Anchor chain 8mm or 10mm

[NormanS]

It's little wonder that it's difficult to get agreement when the anchoring usage and requirements are so different.
For example, here on the one hand, we have the owner of a 19ton boat, where weight is of little consequence, and who is almost permanently anchored.
On the other hand, we have someone who has, or used to have, a lightweight catamaran, where any extra weight will kill its performance, and who anchored occasionally.
We all have different requirements, and our types of sailing vary enormously. One size does not fit all, so being preached at, and encouraged to change our ways, by an exponent of "all weight is bad", becomes tiring.

 

[Neeves]

If you read all the posts you will find no-one is saying all weight is bad - consequently it is not tiring (though reading all the posts might be tiring).

If you feel there is repetition - that's because people don't read all the posts, repetition is the solution

Jonathan

 

[MapisM]

If you feel there is repetition - that's because people don't read all the posts, repetition is the solution

'Dunno if repetition is a solution to anything.
But pretty sure, if it would be banned, there would be no anchor topics at all anymore!

 

[Roberto]

It seems anchoring threads have long been case studies in sociology courses, they have then been offered in behavioural sciences courses, they might eventually become PhD topics in psychiatry

 

[doug748]

I am truly loath to start another anchoring thread but my simple proposition is as follows:
Intend replacing the 21kg plough and chain on 1999 Bav 42, 43.5’ish LOA and 8.5 ton displacement with Rocna mk1 25kg and 60 m G40 8mm and 30 metre octoplait.
Bav say German Lloyds say 8mm good for this size of boat; Jimmy Green tables say need 10mm.
What size would you go with? (oh and what diameter rope to splice on?)

If you have a 10mm gypsy, I would stick with that. I would not splice the rope, it only festers in the locker. Shackle it on as needed, it won't be often.
On your type of boat I would not water things down for a notional sailing performance advantage.

.

 

[Neeves]

If you have a 10mm gypsy, I would stick with that. I would not splice the rope, it only festers in the locker. Shackle it on as needed, it won't be often.
On your type of boat I would not water things down for a notional sailing performance advantage.

.

The weight saving is that of a healthy adult, if you down size from 10mm to 8mm. There will be more room for chain in the locker and you could consider a chain rode longer than 60m (and then you will not need the rope at all). However you know where you sail and anchor - you might never need more than 50m of chain.

With a weight saving of that of a healthy adult - you will make a real impact on sailing performance - especially next time you need to bash into 25 knots and building seas. Its simple - would you not notice the impact of that healthy adult standing on the bow, permanently.

If you do change to 8mm and its associated costs, gypsy, you will need to use a snubber each time you anchor, use the search function on YBW for background.

If you intend selling your current yacht - don't bother to change anything. If I had a Bav 42 and it was a keeper I'd change to high tensile 6mm which approximately has the strength of G30 8mm. The simplest chain would be 6mm G70 which Jimmy Green should be able to supply, we had a 38' cat, 7t, which has the windage of a Bav45/50 we downsized from 8mm to 6mm.

This what 75m of 6mm looks like, bottom 2 drum in comparison to 50m of 8mm, top 2 drums..



Jonathan.

 

[NormanS]

Hmm, the trim and performance of many boats would actually be improved, if instead of maybe four or more people crowded into the cockpit, one or more went forward.

 

[Neeves]

Hmm, the trim and performance of many boats would actually be improved, if instead of maybe four or more people crowded into the cockpit, one or more went forward.

Great minds think alike - your wish is achievable

https://catamarancompany.com.au/boat/320625/leopard-catamarans-44-forward-cockpit-lounge/

I never would have predicted you would hanker after a catamaran.

Josephine and I went round the yard building this development - we lacked the courage, maybe we should have had your advice

Jonathan

 

[geem]

Hmm, the trim and performance of many boats would actually be improved, if instead of maybe four or more people crowded into the cockpit, one or more went forward.

