Select Page

The rig of a sailing boat is put under huge stresses and strains so it is important for inspections of a yacht’s spars and rigging to be carried out at regular intervals.

All the elements of a sailing rig – the mast, spreaders, boom, kicker, stays and the fittings that hold everything together – are subjected to considerable forces when at sea.

Less obvious perhaps is that the process of cyclic loading, the cause of metal fatigue, continues unabated even when a boat is rocking gently on a sheltered mooring. The rig components continue to push and pull against each other, day in and day out. Added to the all stresses and strains imposed on the rig components are their susceptibility to different kinds of corrosion, caused in the case of aluminium masts both by exposure to the marine environment on the one hand and also by galvanic corrosion. This occurs when stainless steel or bronze fittings are fitted to aluminium masts and not adequately insulated from each other, which causes the aluminium to corrode. While wooden masts do not suffer from galvanic corrosion, they are susceptible to rot and de-lamination.

Rig care

As with many other kinds of boat care, regular checks, preventative maintenance and the correct set up of mast and rigging are key to ensuring longevity and preventing failure. With sailing boat rigs in particular, the integrity of all their parts is vital. The mast and rigging is a lightweight structure designed to be rigid and strong, a bit like a house of cards – if one of the components fails then the whole house comes tumbling down. Even if one part becomes loose this can increase loads on other parts, causing them to fail.

While doing regular checks of your rig throughout the sailing season is good practice, so too is a more detailed inspection when the boat comes ashore and if needs be the mast can be taken down. Even if the rig remains unstepped ashore it still needs to be checked by a trained eye.

Understanding your rig

There are many kinds of mast and rig configurations for sailing boats and it is important for boat owners to fully understand the rig set up of their particular boat. This understanding will help them know what to look out for when doing their regular checks. Here are a few questions that owners should be able to answer:

Standing rigging

  • What are the main causes of rig failure?
  • When was the mast last unstepped? Once every two or three years is generally recommended.
  • When was the standing rigging last inspected? Annual inspections are usually recommended.
  • When was the standing rigging last replaced? Once every ten years or so is usually recommended for wire rigging and about fifteen years for rod rigging.
  • Where are the main stress points on your rig?
  • How do you check the rig alignment?

Running rigging

  • When was the running rigging last inspected?
  • When should it be replaced?
  • What maintenance needs to be done?

Causes of rig failure

While many sailors live in fear of rogue waves and capsize, most dismastings happen either because of equipment failure or operator error. Leaving aside operator error, the main reasons include the failure of chainplates, spreaders, turnbuckles and tangs caused by either metal fatigue, corrosion or a combination of the two.

Chainplate failure is one of the most common causes of dismasting. Chainplates are not easy to inspect as they are hidden from view beneath the deck. Corrosion happens out of sight where the metal cannot be inspected without the plates first being removed.

Other causes are the failure of terminal fittings, clevis pins, cotter pins and all the parts that hold a rig together.

Surprisingly perhaps, the mast and stays are rarely the components that break first and cause a dismasting.           

Stresses and loads

The components of a rig are designed to withstand certain stress levels and loads caused by a boat under sail in varying conditions. The correct adjustment of the rig is important to maintain the rig’s strength and longevity for a number of reasons – not just the boat’s performance and ability to point to windward. These include:

  • If the rigging is slack problems can develop as it moves about, causing fatigue.
  • Rig components can become weakened by vibrations caused for example as sails flog in strong winds, or by shock loading caused for example by accidental gybes.
  • The misalignment of part of a rig can cause other parts to be overloaded resulting in metal fatigue and eventual failure.
  • Stress coupled with corrosion will accelerate the potential for rig failure.

Crevice corrosion

Some surface rust on stainless steel rigging is normal and usually polishes off very easily. While stainless steel does not rust in the way that regular steel does, it does suffer from crevice corrosion.

Crevice corrosion occurs because the stainless steel has been deprived of oxygen. As a result its protective oxide film breaks down, allowing chlorides to infiltrate and corrode the metal. This happens around joints and under fastener heads and where pieces of metal are in close contact. Chainplates often suffer from this type of corrosion where they pass through the deck and sea water has saturated the deck core.

Crevice corrosion also takes place where cyclic loading has caused stainless steel to develop hairline cracks on the metal’s surface. Sea water then gets into the cracks and the corrosion slowly takes hold.

