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All rusted up - Guide to anchor chains

Tue, 08 Oct 2024 13:10:11 GMT

Links Marine Services guide to anchor chains

Buying a new anchor chain is a big expense for any yacht and there are many factors to take into consideration before laying out the cash.

How to tell if chain is damaged or stretched?

As the old saying goes “A chain is only as strong as its weakest link“ then potential disaster. So how do you check for damage? This could be corrosion, faulty links or stretched chains. What signs should you be looking out for?

It goes without saying that each time you let out the chain or pull it in you would keep an eye out for any damage, corrosion or pitting but every year it is worth giving it a thorough check. To add longevity to the chain the first action to take would be to end for end the chain.

Corrosion

On stainless steel anchor chains corrosion will show up around the weld and if you have what looks like worm holes these are normally the result of an earth leak. It is important to bear in mind that if the boat has any sort of earth leak – when the anchor is on the ground it will act as an earth point – and stainless is extremely susceptible to electrolysis. The same will happen if you have a steel chain with a stainless anchor - corrosion will appear on the swivel pin, shackle and flukes of the anchor where it digs into the sand. If there is an earth leak corrosion can weaken and eat an anchor chain extremely quickly in the worst case scenarios within a couple of months.

On steel chains it is always good to keep an eye on the Kenter links as these are generally not galvanized and tend to rust quite quickly.

Bent or stretched links

On marine stud link cable - (this is a strong chain and has a stud across the middle which gives extra rigidity and helps prevent any link distortion under extreme loads) – Check if any of the studs are disconnected or not sitting square in the links. They should be at an angle of 90 degrees.

Stretch

According to LLoyds the maximum acceptable wastage is between 10-12%. So how should you measure this?

You will need to measure stretch over at least 5 links (If you only measure one link you will not get an accurate result as a single link may have slight distortions.)

Lay out a length of chain and measure the overall full length of five links and compare it against the tables available for that size of chain, with maximum allowable tolerance of 2.5%.

Re-galvanising - pros and cons

Often a chain will be fine but just corroded - bleeding rust onto your scrubbed decks and freshly polished paint work. Re-galvanising can be a cost effective option and but there are a couple of points to take into consideration.

Before re-galvanising the chain needs to stripped and cleaned, chain has so many nooks and crannies and areas where the links are touching each other it is hard to effectively clean it.

This means that the galvanising can’t properly adhere to these areas and once the chain has gone round a couple of times it will start to come off - leading once again to rusty paint work.

It is also worth noting that the chemical process of re-galvanising can have a detrimental effect on higher strength chain Grade 40 and above eventually weakening it. “Hydrogen embrittlement” is the problem causing the metal to become brittle but unevenly (perhaps just one or two links in the chain.) o you are probably fine re-galavanising lower grade chains a couple of times but if you do it anymore than this it would be highly advisable to get the whole length of chain (not just a section) pull tested to at least twice its working load. The reason being the chain is a series of interconnected links - any part of which could be weak through general wear or through hydrogen embrittlement.

NEW CHAIN

Once you have established that the chain needs to be replaced for one reason or another. What do you need to bear in mind?

The first thing to check is the Gypsy. Unfortunately if the chain has been damaged that might mean that accumulated wear and tear will have built up on the gypsy causing teeth to wear out etc so it is always best to have a good look at this as well.

Marine stud link chain cable is normally produced in lengths of 15 fathoms (27.5 metre) but can be made to measure as a single length and certified and connected to your anchors.

For connecting your lengths of chain to each other kenter links are used but be aware that they are very slightly wider than the standard chain links and these can bind up in the gypsy and get jammed in the spurling pipes.

When we are asked to supply new chain we need to know the length and size of chain needed and the grade of steel required (which can be seen from the previous test certificate. The Test Certificate will show the approved classification society from Lloyds Register and other class societies to be either grade U2 or U3. We also need to know what extras are required such shackles and swivel forerunners.

