80# Manson Supreme Surprise!

[SVNeko]

Originally Posted by foggysail

I believe we all learned something from my thread. Unfortunately there ARE times when proper scope is impossible to apply in crowded anchorages. This time, it was my fault. There were obstacles such as moorings to avoid but I could have and looking back should have employed greater scope.

I still believe had I set the anchor properly during me initial setting, that may have helped avoid the situation that later followed. Got to chin up, poop does happen. It was worth my sharing this event in any case!

Foggy

Agreed. Thanks for sharing. Maybe you picked a marginal spot and should have anchored where you had a bit more room.

[noelex 77]

Thanks for the GPS trace it shows a lot and its possible to do a forensic analysis on the data.
This is my raw data: (note these involve making some reasonable assumptions. I have listed the measurements to the nearest foot. It its sensible to keep in mind that this implies a precision that is not present from the limited information.)

Total movement 207 feet
Rode length 64 feet
Distance from the anchor to the bow at the start of the "handle" 48 feet
Length of handle 75 feet

Probable drag (assuming GPS aerial is 25feet back) 29 feet

I would conclude from this that the anchor did drag. Although with the small amount of drag (29 feet) its not possible to reach a definitive conclusion. Particularly as the trace was not generated from a satellite differential fix.

The "handle" part of the trace does show the boat was slowly moving backwards at this stage. At the start of the handle the bow was only 48 feet from the anchor. So the backwards movement was likely to be chain pulling through the weed. The pattern of backwards does not subsequently change. Which it should do once the rode is stretched out.

The characteristic rapid short drag followed by some holding as the anchor catches is absent which is puzzling.

[foggysail]

Noelex---

AT TIMES YOU AMAZE ME!!!

My calculation of the handle length pretty much agrees with your number. I only calculated the latitude change ignoring the longitude and also made assumptions. But why do you assume the drag to be only 29' while I assume the handle length to represent drag?

Foggy

[sailorboy1]

Foggy what is your plan going forward, a new 200# Never Drag?

My 60# MS has never drug, but all anchor drag in time and I hope to plan my day to be a non-event.

[foggysail]

Originally Posted by Don L

Foggy what is your plan going forward, a new 200# Never Drag?

My 60# MS has never drug, but all anchor drag in time and I hope to plan my day to be a non-event.

Don-- I got a GREAT PRICE ON A 150# MANSON BOSS from Defender. No need to go to the 200 level

I assume you followed my anchoring anxiety over the recent years with Bruce, two huge Deltas and finally my MS. Joking aside, I intend to exercise better judgement when I lower my MS along with pulling on the chain with both engines. Will power the port engine first, then the starboard and repeat several times to work the anchor into the deep followed by pulling with both engines together.

All in all the slip did not result in the boat floating across the harbor so I think with better setting and proper scope when I can should be fine. If I get another AAAHhh POOP, just maybe I'll look into the 200 job you alluded to

[pbiJim]

I don't know how the size of your anchor relates to the load that your particular boat puts up, so I'll just make some general comments about what your description of the events suggests to me.

I see two possibilities. 1) The anchor set, but the mud was so soft that the anchor dragged through the mud. 2) the anchor didn't set, & the chain fouled itself in the grass well enough that it felt to you like it had set. In that case, you were dragging while tangling in the grass, which slowed down the drag.

I've never stopped in at Cuttyhunk, but I have been to Block more than once & that is sort of the same neighborhood, if you stretch your imagination a little. If the mud where you anchored was anything like what I saw at Block, then my guess would be option #1, especially with slightly short scope. That's my best guess anyway.

I recently went to a hurricane prep seminar in Miami. It was given by some old-salt types that keep their boats in & around Biscayne Bay. The bottom there is pretty loose & a little grassy. Those guys swore by a piece of advice that is probably going to upset a few people who are used to different conditions. They firmly recommended to leave the plows in the field where they belong (their words, not mine). They described the type of dragging that you experienced, a long slow drag. They were talking about CQR & Delta type anchors, so it's not really an apples to apples comparison with what you have, but I suspect that there may be some degree of correlation in that bottom type. They all wanted Fortress & Danforth type anchors in that soft bottom they live with. ...just food for thought.

[mrohr]

My guess is that the chain was holding the boat until the wind came up and the chain gradually pulled through the bottom muck in another direction until the anchor dug in for the first time. there was very little dragging of anchor.
Fwiw: Try dragging a length of chain across your lawn ,most here would find it impossible with only a few meters out. Now try doing the same in thick muck ;you will need a truck. My MS anchor always sets quickly and has never dragged ,but when I snorkeled over my old CQR anchor I often found it was the chain holding the boat.

[sailorboy1]

Originally Posted by foggysail

Don-- I got a GREAT PRICE ON A 150# MANSON BOSS from Defender. No need to go to the 200 level

So that is almost twice the weight, and probably like 4 times the surface area?

Is your windlass going to be able to pull that baby back up with the 200# of black muck it is going to carry?

You going to be sleeping so hard now during a gale that you wouldn't heard the other dragging boat bumping along your side as it goes by.

[pbiJim]

Originally Posted by mrohr

when I snorkeled over my old CQR anchor I often found it was the chain holding the boat.

When I was younger, I often dove on the moorings near where I lived. Even in an area with strong tidal flows, I seldom saw more than half of the chain on the mooring move after a tidal shift. I never saw the chain pull into a straight line unless the winds were over gale force. The one that I looked at most often was a 250 pound mushroom with 20 feet of 1/2" chain holding a 25 foot wooden sloop with a heavy iron keel.

I think that many people underestimate the effect of anchor chain.

