What is this hole for?

[EmeraldCoastSailor]

My $50, 37# generic plow was my forward tandem anchor through Michael but it looks to me like it’s set up for tandem anchoring via its connection points. Using one shackle instead of many more shackles and a 10” chain would make it simpler. Can anyone confirm what the forward hole is for?

[JPA Cate]

First off, I'm only guessing, but since so much of the FL waters are shallow, I'm wondering whether it might be for direct attachment of a snubber, so that you let go both longish snubber and chain at the same time, then take up on the snubber line, for a smoother ride at anchor.

Tandem anchoring is pretty much universally not recommended. If you do a CF Custom Google Search on "thinwater"'s posts on the subjects, he's aware of the actual data gathering process to support that non-recommendation.



Ann

[Snowpetrel]

Looks like the top hole is for a steeper setting angle, much like the fortresses mud setting. I suspect it would give greater holding in soft mud, but make it harder to set in a firm bottom.

[thinwater]

I've never seen it done that way. I would guess it is for securing the anchor in the roller.

A second hole, like that, if used for the main rode, will change the setting characteristics of the anchor. In fact, every rock slot does that. But whether it is better depends on many factors. I would test it, not guess. The few that I have tested with alternate holes like that, were not consistently improved in any bottom type; the main setting always seemed best. Not surprising.

I'm not a fan of tandem anchoring, but even when it does work, that is the wrong place to attach the second anchor. With any shift in direction, it will tend to roll the anchor out. Better to attach farther up the line. I think it is just in the way, which explains why it is not done that way.

[thinwater]

I never liked tandem anchors, because with a change in direction, the lead anchor always rolls out and is pinned on its back, a possition from which it often does not recover. All of the manufacturers, other than Rocna, agree.

So how did the in-line tandem get popularized?

Some time ago I was reading a 1920s sailing book, pre-CQR and pre-Danforth, and they showed a tandem anchor set up. They liked it for mud, not rocks. And their reason made sense because...

• The anchors were both traditional fisherman style. There was no back to roll over onto. If it rolls, it is ready to dig again.
  
• A fisherman is quite poor in mud but good in rocks.
• A fisherman doesn't really bury well, so the negative impact of the secondary rode is small.
  
• V-arrangements are fatal with fisherman's anchors; you will foul for sure. In-line is the only way you can use two anchors. Modern anchors bury, reducing fouling concerns.
  

So in-line tandems are traditional... but outdated and wrong with today's anchors. It is an obsolete tradition that continues only because we forget that today's anchors are VERY different from fisherman's anchors of yore. But if you have a Northill, go for it; it should work.

[Dave_S]

Not really knowing but on the physics of it, I'd say the forward one is to tie a marker on it to pull it out if it gets stuck and the rear one near the usual attachment point would be for attaching another anchor.

[EmeraldCoastSailor]

I realize tandem anchoring isn't favored by most but I am not sure of a better approach for ultimate storm conditions other than getting a huge storm anchor and swapping out the primary. Perhaps a big expensive Fortress that breaks down for storage and doesn't add too much weight.

I leave it to you to decide if my tandem approach worked in the 150 mph sustained winds of Michael: My 35# Delta (primary anchor) dove about 12' deep in mud after dragging about 250' across Watson's Bayou in Millville, FL. The 37# generic plow was attached via 24' of chain to a big shackle that was connected to the Delta via 10" of chain and of course the chain back to the boat. The generic plow had a trip line attached and was recovered; I am guessing it was 3-4' deep in the mud. Not sure I will ever get the 35# Delta back. IMHO a 35# Delta wasn't enough anchor for my 35' sailboat for such a storm. Maybe no anchor would have been enough and I am just lucky.

[a64pilot]

I think your idea of a stupid big Fortress is a good one, better than tandem anything

[NevisDog]

Originally Posted by EmeraldCoastSailor

...I leave it to you to decide if my tandem approach worked in the 150 mph sustained winds of Michael: My 35# Delta (primary anchor) dove about 12' deep in mud after dragging about 250' across Watson's Bayou in Millville, FL. The 37# generic plow was attached via 24' of chain to a big shackle that was connected to the Delta via 10" of chain and of course the chain back to the boat. The generic plow had a trip line attached and was recovered; I am guessing it was 3-4' deep in the mud. Not sure I will ever get the 35# Delta back. IMHO a 35# Delta wasn't enough anchor for my 35' sailboat for such a storm. Maybe no anchor would have been enough and I am just lucky.

