Smallest length of Chain for chain/rope

[carlosproa]

I am thinking of doing away from all chain setup to a 3/8 HT chain and rope combination.
My vessel is a light 33ft EDELCAT33.


My sailing area is mostly South Florida/keys and the occasional trip to Bahamas.
The question is whether it makes any difference between a 20 ft or 50 ft chain and whether a 3 strand or 8 plait makes a difference.

[smj]

Originally Posted by carlosproa

I am thinking of doing away from all chain setup to a 3/8 HT chain and rope combination.
My vessel is a light 33ft EDELCAT33.


My sailing area is mostly South Florida/keys and the occasional trip to Bahamas.
The question is whether it makes any difference between a 20 ft or 50 ft chain and whether a 3 strand or 8 plait makes a difference.

On an Edel 33? I would go with 1/4” g4, save some weight.
For S Florida, Keys and Bahamas we have usually run between 50’-80’ of chain then 3 strand nylon. Put your money into an appropriately sized new gen anchor with a large fluke area and be done

[Ded reckoner]

There is a good applications article at https://sailing-blog.nauticed.org/an...hain-and-rope/ . Interpreting the catenary mathematics, they say, "as you increase the wind speed force value (H), the chain length must increase to maintain the catenary shape. You can also see that if you use heavier chain, the chain length can decrease. And obviously, as you increase the depth, the chain length goes up." A simplifying approximation is given as, "Chain length = 50ft + 2 times the depth."

Sailing in South Florida, the Keys, and the Bahamas is problematic with rope rode because of coral formations which can cut rope easily under adverse conditions. There are environments where rope rode would be fine, but chain is preferrable where you indicate you're going.

[smj]

Originally Posted by Ded reckoner

There is a good applications article at https://sailing-blog.nauticed.org/an...hain-and-rope/ . Interpreting the catenary mathematics, they say, "as you increase the wind speed force value (H), the chain length must increase to maintain the catenary shape. You can also see that if you use heavier chain, the chain length can decrease. And obviously, as you increase the depth, the chain length goes up." A simplifying approximation is given as, "Chain length = 50ft + 2 times the depth."

Sailing in South Florida, the Keys, and the Bahamas is problematic with rope rode because of coral formations which can cut rope easily under adverse conditions. There are environments where rope rode would be fine, but chain is preferrable where you indicate you're going.

Can’t think of anywhere in S Florida, the Keys or Bahamas where our anchor or rode came close to coral heads.

[SailingHarmonie]

For your boat 3/8" high test chain (G4) is way, way, WAY over the top overkill. I have a 38,000 lb displacement monohull that has circumnavigated--twice--with that grade/size chain.

If I was you, I'd drop to all 5/16" chain and be happy with a 40% weight reduction. Heck, on that boat you might be able to use 1/4" G4, and save half the weight you carry now with no compromise in ease of windlass handling and chafe protection.

Think about it...

[carlosproa]

Thanks for the feedback. Lots to think about. I am sinuses to all chain but not too happy with human power as I am getting older and a windlass maybe the way to go. It does keep me in shape though

[JPA Cate]

@carlosproa,

Hello, Carlo,

This will have to do with when the wind is up, where will the rope be with relation to the coral, when it is all straight out in front of you. If you can figure out where the tip of the chain would be, add a 20% safety factor, and put the excess chain in the bilge, or whatever passes for it on the cat. Coral cuts wet nylon like a sharp knife cuts line. It's really important to keep the springy, light weight part of the line safe. So, figure out the ugly arithmetic, and be well, and stay safe.

Ann

[smj]

Originally Posted by carlosproa

Thanks for the feedback. Lots to think about. I am sinuses to all chain but not too happy with human power as I am getting older and a windlass maybe the way to go. It does keep me in shape though

On our current cat we have 80’ of 1/4”G4 with 200’ of 1/2” nylon going through a small Maxwell RC6 windlass that has a rope/chain gypsy. Attached on the end is a Mantus 45.
Being a shallow draft catamaran it’s rare that we anchor in waters over 8’ deep in the areas you specify, so also rare that we use more than the 80’ of chain with a 30’ bridle attached. Has worked well for us.

[Tupaia]

20ft is real short for chain.I would have said 30ft would be a minimum. Most combination (rope/chain) gipsies will not work with multiplat so 3 strand is the way to go.



You can easily get round the coral / rope problem by attaching a small buoy to the rope at a distance of depth - 1m from the rope chain connection. This will just lift the end of the chain off the bottom and the rope will extend vertically to the surface. The remaining rope between the buoy and the boat will remain on the surface. When under load (wind) the buoy will be pulled under but the angle will be such that the rope never comes into contact with the bottom or coral. Adjust according to the height of any bommies in the vicinity.

[landsend]

Anchoring in S Florida if you are even close to having your anchor

rode cut by coral you will have been arrested for environmental destruction!
There are plenty of places to anchor away from coral.

[David Mathis]

We've never cruised south Florida but our 43' boat has been in a few nasty blows without problems. For many years we have carried 30' of 5/16" chain then 200' of 9/16 three strand. We have no plans to change it.

[MicHughV]

Some years back I bought two buckets of 5/16" High test chain from a ship chandlery. They were conveniently at around 75' long each.
Ever since then, this has been my rode selection.....75' chain, followed by 150' of 5/8" nylon rode. By luck or design, this has been, for me, the perfect selection, for the past 35 years, and like above, would never change it.

[Adelie]

Originally Posted by carlosproa

I am thinking of doing away from all chain setup to a 3/8 HT chain and rope combination.
My vessel is a light 33ft EDELCAT33.


My sailing area is mostly South Florida/keys and the occasional trip to Bahamas.
The question is whether it makes any difference between a 20 ft or 50 ft chain and whether a 3 strand or 8 plait makes a difference.

For short chain mixed rodes, the rule of thumb I received and agree with is 1 boat length of chain.

For long chain mixed rodes 100-125’ of chain.

Using nylon 3 strand has slightly more elasticity than 8-plait. Either would be fine using nylon.

Using something else, I have no opinion, I believe that nylon should be part of the anchor rode system due to electricity which decreases spike loading.

[MicHughV]

I have often dived on my anchor in a blow, and it has been interesting to note, that say, with 75' chain out plus 75' of nylon, it's rare to see more than about 10-15' of chain off the seabed, the rest of the chain just is laying flat on the seabed.
I can see the chain lifting up and down as waves pass by, but the weight of the chain plus the elasticity of the nylon keeps everything in check and working in harmony.