Emergency stern anchor sizing

[Unity]

I want to add a stern anchor that I can easily throw on the event of a dangerous situation like a lee shore and loss of engine. Think of this as an emergency last resort. It would not be a primary or storm anchor - only for tossing when all else fails while at the helm and unable to deploy the bower fast enough.

My question is ... what anchor, what size and what rode/chain?

My boat is a Beneteau 523 (52 feet) and I’m thinking that I want the anchor easy to deploy (not heavy, always ready on the stern rail). For reducing weight, the Fortress is the anchor I’m considering and using all 8-plait rode (no chain) to keep it easy / ready / light. I’m also considering dropping a size down or two down to reduce weight to make it easier to manage in an emergency. At 52 feet, the FX-55 is the “recommended” anchor but it’s still big and a bit unwieldy to throw, and it’s 32 lbs without chain or rode (which means I won’t be able to throw it very far!)

So...

1) is Fortress a good anchor to “throw” in an emergency? Or are there better (yet not too heavy to toss) anchors to consider for my 52 footer? I worry the flukes might not grab well when tossed and clearly I won’t have time to adjust the angle.

2) can I downsize the anchor (such as to a FX-37, 21 lbs), or considering this is for emergency use only should I actually be upsizing it even given weight to help improve odds of a rapid set?

3) can I go all 8-plait rode since I’m not planning on staying on it but rather want a fast grab to buy time to handle the emergency, or should I still have some chain (though that will make deployment more challenging)?

4) can I downsize the rode since I’m not using it for more that handling an emergency? Generally I believe I should use 3/4” rode, but it would be much easier to manage and stow with smaller diameter line.

Anything else I should consider? Any advice on handling such emergencies also appreciated!

Chris

[Unity]

Seeing as nobody replied thought I’d ask an easier question: What anchor/size do you use on the stern and why / for what purpose?

[Jammer]

I shall, with due humility, endeavour to help.

Originally Posted by Unity

I want to add a stern anchor that I can easily throw on the event of a dangerous situation like a lee shore and loss of engine. Think of this as an emergency last resort. It would not be a primary or storm anchor - only for tossing when all else fails while at the helm and unable to deploy the bower fast enough.

While it is true that an anchor is an important piece of emergency kit, they cannot be deployed effectively in indiscriminate haste, and there are particular risks to hand-deploying an anchor from the stern. Among these are the hazard of something or someone getting caught in the rode, and the downward forces on the stern that can cause a wave to fill the cockpit.



In most cases it should be possible to sail away from a lee shore. Have the sails ready to hoist, even if intending to motor. Even if it is not possible to make headway, it should be possible to buy some time to prepare the bower for use.


So, I guess I would start out by saying that what you are doing is not a standard practice and may not be a good idea.

My question is ... what anchor, what size and what rode/chain?

My boat is a Beneteau 523 (52 feet) and I’m thinking that I want the anchor easy to deploy (not heavy, always ready on the stern rail). For reducing weight, the Fortress is the anchor I’m considering and using all 8-plait rode (no chain) to keep it easy / ready / light. I’m also considering dropping a size down or two down to reduce weight to make it easier to manage in an emergency. At 52 feet, the FX-55 is the “recommended” anchor but it’s still big and a bit unwieldy to throw, and it’s 32 lbs without chain or rode (which means I won’t be able to throw it very far!)

There is a growing body of evidence that suggests that the modern anchor designs (Rocna, Mantus, Spade) are more likely to set on the first try and more likely to reset if they drag.


A smaller anchor with a substandard rode is less likely to do its job.

Anything else I should consider? Any advice on handling such emergencies also appreciated!

Maintain situational and navigational awareness at all times
Take steps to be sure your engine is reliable
Take steps to be sure your other systems are reliable

Have sails rigged and ready to hoist whenever underway
Know how to get your boat to heave to and practice it
Build skills for yourself and your crew at every opportunity
Racing is good practice
Drills are good practice
Helping other boats is good practice
Deal with emergencies early, ideally before they are emergencies

[Jammer]

Originally Posted by Unity

Seeing as nobody replied thought I’d ask an easier question: What anchor/size do you use on the stern and why / for what purpose?