We carry 60m of ISO10mm chain. If I swapped this for 8mm chain, we would save 42kg. Our chain locker is a surprisingly long way back from the bow, and it's below the waterline. For this reason the watertight crash bulkhead has a 19mm through bulkhead fitting to take a drain pipe to the central sump under the saloon. The 42kg weight difference is not worth worrying about. It's 42 litres of water. We have a water tank that holds 800 litres

 

[doug748]

We carry 60m of ISO10mm chain. If I swapped this for 8mm chain, we would save 42kg. Our chain locker is a surprisingly long way back from the bow, and it's below the waterline. For this reason the watertight crash bulkhead has a 19mm through bulkhead fitting to take a drain pipe to the central sump under the saloon. The 42kg weight difference is not worth worrying about. It's 42 litres of water. We have a water tank that holds 800 litres

Is that correct 42kg? That is trivial on the OP''s boat. Even if it were double, as others claim, a very useful investment on a larger cruising design.

.

 

[geem]

Is that correct 42kg? That is trivial on the OP''s boat. Even if it were double, as others claim, a very useful investment on a larger cruising design.

.

You can do the maths yourself. Just go on Jimmy Greem website and look at the weight per metre of 8 and 10mm chain

 

[Neeves]

It depends on the origin and specification of the chain but approx

6mm 0.85kg/m Min Break Strength 1,630kg

Difference for 100m = 60kg

8mm 1.45kg/m. Min Break Strength 3,260kg

Diiference for 100m = 80kg

10mm 2.25kg/m. Min break strength 5,100kg


To put into context a Bav 30 weighs 4,600kg and a Bav 50 14,000, dry. You need to add fuel and water. (and all the toys)


then google something like

Is weight in the bow of a yacht useful

or

How does extra weight in the bow affect performance of a yacht

or variations of same

And then ponder as to whether your post is accurate - and post again.

Think of the size and weight of a typical yacht.

There are spreadsheets for rode size, the size of the chain vs yacht size, The spread sheets are similar from different suppliers, Lewmar, Jimmy Green and any background supporting the data is sparse or missing completely. The spread sheets are 'similar' and honed over decades. The major factor behind the spreadsheets is windage and the affect of chain weight on the usefulness of catenary (crudely - bigger yachts need more positive benefit of catenary and therefore need bigger/heavier, chain.

There are alternatives to catenary.

Jonathan

 

[Tranona]

The weight and volume may well be valid on modern boats where the chain locker is right in the bows and high up (as in the Bav 42 that started this), but largely irrelevant on older heavy displacement boats like mine, geem's and norman's where the chain locker is further back and lower down.

With the Bav 60m of 8mm is more than adequate - there is really not enough space in the locker for the same length of 10mm. Self stowing is already difficult because of the shape of the locker and the lack of fall. Agree also with the suggestion of not splicing rope onto the end and leaving it in the bottom of the locker because the drains are small and under water when sailing so it will bee permanently wet. I discovered this the hard way with my similar Bav 37 and went back to the 50m 8mm and 20m 12mm rope ready to shackle on - almost never used.

 

[eddystone]

I applied my vernier gauge to the chain and it was 11mm+, so allowing for the thickness of the rust I assume existing is 50M of 10mm. So think I will stick with 60M (only another 16kg) of G4 10mm and not have to change the gypsy. Seems to be plenty of space in the locker for more chain.

 

[noelex]

So think I will stick with 60M (only another 16kg) of G4 10mm and not have to change the gypsy.

When ordering 10mm chain, it is crucial to be aware of the existence of two distinct sizes, commonly referred to as DIN and ISO. While some gypsies will accept both types, many are specific, and the incorrect type of 10mm chain will be incompatible.

It is not uncommon for people to order the wrong type.

The difference is in the pitch or the internal length of the chain link. This is 28mm (DIN) or 30mm (ISO). Check the existing chain and make sure you order the same, or look for some numbers on the gypsy to see which type of 10mm chain it is made to fit. The other option is to buy a small sample of the new chain and wrap it around the gypsy. It will be readily apparent if it fits.

