All Chain vs Chain and Line Anchor Rode

[psneeld]

One can follow conventional wisdom...plenty on the net...or follow maverick theories and take your chances.

 

[Datenight]

Datenight,
Nice to hear about your brother-in-law, Friday Harbor and Griffin Bay but how much chain do you have?

Hi Eric,

We are currently anchored in the 16' of water with 100' of the 350' deployed. Anchor is a Rocna 33, chain 5/16. Stuck like glue.

Rob

 

[Nomad Willy]

Very good Rob.

350’ of chain. Ever come close to running it all out?
That would be a grind getting all back up.
I like having a long rode for emergencies. Will keep you off a lot of beaches that would pound a boat to pieces.

 

[Datenight]

Very good Rob.

350’ of chain. Ever come close to running it all out?
That would be a grind getting all back up.
I like having a long rode for emergencies. Will keep you off a lot of beaches that would pound a boat to pieces.

No we've only been on the boat since 1 July, it's a charter. We did have about 170' out in Deer Harbor.

I don't think we ever had more than 150' of our 300' of chain out on the east coast.

Rob

 

[Art]

One can follow conventional wisdom...plenty on the net...or follow maverick theories and take your chances.

Or... of course: One can also do what they have done for successful anchoring during the previous 5+ decades.

And, while so doing, enjoy occasionally reviewing posts on this thread where oh so many "Anchor Experts" layout their wisdom on ways and reasons that make sure the anchor gets and remains fully set!

That said - There are some good posts here which do adhere to the general laws of physics!

 

[Nomad Willy]

Rob,
You mean Deer Harbor in the San Juan Is Washington state?
Overnighted there twice. 18 knots or so bouncing around on my fenders. Others said it was a blow hole.
Never really been to the right coast. Hear there’s not much water.

Art,
Yes.
Only thing odd about what I’ve done is to not live by bigger is better. And of course I’ve never used much chain. Consider Chapman’s book on small boat handling to be conventional wisdom and he always has said “a short length of chain”.

But cutting things off of an anchor is not conventional wisdom. Done a lot of dragging ... but always during setting. Once set I’ve not dragged an anchor. A lot of that is luck as I’ve stayed in a lot of calm anchorages in SE Alaska. The mud up there seems to be quite clean or perhaps w a high degree of sand. Mud down here in Puget Sound is more sticky and troublesome. But in the past in the Sound I’ve stayed tied to floats in harbors more than anchoring. I like to go “up town” in interesting harbors.

But I’m sure many others consider what I do amounts to “maverick theories and taking my chances” (as psneeld has said) but it’s resulted in a lot of fun and secure anchoring. Luck? Perhaps. But I accept it.

You have a scientific mind Art. I’m surprised you’re not in the thick of it experimenting w anchors. But you’re surrounded w delta mud.

 

[Art]

Rob,
You mean Deer Harbor in the San Juan Is Washington state?
Overnighted there twice. 18 knots or so bouncing around on my fenders. Others said it was a blow hole.
Never really been to the right coast. Hear there’s not much water.

Art,
Yes.
Only thing odd about what I’ve done is to not live by bigger is better. And of course I’ve never used much chain. Consider Chapman’s book on small boat handling to be conventional wisdom and he always has said “a short length of chain”.

But cutting things off of an anchor is not conventional wisdom. Done a lot of dragging ... but always during setting. Once set I’ve not dragged an anchor. A lot of that is luck as I’ve stayed in a lot of calm anchorages in SE Alaska. The mud up there seems to be quite clean or perhaps w a high degree of sand. Mud down here in Puget Sound is more sticky and troublesome. But in the past in the Sound I’ve stayed tied to floats in harbors more than anchoring. I like to go “up town” in interesting harbors.

But I’m sure many others consider what I do amounts to “maverick theories and taking my chances” (as psneeld has said) but it’s resulted in a lot of fun and secure anchoring. Luck? Perhaps. But I accept it.