I have recently moved my Danforth to my bow rail, since my boat did not come with a bow anchor but had an assortment of anchors in the cockpit locker. It is good enough for what I do, and has a part-chain rode, which is what you have when you have a 25' boat with no room for a windlass or chain locker.


With the Danforth on the bow, I have a couple of very low-tech fluke anchors and another part-chain rode to deploy from the cockpit. I keep them mainly as a hedge against losing the Danforth. If I really wanted to anchor from the stern, I'd go get the Danforth from the bow and carry it back. The only reasons I'd use a stern anchor would be to hold the boat in a particular orientation or to try to kedge off of something.

[Don C L]

So I routinely set a stern anchor, so that colors my view, BUT I still think it is wise for any boat to be rigged to deploy a stern anchor. Now I see that you have a sugar scoop so rigging a stern anchor that is always at the ready won't do the aesthetics much good, but only you can weigh that one. As far as throwing an anchor in case of emergency, I would recommend: no. First of all even a Fortress big enough to reliably stop your boat in a hurry will be cumbersome to be pulling out in a panic and dangerous to your self to be throwing. And it will need chain. It is important to be able to feed out the rode fast enough to be sure the anchor (like a Fortress or Danforth) is not allowed to fly or skip along the surface of the bottom (if the boat is moving fast.) The chain ensures the stock of the anchor will be down flat too to ensure the anchor bites.
If you really want to have a stern anchor at the ready, and you will not be planning to use a bow anchor for emergencies then it is best to have a samson post or beefy cleat, roller, chain, rode and anchor permanently in place ready to go, and personally I'd use an anchor and rode sized for what is normal for your boat, though not necessarily storm anchor size. Although with Fortresses you can get a pretty big anchor for not much weight, so I could definitely see having a big Fortress or Danforth back there. You may get some folks making fun of your stern anchor, but if you ever need it you'll never regret having installed it!

[DefinitelyMe]

In my opinion:

- A fortress is an excellent choice for a stern anchor. Also consider a Flook anchor if being able to throw it any distance is something you want and you're not in an area fraught with coral heads and/or rocks (presume not since you're talking about an all-rope rode?)

- Yes you can down-size considerably, especially if you go with a Fortress. Fortress anchors have incredible static holding power in sand or mud. Higher than the new generation anchors. They just don't reliably re-set, or swivel, and they don't penetrate as well as some others. If in sand or mud no problems, and re-setting and swivelling are not a concern for a stern anchor.

- yes you can use surprisingly lightweight nylon Rhode. 1/2" would be fine for your boat for a stern anchor. Chafe is the enemy, not load. 1/2" nylon has a breaking strength of about 2.5 tonnes. Fine for a stern anchor on your boat. Having said that, it just looks a bit wrong to me to have something so skinny holding all that strain. 5/8" gives a bit more piece of mind in that regard? I really wouldn't go any thicker than that for the application you are looking at.

[thinwater]

Before your momentum is gone, spin into the wind and drop the bower when the boat stops. It's really difficult to place an anchor properly if the boat is not stopped.

This will stop you faster, more dependably, and farther upwind than deploying a stern anchor. Visualize it and it will be obvious. The only special step is making sure that your bower is ready to run, which is simple enough. You should be able to get the anchor on the bottom before the boat stops moving. This is a skill you should already have well-practiced.

I've done this in haste a few times, and it makes FAR more sense than deploying from the cockpit. BTW, if you are motoring and the engine dies, after that one spin of the wheel, there is not reason for you to stay in the cockpit. There is nothing for you to do there.

Have you considered the impact force of stopping a ballasted boat moving at more than 1-2 knots? It is greater than the storm load on your bower. Try dropping your bower while going astern at 5 knots. That will be educational. Start slow. I seriously doubt you will get past 2 knots before you scare yourself with the forces involved. E ~ 30000 ft-pounds at just 4 knots. 100 feet of 3/4-inch line will stretch about 20 feet with a peak load of about 3500 pounds (30% breaking strength new with no knots or sharp bends)... if the anchor holds that. 1/2-inch line will probably snap. At 6 knots the energy is twice that. Remember that anchor loads assume the boat is stopped. (I have tested this with a load cell for an article on bump-setting anchors--the forces can be creepy).

I fear you are developing an emergency plan that won't work when you need it to. Too many complications, special skills, and moving parts. The bower system, on the other hand, is completely engineered. So just don't, unless it is for stern anchoring.

