Stern anchor

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klee wyck

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In lieu of stomping on Peter's thread (Weebles), I offer this comment here in response to his comment from the other thread.

Peter said:

"Stern anchor. Separate topic/thread as it's rare in the US except for those who anchor in tidal rivers. My current thinking is a smallish single piece anchor (vs a Danforth style) around 8kg with 2m of 1/4" chain and 150' of 1/2" braid all stored in an insulated shopping bag like Costco sells. Easy to store, easy to repack. I'd love a reel of webbing but they are dang expensive in the US, plus I don't have a great place to mount it though I suppose I could figure out something."



I share the sentiment above regarding stern anchors. I have come to think they are underappreciated and therefor under used for the conditions you are seeing. While I expect it is not as common in the Sea of Cortez where we are as it is in the mainland coastal roadsteads that you are experiencing, we have gotten tuned up a bit when winds fall off from swell.
The big cat is really comfortable in a good swell as long as the wind keeps her nosed into it. But it is common in the SOC for a northerly to run a few days creating a good swell on several hundred miles of fetch. That swell may take a couple of days to decay once the wind falls off and changes direction from onshore.
If the cat decides to straddle the swell under those conditions, my bunkmate gets really grouchy, and I get highly motivated as you might imagine.
The stern anchor is like magic under those conditions.
I have a Fortress with a section of chain hanging from it and the reel you see in the photo, which when combined with the use of the winch in the photo, leads to world peace.
The winch pulls the stern bar tight to the bow anchor in line with swell and all is well in my world.

Highly recommend this under the conditions you describe.
 

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What size Fortress are you using with the big girl, Bill?
 
What size Fortress are you using with the big girl, Bill?

Not sure, Jeff, but will try to find a number on it when we get back aboard. It is one of the bigger ones and seems like it might weigh around 45#?
I know when it buries itself in that firm sand, it takes a good bit of torque to bust it out, even compared to a much heavier modern bow anchor.
 
I talked to one part time cruiser (sail) who recently set a stern anchor for the first time. They used a full sized anchor for their Passport 45 ketch. It took them 1.5 hours to retrieve the anchor. Sounds like a long time but when I think through challenge of receiving a 20kg anchor with 30-feet of 5/16"" chain backed by 3/4" rope, suddenly seems pretty dang daunting. I'm sure they'd do it differently next time, but my takeaway is that for a stern anchor where the full force of the boat will not be required, smaller is better. Must be easy to stow, deploy, and retrieve. Using a "full capacity" spare anchor and rode (even if rope/chain) misses on all fronts.

My thinking is that to just keep the boat from swinging doesn't take much. Using a ubiquitous 42-foot trawler as a base, would a 6-lb Fortress/Guardian with 6-10 feet chain and 125' 3/8"" 3-braid be suitable?. A flat rope reel would be even better, but those are not commonly available in the US (except for Ultra with a very high price).

Thoughts? There is zero testing on stern anchors for alignment vs carrying full weight of the boat

Peter
 
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Agree that stern anchors should not be bigger than what can be handled by a person in a dingy and broken out by hand/dingy use.

A more normal sized anchor can be/should be used for double anchoring as in storm or Bahamian moor...as both can be expected to need the full holding power of the other. But they must be able to both be broken out with the main vessels and appropriate handling gear.

If not thought of in this way, I personally had a tiny stern anchor so stuck I nearly cut it loose as getting it in the dingy was taking too long and getting dangerous....and as an assistance tower had to cut loose many anchors tied to the stern of vessels when they were not possible to be safely broken out even with 2 vessels on scene working on breaking them out.
 
Agree that stern anchors should not be bigger than what can be handled by a person in a dingy and broken out by hand/dingy use.

A more normal sized anchor can be/should be used for double anchoring as in storm or Bahamian moor...as both can be expected to need the full holding power of the other. But they must be able to both be broken out with the main vessels and appropriate handling gear.

