How About a Running Start?

[thinwater]

Power setting was discussed recently. But that only tests up to about 20-35 knots, depending on the boat and motor (outboards are on the low end). And that is assuming you have a motor.

What about backing down on the anchor with some speed, and using momentum to set the hook. Many of us have done this on engineless boats. Assume that the hook is already set to some extent, though not necessarily.

1. In soft mud this may do more harm than good, because the soil tends to liquefy when you hit it quick. But sand does reasonably well with short burst of tension.
2. The speed should be no more than about 1-knot. Assuming you have enough catenary (deep water) or a long snubber, the force will about equal storm tension (I'm not guessing--I did some testing with a load cell).
3. Assuming there is stretch, as described in (2), the impact is not a bang, but a surge over 5 seconds or more. In principle, it is something like using nylon rescue straps to snatch a stuck vehicle out of a snow bank.

I've been known to do this by simply hauling the scope short by hand, and letting go. The boat drifts back and thumps on the anchor.


But does this also make sense as a means of setting an anchor more deeply if real wind is expected, in addition to power setting? It might be specifically applicable to outboard-powered boats.



Thoughts? Experiences? I have a few, but I would rather not lead with them.

[Hudson Force]

I would be skeptical in considering any true advantage. I have set anchors while under sail and "rounding up" after dropping the anchor with a long nylon rode. This seemed to work well, but I was not pulling directly and I was at a slow speed.

I can remember watching a large power vessel trying to anchor for more than an hour in Salt Pond at Block Island. He continued to power back quickly while dropping his anchor without success. I am sure others, like me watching him, knew that he would have succeeded if he had just dropped it gently and set it with little movement in reverse at first. Powering back is excellent to set an anchor well, but at the start, too much power will often make the anchor skip along the surface.

The guy in Salt Pond eventually gave up and left for the Marina.

Edit: I went back to read your post again and noticed that you said the speed should be "no more than about 1 knot". Well, with a knot or less easing back seems to be standard procedure. We like to be moving in reverse at the time the anchor contacts the bottom in order to present the anchor at proper alignment and to extend the chain without dropping a "pile" in one spot. I think that the best practice requires laying out the chain or nylon rode at a rate that approaches your speed in reverse. Therefore, we do end up tensioning our rode with some way on in reverse. We commonly set first at a low rpm and then ease up to a higher rpm to "set".

[thinwater]

Originally Posted by Hudson Force

I would be skeptical in considering any true advantage. I have set anchors while under sail and "rounding up" after dropping the anchor with a long nylon rode. This seemed to work well, but I was not pulling directly and I was at a slow speed.

I can remember watching a large power vessel trying to anchor for more than an hour in Salt Pond at Block Island. He continued to power back quickly while dropping his anchor without success. I am sure others, like me watching him, knew that he would have succeeded if he had just dropped it gently and set it with little movement in reverse at first. Powering back is excellent to set an anchor well, but at the start, too much power will often make the anchor skip along the surface.

The guy in Salt Pond eventually gave up and left for the Marina.

Edit: I went back to read your post again and noticed that you said the speed should be "no more than about 1 knot". Well, with a knot or less easing back seems to be standard procedure. We like to be moving in reverse at the time the anchor contacts the bottom in order to present the anchor at proper alignment and to extend the chain without dropping a "pile" in one spot. I think that the best practice requires laying out the chain or nylon rode at a rate that approaches your speed in reverse. Therefore, we do end up tension our rode with some way on in reverse. We commonly set first at a low rpm and then ease up to a higher rpm to "set".

Watching people try to set anchor while going to fast is always amusing. The bottom must look like a plowed field, some places.

The first assumption is that the anchor is already set. The second is that the bottom is firm enough (good sand, not a thin layer or coarse) to hold far more tension than the engine can produce.

You are right in that 1-knot is not that much faster than normal backing. In fact, it must be a moderate, controlled process or the something will break. I remember when I had a no-engine boat, I would often haul up to short scope a few times and purposefully let the boat drift back a few times. It worked well. For a multihull, like mine, backing at 1.5 knots is actually more appropriate, because I do not have the mass of a keel providing momentum, and my engine can provide only about 25% of storm load in setting force (270 pounds vs 1100 pounds).

[a64pilot]

Dropping anchor under the main and letting it back wind and drive the boat backwards works well for me, and I doubt I get much more than a kt that way either, however for a boat my size, I'm a little heavier than average, and weight of course gives inertia.
So 1 kt may work well for us heavy displacement Mono's, but a light weight Cat it may be more windage that sets the anchor as opposed to inertia?

[DMCantor]

This sounds like a great way to pop the anchor out of an otherwise very suitable seabed.