Interesting. After dragging 250' yes I'd guess you are correct - like me, you got lucky: lucky they eventually dug in (or hooked up on something big - Deltas and ploughs are notorious for doing the opposite) and lucky the wind direction didn't change enough to trip your single-point mooring. If you can't recover the deep-buried Delta that tends to suggest it alone would have held you and the plough didn't help, more likely hindered it diving deeper.

But congratulations on surviving 150mph winds at anchor - that deserves a medal. How much scope did you have, 10:1? More than 10:1?

[LeeV]

Marker bouy

[Mike Banks]

Marker/recovery buoy.

Use a Bahamian set plus kellet on the main rode before the divide. Then it does not matter what wind or tide do--you will always besecure.

[EmeraldCoastSailor]

Originally Posted by NevisDog

Interesting. After dragging 250' yes I'd guess you are correct - like me, you got lucky: lucky they eventually dug in (or hooked up on something big - Deltas and ploughs are notorious for doing the opposite) and lucky the wind direction didn't change enough to trip your single-point mooring. If you can't recover the deep-buried Delta that tends to suggest it alone would have held you and the plough didn't help, more likely hindered it diving deeper.

But congratulations on surviving 150mph winds at anchor - that deserves a medal. How much scope did you have, 10:1? More than 10:1?

The wind was hard from the east and even harder from the north and then from the west. All the dragging occurred from east to west; doesn't appear I dragged to the south at all. Delta must have set by then. I had 135' of chain and 3 nylon snubbers connecting chain to boat; 2 were hitched (1 hitch failed) and 1 was my normal hook moused to the chain. I also had my nylon rode spliced to the chain. I tried to balance all 4 in terms of tension. I'd say add about 15' from bow to chain of nylon connections for a total of 150' out in 12' of water where I dropped, 6' where I ended up, and not sure about storm surge but there was plenty. Funny thing is that just to the west of my boat were dock pilings. Given where I ended up dragging to I can only guess that storm surge was enough to keep my boat over the pilings as the scope certainly was enough to have the boat over the backyard of the property with the dock. When the wind shifted north it put the boat in deep enough water. I found her next day floating free in a NW breeze.

[Boatguy30]

I'm unclear how much chain was used between the anchors. And the plow was shackled to the trip line hole on the delta? Also a bit unclear on how it all worked with the wind shift. Would certainly make for a good separate post and possible a bit of money thrown at it by practical sailor or cruising world to analyze it.

[EmeraldCoastSailor]

Originally Posted by Boatguy30

I'm unclear how much chain was used between the anchors. And the plow was shackled to the trip line hole on the delta? Also a bit unclear on how it all worked with the wind shift. Would certainly make for a good separate post and possible a bit of money thrown at it by practical sailor or cruising world to analyze it.

I agree it would be an interesting situation to study more scientifically but not sure how to go about that effort. Here is more detail on my chain setup (all 5/16"). 134' of chain from boat to 7/16" SS shackle connected to a bigger 1/2" galvanized shackle. Also attached to the 1/2" galvanized shackle were two other 7/16" SS shackles, one connected to 10" of chain to the Delta (primary) and the other connected to 24' of chain that connected to the generic plow (tandem). The big 1/2" galvanized shackle served as a hub that led to the boat (134' of scope), to the tandem anchor (24'), and 10 inches of chain to the primary anchor. I threw out the tandem first drifted back and then released the primary. The forward tandem plow anchor had a line and float attached to its trip hole which I used to successfully recover the anchor. Nothing was attached to the trip hole of the primary (Delta). I hope that helps.

I also had a Fortress 16 on its own chain rode arrangement out more to the north than the tandem arrangement. It must have held to a meaningful degree but chafe parted the rode and the Fortress was lost.

[thinwater]

Originally Posted by Boatguy30

... Also a bit unclear on how it all worked with the wind shift. Would certainly make for a good separate post and possible a bit of money thrown at it by practical sailor or cruising world to analyze it.

https://www.practical-sailor.com/iss...g_12056-1.html


I've never seen a picture posted that shows both elements of an in-line tandem that is set after a wind shift. If someone has some, please share. Or set two on a beach, veer 30 degrees to one side, pull to at least 50% of the holding capacity of the anchor, and photo.


I'm not sayin' it's impossible. I bet it does work, some times. I'm saying I have tried repeatedly and failed.


The working load on a 35' boat anchored in 150 knots with snubbers is about 1500 pounds. A single 35# Delta can hold that much once it reaches good mud. It can only hold 1/2 to 1/3 that in poor mud. But we don't know.


Is 35# enough# I know I anchored a 45' boat in 60 knots with a 25# Delta in mud a number of times. I think the boat would have dragged pretty far until it found something firm... which it did. But we don't know.