ANCHORING - ROPE vs CHAIN vs COMBINATION(s):
As with most things, there is no a right nor wrong answer to the rope-chain question, nor can the question be examined in isolation.
The anchor rode is (1) part of a
mooring system, itself (1) part of the larger boat system. Any consideration of any one part must take place within the context of the whole, with reference to a multitude of related variables.
What on earth an I getting at? Prior to any specific analysis of Rope & Chain, there are a few questions each of us must answer:
Q1 - Bottom &
Depth
- Over what types of bottom, and at what depths am designing my anchor system for?
Etc...
Q2 - External Constraints
- Are my expected
anchorages crowded, limiting practical scope; or can I expect to have room to lay out 10X
depth or more?
- Are there
reefs, rocks, bars or other obstructions that will constrain my choices?
- What do the locals do? You’re, more or less, obliged to observe local custom, and mimic the set-up of your neighbors.
- How protected (or exposed) are your intended
anchorages (to
wind & wave/surge)?
- What other unusual features might you contend with? In very well protected and steep-to
Lake Superior anchorages, I often tie Bow to Shore, /w stern anchor set .
Etc...
Q3 - Internal Constraints
- What is my dollar
budget? Tho’ listed first, I advise that this is the least important factor.
- What is my weight & space
budget? Every boat will be limited in the amount of weight she can safely carry, and (to a lesser extent) the space that may be devoted to ground tackle.
- What can I, and my crew handle? There’s no point in carrying
gear that you are unable to effectively deploy. Although a
windlass is a wonderful luxury, I would not rely on it’s infallible
reliability (except, perhaps on the largest yachts) - and would insist that I be able to manually handle the ground tackle in an
emergency situation.
- What is (or can be) my
deck hardware set-up? What type and capacity are my fairleads,
cleats, bollards, chain locks, and other strong points; and what is their suitability to a particular rode type?
- How many set-ups can I carry? I’ve never cruised with less than three (3) complete anchor set-ups, each slightly different from the other. My habit, in the
Bahamas, was to carry four (4), with the fourth being matched to my prime (for Bahamian Mooring).
- What is my level of situational awareness? I can sleep soundly through the
wind noise & wave action of a storm - but any new mechanical sound will awaken me instantly. I’m used to the normal boat noises, but any untoward clink, clunk, or bang gets my immediate attention. I will detect any shock loads transmitted to the
deck hardware, but will blissfully be totally unaware of the wailing wind, or pitching and/or heeling that would have presaged the event.
Etc...
Q4 - Intended Usage
- Lunch hooks are just as important as long term anchorages, but should be simpler to deploy and raise. Notice, I said “should” be (not “can” be). This is to comply with two principles I always (try to) adhere to:
(A) If it’s worth doing - do it right. Half-assed measures will always come back to bite you!
(B) Make it easy (on yourself) to do it right. I’m lazy, and may not always do the “right” thing, unless it’s (more or less) easy.
- Obviously, overnight (& longer) anchorages require a much more secure
mooring, and are worth an exponentially larger investment (in time, energy, and money).
Etc...
I think we are all aware of the basic properties of Chain & Rope, so I won’t burden you with a detailed recapitulation - but please bear them in mind as we analyze some of the features, functions, and benefits of various set-ups, intended to satisfy differing purposes under differing constraints.
ALL CHAIN:
Will be heavy, strong, inelastic, chafe-resistant. expensive, and difficult to belay.
ALL ROPE:
Will be light, (can be ) strong, stretchy, prone to chafe, cheap(er), & easily belayed.
ROPE & CHAIN:
Will have moderate weight (depending upon ratios), strong, chafe-resistant on bottom, but prone to chafe topside, moderately priced, easily belayed but requires an additional shackle joint.
- 3/8" High Test Chain has a published WLL of 5,400# (33%), a breaking strength of 16,200#, weighs about 2#/Foot, no appreciable stretch, will not abrade, and costs about $3.80/Ft.
By comparison:
7/8" Three-Strand Nylon has a calculated (I use 20%) WLL of about 4,700#, a published breaking strength of 23,500#, weighs a mere 1/3#/Ft, about 15% stretch, will abrade/chafe, at a cost of about $1.80/Ft.
Note the differing ratios of Working Load Limit (WLL) vs Breaking Strength;
(Chain WLL = 33% Strength -while- Rope WLL = 20% of Strength)
AN ADEQUATE ROPE-CHAIN (Compromise) SET-UP for “Southbound”:
(C&C 29 low-profile, /w 5.5'
draft & approx. 8,500 loaded - 6,700# dry displacement)
Assuming typical depths of 8 - 12' (/w 25' max. depth) over either sand (soft or hard) or hard-pan (shale,
coral, rock) and very occasional
grass, in fairly crowded Bahamian anchorages , where Bahamian mooring is the ‘norm’:
OMO - I propose a primary set-up consisting of:
(2) 25#
Fortress “FX-37 Anchors (equivalent size to a 60# Danforth 60H), (manufacturer’s suggested for 46-51' Boat @ 3,000# WLL)
each c/w
(20 Ft.) 5/16" Stainless High-Test Grade 4 Chain (3,750# WLL - 30# total weight/each)
or Better Alternative
(20') 1/4" Transport Grade 7 Chain (4,200# WLL - 20# Wt. ea - likely cheaper too)
(250') 7/8" Tree-Strand Nylon (4700# WLL)
(18#) Sentinel Weight (actually mushroom river anchors for dinghies)on (35') 3/8" leash (which can double as
dinghy painter/dockline)
Chafing
Gear [actually anti-chafing
] consisting of long snug-fitting (not tite) 1" I.D. polyester-cotton sleeves, inside 1-7/8" loose clear vinyl hose . Note: there are now better anti-chafe products commercially available.
