Along with the development of modern materials and advanced design techniques, the modern rig has become a complex engineering structure. It has taken the designer a considerable amount of time to conceive and the professional rigger even longer to construct, making it a very expensive part of any yacht. A basic understanding of the rig structure and the application of some simple precautions can enhance the life and functionality of the mast and rigging.
Masts can be made of timber, aluminium or carbon fibre composites. Wooden masts are very rare these days and are only found on traditional-style cruising yachts and vessels like couta boats. Aluminium masts are by far the most common type of mast, due to their relatively low cost and ease of manufacture in comparison to other materials. They are composed of an alloy specially designed to cope with heavy loads and the harsh marine environment, whilst also minimising weight aloft. While aluminium has proven very successful as a mast material, developments in composites, especially epoxy resins and very high strength synthetic fibres, have brought some exciting new possibilities. Many serious racing yachts utilise composite masts because of the weight saving and added strength over aluminium. While these masts have proven to be very successful, there are still many unanswered questions with this space age material. Some recent high-profile mast failures attest to this. However, as the technology matures many of these questions will be answered and costs will come down, making carbon fibre masts more affordable for owners of smaller yachts.
Stainless steel dominates the rigging environment and has done so for quite some time. But the development of composite fibre materials from the space and aeronautics industries has brought a variety of exotic materials that are now being used in rigging applications. These materials are lighter and stronger than stainless steel, but are currently a lot more expensive. There are still some issues to be dealt with as these new materials become more common, but they will, no doubt, be addressed over time.
Failure of a rig is usually due to one of the following reasons: Misalignment; hard and soft surfaces rubbing together; something fixed moving; breakage due to poor condition; old age; excessive loads or insufficient lubrication. These problems can be attributed to poor set-up, alignment, design or maintenance. Many of these problems can be eliminated by selecting a good rigger to construct your rig. Professional riggers understand all of the issues and will do everything possible to eliminate or minimise the possibilities of breakage or failure. A less thorough rigger may not be so careful with some of the small details and this can also lead to the failure of the entire structure.
There is much that the yacht owner can do to ensure the longevity and functionality of the rig and this starts with rig inspections. Regular rig inspections should be a matter of course. Many serious yacht racers perform this task after every race as a fault may lead to the yacht’s withdrawal from subsequent events. The reason inspections are performed after a race, rather than beforehand, is to give the team sufficient time to perform any necessary repairs before the next race.
It is a good idea to delegate this task to one crew member, who will then become very familiar with the rig and be able to identify issues before they develop into something serious. Choose a person who has a practical mind and a common sense approach and preferably one who understands the principles of light-weight structures. Ask your professional rigger to accompany the designated person up the rig for the first inspection. The rigger will point out all of the important areas and give the delegated crew member a good foundation from which to develop a sound understanding of the rig.
It is also a good idea to get a professional rigger to inspect the rig annually. Remember, a rig is a complex engineering structure and this small investment may save you a lot of heartache.
Start at the top
The best place to start a rig check is from the top of the mast. Begin by inspecting the condition of the wind instruments as the harsh UV light can quickly break down the plastic components. If it looks old and tired, it’s better to replace it rather than have it fail whilst under sail.
Next, inspect the lights; start by making sure they all work properly and look for signs of corrosion and water leakage.
The mast crane and mast cap should be inspected for cracks, movement and other damage. Cracks frequently start at the intersection of the mast and the mast cap or mast crane. If movement is detected, this could be very serious so consult your rigger for advice. Whilst inspecting the mast crane, closely examine the sheaves for chips, cracks, elongation in the central hole and general wear and tear. Sheaves that show signs of any damage or wear should be replaced immediately to avoid unpleasant consequences, such as the inability to lower a sail.
Also check the condition of all split pins or rings to ensure they are still sound. Elongation of the holes in the mast crane (for the clevis pins) could indicate excessive force, wear, ageing or other serious problems. Again, consult your professional rigger.
Next, look at the attachment of the cap shrouds as well as the forestay and the backstay. Carefully inspect all swages for damage or deterioration. Look for cracks, elongation, bending, wire breakages and misalignment. Misalignment can often be the cause of many other problems. Any pins and split pins should be thoroughly inspected. Check the wall of the mast for any damage, too. And take your time as the few extra minutes may well pay large dividends.
Be sure to examine any damage caused by the halyard being wrapped around the forestay. Forestays made from rod rigging may show signs of bending and Dyform (or wire) forestays can show signs of strands parting. These warrant immediate action.
As you move down the mast, look for any signs of damage to the wall of the structure. Stop and inspect any intermediary fittings. After reaching the spreaders, closely inspect the spreader attachment system. Look for loose bolts or rivets and check that the spreaders are firmly attached to the mast, ie: they don’t wobble. Inspect the mast immediately adjacent to the spreaders to ensure the mast wall has not been damaged or dented.
