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Old 24-06-2015, 17:11   #16
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Re: Anchor Chain thickness 35ft Cat?

If hand hauling and not going all chain anyway, I would think 8 meters or so of chain would be plenty. How is Dyneema going to be on the hands? Small and slippery I
think...? Not forgiving stretch wise either...
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Old 24-06-2015, 17:18   #17
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Re: Anchor Chain thickness 35ft Cat?

40 foot Searunner tri, 12K, 300 feet of 1/4" High Test chain, 15 kg Rocna.
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Old 24-06-2015, 17:25   #18
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Re: Anchor Chain thickness 35ft Cat?

Our 36ft Mahe came with 70m of 10mm galvanised chain. Quite a lot of weight and 8mm should be enough but i'm not going to throw it away
the Mahe is much heavier design than the mira so that is not much of an issue

I have seen on your website that you intend to install a desalinator so i guess you plan for a long term cruise south. There you wil have to deal with rock and coral so any sort of rope will chafe.

for a boat of the size and weight of the mira i'd prefer 8mm chain with a windlass for ease of handling. If this is not possible then some heavy 10mm chain leader to assist the anchor in digging in plus some stretchy line. 3strand nylon is ok. I prefer double braided rope but this can be even more prone to chafe.

Going for chain leader, dyneema and nylon will be a hassle. Just a nylon bridle is not enough stretch so you will need to attach the dyneema to some nylon on the fly according to depth. With regard to cost, dyneema line thick enough for the loads including some safety margin for chafe is not much cheaper than chain. Better get chain and a cheap / used windlass.
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Old 24-06-2015, 17:45   #19
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Re: Anchor Chain thickness 35ft Cat?

Quote:
Originally Posted by Cavalier MK2 View Post
HeyFranziska, glad to see you got another boat. A boat length of chain is plenty, Chris White thinks 25' is enough. Certainly nothing heavier than 5/16, for your boat I'd use 1/4. I'd skip the dyneema rode and use nylon 3 strand. It will be far better for shock loads than the nylon bridle only and can be quickly spliced if a section is ever chaffed.
I am not well up with Chris Whites progressive "Cat" thinking, but i like his designs and history....can you/anyone expand on the "25' is enough" opinion?
especially if it applies for coral/harsh bottom infused waters...

Bob
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Old 24-06-2015, 17:58   #20
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Re: Anchor Chain thickness 35ft Cat?

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Just a nylon bridle is not enough stretch so you will need to attach the dyneema to some nylon on the fly according to depth. With regard to cost, dyneema line thick enough for the loads including some safety margin for chafe is not much cheaper than chain....
A bold statement without basis, I think. We have not stated a maximum length or diameter for the bridle. And of course, some folks anchor on all chain, no significant snubber.

If the snubber is long--35-40 feet is not uncommon-- and the correct size--3/8" or 10 mm--the loads will be quite low, no matter the rode. I have done load testing using a chain and Dyneema rode for this specific reason (the no-snubber data is with a Dyneema bridle).

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Old 24-06-2015, 18:40   #21
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Re: Anchor Chain thickness 35ft Cat?

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A bold statement without basis, I think. We have not stated a maximum length or diameter for the bridle. And of course, some folks anchor on all chain, no significant snubber.

If the snubber is long--35-40 feet is not uncommon-- and the correct size--3/8" or 10 mm--the loads will be quite low, no matter the rode. I have done load testing using a chain and Dyneema rode for this specific reason (the no-snubber data is with a Dyneema bridle).

Table is too fuzzy to read on my end. Maybe post at a higher resolution?
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Old 24-06-2015, 23:22   #22
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Re: Anchor Chain thickness 35ft Cat?

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A bold statement without basis, I think. We have not stated a maximum length or diameter for the bridle. And of course, some folks anchor on all chain, no significant snubber.

If the snubber is long--35-40 feet is not uncommon-- and the correct size--3/8" or 10 mm--the loads will be quite low, no matter the rode. I have done load testing using a chain and Dyneema rode for this specific reason (the no-snubber data is with a Dyneema bridle).

If going for all chain with no bridle/snubber one still has the 'stretch' of the catenary. At least in less than gale force winds. Dyneema doesn't weight much so no catenary and much more shock loads even in light winds.

A 35-40ft bridle leg length is more than most seem to like for various reasons.