You have a scientific mind Art. I’m surprised you’re not in the thick of it experimenting w anchors. But you’re surrounded w delta mud.

Hey Eric

I am glad that you and others have time to experiment with anchors and anchoring. Always good to read your insights/results. I do have an "anchor setting" improvement item I'd like to find time to try on basic Danforth design anchor. Just tooooo busy these years on other projects in my world. Surely will post on TRF if/when I get chance to experiment. I, like you, only have dragged while setting; once set - no drag! It is important to know how to best deploy and then officially "set" an anchor... a lot of boaters do not well understand those features of anchoring.

 

[Datenight]

Rob,
You mean Deer Harbor in the San Juan Is Washington state?
Overnighted there twice. 18 knots or so bouncing around on my fenders. Others said it was a blow hole.
Never really been to the right coast. Hear there’s not much water.

Eric,

Yes the San Juan Islands. We are chartering a North Pacific 43 for the month. Anchored tonight in Garrison Bay San Juan Island. Tmorrow back across the border to Canada. The plan is Ganges on Saltspring Island. Just so you know we have 50 feet of chain out tonight!

We boat mostly in Southeastern Connecticut, Long Island Sound. Block Island and Narragansett Bay RI, Buzzards Bay the Cape and Islands. We have also been to Boston and points north to Maine.

The water in most of those places is pretty good but much less than we see here. A typical cruise shows depths maxing out around 150 feet.

I have done deliveries from New Orleans to Savannah, GA and the water can get thin there.

Rob

 

[sahockey]

It’s just physics. Sorry for such a short and flippant answer. What I meant in this response was the mechanical advantage achieved when someone pushes or pulls a tight rope tied between two objects. For instance if a car is stuck you can attach a long rope between the car’s bumper and a large tree drawing that length of rope in tight. Then pull or push the center of the rope perpendicular to the direction of the rope to help free the car. This would be similar to using a block and tackle a chain or cable hoist or other mechanical advantage devise. Of course today’s cars don’t have bumpers but you can still attach to most cars under the new style bumper to the transportation hook or loop found in two places in the front bottom of today’s cars.

 

[FF]

Many folks understand that some anchors work better than others in certain bottoms.

But how many use just one anchor line for every condition?

One advantage to a short chain and nylon is light line 7/16 or 1/2 inch can be used in modest weather for a smoother ride and the 7/8 or 1 inch can be deployed when the storm flags go up.

 

[O C Diver]

My view on different anchors and rodes is that as boats and ships get larger, even though they have more space, you generally see only one setup (or 2 that are identical). So for me, while I have 2 different anchors (primary and a backup), I only ever use the primary (with an all chain rode). If I felt the need to change the cushioning effect, it would be a simple matter to use a longer and or lighter snubber. I view this kind of like dock lines. Never felt the urge to use smaller diameter rope because I'm only docking for lunch.

Ted

 

[Mako]

My view on different anchors and rodes is that as boats and ships get larger, even though they have more space, you generally see only one setup (or 2 that are identical). So for me, while I have 2 different anchors (primary and a backup), I only ever use the primary (with an all chain rode).

Yes and that setup is usually big stockless anchors nested into a hawsehole with an all-chain rode, of course.

As I've been reading classification rules, I've noted in the CCS that for yachts they only specify one anchor. For "ships" however there are always 2 specified, once you get above the absolute minimum size.

I've never really seen the advantage of 2 anchors off the bow and would likely never deploy both at the same time. I suppose you could install 2 different styles of stockless, one for general use and the other for mud, but still it doesn't seem like much of an advantage, especially if the primary is huge and heavy.

A backup can just be kept down in the lazarette, ready to be lifted out with the davit.

Have you found opportunities where you deployed both at the same time off the bow?

