So you have a high tech halyard line on your boat already and you still seem to lose halyard tension over the course of the day?
The first place to look is the way you secure your halyard. On most boats bigger than 25-30’ this will be a standard clutch. We will primarily talk here about boats with standard clutches as opposed to cam cleats or a horn cleat. I should also mention here that I’m primarily talking about upwind halyards here. Downwind halyards tend not to get as loaded up as an upwind halyard and as such usually do not exhibit slip in the same manner. Additionally most people are less likely to notice halyard creep on a spinnaker
than they would on a jib or a main sail.
After you set the sail, mark the halyard line (if you don’t do this already) and look where the mark is relative to a scale or the clutch itself. Most people put a deck stickers somewhere near the clutch and either mark it with a pen or a whipping so they can determine a repeatable setting.
So when you go sailing, does the line slip through the course of the day? Let’s assume it does. If it slips a little through the day the first thing you want to look at is the clutch itself. Is the halyard line diameter appropriate for the clutch? Most clutches have various innards that allow them to accommodate a wide range of diameters.
Spinlock XTS clutches for example, currently have two cam sizes. The small range is 6mm to 0mm and the larger range is 8mm to 14mm. As a general thing in order to get the highest performance you want the diameter of the line you’re using to be at the upper range of what the clutch is rated to hold.
This might be a good place to say that line diameters can vary. Cordage manufactures have tolerances for line diameters. For example in order to be considered x diameter it must be +/- x% of the diameter. Just as anything else can have variation in production runs, so can cordage. Some lines run a bit bigger or smaller as a general thing and also line has a tendency to “shrink” down as it is loaded up and the line is put under increased strain so I would recommend taking a set of calibers to the line to see what diameter the problem halyard is.
If you find that you’re at the lower to middle range of what the clutch recommends using and you find the halyard is slipping you might consider bulking your halyard.
Bulking your halyard line can be accomplished in two main ways and serves three main purposes.1) It helps mitigate the potential for halyard-clutch slip2) If you halyard sheave box at the top of the mast is small and you don’t want to strip your halyard, bulking can help you size up to fit the clutch3) Smaller diameter line is less money. Depending on the length of the halyard, the added cost for labor can easily make up the difference of going up a size in the line.
Now there are two main ways to bulk a halyard line. Either you can add cover on top or you can add core inside
- Cover Bulk added: good for existing halyards, easy to add on, cover doesn’t necessarily need to be buried into core. Also good if you’re seeing a lot of abrasion. There are high tech covers that you can get/use that resist abrasion. Also good because if you’re comfortable working with line, this is something you can potentially do at home. Bad for halyards like a spinnaker where it needs to run well. Because it is not buried this has a tendency to catch or snag on the jaws of the clutch. note, this is best used in an application where you can keep the clutch open all the way until you get the bulked area through the clutch and then close the clutch.
- Core Bulk added: preferred method for new line. Runs well. line on the inside can be tapered so it is less likely to snag or catch in clutch. More durable since there is less to abrade. Good because it can be blind stitched as well so it is less likely to slide around on the inside of the line. Bad because it is either difficult or impossible to do on existing line.
Now let’s assume that the line looks good and that you’re at the higher end of what your clutch recommends. Overtime the innards of the clutch can wear down and the cam and or plate can lose some grip as well as the spring cam arm can lose some spring. Spinlock clutches are great about replacement parts. They’re easy to replace but you do have to remove the clutch from the deck so if you’re going to the trouble to replace the cam or the base plate, I’d recommend replacing both while they’re off the deck.
Spinlock has replacement parts for the XA/XAS, X/XTS and XCS clutches. Replacing the clutch parts is actually fairly simple. Here is the great video blog produced a few years back to help walk you through the Rebuilding a Spinlock Clutch process.