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Old 17-04-2012, 19:26   #211
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Re: Chain Versus Rope Scope ?

Cool then my setup will work just fine and I don't have to spend any money
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Old 17-04-2012, 19:41   #212
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Re: Chain Versus Rope Scope ?

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I'm guessing 15' at low tide and 60' deep at high tide. At 60 ft deep that's 420' of chain at 7to1 or do you use chain and rode ?
No they tides here vary between 6 and 11 feet and you will find most anchorages between 15 and 60 feet at mean.

7:1 is insane in most conditions with a properly sized anchor. See my earlier posts with regard to chain:rode and do yourself a favor and read Peter Smith's article here.

In 15-30 feet 4:1 is almost always enough for the conditions you'll experience in the PNW summer. Most anchorages are well protected and you'll have a choice of harbors which allow you to choose a leeward anchorage. Most will be too tight for more than 4:1, in a blow make sure your neighbors are aware of your scope and watch for others dragging, there are a lot of charters in the islands.
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Old 17-04-2012, 19:44   #213
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Re: Chain Versus Rope Scope ?

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I'm no physicist, just a sailor.

When naval ships give up their chain in favor of heavier anchors backed up with nylon, I'll do the same.

Until then, I'll sleep better with all chain.
Ship rodes are chain for practical reasons. The anchors used by ships are designed to rely on entirely different strategies for bottom holding as well.

Equating a ship anchoring system to a yacht's anchoring system is a sure way to delude yourself into tragedy. Science is your friend.
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Old 17-04-2012, 19:52   #214
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Re: Chain Versus Rope Scope ?

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Equating a ship anchoring system to a yacht's anchoring system is a sure way to delude yourself into tragedy. Science is your friend.
Being an engineer I agree with that of-course. But you leave out the part about experience. It doesn't matter how much science there is to support one solution when it is outperformed by another solution all the time.

If there would be a 50/50 mix of chain vs rope rodes in use in an anchorage and a squall passes through, 80-100% of the boats that drag are rope rode. That is the kind of evidence that can't be ignored.

About prop cutting through rodes: chain is not immune to that, the only difference is that the prop gets damaged too. I've seen plenty of chain rodes cut by props.

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Old 17-04-2012, 19:53   #215
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Re: Chain Versus Rope Scope ?

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We are hopeing to sail to the San Juan islands and Seattle this summer and wondered how deep your gunkholes are normally ?
keep in mind there is about a 10' tidal drop...look closely at your charts to check bottom conditions...rock,mud sand, sand w/sea weed.
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Old 17-04-2012, 20:06   #216
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Re: Chain Versus Rope Scope ?

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Being an engineer I agree with that of-course. But you leave out the part about experience. It doesn't matter how much science there is to support one solution when it is outperformed by another solution all the time.
Yes, but that assumes that the anchors are all the same type, all use the same scope in the same conditions, were all correctly set, etc.

The variables are many.

Experts and prominent yacht designers agree that chain or rope make little to no difference, it's scope and anchor weight that matters. The only caveat is that certain anchorages have very real chafing considerations that need to be accounted for and chain is your friend here for the portion of the rode on the bottom.

Both have advantages. Some real, some perceived.

The reality is that most have confused perception with reality in many cases.

This is like the global warming debate. There are those who will always insist all chain is the only safe way to anchor, but the reality is that the science disagrees with that in study after study when anchoring small vessels.
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Old 17-04-2012, 20:16   #217
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Re: Chain Versus Rope Scope ?

@Joe: I know what you mean, but I wasn't talking about chafed through rope rodes... I was talking about dragging boats.

You may well be right that it wasn't the chain vs rope that makes the difference: for all we know, owners of rope rodes tend to select lousy anchors...

My personal belief is that you can get too much stress, which pulls the boat too far forward in lulls... even over the anchor in some cases. I belief all chain with rope snubber is the way to go, although I did experience rope snubbers vaporizing in hurricane conditions. At some point it becomes steel holding it with nasty shockloads. However, that's still better than the rocks IMHO.

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Old 17-04-2012, 20:23   #218
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Re: Chain Versus Rope Scope ?

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There are those who will always insist all chain is the only safe way to anchor, but the reality is that the science disagrees with that in study after study when anchoring small vessels.
Exactly. The same science tells us that Danforth / Fortress anchors are the best choice because their holding power is the best. Every test they win and get endorsed by the scientific researchers and magazines that publish it. And every time sailors fall for it and head out with a Danforth on the bow roller. And every time we need to save them

If you need to make a choice between weight in the rode or weight in the anchor, then I agree it's the anchor that should get it. But still better is to have the bigger anchor and the chain rode. To save weight, get G.7 chain a size smaller.

