Gaff v Gunter lug

[Sabrat]

Since most small boats don't set topsails, why is the gaff rig so popular compared to the gunter
lug?

What are the main diferences and advantages/disadvantages of Gunter lug/gaff sails in boats under 25'?

[Wensum]

Good question, Sabrat. Don't know the answer, but I guess it's just aesthetic. To have gaff rig without a tops'l seems to me to defeat its purpose. For gaff rig the tops'l is crucial going to windward.
I imagine the gunter rig evolved from the gaff and tops'l for ease of handling for the leisure sailing market. My 25' Broads boat is gunter rigged; I don't have to mess about with a tops'l yet can still set up the topping lift and scandalise the main for manoeuvring under sail, which was one of the advantages of the gaff rig, particularly in fore-and-aft pilot vessels and trading ketches of yesteryear.

[brian.cunningham]

Gaff rigs have a lower center of effort for the power. So they're used quite a bit on boats with small righting abilites.

[Sabrat]

Not having used either sail I have to admit I am confused about these rigs anyway. What makes a high peaked gaff as opposed to a gunter lug sail?

They both have a boom, a yard, and they dont protrude forward of the mast. It should be obvious but I can't see it in pictures. Is it just a matter of evolution?

[Ron Williamson]

The gaff(if that's what it's called) on my gunter-rigged Mirror, sets well above the mast-head,almost vertically.
On the Mirror,the mast is much shorter,relative to the gaff,so that the whole rig can be stored inside the boat.

R

[John Kohnen]

Originally posted by Ron Williamson:
The gaff(if that's what it's called) on my gunter-rigged Mirror, sets well above the mast-head,almost vertically.
...
RWhat makes the difference between a high-peaked gaff and a gunter is that the upper spar of the gunter rig is called a "yard." tongue.gif

John

[Don Maurer]

I thought the difference between a gaff rig and gunter was that a gaff has two halyards. The peak halyard controls the angle of the gaff enabling you to reduce sail in a hurry. The throat halyard to control the height of the sail. The gunter has a single halyard so the angle of the gaff is fixed.

[Meerkat]

The folks at classicmarine.co.uk say that the difference between a gaff and a gunter is the angle between the upper spar and the mast. It gets a bit ticklish as to when a "high peaked gaff" turns into a gunter.

What I'm curious about are discussions of reefing a gunter that seem to imply that the sail must be fully lowered to reef and then rehoisted? 'Zat so?

[Todd Bradshaw]

I suppose it would depend upon whether or not you needed to re-tie the halyard to a different place on the yard, but can't think of any other reasons off the top of my head. This is a pretty convoluted issue and there don't seem to be too many absolute truths these days, but in general -

Gaff Rig in a nutshell: Stiff, stout mast with little, if any, flex. Substantially lighter construction on the gaff itself. Usually both peak and throat halyards - though there are some gaff rigs with a single halyard rigged through a series of blocks to do both functions (as it pulls up, it also pulls the peak tight) and others using a fixed bridle on the gaff. The halyard on these pulls the gaff up and the fixed bridle keeps it's angle pretty much constant. Gaff sails are designed and built with seperately calculated and shaped (rounded) luff and head edges due to the markedly different angles and flex characteristics of the spars those edges are attached to. The throat area's job is to tie these two different portions together into a smooth shape and to help create draft in the upper part of the sail.

Gunter: In it's purest (and probably oldest) form, we have the sliding gunter. The yard is fixed by hoops, rings, etc. surrounding the mast in a truely vertical position (or at least parallel with the mast, if the mast is raked). The single halyard does little more than pull the yard (and the top of the sail with it) straight up the mast. It's essentially a means of having a two-piece, telescoping mast, primarily for storage reasons. An effort is usually made to give the lower, mast section and the upper, yard section pretty similar diameter and flex characteristics, the same way you would do if building a two-piece mast which acts like a one-piece mast for a Laser or similar boat. Thus, the lower mast section is seldom as heavy and stiff as a gaffer's mast. The sail is also cut as if the mast and luff are one continuous piece. This is sometimes easier said than done, but the sail is designed as a three-sided sail, not a four-sided sail and the throat's job is basically not to screw-up the set of this long, two-sectioned luff.