[Paul L]

I would think a Fortress 37 would be a good choice. You could even go one smaller considering you are not using it as a storm anchor but as a tempoary stopgap. 5/8 line with maybe 25 feet of chain. I know the chain complicates things a bit, but fortress anchors are pretty light for their size and benefit from some extra weight at the stock to help them set. If you launch a Fortess with the boat moving significantly it will sail through the water. The anchor is more likely to be used as a kedge set from a dinghy or a stern anchor to keep you pointed into the swell, but still be available for an emergency.

[Sojourner]

I'd upgrade my bower tackle in terms of strength and reliability and ability to remote drop. In my case I have a cockpit windlass control on the Amel, but if you don't, that might be a better solution: Turn into the wind, stop momentum, and hit your main anchor from the cockpit.

[Tillsbury]

I agree. Especially on a 52 footer, you want to be able to reliably drop and raise a good reliable anchor from the helm with ease. Stern and kedge anchors are for once that’s down, or in case of failure.

[Suijin]

I have a fortress fx-28 on the stern of my 40’ 28,000 lb. boat, in a bracket on the push pit. It’s rigged with 15’ of 5/16” chain and then to 3/4” three strand (overkill but it’s a dual purpose line). It’s rigged so I can connect the chain to the rope portion and just toss the anchor. Have never had to deploy it in anger thankfully.

Honestly I think the fx-28 would be sufficient for your intended purpose. It’s a big anchor. Anything bigger on your stern rail will be a pain to manage.

Check out Windline for fortress rail brackets.

[mickt243]

Why are you “throwing” an anchor?

[thinwater]

It's not going to work....


Much better to simply spin into the wind and anchor. Why not leave the cockpit? if the engnie is dead, there is no need to be there? You should be able to walk to the cockpit at a casual pace and get the anchor down before the boat stops coasting forward. I assume you do this every time you anchor. I always anchored single handed this way. Easy peasy.

[Steadman Uhlich]

Originally Posted by thinwater

Before your momentum is gone, spin into the wind and drop the bower when the boat stops. It's really difficult to place an anchor properly if the boat is not stopped.

This will stop you faster, more dependably, and farther upwind than deploying a stern anchor. Visualize it and it will be obvious. The only special step is making sure that your bower is ready to run, which is simple enough. You should be able to get the anchor on the bottom before the boat stops moving. This is a skill you should already have well-practiced.

I've done this in haste a few times, and it makes FAR more sense than deploying from the cockpit. BTW, if you are motoring and the engine dies, after that one spin of the wheel, there is not reason for you to stay in the cockpit. There is nothing for you to do there.

Have you considered the impact force of stopping a ballasted boat moving at more than 1-2 knots? It is greater than the storm load on your bower. Try dropping your bower while going astern at 5 knots. That will be educational. Start slow. I seriously doubt you will get past 2 knots before you scare yourself with the forces involved. E ~ 30000 ft-pounds at just 4 knots. 100 feet of 3/4-inch line will stretch about 20 feet with a peak load of about 3500 pounds (30% breaking strength new with no knots or sharp bends)... if the anchor holds that. 1/2-inch line will probably snap. At 6 knots the energy is twice that. Remember that anchor loads assume the boat is stopped. (I have tested this with a load cell for an article on bump-setting anchors--the forces can be creepy).

I fear you are developing an emergency plan that won't work when you need it to. Too many complications, special skills, and moving parts. The bower system, on the other hand, is completely engineered. So just don't, unless it is for stern anchoring.

[Suijin]

Originally Posted by thinwater

It's not going to work....


Much better to simply spin into the wind and anchor. Why not leave the cockpit? if the engnie is dead, there is no need to be there? You should be able to walk to the cockpit at a casual pace and get the anchor down before the boat stops coasting forward. I assume you do this every time you anchor. I always anchored single handed this way. Easy peasy.

In truth my fortress is at the stern rail largely for storage convenience. It’s primary purpose is for the occasional bow and stern anchoring, but it’s also there for a *dire* emergency... like losing power approaching a bridge down current on the ICW or rounding a rock breakwater downwind. Certainly if I can use the bow anchor that is preferable for a number of reasons.

And whoever asked about throwing, that was a figure of speech.