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. 

Final tip

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

Stress cracks on GRP boats

It is quite common to find cracks in the gelcoat when inspecting the deck and superstructure of a GRP boat. It is important to differentiate between a gelcoat crack and a scratch.

Essential boat engine checklist

Boat engine checklist Engine oil level check Even if you have checked it previously, confirming the engine oil level is up...

Steel and Aluminium Hulls

The two metals used for hull construction are steel and aluminium. These are both very strong materials and will last a long time as long as they are cared for, which primarily means protecting steel boats from rust and aluminium boats from electrolytic action.

Docking a Motorboat

Docking a motorboat can be a challenging task, especially for beginners, but with practice and attention to detail, it becomes much easier. Here’s a step-by-step guide to help you dock your motorboat safely and efficiently.

Sailboat rig checks – Part 2

In part two of Sail boat rig checks we run through some useful rig maintenance tips and then finish with a brief look at what a professional rig check involves.

Boat engine basics

Boat engines come in all shapes and sizes and include inboards, outboards, petrol, diesel, electric and hybrid systems. Some engines are...

How diesel engines work

The basic principle of a diesel engine is less complex than that of a petrol engine. No spark plug or ignition system is needed, making the basic diesel engine a comparatively straightforward system that results in fewer faults and has lower maintenance costs than a petrol engine.

How to operate a winch

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

Keeping boat records and doing checks

A boat’s records should provide information about maintenance schedules, when major work was done and when equipment was replaced or added to the boat. Without this information you are left guessing when things are likely to need replacing in the future and also what the costs are likely to be.

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...

Boat plumbing maintenance & troubleshooting

A boat’s fresh water system needs annual maintenance to keep it in good condition. Some boats have far more complex systems than others, with pressurised hot and cold water, associated pumps, an accumulator, calorifier and pressure valves, all to keep a boat owner busy.

Boat maintenance – what does it involve?

The maintenance of a boat involves things like cleaning, varnishing, painting, polishing, antifouling, servicing the engine, servicing the seacocks, and maintaining the gas and plumbing systems. It all amounts to a fairly considerable amount of work that can’t be ignored if you are to keep your boat in a safe and good condition.

ColRegs Nav Lights & Shapes, Rules Of The Road and IALA Buoys Apps

ColRegs Nav Lights & Shapes, Rules Of The Road and IALA Buoys Apps Make Learning Rules on iPhone, iPad, iPod and Android...

Learn ColRegs: Traffic Separation Schemes

Learn ColRegs Rule 10: Traffic Separation Schemes. (c) A vessel shall, so far as practicable, avoid crossing traffic lanes...

Boating Rules of the Road – International ColRegs

    International ColRegs Rule 7: Risk of Collision Anyone who is responsible for a vessel at sea, from the...

Preparing for sailboat cruising

Preparing for a sailing trip entails a lot of planning. In this blog, we take a look at some of the many safety aspects that a skipper needs to consider before heading off on a cruise.

First aid at sea – four common emergencies

In this blog we look at what to do in the event of a crew member choking, drowning, or suffering from hypothermia or fatigue. Knowing how to cope with them could well save a life, while not knowing could result in an avoidable tragedy.

The Round The Island Race 2023

This year’s Round the Island Race turned out to be a really thrilling and competitive event. 1100 boats entered the race, which took place on Saturday 1st July. The race started from the world famous Royal Yacht Squadron line in Cowes UK, with the largest and fastest boats starting first, leaving the rest of us to wait our turn.

How a propeller works

Have a look around any boatyard and you will notice quite a variety of propellers – some have two blades, some have three and others have four or more. While most propellers are completely rigid some have blades that fold.

Pre-start engine checks

According to the Royal National Lifeboat Institution (RNLI) almost one third of emergency call outs at sea are caused by mechanical failure. Many engine breakdowns are avoidable. The best way to avoid a breakdown is to carry out pre-start checks before heading out to sea.

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...

Tacking a sailing boat

Tacking is the sailing manoeuvre used to change a boat's direction through an oncoming wind. Tacking a sailing boat calls...

Sector lights, directional lights, leading lights – how do they differ?

Sector lights, directional lights and leading lights guide vessels safely through hazardous waters or narrow channels at...

VHF DSC radio – how best to communicate at sea

There are many ways to communicate with others at sea. What makes the VHF DSC radio the best form of short range...

Understanding tide tables and tidal curves

There are many factors that influence local tidal patterns and it’s essential for every sailor to have a good understanding of tide tables and tidal charts to ensure they can calculate the level of tide at any given time.