All chain anchor rode - how long?

[Derek Rowell]

I'm moving to Plan B on my windlass installation. The original plan was to have 200 ft of rope and 40 ft of chain, but unforunately the geometry of my boat requires a couple of gentle bends in the hawse pipe (3" PVC) from the windlass to the chain locker, and the friction is enough to cause the rope to form loops in the pipe and jam. The only choice I see is to go with all chain.The question is - what is the common wisdom on how much chain (5/16 HT) to purchase? I've never used all chain before. Cruising ground is New England coast. My proposal is 200 ft. Reasonable?

 

[Paul (Affinity C320)]

Generally, 7/1 scope

Is what most people use. 10 ft of water = 70 ft of chain.

 

[Don K.]

Chain Locker

Is your locker deep enough for 200' of chain The chain will want to pile up like a pyramid. I am not so sure I like those gentle curves.

 

[Paul Akers]

Chain Scope

From what I have read, the general suggestion for chain scope is 3:1. For rope scope it's 7:1. So if you carried 210' of rope rode in your cruising grounds, then 70' of chain may suffice. It really depends on your expectations of anchorage depths.

 

[Derek Rowell]

Paul, Paul, and Don

From what I read 5:1 scope is more realistic for all-chain - so let's split the differece . Paul Akers - we sail the same waters, and although I usually anchor in 10 - 15 ft, I was taking as worst case the 30+ feet in the middle of the Great Salt Pond in Block Island. Don, the "gentle curves" are necessary because on the Pearson 422 (and probably the 424) the windlass has to be mounted on a very small raised foredeck close to the bow. A vertical hawse-pipe from the windlass would cut right through the bow! The chain locker is actually voluminous, but is in front of the v-berth beneath the on-deck anchor locker. The hawse pipe therefore has to pass through the anchor locker, but a straight (sloped) pipe interferes with the windlass motor, therefore the need for a vertical wiggle. I have fitted the pipe and chain slides very smoothly, but as I said at the outset 5/8" nylon tends to coil and jam inside the pipe because it is not heavy enough.

 

[Bill Bell]

We carry 150'

For our Florida and Bahamas cruising we carry 150' of 5/16 ht chain on the 45# plow and 40' chain and 200' nylon on a 45# bruce. I don't think that I have ever anchored in more than 20' feet of water. I use about 5:1 scope for normal overnight anchoring, 3:1 in tight situations. If we know that a big blow is coming we might use 7:1 if we have the room. Normal anchoring depth is 8-12 feet and only the first 50-60' of chain is all that ever sees the saltwater.Bill

 

[Ray Bowles]

All chain rode

Derek, We spent the past 2 yrs as liveaboards in the Gulf and Fl. Keys on our 38 IP. We were on the hook for approx 3/4 of that time. We had 330' of 3/8 chain on our 45# CQR primary and 150' of 3/8 chain and 250' 3/4 nylon on our 35# Bruce secondary. I always set a min of 7 to 1 scope (measured from the bow anchor roller to the sea floor)which was usually about 15 feet or a scope of approx 100 ft. We always backed the anchor and chain down at 50 ft and then laid down the remaining 50 ft with an additional backdown.We found out that our 26,000# boat with its 50 hp Yanmar was unable to back down all that chain in one pull and thereby not burying the anchor. In the south the occurance of very strong thunderboomers was quite frequent and they never cause us to pull our anchor. We experenced 2 windstorms that measured 50knots plus and it only moved approx 1/2 of our rode. Many of our friends pulled their anchors and midnight is no time to reset or even worry about your anchor. We only used the pair of anchors twice in 2 years and that was for known storms.Run your hawser pipe to the highest and widest area of your locker or the chain will quickly pile up to the bottom of the pipe and require someone to go below to move the pile so you can retreive the rest of your chain.Sorry this is so long and fair winds to you.Ray

 

[newly anonymous]

plenty

I use 200' of 5/16 BBB on my primary rode, and have never felt the need for more. You don't need a 7:1 scope when it's all chain. 4:1 on chain will give you better purchase than 7:1 on nylon. I guess the big question is whether you feel you'll ever anchor in deeper than 50' of water. I won't.

