How to Measure the Length of Sailboat Halyards | Expert Advice

Hi. This is Kyle from APS and I’m here to show you how to measure halyards on a keelboat. You would need to do this if you don’t have your boat’s measurements, or if you’re racing and you don’t have access to your one-design measurements, or you just simply want to measure these right on the boat.

Measuring Tape Attachment

All you’re going to need is a 100-foot fiberglass tape measure. ¬†You don’t want to be using a metal one as they can kink. Let’s get started. I’m going to measure this main halyard and it will represent measuring any halyard… I’ll talk through the differences between doing the main, jib or spinnaker as we go through this.

On my tape measure I have a piece of halyard leader that is tied on here very securely. I’m making sure the shackle is closed tightly and I’m going to simply just tie the end on here. I’m going to do a couple of overhand knots, at least three. When doing these, if this were to come apart, somebody is going up in a harness or a bosun’s chair to retrieve this. An ounce of prevention, tape your knots when you’re doing these kind of things so they can’t come undone. Hold this down and I’m just going to simply tape my ends so they can’t untie themselves.

How to Measure a Sailboat Halyard


Hoisting the Measuring Tape

Okay, so that’s ready to go up. As a one-man operation here, I’m going to hold this in one hand, keeping my fingers away from this and I’m just simply going to sky the halyard, pull it all the way to the top. Once I’m there, I’m going to clutch or cleat it off.

How to Measure Sailboat Halyard Length


Measuring Leg One – From Mast to Attachment

Now, I would be tempted to just take this up to where I would attach it to the mainsail and say that’s the length. Well, that’s not necessarily the case because this has dual purposes. This main halyard could be a topping lift for the boom. If that were the case I would put the boom down on the deck and I would bring this back and measure to the end of the boom which is going to be longer than just attaching it to the mainsail. This cruising boat where I have an aerated toe rail, I might be storing my main halyard over here so it doesn’t bash and make noise on the mast. That’s my first measurement.

If this were a jib halyard, I would not measure it just to the head of the jib on the deck. Maybe I store it down on a pad eye even lower, on the deck or I use that halyard as a lift for my dingy through a whisker pole. Think about the longest extension of the working end of that halyard. Spinnakers, same thing. Where am I launching it from? Is it coming out of the companionway? Is it on the deck on the bag? Is it coming out of a forward hatch? When I’m dowsing it, where is it going? How long does that halyard need to be to get it down below or down that hatch, and that’s the point to which you want to take this measurement.


How to Measure the length of a sailboat halyard


Measuring Leg two – Down the Mast

Now to do the second measurement which is the length that’s inside the mast, that’s a little simpler. I’m just going to walk forward. I’ve got my halyard skyed and I’m just going to go down here to the turning block and I’m going to pull this very taut. It’s a windy day. I can take my measurement here. It would be the same for whether it was the main, the jib, the spinnaker, and I’ve got my two lengths.

How to measure the length of a sailboat halyard


Measuring Leg Three – Mast Base to Clutch or Cleat

We’ve got our two measurements. We’ve got the halyard going up the mast and coming down. I’m going to start from right here in measuring my deck length needs. Right at the turning block where I stopped before, I’m just going to run back to just behind the clutch here and I’m going to note that around seven feet.

How to measure the length of a sailboat halyard in the mast


Measuring Leg Three – Clutch or Cleat to Bitter End

The last line measurement I need to take is the actual tail. What’s the maximum number of wraps that I would ever put on this winch, and then what’s the longest length that I would ever need? I’m thinking that’s probably pretty good so I’m just going to mark that. Take this off, grab my tape here, run it that length and I’m looking at 12 feet.

How to measure sailboat halyards on the boat


Total Halyard Length

I’ve got my four actual line measurements. I’ve got from the very end of the halyard up and then I usually add a foot at the top because the tape didn’t go all the way up flush against the crane or the sheave box and the line’s got to travel inside and possibly over a second sheave so I just add a foot in there so I don’t miss anything. I’ve got the first length, I’m adding a foot at the top, my down length and my two measurements here and that’s the length of the halyard that I need.


Total Cut Length of Rope Required

To determine the cut length of rope needed to make a measured halyard (finished halyard length), add 2′ for an eye splice in the working end (for high tech or double braid eye splices), and add 1′ if you will have a reeving eye (Flemish eye) in the other end.

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