New anchoring system thoughts

Rope is a POOR choice for anchoring. You will foul it with your propellor or keel. A rope rode is very difficult to handle. Dont go there.

 

Nonsense.

I've lived at anchor since the early 2000's, only coming ashore just now to build this boat. Other than that, I've spent nearly every single night at anchor, so thousands and thousands of them.

I do not use docks. I only anchor.

My anchor tackle consisted of:

*a Delta anchor
*33 meters of heavy chain spiced to another 33 meters of heavy rope rode
*appropriate anchor bridle (snubbers and shock absorbers)

Rope rodes are no more likely to foul your prop (or keel if you are so unfortunate to require one ha ha ha). Proper anchor line does not float, so it does not foul your bottom unless you are very bad at handling a boat and motor into your own anchor line.

Handling a rope rode is so easy, you can barely notice a difference between rope and chain.

As the ropes is pulled through the chain gypsy on the windlass, it fits nicely into a little "V" shaped groove. When the splice goes by and the chain starts feeding onto the same gypsy, the chain grabs in the link slots and pulls up just the same as the rope.

The only thing different is weight and ability to withstand chafing. Maybe also cleaning is more effort with the rope.

 

Interesting idea to contemplate. If you can simplify and lose weight, why not?

But -

Coral and rocky bottoms. Are you sure you'll only ever lay over friendly sandy muddy bottoms?

I agree with mp above. Laying in a breeze to your all-rope rode will keep it layed out. Later on when the wind drops and the tide turns, boat goes for a wander around.....you'd want a weight on your rope to keep it hanging straight up and down, or you will be diving the next morning trying to undo the knitting.

Yes both your chain or your rope will be pulled out bar taught in a consistent blow.....but in an anchorage with strong gusts and lulls, you'll be snatching up hard at the end of your totally non-stretch rope every time a gust goes through. How you going to attach a nylon snubber to your thin slippery rope?

It's good to think outside the square. Wheel can't always be re-invented successfully.

 

As I see it there are two possible extremes of anchoring systems, on one side you have no anchor, and just a huge chain providing dead weight to keep the boat in position. On the other side of the continuum you have a huge anchor, and the lightest line possible to connect the anchor to the boat.

Most boats currently are pretty close to the no anchor system, with anchor weight making up around 4% of the total anchoring system's weight.

Michaels suggestion above for a system for instance is 100m of 8mm chain with a 50lbs anchor attached. Speccing this system we get a total weight of the system, ignoring the windlass, of 348lbs, with the chain weighing in at 1.35kilos/meter, the chain by the way has a SWL of around 4,000lbs. The other extreme option would be 3/16" amsteel blue that weighs in at 1.5kilos/100m, which would mean if you kept the same net weight you could use a 345lb anchor.

A more practical option might be using something like 5/8" amsteel which would give a huge working load safety margin, and if abrasion is an issue would allow more than half the line to abrade before degrading to the strength of the chain it replaces, and at a weight of around 30lbs would still allow for a 315lb anchor.

Alternatively you could double the amount of line you carry to 200 meters, add a 30' chain leader for abrasion resistance, and still be left with a 250lb anchor at the end. Note that this is the same size anchor (within 3lbs) that Steve Dashew uses on his FPB 83 with a displacement of 90,000lbs. This would allow much better deep water anchoring, expanded scope in storm conditions, a scope of 32:1 in 20' of water, the abrasion resistance of chain along the bottom, and keep the weight the same.



Ocean,

There are other ways to induce stretch into a system, assuming it is desirable, like adding snubbers to the line. But with the greater holding power of the large anchor as compared to the all chain rhode, you shouldn't need as much line out in the first place, and in real storm conditions If the boat survives, I am fine untangling line later, heck I have had to untangle chain after a storm.

 

This is how it's done:

 

That is a nice one for anchor on wire cable. And not very expensive, around $780 if I remember well.

Look at the manufacturer who sells them direct:
http://www.krmfg.com/krm.nsf/Products/Winches



This is not a tentative of "product placing" it is just that I was looking for these kind of winches for years, the manuals winches with large reels almost disappearing from the market, and I find these one.
So I hope I don't transgress the rules.
Lister

 

I retrieve my anchor from the flybridge with a button. When I see the anchor slam into its park im off. Is there another way?

 

Tnx 'Stumble' - BUT - there is no gain there. In fact there is a net lbs weight loss. Not the way that I'm going to pay good money to go.

Thank you for your answer BUT "300' of light weight line" say 12 mm nylon/poly/or whatever - c/w shackles etc - weighs more than the 60 lbs you have left over & that was just to break even. No good to me at all. Doesn't make your point very well at all - 'you will not be elected to the board' ha ha

I need to anchor in coral regularly - that's just where I livee & sail - - now a 40' light weight - high windage - 'flighty-type vessel' of somewhere between 'light-boat' of 7000 lbs or less & the same boat in 'cruising-mode' at up to 14000 lbs should have - in your humble opinion ???

2 anchors of 35 to 40 lbs each - plus 60' of 1/2" chain plus 150' of 5/8" poly/nylon or whatever - - as a spring ? ? ?

Would you suggest maybe 2 anchors of 120 lbs plus 20' of 3/8" chain plus 150' of 1/2" rope.

All I'm trying to do here is learn - so please be understanding of my short commings. Thank-you.