How to measure the chain

It is in measuring the size of chain where mistakes are generally made and we often have to go down to the boat to double check.

The size of chain should be in the ship’s papers and the gypsy will be marked to a chain size but if you can’t find it there then you will need to measure up.

When taking a measurement it is best to check several links but make sure they are not next to each other as one link might give a rogue measurement. Before you measure you should scrape off rust and salt build up. The same for any thick areas of galvanising - look for the thinnest areas to measure from. A common link is measured by wire size (diameter of material), internal length and the outside width. Stud links are measured in the same way. The best place to measure is at the end of link at 45 º angle.

If in any doubt drop us a line at info@linksmarine.es and we can come down and help measure up.

This article was first published in The Islander magazine in 2019

To replace orginal throttle controls

Tue, 01 Oct 2024 12:38:32 GMT

Fabricating new bridge engine controls

ORIGINAL ENGINE CONTROLS TO BE MODIFIED

The engine controls on the bridge wings required modification due to the installation of a new electrical control system. Our task was to create a new control cover that maintained the original style to align with the age of the boat. See our instagram pos t @

Before and after - Structural refit of sundeck

Tue, 01 Oct 2024 11:51:52 GMT

One of our latest major structural refit projects. Fabricating a new sun deck and jacuzzi deck in aluminium plus all the deck furniture

BEFORE

AFTER

The major challenge of this project was that all the parts had to be designed and fabricated before hand in our workshop in Marratxi, as the boat was on a very tight schedule, and would only be in Palma for a short time for the fitting stage.

Rudder replacement after Orca attack on S7Y Wildlife

Tue, 01 Oct 2024 11:03:45 GMT

A whale's tale

There have been numerous reports in the press of the shocking stories of Orcas attacking small vessels, so much so, that as far back as 2020 sailing vessels under 15 metres had to be prohibited for their own safety from sailing off the Galician coast.

The crew of SY Wildlife had firsthand experience of this back in May 2023 when they were terrorized by a group of 3 Orcas for an hour and a half as they were making passage from Lanzarote to Palma de Mallorca. The first the crew knew about the attack was a loud thud on the hull which they assumed must have been from the hull hitting a submerged container. But as they looked over the side towards the stern they saw two pieces of red debris floating off into the distance, which unfortunately for them turned out to be bits of their fibre glass rudders …… and then they spotted the orcas circling under the boat.

The crew weren’t immediately panicked and as per protocol provided by Orcaiberica.org they slowed the vessel, stopped the engine, turned off the auto pilot and left the rudder to track, hoping that the whales would soon enough get bored and go away. But once the boat had been turned 360º the panic set in.

The captain called Tarifa traffic control to explain their predicament. They could see the whales pushing the rudders with their noses under the boat to such an extent that the connecting rod between the two rudders was broken and one of the rudders had been pushed to completely face the other way leaving boat un-steerable.

Luckily for the crew they then had a small piece of luck as the Orcas through their prodding of the rudders managed to push the rudders back into the correct position and the boat was once again steerable.

The crew started the engine and got under way eventually limping into Gibraltar. On arrival the Harbour Master told them the nearly unbelievable news that there had been 57 attacks in the last 60 days – 3 of them on the same day as Wild life attack!

There are two main theories that have been put forward to explain this behaviour. The first being that one of the Orcas suffered from either being struck by a boat or entangled in fishing line and has then taught this attacking behaviour to younger whales as revenge for injuries sufferered. The second theory made recently in by Renaud de Stephanis a marine biologist undertaking research for the Spanish government into this behaviour and reported in the Daily Telegraph on 27 June suggests that the mammals were possibly playing and received a “massive adrenaline rush” from the attacks.

Whatever the reason for this behaviour the consequences can be devastating and several boats have been lost. Luckily for SY Wildlife Links Marine Services were able to rebuild in aluminium the two rudders using the existing rudder stock and were able to get the boat back up and running in a couple of weeks.