Backed up by:
(1) 35#
Delta Anchor
c/w
(70') 1/4" Grade 7 Chain
(200') 7/8" Three-Strand Nylon c/w Chafe gear
(1) Sentinel c/w (50') Leash.
(2) 50' x ½" Snubbers c/w
claw (can
claw to chain or hitch to rope)
and
(1)
Fortress “FX-11" (rated for my boat - but normally used /w dinghy)
c/w
(10') 1/4 Stainless High-Test chain (1570# WLL) fitted /w (75') 3/8" Nylon (880# WLL), and supported by (backup) (150') ½" Nylon (1500# WLL).
and (just because I own it)
(1) 22# Bruce c/w 50' Chain + 150' Rope etc ... (I’d prefer another 35# Delta set-up)
The 35# Delta is stored on bow rollers /w rode in buckets in bow locker.
The Fortress’ FX-37's are stored in PVC Pipe “Rocket Launchers” on pulpit /w rodes in bucket in bow locker.
The buckets (plastic
paint pails) allow me to easily unwind rode wraps.
The FX-11 assembly is either in the dink, or a rocket launcher on the pushpit /w rode in bucket.
The Bruce assembly is buried in the (bottom)
cockpit locker
.
So, what are the advantages and disadvantages of my anchoring complement (above)?
For DEPTH & BOTTOM:
I’ve proposed 270 of primary rode, allowing a safe storm anchorage in up to 20 feet of
water [(20' depth + 4' freeboard) x 10X scope] + 30' on deck (to cleat & mast). This should be sufficient for the Bahamian and
Lake Superior anchorages specified.
My two prime Anchor & Rode assemblies, including sentinels, weigh about 100 Lbs Total / each (light, strong, & long)
Were I cruising the Pacific, or elsewhere with greater anticipated depths, and more bottom hazards (coral, rock, etc.); I’d want lengthier effective rode, and higher chafe resistance. This would require either:
A higher Chain to Rope ratio (especially where greater bottom chafe hazard)
or
More total rode length (add chain first)
For EXTERNAL CONSTRAINTS:
I’ve proposed a complement of four set-ups, providing flexibility of choice in dealing with various situations. I can lay greater lengths of chain, as the bottom conditions dictate, but don’t carry the weight penalty of all-chain.
I have traded the desirable benefits of greater lengths of chain, for the (more desirable) flexibility afforded by longer & more numerous anchor assemblies.
My set-ups are obviously a compromise - I’d love to have more iron in the
water - bigger and heavier are better! We all have to solve our own (compromise) cost-benefit equations - the only constant being the ability to generate an INFORMED balance sheet.
For INTERNAL CONSTRAINTS:
“Southbound” is a
small boat, with a relatively large
anchor locker. Though severely limited in my weight-carrying ability, I do have space (volume) , hence numerous but not overly-heavy assemblies.
The use of sentinels puts considerable down-force at the end of the lever arm (where I need it), increasing the catenary and ‘effective’ scope of the rode, at a relatively light o/all weight. It’s a lot of “bang for the buck”.
Likewise, being fairly light weight, either my mate (Maggie @ 105 Lbs) can handle the gear under most circumstances. Even a 70' bucket of chain can be a handful, when trying to
dinghy out an anchor in a blow.
Deck Hardware deserves a full and complete discussion on it’s own - so suffice it to say:
Numerous, Big, and Strong are the imperatives.
Some might argue that I undersize my rope chain snubbers; but I’ve never had one of mine break, allowing the chain go tight (and sound the alarm). I have heard a neighboring boat’s snubber
alarm. His chain loop was too small, and when the snubber stretched out, his chain suddenly took up the load. I could hear and see it from 100 yards away (in a storm). There is one additional advantage to a smaller-diameter snubber - namely "Engineered Failure Mode" - when the snubber breaks, I'm alerted to the neccessity to take further action, which I am able to do. I have no objection if you’ve space for a larger-diameter snubber, and it makes you feel better.
I always have three anchors instantly ready to go. Not only does this serve us well in an
emergency, but it makes it easy to deploy them under routine conditions. I find it (personally) important to make it easy to consistently and constantly do the right thing - routine tends to lull ever-one into complacency - AND I’M lazy.
I hope that this discussion leads to further comment, argument, and anecdotal exemplars.
Regards,
Gord
...Carry many, use what makes the most sense...that's what I do
I actually had to empty 3 jerry jugs (water), use small stuff to tie the anchor rope/chain combination, and an anchor to the jugs, put on my life jacket and wetsuit , fins and mask, and go over the side into the water...Using the jugs to float the anchor and rode , with the bitterend attached to the boat, I swam the rode out until I reached the end and then cut the anchor loose from the jugs...After a swim back and some help on board, everything was set and we had a secure, if be it nervous, ride through the hurricane... 
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