 

[Nomad Willy]

Quoting myself from post #54;
“On a long ago TF thread w Marin Faure taking part it was discovered by some scientific study that the ideal place for weight on an anchor rode for max catenary effect was 5-10’ up from the anchor. I had always thought before that that the best place was right at the end of the anchor shank. I’m not absolutely sure about this as I haven’t seen the scientific study .. but I think it is so. So it would seem if you had a kellet or anchor buddy that would be the best place for it.”

Edit:
I mistakenly edited my edit (slightly) but it hasn’t changed the meaning. Sorry

So if one was using a Kellet it would seem the best place for it. Running the Kellet down 10 or 15 feet would seem to produce practically no benefit at all. But running it down to the anchor and then back up 10-15’ would seem to be the optimum arrangement.

If weight on the anchor rode made the anchor perform better then more weight would be even better. And using chain from the boat to the anchor would indeed increase the weight on the rode so anchor performance should be maximized. I’m saying the added weight (all chain) forces the weight to be evenly distributed along the rode so most of the chain is a long way from the ideal place for weight on the rode. The combination rode allows the operator to place the weight wherever it provides the most benefit.

And highly related to this is the fact that weight on the rode (to have more beneficial angle of pull) has less affect as the scope shortens. A weight in the middle of a rode has less affect at 2-1 scope (very little) that it would have at a 10-1 scope. A good reason for long scope if you’ve got catenary.

If you had a vertical rode it would seem there would be no benefit from weight added to the rode but a vertical rode (or nearly so) may be the result of a heavy rode if there is wind involved. If most of the added weight was high on the rode the bottom to shank angle (BSA) would be very wide or a high angle. Close to pulling straight up. Not good for anchor performance. If you had the same weight very low on the rode the BSA would be minimized thereby maximizing anchor performance. And before there was enough wind to raise the rode at the anchor shank off the bottom there would be a totally horizontal rode parallel to the seafloor. Ideal.

So the position of weight has a profound effect on the ABA and anchor performance that results from less or lower anchor to bottom angle. We have considerable control over it and hence control over anchor performance.

 

[Nomad Willy]

Mako wrote;
“I've never really seen the advantage of 2 anchors off the bow and would likely never deploy both at the same time. I suppose you could install 2 different styles of stockless, one for general use and the other for mud, but still it doesn't seem like much of an advantage, especially if the primary is huge and heavy.”

The advantage is to have two anchors at the ready that performed best on very different bottom types. Almost no advantage if the two anchors were of the same type. Even of the same type there could be an advantage. Like a Rocna and a Supreme. The Supreme has phenomenal performance on short scope whereas the Rocna has a bit of an advantage on long scope. But unless the conditions were extreme the difference would not likely be noticed.

Another advantage could be if you had an chrome Ultra as your primary and a Claw secondary and wanted to anchor in an anchorage that was known for having a great deal of old logging debris on the bottom .. you may be inclined to deploy your Claw especially if the weather was benign.

Two thoughts for two anchors.

Regarding two anchors deployed at once ..... ?
How-a-bout 15 anchors out and set?
Seems to me your boat won’t be going anywhere.
So perhaps more than one anchor out may have merrit.
But I’ve never done it and have no plans .. like you.

 

[O C Diver]

Have you found opportunities where you deployed both at the same time off the bow?

I think they refer to that as a Bahamas rig.
I don't do that and haven't seen the need for it. I prefer to anchor in areas that are shallow (6 to 20' at expected low tide), with 7:1 scope, and an anchor that pivots or resets well.

Ted

 

[dhays]

For piece of mind I would love to have two anchors on my bow roller. Not to use to anchors at once but for security if I loose one or if I have to abandon one that is fouled. I could keep a spare in a locker, but it would be a pain to dig out during some "event".

But, I'm an irresponsible boater and only have one anchor on board. Someday.....

 

[Art]

For piece of mind I would love to have two anchors on my bow roller. Not to use to anchors at once but for security if I loose one or if I have to abandon one that is fouled. I could keep a spare in a locker, but it would be a pain to dig out during some "event".

But, I'm an irresponsible boater and only have one anchor on board. Someday.....

