Gunter reefing systems

Revisiting the perennial question of how best to modify a Gunter-rigged Mirror for slab reefing...

The simplicity of David Sumner's ingenious two-halyard system on Curlew, documented in his "Mirror Mods" videos: is very appealing. It seems simpler (both to make and less parts to fail) than the wire span + sliding saddle or the sliding track along the yard (gaff) suggested in Roger Barnes' Dingy Cruising Companion, whilst still allowing reefing without fully lowering and re-hoisting the main each time.

But both Jeckyls and the DCA recommend having two rows of reef points, allowing two reefs. This means having three different main halyard attachment points on the yard. And if one wants to avoid fully lowering the main each time one reefs as on Curlew, this would mean three separate main halyards.

I was contemplating something similar to the mechanism shown in Figure 9 of this Duckworths article:

This has a "bridle" to hold the yard against the mast, formed by a line attached to the yard below the halyard attachment point, running around the mast, through a fairlead on the yard and down to a cleat. (Easier to understand from the picture than my description!) The idea being that, for hoisting and lowering, this parell line can be slackened off so the "bridle" can slide up and down the mast easily, and when reefed this line can be tightened to hold the yard against the mast even when the main halyard isn't fully hoisted.

The advantage of this is that it could accommodate as many reefs as you like (even roller reefing if you want), with only one extra line and a couple of farileads. But I suspect there might be a lot of tension on the bridle when reefed, as it's the only thing holding the yard againat the mast, and the fairleads where the bridle attaches to the yard might be weak points.

Has anyone tried something like this on a Mirror? Do people have alternative solutions that accommodate multiple reefs? Or do most people make do with a single reef on the Mirror?

Imagine a short tube (couple of inches in height) that goes round the mast and which can slide up and down the upper half of it, but with a fitting on the mast to stop it going lower than a certain height which we'll call the limiter, so the limiter determines the lowest height the gaff can be held at when reefed (which would be about as low as the gaff can go anyway without getting in the way of the boom and the bundled up reefed part of the sail). Now imagine a fitting on the gaff that hooks into a loop on the ring just like the end of a spinnaker pole clipping onto a ring on the corner of a sail - you'd swing the gaff up and clip it to the ring just by pulling the thin string running from the bottom of the gaff up to its hook to open up the hook, then let go the string to lock it on. To get it right up against the mast there should actually be two hooks and two loops, one to either side of the tube.

The halyard would attach in the normal way just above this new hook part on the gaff and go straight up to the pulley in the top of the mast, so it simply pulls the gaff (already vertical) straight up as far as you want it to go, but it's the tube that holds the middle of the gaff against to the mast and not the halyard, while the tube is also free to rotate. You'd be able to reef easily all the way down to the limiter. The big advantage of this is that the ring has no need of a halyard and never needs to be tightened or slackened off - it just sits there independently. This involves the minimum complexity and maximum utility.

This system also adds to safety by ensuring that it would take more than one thing to snap for the gaff to break free, and even if both rings failed it would still be held high by the halyard - one of the excuses for switching to the Bermudan mast was safety, and another was easier reefing, but this eliminates the danger and makes reefing easy too. With rotation of the tube maintaining better gaff alignment, there may also be no performance deficit, aided by more careful shaping of the bottom half of the gaff.

Another thing I'd do is redesign the lacing system for the lower part of the sail so that there are independent loops for each eyelet which can be disconnected and reconnected with quick-release mechanisms, and perhaps these would just stay on the mast. Maybe they could be solid rings going round the mast, though I can't remember if any would have to get over the spinnaker pole attachment ring - if so, the upper one(s) needn't be complete rings, but could still go round the mast far enough not to pull off.

PuffinInTegel's picture

Toby, I assume you've browsed all the references to "reefing" on the forum (I get 3 pages of hits).
My solution is similar to the duckworks set-up in that diagram. I tie a line to the halyard strap on the gaff and shackle a small block onto the other side of the halyard strap. The line is passed around the mast, through the block and down to a cleat on the bulkhead below the mast step. When I slacken off the halyard to reef the sail, that line goes slack as the gaff comes down. When the gaff has reached the desired (lower) position, I pull the line tight to pull the gaff firmly against the mast. The sail is rolled around the boom.
As I wrote in one of the other threads on the subject, I do not consider a vang to be necessary when the sail is reefed, as one no longer needs maximum sail efficiency when there is too much wind. When you sail close-hauled as shown in the video clip, the mainsheet pulls the sail fairly flat anyway.

David - nice idea! I like the fact it eliminates the extra rope. I wonder if PVC pipe would be strong enough for the slider, at least for a prototype... Tensile strength of PVC pipe is surprisingly high:
Like with the original Duckworths rope version, I suspect it's the attachment to the yard that'll be the weakest point, rather than the slider. But given that a single attachment point is strong enough for the halyard to support the entire sail and yard, perhaps this isn't a problem as long as the fittings are decent.

Gernot (PuffinInTegel) - I had searched the forums,.but I think I only managed to find two reefing threads, not three. And I didn't see / missed your solution. (Do you have a link you could post here?) Great to hear the Duckworths-like solution works in practice on a Mirror! I take your point about getting away without the kicker/vang whilst reefed. I think I personally prefer not having to roll the sail around the boom, just to avoid the hassle. Single-line slab reefing is very convenient at that end of the sail, though haven't tried on the Mirror yet. But more personal preference, than sail performance considerations.

PVC would be fine if you wrap a few layers of carbon-fibre material round it. It's only a little over a tenner for several metres of 15cm wide cloth (see link below). The main worry otherwise would be a crack spreading through the plastic and the whole thing ripping off with ease, but even a couple of layers of carbon-fibre would prevent that happening.

I don't know how easy it is to get small quantities of the usual brands of epoxy at reasonable price, but I've been using a stuff called Craft Resin to make Andean flutes and do all manner of household repairs, and it's so strong that my flutes can double up as martial arts weapons. It would certainly be up to this task:-

This design idea takes the pressure off the halyard and its fitting on the gaff and transfers it to the ring which should be considerably stronger. There are a few remaining problems though. I don't know where you can buy the hook parts that go on the end of spinnaker poles, so you may have to take them off spinnaker poles. It's worth asking around to see if anyone has bent ones looking for a new use.

The next problem is getting or making loops on the ring for the spinnaker pole parts to clip onto, and how to attach them to the ring, but it occurs to me that the simplest way to do this would be a D-shaped metal ring that goes all the way round the middle of the PVC ring. The hooks from the spinnaker pole would clip into the two corners of the D, while the straight part of the D would be between the mast and gaff, and the middle of that straight part of the D could be embedded into the ring to help get the gaff as close to the mast as possible.

Lining the ring up to clip the gaff to it shouldn't be too awkward as you can swing the gaff up toward it from a fair distance round to either side if necessary, and when you lower it you'll always try to release it when it's aligned directly aft.

The string or strings to release the hooks can run up in some of the space between the mast and gaff to avoid extra drag. They only need to be long enough to reach while sitting in the boat with the gaff in its lowest vertical position. If you use two strings, both should be accessible from the same side of the gaff so that they can both be released at once.

PuffinInTegel's picture

I've essentially only repeated my original description. When I get an opportunity, I'll rig my boat up and take a few photos.
The former comment was at .
Gernot H.