 Galvanic corrosion

Aluminium masts with stainless steel fittings are at risk from galvanic corrosion. Galvanic corrosion is the transfer of electrons from one metal (the anode) to another (the cathode). In this case the anode is the aluminium and the cathode is the stainless steel. Positively charged electrons flow from the the anode to the negatively charged cathode. Galvanic corrosion also requires an electrolyte, a liquid that enables the electron flow to take place. In this case salt water is the electrolyte and a very efficient one.

Note: All stainless steel fittings should be insulated from aluminium masts by washers or sealant

You Need To Understand The IRPCS ColRegs To Pass Your Yachtmaster, Master of Yachts and Coxswain Certificate of Competence

IRPCS ColRegs Rules of the Road at Sea and Yachtmaster Learning, understanding and remembering the International Regulations...

The VHF DSC Radio jargon buster

AIS - Automatic Identification System This system is used by shipping. It allows another vessel or coast station to use...

Understanding your boat’s compass

Article submitted by Mike Rossiter, Certificated Compass Adjuster. Since the magnetic compass was first used by the Chinese...

First Aid Afloat – how to deal with a fracture at sea

First Aid Afloat A closed fracture does not break through the skin. An open fracture is when the bone punctures it. A...

How to operate a winch

Winches are drum shaped mechanical devices used to handle halyards, sheets and control lines. One of the important crew...

Essential Boat Spares for Safety

  Boats Spares Tool kit What you carry in the boats tool kit will be useful for many boat repairs, but you might want...

Rewiring a boat – overcoming the challenges involved

Skippers need to have a basic knowledge of boat electrics, to avoid potential problems and to be able to solve them when...

Hourly Checks when sailing or motoring

  Hourly Checks Get into the habit of carrying out these checks and both yourself, your crew and your boat will be...

First Aid Afloat – jellyfish stings

  Wherever you are boating in the world I am sure you will be using a pilot guide to aid your navigation. Often in the...

Essential yacht tender safety for skippers and crew

Essential yacht tender safety - the dangers inherent in using a dinghy to get ashore from a moored or anchored yacht are all...

ColRegs when sailing single handed

  Don’t neglect the Colregs when sailing single handed Sailing single-handed represents several challenges for...

Getting a tow for your sail or power boat at sea or on inland waterways

FREE tips from the Safe Skipper App for iPhone/iPad/Android: Getting a tow for your sail or power boat Plan how to secure a...

Capsize – understanding the risks

A skipper should know how their boat will cope with rough seas. By working within known limits and understanding the risks,...

Know your Navlights & Shapes – essential for all skippers

Know your Navlights & Shapes International Regulations for Preventing Collisions at Sea (ColRegs) Anyone who is...

Always have an emergency grab bag to hand when at sea…

  Grab bag: In the event of having to abandon ship, it is recommended to have a designated waterproof bag to carry...

How to predict wind direction and strength by reading a weather chart

Weather charts, also known as surface pressure or synoptic charts, contain a lot of information that helps weather...

A five day sailing cruise of the Solent, UK

Welcome to our virtual Solent sailing cruise – a five day sail in the south of England from Bosham Quay in Chichester...

Essential Yachting + Power Boat Safety Briefing

Yachting Safety Briefing   Down below Lifejackets and harnesses - fitting, when to wear, clipping on Gas - risks,...

ColRegs – avoiding collisions at sea

ColRegs - avoiding collisions at sea ColRegs Rule 8: Action to avoid collision (a) Any action taken to avoid collision shall...

Fire prevention on boats

  Fire prevention on boats - common causes of fire: • Smoking below decks • Galley cookers • Build-up of butane or...

Boat ownership

Owning a boat is a big commitment that should bring no end of satisfaction for the owner as well as the owner's family and friends. In...

Distress flares – which flare, how & when to use?

How to use distress flares at sea Flares should be kept in a waterproof container in an easily accessible location such as a...

Tools and spares for your boat

It is wise to have a comprehensive and well-organised tool kit and a supply of spares for your boat. This is both for routine...

Boat Engine Failure – what to check

Engine failure If your engine fails or is overheating there are a number of things to check immediately: • Air filter...

Essential Knots: Bowline

Essential Knots: Bowline Use: Making a secure eye or loop in the end of a rope. Bowlines have many uses on a boat, for example to make a...