Next, inspect the attachment system for the lower or intermediate shrouds or diamonds, ensuring there are no loose pins, split pins, bolts or nuts etc. Carefully inspect all swages for damage or deterioration. Then inspect the mast hound for signs of movement, loose rivets or bolts etc, as well as damage to the mast wall.
Move out to the tip of each spreader and inspect the attachment system for the shrouds. First of all, ensure the tip of the shroud (often a casting) is still firmly attached inside the hollow spreader extrusion. Then inspect the system employed to attach the shrouds to the spreader. Again, look for signs of wear, breakages, corrosion or movement. It is also a good idea to sheathe the tip of the spreader with leather to prevent damage to sails.
Don’t forget to inspect the yard arm fittings (typically found on a serious cruising yacht). Nothing could be more embarrassing than to hoist a courtesy flag, only to have it fall down on top of you.
The deck lights attached to the underside of the spreaders are very important and should also be closely inspected as they are frequently subjected to abuse from halyards and flogging sails.
Base of the mast
Many people forget about the foot of the mast, despite the fact that it is one of the most important areas of the rig. The base of the mast lives in a salt-laden, damp environment and is subject to high stresses.
Deck stepped masts
Because the mast step is on deck, it collects salt water deposits, which cause severe corrosion to both the mast step casting (usually aluminium) and the foot of the mast. If the mast has sheaves fitted to run halyards aft, check their condition carefully, just as you did at the top of the mast.
Any corrosion at the foot of the mast should be removed and the surface treated to prevent further deterioration. Severe corrosion should be treated seriously as it undermines the stability of the entire rig.
Keel stepped masts
There are two areas that require careful examination with keel stepped masts: Firstly, where the mast penetrates the deck (the partners) and secondly at the foot of the mast.
It is very common for water to be trapped in and around the mast collar that seals the deck. This area often leaks, especially as vessels age. This frequently causes corrosion to the mast wall and collar fitting. If the yacht has been sailed hard or has running back stays fitted, it is not uncommon for the mast to have been bent or compressed in this area. A thorough inspection is well worth the effort.
The keel step sitting in the bilge is frequently forgotten and can be in poor condition. Remember, this part of the mast provides the stability for the entire rig so it demands regular checks and maintenance.
Deck level fittings
Chainplates (including the backstay chainplates) and the bow fitting are often bypassed in the rush to complete the job. These fittings demand close inspection as they are constantly subject to heavy loads, which are dramatically increased when the yacht is under sail. Look for cracks, elongation, signs of rusting, movement and other damage. Signs of movement are serious; consult your shipwright.
Next, inspect all the turnbuckles. They should be securely locked off to prevent them working loose. There has been more than one mast lost due to a turnbuckle letting go. If the turnbuckles are showing signs of rusting, it is definitely time to replace them. Always replace all of the turnbuckles at the same time; not just those showing signs of deterioration.
Forestays that carry hanks are subject to additional wear so inspect them for damage, wear and loose strands (if made of wire). Loose strands indicate that the wire has exceeded its serviceability so replace it.
Backstays made of modern composite materials are subject to damage from mainsail battens. Often these battens chafe the backstay and weaken the fibres of the stay; this can cause it to fail completely. One or more rollers fitted up the backstay in strategically located positions can eliminate this problem and also ease the mainsail through in light airs.
The boom vang and gooseneck are items that are often ignored. These fittings should be inspected for cracking and excessive wear. Ensure that the fitting remains firmly attached to the mast. There should not be any sloppy movement between the pins and gudgeon. Get your rigger to fit a bush into any worn gudgeons. If the yacht has a solid boom vang fitted, check if the boom has become bent from winding the mainsheet on too hard.
The mainsheet attachment point also warrants close inspection; look for signs of excessive wear, cracks and other damage. If the boom has a central sheeting attachment point, check that the boom has not been bent by the excessive enthusiasm of a mainsheet gorilla.
The mainsheet and headsail track should also be closely examined for wear and damage. The mainsheet car should be removed and overhauled once a year to ensure it provides good service.
All running rigging should be included in the inspection process. Halyards are particularly susceptible to wear as they carry heavy loads. The head of the halyards is especially vulnerable, as they carry the heavy sail and must also turn around a tight sheave. If the halyard is made of one of the modern lines (such as PBO, Vectran or Spectra), the polyester cover will probably have been removed to prevent chafing and jamming. This area should be treated with rope paint such as ‘Corebind’. Halyards made of these modern materials are liable to wear and will typically only last 18 months to two years before failing.
Sheets are also subject to heavy loads and frequent use, hence they should be replaced if they are worn out or there is any doubt about their condition. And like all other rigging components, they should be thoroughly flushed with fresh water after time on the briny to remove damaging salt deposits.
Some aluminium masts are sleeved to add additional strength in a particular area. If your mast is sleeved, always inspect the rivets or screws holding the sleeve in place. If they show signs of damage, deterioration or movement, get a professional rigger to inspect as soon as possible.
Special thanks to Bruce Clark from Sydney Rigging Specialists Pty Ltd for assistance in compiling this article.