If not thought of in this way, I personally had a tiny stern anchor so stuck I nearly cut it loose as getting it in the dingy was taking too long and getting dangerous....and as an assistance tower had to cut loose many anchors tied to the stern of vessels when they were not possible to be safely broken out even with 2 vessels on scene working on breaking them out.

For those unfamiliar, a boat left to its own will lay parallel to a swell. The scenario is you anchor during the day when there's a breeze that holds you somewhere bow into the swell. Around midnight, the wind dies completely and the boat rotates beam-to the swell tossing me from my bunk.

Psneeld - what's the best guess of minimal stern anchor setup for your old Albin 40? I bought a Mantis 2.5 lb anchor for my dinghy and have been stunned that I have to be right over it to pull it free. I don't think it takes much, but not sure how much is enough. Thoughts?

Peter
 
Think that is determined by exactly how and under what conditions you plan on using a stern anchor.

I think even the smallest can be a handful to get up from a dingy if buried well.

I never used one with my Albin 40 but my last liveaboard, a 37' Convertible had a roughly 5lb Bruce that I almost had to cut loose. My mistake there was underestimating the tidal flow and resulting pressure on the big, wide, deep stern. Couldn't Bahamian moor due to room/swing and really didn't think I needed to.

So a small, well set anchor with OK holding power will hold enough for what I would use a stern anchor for.... if it doesn't hold you for what you need due to bottom, difficulty in setting, etc.... I would rethink my anchoring situation. Would not let it soak for more than 1 night...would reset after that.

For situations in deep water with maneuvering room, a second anchor of "backup primary size" would be OK...just lead the rode to whatever cleat you want, just have enough rode to drive to either anchor and pull one, then the other.
 
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I use a stern anchor periodically to hold the boat in position, often in narrow channels.

My offering to the discussion is how small an anchor you can gey away with. The Fortress anchor I use came with the boat for use with the dinghy. It has probably 6' of 3/16" chain and 300' of 1/2" rope. For working in mud or sand, it's all about scope. As I'm usually at the end of the channel, water depths are less than 15', often less than 10'. It's not uncommon to be 15 or 20:1 scope. The long line combined with small diameter eliminates any shock loading on the anchor. Once set, it's amazing the holding power that can be generated with that kind of scope and stretchy 3 strand nylon line. Somewhere around 15 knots is where the anchor starts dragging, but my goal is to use the main anchor up wind and the small anchor for keeping the boat from hitting the sides of the channel or running aground in shallow water.

In a narrow channel at Isle Royale last summer. The 1/2" stern anchor line is to the right of the dinghy, keeping me centered in the channel.
20230713_061108.jpg

Ted
 
I talked to one part time cruiser (sail) who recently set a stern anchor for the first time. They used a full sized anchor for their Passport 45 ketch. It took them 1.5 hours to retrieve the anchor. Sounds like a long time but when I think through challenge of receiving a 20kg anchor with 30-feet of 5/16"" chain backed by 3/4" rope, suddenly seems pretty dang daunting. I'm sure they'd do it differently next time, but my takeaway is that for a stern anchor where the full force of the boat will not be required, smaller is better. Must be easy to stow, deploy, and retrieve. Using a "full capacity" spare anchor and rode (even if rope/chain) misses on all fronts.

My thinking is that to just keep the boat from swinging doesn't take much. Using a ubiquitous 42-foot trawler as a base, would a 6-lb Fortress/Guardian with 6-10 feet chain and 125' 3/8"" 3-braid be suitable?. A flat rope reel would be even better, but those are not commonly available in the US (except for Ultra with a very high price).

