Preventers and gaff rigs

During the recent GCBSR, we spent quite a bit of time running downwind wing and wing. We were getting shoved around a bit and accidently jibed the fore over quite a few times (more than I will ever freely admit!).

We considered rigging a preventer, but I had never used one on a gaff rigged sail and was concerned about sail damage if the gaff went over and the boom didn't. I don't know how likely this is, since I would assume the gaff would be sagging more off the wind than the boom.

On the trip home, in much less wind, we did rig one and it worked fine. I am curious about other peoples thoughts and experiences.

Anyone use preventers?


Yes to preventers

We often use preventers on Comet II on the fore and main as needed (both gaff). We have had the gaffs go over and just gybed them back--we have never suffered any damage. I could see that there might be damage, but I'd worry more about the result of an uncontrolled gybe!
Alex Rhinelander
Schooner COMET II

Yes to Preventers

We always use preventers. Have not been on a boat (schooner or otherwise)that does not use them as a safety consideration (ever been hit in the head or seen someone hit by a jybing boom and been carried overboard with it?)

Its a good safe practice. Even in light airs.

Yes to Preventers

We have used them a lot on the foresl over the years and never had any damage if it tried to jibe. The gaff just tries, then comes back. On the main I prefer a vang from part way out the boom set with block and tackle to the rail. Takes some of the twist out of the sail and keeps it off the shrouds and spreaders. On bigger boats with bigger crews they used to rig preventers on the gaffs as well, at least on the long runs. But God help any man overboard! I've never tried a gaff vang downwind but they do work well to windward by getting the sag/twist out of the fore. There are a couple of ways to rig a fore gaff vang, but the right way works best.

Gaff Vang

Vern, you bring up a good point on vangs. The original 309 sail plan by A Neilson did not include a foresail gaff vang at the peak. Carl Alberg did our original sail plan, and in addition to moving the foremast a little aft, his plan included a vang for the foresail gaff. There is a block on the mainmast just below the spring stay that leads a line to the end of the gaff boom where its is secured with a bowline. It doesn't require much effort to pull in when going to windward so we just cleat it off on the main pinrail. It pulls the peak of the foresail up and in and removes the twist. Its also usefull if the gaff jibes aloft when you have a preventer on the foresail boom, as you can pull the gaff back across with a tug on the vang, and then let it back off gently. We also occasionally use it reaching off with a fisherman if the end on the gaff is rubbing up too hard on the fish. For a smaller schooner, its very simple to rig and has a lot of utility.

Just remeber to slack it when you go to lower the foresail, or you look pretty stupid with the throat half way down and the peak hung up by its tail.

A bit confused

Vern, I'm a bit confused. It was my understanding that a boom vang, by definition, is attached to the same pivot point as the boom gooseneck, ie the mast. Its job is to apply downward tension to the boom regardless of the point of sail. How does that prevent an accidental jibe? If it is moved to the rail, doesn't that make it a preventer?

boom vangs and preventers does.
Barnacle Bill

Fore Gaff Vang

Boom vangs and preveneters are similar but differ in attachement points. Also don't confuse a fore gaff vang and a boom vang. A forsesail gaff vang and a boom vang are two entirely different sail tensioning lines and are attached to different spars. Go to Carrick and Henderson, John G. Alden and His Yacht Designs page 134 to see how the fore gaff vang is rigged on Twighlight and then see comment on photograph at top of page on Page 136. I think the purpose of the fore gaff vang will be immediately apparent. Most schooners, even Alden's don't commonly have them in the sail plan. I have seen very few schooners that use them today. The sail plan on Lalenta II on page 179 and Grenadier on page 194 also show a fore gaff vang, as does Malabar VI on page 46.