[Delfin]

Originally Posted by foggysail

Last week Wifey and I took our 40' Silverton Aftcabin, completely canvas enclosed powerboat to Cuttyhunk, a small island off the coast of Massachusetts. I was in a hurry to get the anchor down and set, dropped out about 50-60 feet of 5/16 chain where the water depth is about 6' at low tide, about 10' at the high.

My 80# MS has performed above expectations since I installed it last year so I put only one engine in reverse and tugged until it set. That I know is not the right way to set an anchor but the anchor is soooo reliable, I though at the time it was good enough. With that, I set my GPS as always so I could monitor any position changes.

Where I anchor at Cutty, virtually nobody else does. It is an area most fear as shallow but that is another story. What Cutty does have is a proliferation of ell grass, most 4-5' tall! It was a nice day and a better early evening, the type stories are written about.

Things changed later along with the wind moving to out of the NE blowing a steady 25K with gust over 30. I checked the GPS around midnight, it looked like we had slipped about 60' that I think occurred with the wind change. The mulitple plotted lines on the GPS indicated if we had slipped, we were then holding.

I checked several times during the night and early morning hours and indeed, we were moving, not much but moving. Maybe a total of 75' but we were limited to how far the boat could slip because of a moored sailboat along with a large, moored floating fishing bait box. At eight AM it was time to move after slipping about 125' as measured on the GPS. Some fun lifting the anchor and trying to control the boat in the heavy wind and well over 2' harbor chop.

We moved to one of the nearby pilings and spend the next two days listening to the howling wind and the slapping chop on the boat's hull.

Now I have an uncertainty factor.... did the anchor slip because I failed to properly set it? With the huge wind load my boat has, why did not the anchor set itself rather than just continually slip? The bottom below the ell grass is pure heavy mud.

Foggy, I suppose it is possible that by anchoring quickly, you overlaid the anchor with chain, which got wrapped around the shank. That can pull the anchor sideways, scooping up mud and supplying some holding power, but not enough. Was their more mud on one side of the anchor that you recall?

[SkiprJohn]

Possibility that the anchor set in the original conditions, hence all the mud. Once the wind changed direction and velocity the anchor could not reset due to all the mud that was clinging to it and just dragged across the eel grass with the chain. More scope and a deeper set may have been the answer but its hard to say since we don't know what really happened down deep. We only know the result was a drag.

[foggysail]

Originally Posted by Don L

So that is almost twice the weight, and probably like 4 times the surface area?

Is your windlass going to be able to pull that baby back up with the 200# of black muck it is going to carry?

You going to be sleeping so hard now during a gale that you wouldn't heard the other dragging boat bumping along your side as it goes by.

I was joking Don about that 150# job. But if I had to, I believe the windlass could easily pick up a 200# anchor along with 200#s of sea bottom. My windlass is a Maxwell HWC2200 powered the a dedicated 24vdc battery bank made up with 2 group 29s in series. With that stated, something else might break though.

Now as to "You going to be sleeping so hard now during a gale that you wouldn't heard the other dragging boat bumping along your side as it goes by"

Yeah right on! That is what I want except I do not want them bumping into our boat. The night I described in my OP, there were boats that made it to the shore and not by plan. I talked to the BoatUS Towboat operator who did the retrieval. The ONLY thing that prevented MORE boats from winding up on the shores is that there WERE ONLY A FEW BOATS anchored that night and not many more in the mooring field. Cutty is a tough place to anchor.

[foggysail]

Originally Posted by SkiprJohn

Possibility that the anchor set in the original conditions, hence all the mud. Once the wind changed direction and velocity the anchor could not reset due to all the mud that was clinging to it and just dragged across the eel grass with the chain. More scope and a deeper set may have been the answer but its hard to say since we don't know what really happened down deep. We only know the result was a drag.

Yes John, I believe you're right on! More scope along with a better initial set. But look at the GPS picture. The anchor was still doing a pretty good job holding even with the slow slip.

My boat is 40' in length, with the exception of the bow section... my guess about 15 feet, it is completely enclosed in canvas with part of the canvas as high as 14-15' over the water. That makes for a huge wind load. My calculation was we slipped about 70' using the delta lat readings. This pretty much corresponds with the distance scale at the bottom of the GPS picture.

[noelex 77]

Originally Posted by foggysail

The ONLY thing that prevented MORE boats from winding up on the shores is that there WERE ONLY A FEW BOATS anchored that night and not many more in the mooring field. Cutty is a tough place to anchor.

People do joke about anchor threads, but there are a lot of boats that drag once you get to parts of the world where the anchoring substrate is not ideal.

Be careful around 25knots average wind strength. Below this level boats with poorly set anchors will still hold, but about this wind strength they will start to drag. If they hold at this level their anchor is reasonably set and they usually hold in higher wind.

Around 40knots, or just below, is another transition point at this level a lot of boats with well set anchors will start dragging.

Only rough rules of thumb, but I find them useful.

[foggysail]

Originally Posted by Delfin

Foggy, I suppose it is possible that by anchoring quickly, you overlaid the anchor with chain, which got wrapped around the shank. That can pull the anchor sideways, scooping up mud and supplying some holding power, but not enough. Was their more mud on one side of the anchor that you recall?

The anchor was set, I did pull on it and we were set. What I did not do was to pull on it using alternate engines to work it deeply into the mud and finally pull hard on it with both engines.

I have anchored in this same spot now for the last couple of years. With the anchor really set, I have difficulty pulling it out of the mud so much so that I need to use the engines to free it. The total slip during the night was only about 70' or so over 8 hours. Granted, ZERO slip is what one desires to avoid collisions. We were getting too close for comfort, that was why I left for a piling. I thought about cleaning the anchor and resetting it but the conditions were horrible and it was easier to just grab a piling. Even that was a job to do. Maneuvering my boat with twin 454's was difficult in the 25+K wind so just getting to a piling without banging into others was a challenge.