The folding type of gunter, with a yard that pivots like a gaff, usually has a peak angle of five to ten degrees, compared to the slider's zero degree angle. It may have only one halyard, but can be, and occasionally is, set up with both a throat halyard, to pull the sail up, and a peak halyard for tweaking the peak angle. This is the one which is essentially a really high-peaked gaff rig but there are usually a couple of differences. The mast/yard portions are often lighter, more flexible and closer to each other both in scantlings and in flexibility/stiffness. In most situstions, there is a fairly serious effort made to get these two spar sections to work pretty much as one unit, which is hardly ever the case on a gaff rig. The folding gunter's sail, like the slider's, is almost always designed as a three-sided sail, where the upper leading edge is designed to be a portion of the luff, rather than a seperate head edge/area. Again, the sail-throat's job is to provide the smoothest transition possible around the jog in the mast without messing up the luff shape. It isn't generally designed to build-in draft or shape.

At some point, reductions in the designed peak angle for a folding gunter will essentially turn it into a gaff rig - in terms of the criteria which need to be met to make it work. The sail will need to be designed and shaped as a four-sided sail and the flex characteristics of the mast/yard assembly will no longer allow it to act as one unit. The heel of a low-peaked yard or gaff can apply a fair amount of bending leverage where it meets the mast. Eventually, I would imagine getting to a point where it's better to beef up the lower mast to take one flexible spar out of the equation, which makes both designing the sail and tuning to get good performance in varied conditions easier.

There are so many variables that I'm not sure that an exact line that can even be drawn dividing gaff sails from folding gunters. But it's a complex enough issue that should you ever get into an argument with someone about your rig, it should be possible to simply baffle them with mumbo-jumbo. At least it's more entertaining than "Yes it is!" - "No it's not!" - "Yes, it is!" - "No it's not!" etc....

[ 01-01-2005, 03:25 AM: Message edited by: Todd Bradshaw ]

[Sabrat]

I was promted to ask this by an article in Classic Boat magazine a few weeks ago.

They showed a couple of late 19th century raters with alternate Gaff or Gunter rigs, but the gunters looked like gaffs to me.

So it really is convergent evolution.

Thanks for the info everyone smile.gif

[Andrew Craig-Bennett]

Originally posted by Meerkat:
The folks at classicmarine.co.uk say that the difference between a gaff and a gunter is the angle between the upper spar and the mast. It gets a bit ticklish as to when a "high peaked gaff" turns into a gunter.

What I'm curious about are discussions of reefing a gunter that seem to imply that the sail must be fully lowered to reef and then rehoisted? 'Zat so?About the reefing business.

A true "sliding gunter" with the yard vertical and secured to the mast by two hoops sliding on the mast, with a single halyard, can be reefed very easily until the heel of the yard is at the gooseneck.

A two halyard rigged gunter with the yard making an angle to the mast can be reefed easily IF the peak halyard goes to a span on the yard, up the the point where the peak halyard shackle is at the upper or outer end of the span.

A one halyard gunter other than a sliding gunter, and a two halyard gunter with no span on the yard, cannot be reefed easily.

I think the gunter rig is probably preferable up to 20ft or so, and becomes impractical owing to the size and weight of the yard at 30 ft or so.

[Rex Fearnehough]

Having recently converted my shetland model back to sail, gunter rig, with help from Todd and the forum. I was lucky enough to obtain wooden mast, boom and spar that were approx 80yrs old. So sliding Gunter rig it was.
The first run terrified me and taught me that practising dropping the rig was essential.
The rig is so easy to handle and when the wind decides to catch you out it can be made safe in around 20 secs, not tidy but safe. To reef is simple, with spar peaked or dropped. I have mine loose footed now and made fast to two cleats. So I can reef easily, dog willing, either by unhitching at the cleats or furling around the boom using the goose neck.
The rig was used up here originally, so that you could fish single handed or short handed. In fact E F KNIGHT only had one hand.