 

[Neeves]

When ordering 10mm chain, it is crucial to be aware of the existence of two distinct sizes, commonly referred to as DIN and ISO. While some gypsies will accept both types, many are specific, and the incorrect type of 10mm chain will be incompatible.

It is not uncommon for people to order the wrong type.

The difference is in the pitch or the internal length of the chain link. This is 28mm (DIN) or 30mm (ISO). Check the existing chain and make sure you order the same, or look for some numbers on the gypsy to see which type of 10mm chain it is made to fit. The other option is to buy a small sample of the new chain and wrap it around the gypsy. It will be readily apparent if it fits.

Important warning by Noelex

I'm not aware that there are dual gypsies, at all. I think they are either DIN or ISO - but I may be wrong.

The specification should be marked on the gypsy - if you are lucky it is engraved in (or on) the rim of the gypsy, otherwise it is on one of the facing plates of the gypsy and you will need to take the gypsy off. If you have paper work, an invoice, in your documentation it should be defined, it may also be noted in the instruction manual

From memory Vyv has details on his website.

Its expensive if you get it wrong.

Jonathan

 

[geem]

Important warning by Noelex

I'm not aware that there are dual gypsies, at all. I think they are either DIN or ISO - but I may be wrong.

The specification should be marked on the gypsy - if you are lucky it is engraved in (or on) the rim of the gypsy, otherwise it is on one of the facing plates of the gypsy and you will need to take the gypsy off. If you have paper work, an invoice, in your documentation it should be defined, it may also be noted in the instruction manual

From memory Vyv has details on his website.

Its expensive if you get it wrong.

Jonathan

Lofrans make dual spec gypsies.

 

[Roberto]

I applied my vernier gauge to the chain and it was 11mm+, so allowing for the thickness of the rust I assume existing is 50M of 10mm. So think I will stick with 60M (only another 16kg) of G4 10mm and not have to change the gypsy. Seems to be plenty of space in the locker for more chain.

If yuo want to check what chain standard you have, DIN 766 or ISO 4565:
Chain 10mm ISO DIN.pdf

 

[Neeves]

The weight and volume may well be valid on modern boats where the chain locker is right in the bows and high up (as in the Bav 42 that started this), but largely irrelevant on older heavy displacement boats like mine, geem's and norman's where the chain locker is further back and lower down.

With the Bav 60m of 8mm is more than adequate - there is really not enough space in the locker for the same length of 10mm. Self stowing is already difficult because of the shape of the locker and the lack of fall. Agree also with the suggestion of not splicing rope onto the end and leaving it in the bottom of the locker because the drains are small and under water when sailing so it will bee permanently wet. I discovered this the hard way with my similar Bav 37 and went back to the 50m 8mm and 20m 12mm rope ready to shackle on - almost never used.

Which raises some interesting questions as more knowledge would engender more accurate (or useful) replies.

What is the mix, log term cruisers vs weekend sailors; typical yacht size; how many people have heavy displacement yachts?

A thought I have is that heavy displacement yachts, that are not project yachts, are becoming like hens teeth. They are no longer 'commonplace' and the current rash of builders, Benny, Jenny and Bav et al have squeezed weight out of their models which means whether you buy new or not so old pre-owned - they are lightweight. I'm not so sure that long term cruiser numbers, or proportions, have changed but with the decline in numbers of heavy displacement yachts anyone contemplating the life of the live aboard need think more plastic fantacting than heavy long keel - for example Sea Change/aka Kelpie.

Jonathan

 

[Neeves]

We currently have 12mm chain. 47ft 11.5t boat.
It's up for replacement, and I already have a spare windlass with a 10mm gypsy (plus a functioning stripper arm... which the one with the 12mm lacks... grrr).
I can see a strong argument for buying new 10mm chain. The current stuff piles up quickly in the locker and I need to clear it every 6-8m or so.

If I go down to 10mm, should I be considering a stronger grade?

I don't expect you to take me seriously but I's go for G70 x 8mm - and I am serious.

A decent snubber will replace catenary, the weight and space savings are large.

Your yacht has a similar windage to our 38' x 22'6" catamaran - and we used 6mm

Jonathan