I have seen rope with lead beads embedded in it being sold for anchor rode... insane...

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Old 17-04-2012, 20:26   #219
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Re: Chain Versus Rope Scope ?

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You may well be right that it wasn't the chain vs rope that makes the difference: for all we know, owners of rope rodes tend to select lousy anchors...
Nick,

You may be right here. We often confuse price with performance and those willing to spend money on all chain are often far better in the seamanship department than those who cheap out on rope and a little length of chain.

What I'm trying to facilitate here is a discussion on the science.

Your observation on surging forward is a good one and not one that had come to mind until now.

I appreciate your adding to the discussion.

J
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Old 17-04-2012, 20:37   #220
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Re: Chain Versus Rope Scope ?

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I have seen rope with lead beads embedded in it being sold for anchor rode... insane...
Yeah.. I'd have to agree with you on that one!
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Old 17-04-2012, 21:05   #221
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Re: Chain Versus Rope Scope ?

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I don't just play a physicist on TV, I actually am one.

I've been using samson ice cover over the rode passed through fire hose for chafing gear for years and have yet to experience a problem. I have seen 80+ knots in an anchorage on a 20,000# boat and would never want all chain.

Think of it this way; Anchor and rode are a complete system and that system works best when the weight in that system is concentrated on the bottom.

In high load situations the catenary is gone, full stop. Any advantage the chain's weight provided in terms of holding power is gone and the majority of the weight in that anchoring system is now taught between the anchor and the boat.

In gusty conditions over 50 knots the boat is spending most of it's time at 70-80% of the elongation of a rode like Yale Brait, and that remaining elongation not only saves load on the deck fittings you tie off to, it reduces peak loading on the anchor.

At the same wind strength an all chain rode has virtually no remaining elongation so the task you are asking of the anchor is far more difficult as even in 50 knots there is no remaining catenary to speak of to absorb loading in the gusts.

Put the weight where it will actually do you some good.. in the anchor.

You're more than welcome to use all that chain is you want, just anchor downwind from me in a blow.

everyone has their own idea on this don't they.anyone here know how much strain is needed to remove all cantenary from a chain relative to it's weight. I would guess not too much if it is only perhaps 5 feet, what about 90 feet? by the way, never use braided line for a anchor rode. if you use line, be sure it is three strand. need I explain?
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Old 17-04-2012, 21:16   #222
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Re: Chain Versus Rope Scope ?

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by the way, never use braided line for a anchor rode. if you use line, be sure it is three strand. need I explain?
Yes, mate, you need to explain this suspect statement.

I believe that you will find many experienced anchorers who disagree.

Need I explain?

Cheers,

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Old 17-04-2012, 21:19   #223
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Re: Chain Versus Rope Scope ?

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everyone has their own idea on this don't they.anyone here know how much strain is needed to remove all cantenary from a chain relative to it's weight. I would guess not too much if it is only perhaps 5 feet, what about 90 feet? by the way, never use braided line for a anchor rode. if you use line, be sure it is three strand. need I explain?
I'm with Jim. There's absolutely some 'splainin needed here.

Yale Cordage for one, a manufacturer who specifically designs line for anchoring among other applications, disagrees with you.

See: http://www.yalecordage.com/pleasure-...lon-brait.html

So does the NZ Coast Guard:

"For long lengths of rope, polyester is generally superior to nylon... Three-strand nylon tends to harden in the marine environment and becomes difficult to handle, and tends to twist, and knot, under load. At the high end multiplait (either polyester or nylon) rope makes ideal anchor rode, as it is easy to handle, and stows in less space."
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Old 17-04-2012, 23:38   #224
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Re: Chain Versus Rope Scope ?

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everyone has their own idea on this don't they.anyone here know how much strain is needed to remove all cantenary from a chain relative to it's weight. I would guess not too much if it is only perhaps 5 feet, what about 90 feet? by the way, never use braided line for a anchor rode. if you use line, be sure it is three strand. need I explain?

Synthesis

Less force to lift all the chain off the seabed than you would guess.

You'll have to explain the 3 strand, complete b!tch to work with compared to multiplait.

One point about chain/rode not mentioned is the different ways the boats sheer about in an anchorage, chain calms the dance down a lot in the 90% of normal days.
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Old 17-04-2012, 23:55   #225
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Re: Chain Versus Rope Scope ?

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Ship rodes are chain for practical reasons. The anchors used by ships are designed to rely on entirely different strategies for bottom holding as well.
That's crap. Ship rodes and yacht rodes are chain for the same practical reasons.

That's also physics.
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