A thorough survey of a sailboat’s rig is a job in itself and indeed should be carried out by a certified rigger. For our purposes here however, we are giving the rig a visual once-over to get an idea of its condition rather than a comprehensive assessment.
When looking at a boat to purchase the rig will either be installed or removed and stored. Typically it is assumed a rig stored is much better for surveying, however when viewing for the first time a set-up rig has the advantage of very obviously showing whether or not it is complete. The obvious disadvantage is that much of what you would like to observe is not at deck level. Should you go aloft and have a look? I advise a very definitive NO. You have no idea the condition of the block, line and attachments that would be supporting you at heights that are lethal if you fall. If you want a good look at the aloft portion of the rig, hire a rigger and/or have the mast unstepped and laid out horizontally for your inspection.
Let's first discuss a rig inspection where the mast is stepped and the rigging is in place. This will limit your observations, but you can still learn a great deal. There are five main categories of rigging you should focus on: The standing rigging (the wire rope or solid rod and its attachments); the spars (mast, boom, spinnaker pole, etc); the deck hardware (winches, cleats, cams, blocks, travellers, etc); the running rigging (the line or rope and associated blocks); and finally the sails.
What you are looking for: excessive wear, damage, deformation, corrosion, proper function.
The standing rigging supports the mast(s) and bowsprit if equipped. It will usually be stainless steel wire rope or solid stainless steel rod. In either case there will be a termination and a turnbuckle attaching it to the chain plate or tie-rod that is in turn fixed to the hull structure. Aloft the wire or rod will have a termination attached to the mast at a tang.
How to look: Start with the back stay(s) and examine it from the very base where the chainplate emerges from the deck up to the turnbuckle and its attachments at each end, then up the wire as far as you can see. All parts that are solid stainless steel should be examined closely for cracks, corrosion, and corrosion staining, particularly at attachment points and swage fittings. If you want to be really thorough, use a magnifying glass. On the wire look for distortion, broken strands and corrosion stains. If the rigging is rod pay extra close attention to the termination points as these are the most likely failure points. Do this for each piece of wire (or rod) and its attachments (turnbuckles, terminations, toggles) systematically right round the boat. The simplest sloop will have at least four pieces of standing rigging. If you can, find out the age of the standing rigging. As stainless steel wire and rod is difficult to assess, rigging manufacturers recommend complete replacement at ten-year intervals.
Next check the spars. Most will be extruded aluminum and they are very durable.
Sight down the spar checking for true. Look at the welds, the hardware attachment points, and anywhere the spar will be subject to increased loads. The mast should be examined both from a distance (for true) and from the base looking up. Most of the mast will be too high to make any reliable observations so concentrate on what you can closely examine from the deck. Much of the gear attached to the mast will be in the first six feet from the deck. Make sure to examine the mast closely here for damage, excessive wear or corrosion.
The boom, boom vang, and spinnaker pole are more prone to damage from misuse or accidents so pay particular attention to their condition. Again, attachment points like the gooseneck and sheet bail, and the outhauls, should be examined closely.
The individual items of deck hardware can be numerous so be careful to be methodical in your approach so as to avoid overlooking any. I like to focus first on port side then starboard, starting aft and moving forward examining every piece of hardware as I go. All should be checked for secure attachment, signs of damage or corrosion, and function. Spin the sheaves, work the cams, insert the handles and turn the winches, slide the travellers on their tracks and check the locking mechanism. Broken sheaves are common as are poorly functioning winches, jammed travellers, and non-functioning sheaves.
Finally, check the running rigging. You will likely have developed some notion of the condition of the line from your examination of the other parts of the rig. Now focus just on the line and really observe it closely. You are looking for signs of deterioration from UV and chafe. The most obvious indicator of the line condition is the degree to which it is faded from exposure to UV. If it is significantly faded you will certainly find that on close examination the strands are rough from broken fibres and the line feels stiff. Also look for signs of localized abrasion causing excessive wear. Dirt will also wear the line prematurely so push and twist it to get a look inside and note if it is dirty.
Perhaps the most telling indicator of the line condition is the manner in which it is cared for. If the boat is in off season storage, note if all the line has been de-rigged, carefully coiled, and stowed below (or indoors), or if has been left rigged and exposed to the elements. A boat in use should also show care of the line. Are the headsail sheets de-rigged and stowed at the end of the day? Is the mainsheet coiled and hung off the deck? Are the halyards coiled and hung? Are the lines regularly rinsed with freshwater? High quality line can last a very long time if well cared for. Conversely, it can be worn out in just a few seasons if abused and subject to poor maintenance.
Finally, have a good look at the sails. They will likely be folded and stowed or furled on the boat. The ideal situation is to have all the sails off the boat and in a wide open area where you can unfold them and examine all parts. This will be inconvenient and no one will want to do this. It is up to you to decide how persistent you want to be. A motivated seller with nothing to hide will be willing to make the effort. Once the sails are spread out, walk the entire perimeter looking for chafe spots, repairs, tears, or compromised stitching. Kneel down and grip the cloth in your hands to get a sense of its thickness and stiffness. Scratch at the stitching to see if it is secure and strong. Examine the reinforcement at the clew, head, and tack. Run your hand along the bolt ropes, particularly the luff of roller furler rigged mains and headsails. Grommets and cars should be examined for condition and security.
We have focused on inspecting an installed rig, however, if you are observing a rig that has been removed from the boat and laid out horizontally you will be able to apply the above techniques to all the parts of the rig, not just that observable at deck level. Here are a few areas to focus on and techniques to use with the otherwise un-viewable parts of the rig right there at eye level:
Check all the attached gear on the mast particularly the sheave boxes at the masthead and the spreader tips.
Observe the wire (or rod) from end to end and have a good look at the swages at the mast head and the tangs where they are attached.
While you are examining the masthead check out the VHF antenna, wind vane, anchor light, and any other gear installed (and often neglected) here.
Standing Rig: cracks, evidence of significant corrosion, broken strands.
Spars: corrosion, damage.
Deck Hardware: not functioning, insecure attachment, broken parts.
Lines: old, faded, rough, stiff, chafed.
Sails: worn and thin, broken stitches, missing or damaged grommets and fittings, chafe at bolt ropes and reinforcement.
As the rig is a considerable part of the vessel and its equipment, don't make the mistake of leaving it to the last minute and only giving a cursory look. That may have been the attitude of owners past, leaving the rig in poor shape. Also, use your limited time wisely and focus on the parts that represent the most value and/or expense to repair or replace. For example, a worn main sheet requires little expertise to replace, is readily available, and the cost is low, whereas a mast or sail is a custom job that will cost many thousands of dollars and may take months to acquire, so don't spend an hour examining every line from end to end and then take a quick glance at the mast and sails. Apportion your time logically.