Thoughts? There is zero testing on stern anchors for alignment vs carrying full weight of the boat

Peter

Every boat and every crew will take a different view of this. For me, with winches and wildcats all over the cat, why not use a real anchor for the stern anchor? Otherwise, I would need to stow two anchors, a backup/storm anchor with rigging and a small stern anchor with rigging. I would rather stow one and use the equipment I already have on board anyway to retrieve it. Plus, it seems at sometimes there is a fair bit of pull on that stern anchor, especially when first setting it and using the winch to pull the stern around to the direction I need it. A 45# Fortress is likely overkill, but it works fine and would serve me in a hurricane.
YMMV
 
Every boat and every crew will take a different view of this. For me, with winches and wildcats all over the cat, why not use a real anchor for the stern anchor? Otherwise, I would need to stow two anchors, a backup/storm anchor with rigging and a small stern anchor with rigging. I would rather stow one and use the equipment I already have on board anyway to retrieve it. Plus, it seems at sometimes there is a fair bit of pull on that stern anchor, especially when first setting it and using the winch to pull the stern around to the direction I need it. A 45# Fortress is likely overkill, but it works fine and would serve me in a hurricane.
YMMV

The reason for a small anchor is handling from the dingy if you have to... as I posted if always in deeper water and versatile anchor handling gear, probably no need for a small one.

But I was often in situations where a anchor dinghied to a good spot but in very shallow water required a smaller anchor that could be easily manhandled through recovery and breaking out....and from a somewhat tippy dinghy.
 
With the boat “slewing” from side to side in strong wind gusts, and deploying a lightweight stern anchor to restrict lateral movement, you would need to make sure the anchor is well set and not likely to break out overnight with many hours passing by until checked again the next morning for example.
My only attempt at serious stern anchoring was this scenario, only to discover the short rode had wrapped around the props after the stern anchor had broken free and the “slewing” dragged the rode backwards and forwards around the stern gear.
Lots of lessons learned after this of course, but if we had to move unexpectedly during the night and wanted the props to turn, we would have been very disappointed!
 
I use a stern anchor periodically to hold the boat in position, often in narrow channels.

My offering to the discussion is how small an anchor you can gey away with. The Fortress anchor I use came with the boat for use with the dinghy. It has probably 6' of 3/16" chain and 300' of 1/2" rope. For working in mud or sand, it's all about scope. As I'm usually at the end of the channel, water depths are less than 15', often less than 10'. It's not uncommon to be 15 or 20:1 scope. The long line combined with small diameter eliminates any shock loading on the anchor. Once set, it's amazing the holding power that can be generated with that kind of scope and stretchy 3 strand nylon line. Somewhere around 15 knots is where the anchor starts dragging, but my goal is to use the main anchor up wind and the small anchor for keeping the boat from hitting the sides of the channel or running aground in shallow water.

In a narrow channel at Isle Royale last summer. The 1/2" stern anchor line is to the right of the dinghy, keeping me centered in the channel.
View attachment 145925

Ted

This is where my mind was headed. - long length of 3-brais to reduce shock loading makes sense.

I bought a Mantus 2-1/2 lb M1 dinghy anchor for my dinghy. Steve Goodwin of SVPanope anchor test fame tested it and was shocked at the holding power of such a small anchor. Mantus also makes a break-down 8 lb and 13 lb anchor (HERE). Not cheap, but very easily stowed if that's important which if is for me. Even the 8 lb version would keep Weebles aligned, and would be reasonably easy to haul by hand.

Peter
 
I used to almost always set a stern hook in my sailboat but I try to avoid it with my 65,000lb power boat. I have a Fortress 35 with a heavy length of chain and lots of rode. When I need to retrieve it in the dinghy I need to pull for a lengthy period before I can tell it is actually releasing from the bottom. Patience is the key. I'd like to go a bit smaller as this setup is about all I can handle.
 
I bought a Mantus 2-1/2 lb M1 dinghy anchor for my dinghy. Steve Goodwin of SVPanope anchor test fame tested it and was shocked at the holding power of such a small anchor.

And your experience with that small anchor as a stern anchor on your big boat has been good, even in slewing conditions?
 