I keep redundancy X 5, of anchors aboard. That said... SF Delta oddities can require some very unusual anchoring techniques and needs; depending where in the 1100 mile of sloughs a boat may be.

1. Relatively small galvanized anchor on small pulpit.

2. Large danforth on front deck - #'s 1 and 2 with line rode attached that feeds into hold. #2 has 10' of chain.

One medium large aluminum anchor hanging vertically on portside SS fasteners attached to bow rail [60' line attached that hangs on that anchor]

One medium sized Danforth on starboard bow rail SS hangers with no line.

One aluminum Fortress FX-23 to rear with 175' line and 10' chain.

All anchors I carry are either Danforth or similar to Danforth dual fluke design.

Happy Anchor Daze!! - Art

 

[sahockey]

Different anchors probably have a different angle for optimum setting. Although generally the best setting angle for most anchors is probably parallel to the ocean floor. An example of how a higher angle for setting may be preferable for some anchors would be your regular garden hoe with a flat bottom. If you pulled a garden hoe, keeping the handle parallel to the ground, the best you would be able to accomplish is to scrape the ground. Conversely if you held the handle slightly less than vertical the rake would tend to pull into soft ground.

 

[Nomad Willy]

sahocky,
Yes ... angle for best penetration.
The Supreme has a fairly wide throat angle and it excels in short scope mode. I always thought it was sluggish to set and that could be related to the wide throat angle. Anchors that lay on their side setting probably (well at least I think so) benefit from a narrow throat angle digging into the seafloor. But once dug in and rotated vertically there’s a new throat angle at play. Manson w the Supreme may have gone to the ragged edge on throat angle for good overall performance sacrificing far out scopes like 8-1.

This IMO may show why the Rocna excels on long scope and the Supreme excels when rigged for short scope. Rocna supporters could say “I never anchor at short scope” as if it’s stupid. And Supreme supporters could say “Any anchor excels at long scope”. But this may be a window into just how complicated anchor design really is.

By the way my Supreme sets fast now w the drag of the RB not keeping the effective throat angle excessively wide.

But sahockey, A rule of thumb down through time has been 32 degrees for a throat angle. But I’m sure it varies w anchor design. However 32 degrees is universal for rotating fluke/shank anchors like Fortress, Danforth and I think Forfjord.

 

[sahockey]

I tried two different trials all designed to test different theories on anchoring. Both used a scope of 5-1 with approximately 50’ of cord used to simulate an anchor rode. The water depth was set 5’ with a bowsprit height off the water of 5’ for a total of 10’. I marked the center of the 50’ rode and 5’ in each direction for a total of 9 marks. The high 10’ boat side was run through a pulley to a hanging weight to simulate wind and current. The low side was fastened to simulate a set anchor. In order to facilitate measuring the high side was mounted on a pulley at about 12” above the 10’ mark while the anchor set point was fastened at about a foot off the ground.

The first trial was designed the show where the best spot on the rode was to attach a kellet, chain, or other additional weight. All height off the floor measurements were taken 5’ from the anchor spot. Obviously the lower the height the better the setting for most anchor designs. These heights off the floor varied from flush to 11” in order. The weight placed closest to the anchor location was the lowest working up to 11” for the weight placed closest to the boat. I think this is a significant but not a strong argument where to place the weights because the differences were small. So my hypothesis that the mechanical advantage of placing weight near the center was proven wrong.

In the next trial I added identical weights to each 5’ mark to simulate a chain rode instead of a rope one. I measured this height and then removed 4 weights from the upper half simulating an anchor chain/rope combination. Then all the identical weights were removed and replaced with one weight at the halfway mark that was equal to the total chain weight. Removing the weights at the top of the rode measured 5 3/4” off the ocean floor. The all chain rode measured at 2 7/8”. The all rope rode with all the identical weights placed at the center of the rode measured at 1 3/4”. So here again the all chain rode slightly outperformed the half rope half chain rode. Yet if the weight of all the identical “chain” weights was placed anywhere from the anchor up to the center of the rode it strongly outperformed the all chain rode.

