Anchor chain size/rode length?

[richardsnowstar]

I am about to replace the anchor chain on my Southerly 115 (11.2 m long) but I am not sure how much chain and rode to buy. Can anyone advise me?

I do not anchor very often but want to make sure I have sufficient to cover most eventualities. I don't want to be thinking of adding another 10 metres in a couple of years.

Also the existing chain on the boat is 8mm but I am not sure if this is big enough for this size of boat. What size chain would people recommend?

Also can anyone recommend a supplier of good quality chain?

Thanks in advance.

 

[sarabande]

Assuming you want certificated chain, I'd consider Bradneys

www.brandneychain.com


As for the size, 8mm has a BS of approx 40KNewtons and a mass of 44 kg for 30m, and 10mm has 60 KNewtons BS with a mass of nearly 70 kg for 30m. Both are more than OK for the length of boat, but the extra mass of the 10 should make the catenary absorb swell better, with the downside that manual handling is a bit more puff-making.

FWIW, on a 16 tonne boat of 12m, I had 60m of chain and never needed to use the full amount. I think the most I veered (for UK and N France ) was about 45m.


If you have a windlass you will need to get the chain calibrated for that particular make.


Jimmy Green is an alternative source

http://www.jimmygreen.co.uk/products/chandlery/chain

 

[Norman_E]

Take a look at this. 8mm should be enough. 10mm is much heavier so you really do not want to use it unless you have to. As for length, you need to decide whether you are going for an all chain setup or chain plus rode.

 

[lustyd]

Look at places where you are likely to anchor. Find out the tidal range of the area (difference between high and low) and then add that to the charted depth of where you plan to anchor. Add on the height of your bow roller above water. This will give you the max depth you're likely to need. Multiply by 3-6 depending on who you trust and whether it's chain or rope and you have your length.

 

[Boathook]

Look at places where you are likely to anchor. Find out the tidal range of the area (difference between high and low) and then add that to the charted depth of where you plan to anchor. Add on the height of your bow roller above water. This will give you the max depth you're likely to need. Multiply by 3-6 depending on who you trust and whether it's chain or rope and you have your length.

Good advice. Have some spare rope on board to extend the anchor rode in case you anchor in deeper water. It does sometimes happen.

 

[lustyd]

Good advice. Have some spare rope on board to extend the anchor rode in case you anchor in deeper water. It does sometimes happen.

Thanks, yes I should have said to make it a bit longer for just in case scenarios

 

[Babylon]

Typical scenario

For example, my boat is 27ft (8m) long, no windlass, 25lb CQR bower anchor (don't start!!)

I have 30m of 8mm chain to which is spliced 50m 16mm nylon octoplat, total rode 80m. (All chain would add weight to the bow, also harder to haul by hand, and 30m chain seems sufficient both for adequate catenary and to guard against chafe on seabed; however when chain needs replacing, will go for 50m, so total rode will be 100m)

Typical anchoring scenarios (figs rounded up to nearerst 5m):

Solent
6m depth (at top of tide), calm conditions, lunch stop, crowded anchorage: scope of 3 x depth => 20m chain.
As above but overnight: scope of 4 x depth => 25m chain.

North Brittany coast
13m depth (at top of tide), calm conditions: scope of 5 x depth => 65m chain and rope.
As above but rougher conditions: scope of 6 x depth => 80m chain and rope.

 

[Csail]

I would say 60m of ss chain for uk.ss if you dont use it much as it won't jam.

 

[Stu Jackson]

Reply 6: http://c34.org/bbs/index.php/topic,4990.0.html

 

[aowen]

Have recently put 60m of calibrated G40 8mm chain on my Southerly 110 . This was sourced from Maggi in Italy via Jimmy Green. Had excellent service from them.

 

[vyv_cox]

To solve the size question, the chain sold by Jimmy Green is Grade 40, whereas many of the other suppliers sell only Grade 30. Bradney sell both but you need to ask for the Grade 40. 40 is significantly stronger than 30 for the same weight. This would be the ideal solution for your boat, falling as it does somewhere between 8 mm and 10 mm in many of the tables. You could then have a more than adequate length, say 60 - 80 metres for most cruising requirements, without the penalty of significantly more weight forward when carrying 10 mm.

Stainless steel is available from Bradney in Grades 30 and 40 and it does offer some benefits, particularly in avoiding piling up in the locker and blocking the windlass. However, you will pay four times the money for it, on average. Buy it from a reputable supplier if you go this route as there is some very dodgy stuff on the market.

 

[richardsnowstar]

Thanks for all the advice.

I went for 8mm grade 40 galvanised chain. I would have liked to have bought stainless but couldn't justify the additional cost. For length I went for 40 metres of chain spliced to 40 metres of 14mm rope, time will tell if this is sufficient. I bought from Boat Gear Direct as their prices were very good compared to others and their chain is sourced from Italy, not the far east.

 

[KellysEye]

Our boat weighs 12 tons, fourteen fully loaded. We use 8mm chain and have 90 metres of chain, we anchor in some deep places. I would never use rope and chain, the boat slews around too much. For peace of mind it's worth buying test chain.

 

[richardsnowstar]

As a final comment after a problem with the chain that was down to the courier company, Boat Gear Direct (EYE Marine) were great at sorting it out and quickly replaced it. I even got a better quality rope on the replacement.

A good price and a good service, I would recommend them.

 

[charles_reed]

I am about to replace the anchor chain on my Southerly 115 (11.2 m long) but I am not sure how much chain and rode to buy. Can anyone advise me?

I do not anchor very often but want to make sure I have sufficient to cover most eventualities. I don't want to be thinking of adding another 10 metres in a couple of years.

Also the existing chain on the boat is 8mm but I am not sure if this is big enough for this size of boat. What size chain would people recommend?

Also can anyone recommend a supplier of good quality chain?

Thanks in advance.

Depends on where you're anchoring - I've a much lighter boat than yours and have 8mm chain - 65m of it and 40m of 14mm Octoplait.

The only time I've used the whole lot was anchoring in 28m of water inside laCorunna breakwater.

I do anchor a lots and find I use about 30m of chain most times with 3-8m of textile rode (with a Wichard chain grabber).

I'd opine that you're on the limit with 8mm, ok if you always use a lot of chain and don't try the fallacy of a 2:1 scope.

 

[charles_reed]

Our boat weighs 12 tons, fourteen fully loaded. We use 8mm chain and have 90 metres of chain, we anchor in some deep places. I would never use rope and chain, the boat slews around too much. For peace of mind it's worth buying test chain.

Interesting I always use chain + textile and have had far better anchoring with this than ever I had with only chain.

But then mine's a lightweight, shallow-hull deep fin keeler which dances around and used to try and sail the chain out.

Most pundits recommend chain + textile - have you ever tried it?