My new to me Maritimo 52 came with a 60 lb Ultra anchor that is undersized for the boat along with 300 feet of rusty chain and no rope rode. I’m upgrading to a 77 lb Ultra and 400 feet of chain with 200 feet of rope and planning on keeping the 60 pounder as a spare in the aft lazarette along with 250 feet of prespliced chain/rope in a bucket. I’m strong enough to deploy this anchor off the stern and I could retrieve it by walking it up to the bow and using the windlass on the rope and then manhandling the chain and anchor aboard, but maybe just barely. Does it make sense and is it worth the space in the lazarette to have a third, lighter, fortress-style anchor aboard for stern anchoring? I’ve never actually had the occasion to do so outside of my ICC challenge test (with a small fortress anchor on my old Nordic Tug 37), but I like the idea that I could in a pinch. Overkill?
 
Think it’s here there’s a difference between the average cruising sail boat and trawler. With the sailboat it’s not uncommon to have 6’ or more of draft. It’s not uncommon to need to anchor in tidal rivers so experience a 180* shift. You have two built in windlasses in the cockpit. The primary winches. For the last few boats they were powered. Swing is a concern and occasionally you’re faced with more than adequate swing into the center of the river but inadequate shoreside. Lying parallel to the river keeps you out of traffic and at an adequate depth for 5:1 or even 8:1 scope. Here having an adequate stern anchor means you don’t have to wake up turn on the engine and use the thrusters to make sure you reverse going out away from the shore.
We carried a fortress sized to hold in mud at up to BF8. It was stored disassembled so easy to find a spot for it. We carried a spare rode of line and chain. The primary rode was all chain. (Have the same setup on the NT). Unlike the NT had powered winches in the cockpit.
So would drop as usual. Then let out enough rode to have 5:1 for the fortress. Then drop the fortress. Then take in rode of the bow anchor so both anchors had 5:1.
Leaving would let off chain to be up and down over the fortress. Use the winch to recover until transition from chain to line. Go to swim platform and put a spare line on the proximal chain. Run that line to the other primary. Use a blanket and a fender so chain didn’t mar swim platform. (Kick it down to keep it in place). Once free and once enough chain recovered chain and fortress were light enough you didn’t need the other primary and could do it by hand and keep everything away from the boat.
With the holding of the fortress just about equal to the Rocna we wouldn’t swing but wouldn’t drag either.
Make sure there’s enough rode to allow for tidal rises and falls. Don’t do this in strong winds or currents. Bow first needs less holding power than stern first. Don’t do this if the cockpit is at risk of flooding from green water. In short it’s only for mild conditions and maybe 3-4kts max of current and winds <20kts.
If I was to do new construction would spec a winch/windlass at the stern. For anything around 50’ or up would help docking, anchoring and running a line or webbing to shore and using a stern anchor.
We also used the primaries for the JSD. Never used the JSD in anger but worked in practice. Also would be helpful if using drogue and a bridle to steer if the rudder malfunctioned.
My current boat doesn’t have a safe way to use a stern anchor. I wouldn’t trust a small fortress to hold the boat enough to sleep. So we carry a large fortress and don’t stern anchor. If I’m up I can make sure we go the right way with a current reversal. I’ll tie to a rock or tree off the stern but don’t trust a small anchor placed on a beach except for the dinghy. In short an undersized anchor doesn’t make sense to me. An anchor which requires a lot of time and work to recover seems dangerous to me. So for me stern anchoring is no longer in the playbook.
 
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I anchored in many a tiny tidal creek along the ACIW with only a single anchor and never wound up aground. Came close due to a thunderstorm at the wrong time but only close and could have freed myselt pretty easily.

The trick is wind. Normally the current keeps you near the center of the creek if that's where you dropped the anchor, but when the tide goes slack, you have to guess where the wind will blow you in reference to the channel. I always picked tiny creeks much to others amazement, but I picked them due to usually being near tree lines that protected me from cross winds blowing me into shallow spots.

Occasionally I though stern anchors or Bahamian mooring... but was too lazy and just concentrated on picking well the first time.

Usually having to get up at night to use the head a couple times, checking position with a quick glance out the port was easy enough and never seeing an issue got plenty of restful sleep.

For the couple times when the wind was wrong and strong and the creek neither protected or very wide/deep....it was easy enough to look up about when the current would shift and stay awake long enough to ensure a safe swing.
 

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