Use of a preventor

[s sauer]

Vang + Preventer

I have attached the lower fiddle/cam cleat on a 4:1 purchase boom vang to the base of the mast and the top fiddle to a single 3/8" line thru a single block on a mid boom bail. Adding a snap shackle to the free end of the 3/8" line lets you take it back to the mast base as an 8:1 vang or out to the rail as an 8:1 preventer. Snapping down on the control line at the lower fiddle block will instantly release the preventer/vang and because it's a loose line not led thru an organizer, you can control it from either side of the boat or from the cockpit.

 

[Terry Cox]

Hi David, I've been using a preventer for a few years...

now and swear by it. I use snap shackles on both ends; one connected to the toe rail towards the bow and the other to a boom SS ring. I try to keep an eye on the wind angle, but there have been a few times I was unable to respond to a wind shift fast enough, but the preventer saved my butt.If I were using a boom brake the boom would have swung safely over, but I prefer the idea of the preventer so that I do not need to change tacks just make a slight change in angle of attack.Terry

 

[Joseph Shirley]

To Scott & S. Sauer

Scott, it seems your scheme is similar to mine but with a climbing rope the main should bounce a bit in the puffs and waves, and cause chafe in the line at the shackle; and a std cleat would take longer to release in an emergency. S. Sauer, I think I understand what you describe and I understand how you could release it from either side or the cockpit as long as you had the control line tail with you, and that part's OK; But then if you jibe you have to release the snap shackle from the rail , reset your lower fiddle control line, and then crawl around to the opposite side to set the snap shackle again. If I understand you correctly it sounds like a pain to me, or something for a one time use.But then again there is always more than one way to do everything, and what's good for one, is not so good for the other.

 

[Benny17441]

Simplest and best is end of boom to toe rail.

Mid boom in strong winds can cause boom failure. When cruising in moderate winds we'll move the vang to a mid ship cleat as the h320 lacks a toe rail; furthermore the swept back spreaders do not allow full main deployment. Years back we used to run a preventer to a block forward of the mast to the end of the boom.

 

[Noel Hasty]

I do it a little differently, but it works for me.

On my Hunter 34 I use a short (10-15 feet?) piece of old dock line that I tie to the aft end of the boom and take a couple of wraps around the leeward cleat that is next to my jib sheet winch. This sounds like it wouldn't do much to prevent an acidental gybe, but with the B&R rig I can't let the boom too far out and still be off the spreaders so it is enough to keep the boom from reaching my head. So far this has worked well to control accidental gybes and make intentional gybes smooth and easy.Noels/v Principal Pleasure

 

[Terry Cox]

Just as a foot note, if I need to make a tack change...

while on the run, the first thing I do is to release the bow snap shackle and bring it over to the new tack side. I then make the tack change using the autopilot. If the wind is very strong I will take up most of the main sheet slack before I engage the change so that the boom has a shorter distance to travel. As I engage the change I have already prepared the genoa for the change. Once on the new tack I trim the genoa, ease the main sheet, trim the main and set the preventer.Terry

 

[Jerry Clark H356 SV Persi]

Boom vang thru mid-ship cleat to winch

On my 356 I have two lines tied to the boom vang connection at the boom. Each line goes to the mid-ship cleat and through the hole in it. Each line then goes back to the cockpit and if used, goes on the main halyard winch. To gybe, I use wraps around the winch to ease the preventor line out as I winch in the boom with the mainsheet and winch. After I am sufficiently aligned with the wind, I change prevntor lines and let out the boom while taking up the line and securing it on the winch. This system costs almost nothing and works very well and is very controllable. I have used it in winds in excess of 30 knots.

 

[RichH]

Cheap and easy preventer systems .....

://wichard.ingenie.fr/fiche-A%7CWICHARD%7C7150-0203020000000000-ME.htmlhttp://www.cmi-gear.com/catalog/descenders/index.asp http://www.cmi-gear.com/catalog/descenders/R1000.aspAll attached to somewhere near mid boom (strop-lashed to the boom) .. Just use nylon braided 'kernmantel' type climbers rope terminated into a cam cleat to control the amount of 'slip' desired. Since nylon is 'stretchy' would include a bit of 'elasticity' so a 'sudden stop' of the boom results in less impact. Im currently using preventers permanently rigged from the bow. control line runs from a clutch on top the cabin top to a block on the stem then back to the mid boom .... and results in a lot of 'clutter' on deck. Im intending to use the cmi horned descender as a trial. I KNOW this set-up works in mountain rescue work ... all depends on how much 'tension' is added to the descender to adjust for the correct amount of 'slip'.

 

[Joseph Shirley]

Terry, what do you do if

you don't want to make a course change because of rocks, a jetty, or a boat is to weather; and because of a big shift you are already by the lee, and your main is straining to jibe?By the way you mentioned a boom brake earlier and I've had two of different sizes and didn't like them. They are too sensitive to line tension. Too tight and they won't let you jibe, and too loose and they seem ineffective. I sold them both.

 

[s sauer]

What Boat?

Lots of good and varying info here,and some not applicable to all boats. What is YOUR boat. Newer Hunters with long booms and no backstays, with the main sheeted to the top of an arch are much different from mid-80's mast head, high aspect ration B&R riggs with short booms. For our 28.5 I use a preventer in shifty conditions maybe running wing and wing with the 155% Genoa out on a pole to windward. In higher winds I wouldn't run wing & wing or have the 155 poled out and I'd usually have the traveler dropped down with a smaller Genoa sheeted thru snatch blocks out on the rail to open the slot. Again, what works for your boat?

 

[Terry Cox]

Hi Joseph, I doubt I would ever be in any of the situations...

you describe. I normally use the preventer only where conditions permit, since I solo sail most of the time even when the admiral is aboard. I do not have a boom brake and don't want one. I chart plan my routes with plenty of room, so the odds of rocks, another boat, jetty, etc. in the vicinity are unlikely. Anything is possible. In the situation where a wind shift causes the boom to want to gybe I normally change course to compensate for the shift. I would not use the preventer or main in tight hazard quarters, but the engine instead.Terry

 

[RichH]

I think some misperceive the benefits of a preventer .....

even in 'tight' quarters you can tack/gybe downwind easily and simply LEAVE the boom prevented to one side of centerline ... just sail 'on the lee' of the main and have no fear that the boom will accidently swing to the other side. Racers have been doing this for years even with spinnakers flying ... and it 'works'. Without a preventer if you do suddenly and unexpectedly and no matter how good a sailor you think you are .... some day you 'will' accidently gybe under the 'right' conditions .... and maybe so violently that all the sail slugs break from the mainsail luff, etc. and you instantly make a spinnaker out of your mainsail ... or break the rig/mast due to the impact of the 'swing-over'. It 'does' happen. A preventer or boom brake will help to stop this. After the 'first time' I knocked myself out when single handing due to a totally unexpected and accidental gybe and the boat simply sailed on with me unconscious in the bottom of the cockpit for several hours crossing a busy shipping channel several times, etc. ..... I quickly learned to use a preventer. Could happen to you, I was dammmmmmn lucky.

 

[Joseph Shirley]

Terry I hope you never do get into one of those situations

My example was just to get you thinking. It's never a good thing to have to go forward to release a preventer, especially if you are single handing with the admiral on board.

 

[John]

boom brake

Joseph Shirley below mentioned his dissatisfaction with his boom brake. Any others have experience with this? Similar or different opinions?