rapids and rocks. It is beautiful but the water is kind of cold for skinny dipping.

 

[Wxx3]

What am I missing?
I've always done an anchor watch when winds were above 30+ knots.
Strongest I've seen at anchor is 45 kts, and I was anchored in a river.

The few times I have tried two anchors, it did not seem very effective to me.

 

[MurrayM]

What am I missing?
I've always done an anchor watch when winds were above 30+ knots.
Strongest I've seen at anchor is 45 kts, and I was anchored in a river.

The few times I have tried two anchors, it did not seem very effective to me.

Maybe you haven't seen strong enough winds yet? According to the ABYC horizontal load table, a 40' boat would subject the anchor system to 2,400lbs of force with 42 knot winds, and 4,800lbs at 60 knots...probably much more if the bow is shock loading the system in big waves.

 

[HopCar]

"Roger, that is pretty compelling testimony to why a Bahamian moor with a primary and storm backup makes a lot of sense."


The two anchor Bahamian Moor is not a good choice for a hurricane as you can't predict the wind direction far enough ahead of time to safely set it up. The three anchor set up the OP described will allow for winds from any direction.


Of course the best way to handle a hurricane is to get your boat as far inland as you can and your butt even further inland.

 

[Rogerh]

Parks, I agree. For hurricanes I always use at least 3. I usually anchor 3 or 4 boats anytime a hurricane comes. So far I have been fortunate to never have any break loose. My boating neighbors always ask for help. It usually takes me with help about a half day to anchor one and at least the same to get them underway again. Alot of extra work, not really considering the mess a hurricane creates. I usually try to set up about two to 3 days before the storm and then go back out and check it the day before, usually end up in getting caught in one of the early feeder bands to do my last check. Then it is hunker down at home.
What I have been very impressed with is this hurricane anchoring system. See the link. The only concern I had with it was the single point failure of the swivel. After I got one in my concern was gone. The thing is massive. I would say she ways about 20 lbs or more. Of course now with our 52 MY we have her pulled. Here is the link.
Hurricane Anchor System - Colligo Marine - Synthetic Rigging

 

[HopCar]

Rogerh, that's a nice piece of hardware. I like the idea of a second pennant to the boat.

 

[Delfin]

"Roger, that is pretty compelling testimony to why a Bahamian moor with a primary and storm backup makes a lot of sense."


The two anchor Bahamian Moor is not a good choice for a hurricane as you can't predict the wind direction far enough ahead of time to safely set it up. The three anchor set up the OP described will allow for winds from any direction.


Of course the best way to handle a hurricane is to get your boat as far inland as you can and your butt even further inland.

I wasn't aware that wind direction had to be known to use a Bahamian mooring. Seems like it is pretty agnostic in that regard, but I can see the advantage of three anchors in a hurricane. That said, this seems to indicate that 2 anchors is also approved: http://miami-dade.ifas.ufl.edu/pdfs/disaster/HurricaneManual1.pdf

 

[markpierce]

Maybe you haven't seen strong enough winds yet? According to the ABYC horizontal load table, a 40' boat would subject the anchor system to 2,400lbs of force with 42 knot winds, and 4,800lbs at 60 knots...probably much more if the bow is shock loading the system in big waves.

That would depend on the boat's particular windage. Some of much less than is typical. My neighbor's sailboat has less than mine, and I less than most other motor vessels of similar length.

 

[Nomad Willy]

Yes of course,
The B moor is fine if the wind blows from one of two directions. If the wind turns on the beam extreme tension will be felt on both rodes. A very undesirable situation.

 

[MurrayM]

That would depend on the boat's particular windage. Some of much less than is typical. My neighbor's sailboat has less than mine, and I less than most other motor vessels of similar length.

Yup, it's an average.

 

[klee wyck]

Markpierce,
Thanks for making that point.
First, I will stipulate that I know next to nothing about boats and exactly nothing about anchoring, but I have never been sure why anchor sizing recommendations go by boat length or weight. Just looking for some schooling here. When storm anchoring specifically, isn't this about windage? What forces do length or weight of the boat apply to the anchor system?
I have thought that the surface area presented to the wind by my boat to be what I need to consider for anchoring. When pointed into the wind, I think my boat represents a little under 20 square meters of wind surface and then I discount this to 0.7x that since my bow and upper house has a pretty fine entry into the wind and use this smaller coefficient of drag (arbitrary I know but bear with me).
If this is true, I come up with a force of about 350KG at 50 knots (25kg/sq meter).
If the Forfjord weighs 145# and 300' of 3/8 HT adds another 450# and the wind force is less than 1000# then I am not asking much for holding power from the flukes themselves. Even if I double this wind force to add some force for yaw and surge/waves (only if the chain and bridle have ALL the slack pulled out by wind alone) I don't think I get to 2000# total. The flukes then need only supply 400-1400 of holding force. The old Forfjord has pretty large flukes so even if it is not buried to the center of the earth, it should be capable of that, no?
I would really like to get comfortable with this. I do not relish the idea of multiple anchors and the horror of twisted rodes should I need/want to pull the anchor in a hurry when something else breaks loose and is bearing down on me. I do like the swivel shackle referred to in an earlier post if I get convinced I need to do this.
I think being in the PNW is part of why I am tempted to stick with my plan. Wind over 50 knots is pretty rare in my cruising area and depressions that might bring winds higher than this should give me fair enough warning to get to a protected harbor that would not experience winds this high. I never leave my boat anchored out while not on board for very long unless I am in the tender and then I would have bigger problems than my anchored boat if I got surprised by winds over 50 knots. When on the boat I am sure I would be on an anchor watch with anything more than a stiff breeze since I am a nervous Nellie. I read about the winds you East Coasters are forced to deal with and am pretty sure I would not have the cahones to even own a boat if I lived there.
I will probably be hanging on my single old fashioned hook until you guys enlighten me....plus, doesn't the old Forfjord look cool hanging off that hause?

 

[Delfin]

Yes of course,
The B moor is fine if the wind blows from one of two directions. If the wind turns on the beam extreme tension will be felt on both rodes. A very undesirable situation.

I don't understand how that is undesirable. Aren't two rodes better than one?

 

[eyschulman]

It is hard for me to judge the strain on a anchor system based on wind age and tonnage. For the purposes of measurement and calculations it certainly is a logical place to start, but in a real life situation a boat rarely sits quiet head to wind. What actually happens is a combination of up-down and sideways jerking shock forces causing any calculated forces to be inadequate since each boat has a different reaction to wind and waves. I would instinctively think a heavy sailboat with a deep long keel ridding sail and low freeboard and deck house would come closest to the theoretical calculated loads. Motor boats often with high freeboard varied distribution of large deck house wind age and shallower keels if any, makes me think accurate estimation of how they would react regarding the type and amount of strain on the anchor is not a simple calculation.

 

[HiDHo]

The one and only time I ever used the Bahamian Moor was in Spanish Wells. The two anchor moor, 180 degree's from each other is to limit the boats motion to as small an area as possible in a sheltered or crowded anchorage. In this case anchoring in the middle of the narrow waterway with boat traffic on either side of the waterway.
Also after seeing a boat drag with two anchors out with the rode's twisted I anchor with one anchor. My 45 lb CQR and as much chain as needed with the plan that if it's bad enough to drag this moor I'll pull it in and be able to get underway.