What do you think?

I tried to keep this as concise as possible by not listing all of the measurements or details.

 

[ranger58sb]

But sahockey, A rule of thumb down through time has been 32 degrees for a throat angle. But I’m sure it varies w anchor design. However 32 degrees is universal for rotating fluke/shank anchors like Fortress, Danforth and I think Forfjord.

32° in hard-ish surfaces. The other Fortress setting angle is 45° for mud/soup/slime.

I dunno what the three actual angles are for our adjustable SuperMAX. Might be on their website...

-Chris

 

[Nomad Willy]

sahockey,
I’m very busy packing up for our trip.

But I will comment that putting all the weight in the center does not result in a curved line like a rode would be. And it’s important because the ends (one of which the anchor will be) will have a much higher rode to seafloor angle. You’d need a lot of weights to be close. A length of appropriate size chain 25’ long would simulate a 50/50 combo rode reasonably well if the weight ratio was somewhat close.

But putting the weights 5’ in from the ends .. one end at a time would be telling.

 

[Nomad Willy]

Chris,
Most of the big stockless anchors are made w a 40 - 45 degree shank to fluke angle. I guess it’s felt all that weight in the ctr upper stock area penetration is more assured. I changed my Dreadnought anchor to about 37-38 degrees. Haven’t used it since and it set instantly in mud w about 42-44 degrees angle.

 

[Peter B]

My view on different anchors and rodes is that as boats and ships get larger, even though they have more space, you generally see only one setup (or 2 that are identical). So for me, while I have 2 different anchors (primary and a backup), I only ever use the primary (with an all chain rode). If I felt the need to change the cushioning effect, it would be a simple matter to use a longer and or lighter snubber. I view this kind of like dock lines. Never felt the urge to use smaller diameter rope because I'm only docking for lunch.

Ted

Now that, right there, is a really good answer...

 

[Peter B]

For piece of mind I would love to have two anchors on my bow roller. Not to use to anchors at once but for security if I loose one or if I have to abandon one that is fouled. I could keep a spare in a locker, but it would be a pain to dig out during some "event".

But, I'm an irresponsible boater and only have one anchor on board. Someday.....

If it makes you feel better Dave, in 16 years of anchoring with my Super Sarca, all over Moreton Bay here in Queensland, and on many types of bottom, from clean sand to weapons grade mud, I never, repeat never, ever, even thought about dragging out the rather large Danforth I kept (original second by PO), in the lazaret.

 

[Peter B]

So if one was using a Kellet it would seem the best place for it. Running the Kellet down 10 or 15 feet would seem to produce practically no benefit at all. But running it down to the anchor and then back up 10-15’ would seem to be the optimum arrangement.

Which is precisely how the makers of Anchor Buddy recommend using it Eric. So, great minds think alike, eh..?

 

[markpierce]

Doubt a kellet would be of great help. Little on chain, but some more help on rope. Still, think the kellet effectiveness requires a lot of weight. ... My all-chain, 3/8-inch rode stretches nearly straight in the typical 2.5 mph current here. But my knock-off bruce holds right. Here on a flooded island with no current:

 

[markpierce]

...

All anchors I carry are either Danforth or similar to Danforth dual fluke design.

I gave up on Danforths in the 1980s as a primary anchor. They tended to pinch my hand. Have used bruce-likes ever since. They have never failed me in the San Francisco estuary (bays, rivers, sloughs). My back-up, in the lazarette, is a Danforth-like anchor with short chain and nylon rode, however.

 

[Nomad Willy]

Thanks Peter and re Marks doubts re kellets I think if it was as heavy as your anchor or some more and placed about 3/4 of the way down the rode you would never think of chain. And that would be lighter than all chain. But unless one developed a good system as user friendly as possible it could be labor intensive.

 

[Nomad Willy]

Chris,
The flattest one re post 111 is probably 32 degrees.