I suppose A 6m wide cat typically has something around 5mt long bridle legs. Well at least ours has. How much flex does nylon give at safe workloads? Don't know, maybe 10%? That is 50cm of stretch at workload, and way less on the smaller loads. If the boat is straight both legs share the load, so even less stretch.
Catenary flexing of chain is softer than stretching of nylon strong enough to safely hold the boat in nasty conditions.

Just my two cents...
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Old 24-06-2015, 23:29   #23
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Re: Anchor Chain thickness 35ft Cat?

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Originally Posted by Franziska View Post
Hi Chris, not quite as sporty as Aquaris, but a bit more roomy and better as a liveaboard boat.
Thanks for the thoughts on the chain setup!

By the way what Diameter has the Nylon in this case?

Cheerio Franziska

For 5/16 chain 1/2 nylon rode will have the same breaking strength, about 7500 pounds. For 1/4 chain 3/8 to 7/16 rode.

A Danforth high tensile anchor works really well most of the time. The chain will help it reset and works for chafe. 20 to 25 pounds on your size boat. They don't work well in weeds, a back up in a different pattern for this is good.
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Old 24-06-2015, 23:43   #24
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Re: Anchor Chain thickness 35ft Cat?

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Originally Posted by REsCat View Post
I am not well up with Chris Whites progressive "Cat" thinking, but i like his designs and history....can you/anyone expand on the "25' is enough" opinion?
especially if it applies for coral/harsh bottom infused waters...

Bob
From his book Chris states the chain is there for bottom chafe and to help a wide fluke anchor such as a Danforth reset if the boat is drifting fast. He is also careful to stay out of the ground tackle controversy. There are many expensive new anchors but tests continue to show they don't often out perform the old standby such as the Danforth. I looked through several cruising multihull books besides White's and not one recommended all chain because of the weight penalty. They were authored by Thomas Firth Jones, Derek Harvey, Jim Brown, Charles Kanter and the really vintage one by Mike McMullen. I've anchored this way for years, not needing a windlass. Sometimes I'll set 2 for short swing.
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Old 25-06-2015, 00:28   #25
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Post Re: Anchor Chain thickness 35ft Cat?

Look @ it this way, 6mm (1/4") G4/G43 has a breaking strength equal to the mass of your yacht, so there's zero reason to go with anything stronger (& heavier, plus more expensive).
Also, if you buy chain in bulk, it's pretty close to the same price as any rope rode which you'd use, but with much more; longevity & chafe resistance. Not to mention the catenary effect, plus less wandering when on the hook.

As to using Dyneema for a rode, in addition to the already mentioned, & very valid negatives about using it for this purpose. How to you plan to attach a snubber to it, given it's extreme slipperyness? Meaning that you can't use a rolling hitch, or similar, to attach your nylon snubber/bridle to it.
Perhaps it's just me, but I sense a flaw in the logic there.
Ditto on using it as the primary rode, given it's cost per foot/m, as compared to other rope rodes, or (bulk) chain (sic).


PS: If you truly can't afford a windlass, not even a decent used one (by skipping some of the modern, "necessary" electronic gadgets & nav aids), then you can go with the "Norwegian Steam" version to raise the hook as descriobed in my post (#4) here Windlass. Powered through engine or service batteries?
Given that the chain hooks on leaders thing works on a 9+ ton mono, with 300+lbs of ground tackle, I'm thinking that it'll work on a compartively petite cat.
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Old 25-06-2015, 01:40   #26
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Re: Anchor Chain thickness 35ft Cat?

Chain is about 4 times the cost of nylon rode in comparable breaking strengths and many more times the weight per foot. When it is time to replace the rode the chain wil need regalvanizing or replacing. Rope is cheaper in bulk too. Really owning and sailing a boat on a budget takes better math than fuzzy logic. The weight penalty alone reminds one that sailing better doesn't have to mean spending or carrying more.
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Old 25-06-2015, 03:43   #27
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Post Re: Anchor Chain thickness 35ft Cat?

Quote:
Originally Posted by Cavalier MK2 View Post
Chain is about 4 times the cost of nylon rode in comparable breaking strengths and many more times the weight per foot. When it is time to replace the rode the chain wil need regalvanizing or replacing. Rope is cheaper in bulk too. Really owning and sailing a boat on a budget takes better math than fuzzy logic. The weight penalty alone reminds one that sailing better doesn't have to mean spending or carrying more.
So then, 1/4" G43 Chain @ $1.43/ft costs too much when compared to nylon. Especially over time. I'm curious to hear your refutation of that. You can see the non-fuzzy logic regarding the costs of rope rode, delineated below.