 

[newly anonymous]

chapmans

BTW, Chapman's "Piloting" recommends between 3:1 and 5:1 for all-chain rodes in normal conditions. Page 262.

 

[Paul Akers]

I knew I read that somewhere ;d

nm

 

[Rich Stidger]

My 2 cents....

I am in the same area as you, Derek. I have 160 feet of 5/16 HT and another 120' of 7/16" rode coiled and and tied.I have never put out more than the 160 feet of chain with my 45# CQR. I have a h40.5 weighing 20000# dry and probably 23000# loaded.I use AT LEAST 5:1 and try to use 7:1 if swinging room permits. In 11-15' of water I typically use 90 feet of chain. Maybe that is overkill, but I do sleep well....I try to avoid anchoring in over 30' of water if possible. If a known storm was coming and I was in 30+ depth I would set out some of my rode as well.And as for the piling up of chain in the locker, I have this problem. I stop every 30 feet of so and kick the pile down lower in the locker.

 

[newly anonymous]

boat hook

I always carry a boat hook forward when I'm bringing up a hundred feet or more of chain. Same technique as Rick described, stopping every thirty feet or so to knock it down, but out here in SF bay you don't dare use your shoe for that job or you'd be tracking mud all the way back to the cockpit.

 

[Rick I]

lots of chain

Cruised for years on the old boat (CS36) with a 33# Bruce and a 35# Plow each with 50' of chain and 250' 5/8 3 strand. Would have preferred all chain but didn't have a windlass. Now (B393 with windlass)I have 200' of 3/8 BBB and 150' of 5/8 3 strand with a 44# Bruce knockoff as my primary anchor and the old plow as my secondary. All chain and a good long snubber is much preferrable. While you're at it if you don't have one already, add a washdown pump. Carry as much chain as the boat will allow.

 

[Jose Venegas]

Derek, check out this link

It is a neat model that calculates the maximum horizontal force that an anchor rode can accept before the catenary's angle at the seafloor becomes positive.If you can estimate the maximum holding force that your anchor is designed for at your typical anchoring site, or the maximum wind drag you expect to be exposed to, the model will allow you to estimate the rode length for a given depth.In a recent sail or cruising magazine I saw a similar model discussed to demonstrate that the conventional concept of scope is not the best to choose the rode length.For example, for a depth of 30ft using 5/16 chain, the max horizontal force at a scope of 5 is 635 pounds. However, for a depth of 10 ft, and the same chain and scope the force is only 224 pounds !!!!

 

[Jose Venegas]

Continuation

For a depth of 30 ft and using your projected 200 ft of chain, the model predicts a maximum horizontal force before the catenary angle becomes positive of about 630 lb. According to the web site, wind on a 40 ft boat would cause a drag of 300 lb at 15 knots and 1200 lb at 30 knots. Therefore, you would need quite a bit more chain or you would have to anchor in a shalower place (<15ft) if you are expecting winds in the 30 knot range and use your 200 ft of chain.I am glad you asked the question because I have been questioning this myself.Hope you never have to use

 

[Peter J. Brennan]

The bow rake gets you

When I installed a windlass on our O'Day 37 I first went with 40' of chain and 200 feet of line. The line absolutely positively would not feed through the hawsehole beneath the windlass and just hockled and jammed up. I tried another line, slightly larger, with the same result. So I went to a Delta 35 and 150' of chain spliced to 200' of rope. I also installed a slippery sheet of plastic inside the bow rake to give the chain a slippery slope. But still, if we have more than fifty feet of chain out, it will begin to pile up and eventually has to be tailed by hand into the chain locker under the V-berth. However, there is enough drop so that the tailing can be left for later.We have almost never had to use any of the rope rode portion.The original rode with 40' for chain and 200' of rope is stowed for quick access with a Fortress 23 if needed.