We have no hesitation about backing down at 2400 rpm, but ALWAYS start slow and gentle. My good friend Bill Cullen suggests dropping the anchor and then having a beer before even starting to back down. I think that's good advice.

What's the hurry???

[Panope]

The vast majority of my video anchor setting tests were conducted using boat momentum between 2 and 3.5 knots.

I can say with absolute certainty that the relatively short duration of these pulls are not sufficient to set the anchor as deeply as a sustained pull of much less force.

For example, for my so-called "deep set tests", I spin the boat around and pull the anchor in forward gear (for maximum thrust) at max power for a minute or two. The anchors take some time to dig into their deepest setting. Conversely, the short jerks the anchors receive during my 180 reset test @ 3.5 knots come no-where near as deeply set even though the momentary force is much much greater.

During the dozens and dozens of sets that I have filmed, not once has one of the top performing anchors failed to set initially because I used too much speed.

I have only tested anchors in sandy-mud, and sandy gravel. Never in soupy mud or hard sand.

Steve

[Hydra]

How about leading the anchor rode to the stern, waiting for the boat to orient stern to the wind, and hoisting/unrolling a headsail to "power set" the anchor?

In mud, this would avoid liquefaction.

Alain

[thinwater]

Remember, we're talking about boats that lack the HP to power set with engine alone. Any response that says "just use the engine" is not responsive to the question. Obviously, backing with good power is effective.

----

What's the hurry? It's not about hurry, not at all. Many boats simply lack the HP. An outboard in reverse or some folding props don't do much. Also, the "jerk the anchor out" concern is more about soft mud. We're talking good sand.

Panope. In shallow water, I hesitate to think what the setting force would be at 2-3.5 knots. Remember, you were dragging anchors in. I'm talking about an anchor that is already set. I'm quite sure it would be well beyond the WLL. In deeper water--15' or more--yes, that will work. Obviously, the proper speed depends on a number of variables.

Short duration. I've done a lot of sand testing, and I'm not sure how true that is. Additionally, the assumption is that the sailor has already exhausted engine power--this is an adjunct procedure for a weak or non-existent engine. Finally, the assumption is that a long snubber or a lot of chain will increase the time period.

Lead the rode to the stern. Boy, it would take a LOT of wind to reach the required force. You would not be able to manage the boat, IMO.

[Jim Cate]

I'm not sure where the best location for this question/suggestion might be, but here goes:

For both Nolex and Panope, it would be quite instructive to film or photograph various anchors undergoing the resting or settling phase that some folks ardently recommend. That is, time lapse images of an anchor "soaking"... just lying there on the bottom with no active setting force applied. Various posters have stated that this is the only proper way to get an anchor to hold, but I can't see why this would be true. i've seen anchors on other boats lying on their sides on the top of the seabed, hours after being dropped and then ignored as the boat wandered about, held by the chain's friction with the bottom. No magic settling into the soil that i could observe!

Obviously, there is a difference between this practice, the common slow pull to set and the inertia driven method under discussion here... I for one would like to see the "soaking" myth put to rest... or possibly shown to be effective. And you guys are the ones to do it (in your spare time, of course)!

Thanks for considering the idea, anyway.

Jim

[darylat8750]

I think the "soaking" method only makes sense in very soft mud. Not a scientific test but I used that technique several times on the Chesapeake when just dropping and pulling slowly failed several times in a row. Pulling slightly, stoping and letting it sit for a half hour with very light wind and then it held idle power on 2 120hp engines. This was also using a genuine CQR. After several weeks of doing this I bought a Manson Supreme.

[thinwater]

Originally Posted by Jim Cate

I'm not sure where the best location for this question/suggestion might be, but here goes:

For both Nolex and Panope, it would be quite instructive to film or photograph various anchors undergoing the resting or settling phase that some folks ardently recommend. That is, time lapse images of an anchor "soaking"... just lying there on the bottom with no active setting force applied. Various posters have stated that this is the only proper way to get an anchor to hold, but I can't see why this would be true. i've seen anchors on other boats lying on their sides on the top of the seabed, hours after being dropped and then ignored as the boat wandered about, held by the chain's friction with the bottom. No magic settling into the soil that i could observe!

Obviously, there is a difference between this practice, the common slow pull to set and the inertia driven method under discussion here... I for one would like to see the "soaking" myth put to rest... or possibly shown to be effective. And you guys are the ones to do it (in your spare time, of course)!

Thanks for considering the idea, anyway.