Even if you get 300' of such chain, that's only 200lbs, AKA the weight of 1 crew member. And especially as, in the real world, 300' of 5/8" rope rode is going to weigh about 50lbs, as it never truly dries out when used regularly. So then you're looking at a 150lb difference.
1/4" High Test Steel Chain- Grade 43 Galvanized

Also, your comments about the strengths of materials need a bit of calibrating.
It's kind of unwise to load a rope rode past 25% of it's ultimate breaking strength. And nylon loses 15% of it's strength when wet. So to equal the WLL of 1/4" G43 chain, you need a nylon rode with a breaking strength of 12,000lb+. AKA 5/8" - 3/4" (3-strand) depending on brand. And rope rode in that size averages $1.50/ft (Double Braid, & Brait are similar in cost, or a bit more).
Or, in simple terms, the same price as the chain.

And, call me a simpleton, but by the time it's time to re-galvanize chain, how many times has the rope rode been replaced? Plus, cheap rope, which is poorly made, & or doesn't have good coatings, has a Much shorter life than standard rope rodes, like New England & similar. Which isn't inexpensive cordage to begin with.

That ain't "fuzzy logic" in my book. The math pretty much speaks for itself.
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Old 25-06-2015, 09:14   #28
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Re: Anchor Chain thickness 35ft Cat?

My schooner weighs about 20,000 empty and 23,000 (or so) loaded. I have a Spade 45 on 216 feet of 5/16" BBB (an Ideal Windlass) and a Delta 35 on 208 feet of 5/16 BBB. Have never had a problem in any situation. Both chain rodes have attached 165 feet of 5/8 3 strand nylon, just in case two anchors on over 200 ft of chain each is not enough, but I have never had to use it. I have always anchored on a single anchor with a 5/8" double braid bridle, just for peace and quiet.
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Old 25-06-2015, 09:20   #29
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Re: Anchor Chain thickness 35ft Cat?

The logic gets fuzzy for me in the cost of the weight. It is easy to say 200 pounds is light, leave someone at the dock but on a multihull with a 4000 pound payload that represents 5% of the total because (as you must know) ground tackle weight comes out of the payload. 200lbs is also too much weight to pull in by hand so a windlass becomes manditory, and if electric, more batteries must be contemplated. So now something else has to get left behind. Fine if you understand but the start of overloading if you don't.

How much chain do you need to buy and from where do you get that bulk price? $3 -4 a foot is more common, as mentioned rope prices go down when purchased in bulk too. Might be worth canvasing the dock for shoppers to team up with on a spool of rope and bulk chain.

Strengthwise the working load of chain is 25% of the breaking load, same as your figure for nylon. Bumping a size up on the rode to counter the damp factor won't hurt anything but isn't really necessary in my experience because you are getting into territory past the holding power of the anchor in most bottoms.

As for replacing the rode it lasts a long time,years in fact. With chain it rattles against itself when stored adding abrasion to the salt working to corrode things so it doesn't last as long as you might think. On a mooring in constant immersion I replace my chain section every 2 years because the galvanizing is gone and the metal has started to rust through. The rode is good for 10 years. On the boat chain holds up better but like everything, the more it is used the faster it wears and if you aren't at the dock with surplus fresh water to rinse, the salt keeps on working against you.

Just my real world experience, everyone's will differ but the math does add up. For me being able to pull the anchor up by hand is important. If I budgeted just the chain weight of 200lbs I could stow 3 complete anchor systems that used rode.
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Old 25-06-2015, 09:24   #30
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Re: Anchor Chain thickness 35ft Cat?

I used 1/4" hi test extensively in the s pacific. I would not buy it again. It is simply to lightweight and a modest size 35' mono will really jerk it all over the bottom. Much better to have a shorter length of heavier chain. I carried 270' on that boat and would likely carry 90 or 120' of 3/8" if doing it again. Still up in the air as to what to carry on my 35' cat in the S pacific, but leaning towards 90' of 5/16" as its possible anchor in shallower coral head free areas with 3' draft. 60' is likely enough, but I have a nice piece that's 90' and hate to cut it!
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