Michael - Thank you for your words of advice. Like 'Cat-B' - I've spent a tad bit of time on the water & lived on board through a few cyclones. I do find your assertive statements of fact (which are in all honesty - only your opinion) slightly abrasively worded. I've spent over 1/2 a century on the water. Anchors - whatever their size/shape/weight - - have their place; chain - whatever its size/shape/weight - - has its place & so does rope. To have only 'one' opinion - at the exclusion of all others - is IMHO - nothing short of 'grand-folly' of the highest order.

 

Silver,

Right now my advice would be to go with a standard anchor, all chain rhode and use a nylon snubber. This thread is intended as a thought experiment, at least for now I would go with what I know has worked in the past.

The real advantage to this system would be that you could significantly increase your holding power by going to a much larger anchor, eliminate the chain, and save significant weight aboard. The question I am trying to answer is how much weight could you save.

So instead of using a 60lbs anchor you used a 100lbs anchor, but had the same holding power, you could shave hundreds of pounds off the weight of the boat. But I don't have a way to test this in anything other than mud for now. The reason we have been discussing keeping the same total weight budget, is to illustrate how much weight people are carrying around in chain, not because a 250lbs anchor is reasonable, even under this concept, for a boat this size.

 

Yah I been around a while to. .

Coral is a challenge..chafe , chain wrapped on coral ledges or chunks of coral wedging in the anchor flukes and ruining holding power. No easy answer and no miracle anchor, only seamanship.

But Chain plus the biggest anchor you can handle off your stemhead always wins.

Its critical that when single handed ,in the driving rain , with waves breaking over the bow, that the helmsman can drive the boat, lift anchor and evacuate the harbour.
As you know you must not pull a boat with your anchor winch..you must motor into the anchor...and retrieve.

Many Times as the helmsman motoring forward, struggling to keep head to wind , you have no idea were the anchor is ...only that the strain of 50 knots of wind has been relieved and your chain in coming up.

If the anchor rode were rope it would be impossible to singlehandly retrieving the anchor from the helm and more important when motoring forward, the rode may go slack and since it has no weight , get tangled on keel , rudder or drive gear.

Also , an important detail of the stem anchor handling gear is a grooved roller to keep chain twists on the anchor side and out of the windlass and keep the chain sentered ,plus a keeper to prevent the chain from jumping off the stem roller. When a chain jumps the roller you have a bad situation on your hands.

A digital chain counter is also critical for singlehanded helmsman anchorhandling. Well worth the two hundred dollars.

 

Those who have Yachting Mags from the 50's will note that Danforths were pictured with line with a thimbol, and NO CHAIN.

Also those that go by Da Book , will notice Mr OGG , Danforth designer never seays to anchor with A Danforth , except as a lunch hook.

2 Danforths(overnight ) 3 ,4 ,5 more perminant mooring.

We have cruised for 5 decades with Danforth as the main anchor , and only enough chain to reach from the anchor storage place (hawse hole) to the winch.

This allows any size chain as it never needs a gypsy.

In coral we do use 3/8 all chain , with a very thin long snubber .

We will be finding out if a heavier anchor is "better" as we will be using an 80KG Bruce in place of a 60 lb Danforth .

The Bruce was cheap , and we have a Hyd windlass so it will not be a hassle , except moving the 80KG anchor to the boat!

FF

 

Danforths make a good kedge. As a main anchor I bend their stocks as the boat sheers. Great anchor to have onboard...not suitable as a main

As a storm hook ,the danforth hung behind the main anchor on 10 meters of chain..tandem...is effective. The main anchor handles the sheer and the danforth drags inline.

A very good anchor to have onboard is a mini bruce...I think the little fellow is 5kg. Its used primarily when anchoring stern too the rocks. Take the mini bruce and wedge it between rocks , low down right in the littoral zone, then tie your strern line to it. Fastening a stern line to trees ashore is ameturish..kills the trees... and when the line sags it chafes and catches on rocks.

The mini bruce also makes an effect "J" hook for clearing your anchor or chain. Rig with two lines so that it is self tipping

 

Thanks for the diagram CB.

Perhaps I should clarify; I wasn't asking which knot or bend you might use, rather I was wondering whether your 3 strand laid nylon snubber will grab your thin slippery rope tight enough not to slip along it, regardless of your favoured bend? Not something I've actually tried.

BTW, what's the name of the bend you illustrated? And how does it undo after being under load?

regards all groover

 

So i was able to track down some performance numbers on a couple of anchors from their manufacturers. If you plot out the holding power vs weight of the anchors, you get a clear trend line on them, which I am going to publish here. But basically the max holding power of a new design anchor increases massively with each additional pound of weight in the anchor.

In short holding power goes up almost exponentially with additional weight in anchor, while a deadweight anchor goes up lineraly. In heavy weather though chain actually doesn't add any holding power, though it can have a huge effect at low wind speeds.

I think based on this I am going to give this system a try, as soon as I can find a load cell capable of anywhere close to this level of numbers. Unfortunatly I don't have anything passed about 150lbs.

 

I think you're going to do well. Everything you say in the first paragraph is true and you have me re-thinking some old chain ideas I had for many years.

Also, I think most people imagine low wind speeds when they imagine an anchor working. Seldom do they think about the time when your rode is bar tight and it represents a straight line, completely off the seabed, between the anchor shank and your bow cleat.

Interestingly, this is the time when you need the most holding power and all that is providing it is the anchor itself.

I'm probably going to give this system a try myself, though I'm a bit apprehensive about the difficulty of lifting a huge anchor up. Need a very good windlass for that.