Jim

As Dayrl said, this is a very soft mud issue, and it takes place underground. It is less about settling, than about the soil re-consolidating around the anchor after the disturbance during the initial set. Additional setting pressure, after some times has past, also helps. This is regionally very well known, and some of the posters, quite correctly, hinted at it. It really is unrelated to this thread, which is about sand.

I have done some instrumented testing with yacht-sized anchors. The oil platform guys have research the topic re. multi-ton anchors--it applies to those also.

Not a myth at all, but a very complex topic. Holding capacity can increase from 25-200% over time, given the correct conditions. The trick is in the method.

[Jim Cate]

As Dayrl said, this is a very soft mud issue, and it takes place underground. It is less about settling, than about the soil re-consolidating around the anchor after the disturbance during the initial set. Additional setting pressure, after some times has past, also helps. This is regionally very well known, and some of the posters, quite correctly, hinted at it. It really is unrelated to this thread, which is about sand.

OK, fair enough. I can see the possibility of soil characteristics changing after an initial set has brought the anchor into its correct orientation and perhaps buried it a bit... but that is a different proposition than just leaving it as dropped, which I think has been recommended by some.

And obviously, one can not photograph that which occurs below the surface of the sea bed!

I apologize for dragging (?) the subject away from sand!

Jim

[Panope]

Originally Posted by Jim Cate

I'm not sure where the best location for this question/suggestion might be, but here goes:

For both Nolex and Panope, it would be quite instructive to film or photograph various anchors undergoing the resting or settling phase that some folks ardently recommend. That is, time lapse images of an anchor "soaking"... just lying there on the bottom with no active setting force applied. Various posters have stated that this is the only proper way to get an anchor to hold, but I can't see why this would be true. i've seen anchors on other boats lying on their sides on the top of the seabed, hours after being dropped and then ignored as the boat wandered about, held by the chain's friction with the bottom. No magic settling into the soil that i could observe!

Obviously, there is a difference between this practice, the common slow pull to set and the inertia driven method under discussion here... I for one would like to see the "soaking" myth put to rest... or possibly shown to be effective. And you guys are the ones to do it (in your spare time, of course)!

Thanks for considering the idea, anyway.

Jim

Jim,

I am one step ahead of you Unfortunately the wind driven waves caused a bit of a stir, making the visibility quite poor.

Steve

https://www.youtube.com/watch?v=WKy4QOXi3_o

[Panope]

Originally Posted by thinwater

Remember, we're talking about boats that lack the HP to power set with engine alone. Any response that says "just use the engine" is not responsive to the question. Obviously, backing with good power is effective.

----

What's the hurry? It's not about hurry, not at all. Many boats simply lack the HP. An outboard in reverse or some folding props don't do much. Also, the "jerk the anchor out" concern is more about soft mud. We're talking good sand.

Panope. In shallow water, I hesitate to think what the setting force would be at 2-3.5 knots. Remember, you were dragging anchors in. I'm talking about an anchor that is already set. I'm quite sure it would be well beyond the WLL. In deeper water--15' or more--yes, that will work. Obviously, the proper speed depends on a number of variables.

Short duration. I've done a lot of sand testing, and I'm not sure how true that is. Additionally, the assumption is that the sailor has already exhausted engine power--this is an adjunct procedure for a weak or non-existent engine. Finally, the assumption is that a long snubber or a lot of chain will increase the time period.

Lead the rode to the stern. Boy, it would take a LOT of wind to reach the required force. You would not be able to manage the boat, IMO.

Thin,

Thanks for clarifying your intention, ie low power/no power vessels. In my original responce (post #6) I was focusing on your words "storm tension" from your opening post.

That said, I'm all for using momentum to set the anchor. The abruptness of of the set can give some good feedback about what is happening in the absence of cameras or clear water.

In sub-straits like the ones I have been testing, there really is no reason to put up with an anchor that requires ANY special technique to set. Numerous anchors exist that are simply impossible to move more than an anchor length or two NO MATTER WHAT the skipper does with the controls of the boat (excepting a high power boat).

Regarding the snatch force during my SNUBBERLESS 3.5 knot reversal tests, yes the momentary loads are immense. I'm quite surprised that the only damage incurred (so far) is one bent shank on an arguably undersized anchor (Fortress FX-16).

Steve

[Jim Cate]

Thanks for posting that, Steve, but frankly, I couldn't tell w hat was going on down there, and there seemed to me more than a little force being applied to the shank of the anchor (I think). Looking at the angle that the chain left the bow, it was pulling fairly hard just from the wind forces, and this isn't what I thought the "soakers" were advocating. Further, some have recommended leaving the anchor to "soak" for longer periods of time... even hours.

Anyhow, I remain curious and ready to be convinced.

Jim