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Boom Preventer using Jib Blocks
Posted: Sat Nov 29, 2008 10:16 am
by c130king
I am getting Bill's EZ Cleats (as soon as he gets the right hardware in). So I was wondering...?
1. Do you still need to use the blocks on the cockpit tracks for the Genoa if using the EZ Cleats?
2. If not, would putting the blocks on the Jib track on top of the cockpit work for a block to use as a boom preventer with the line led back to the cockpit?
3. And where would you attach the line to the boom? At the very end? At the boom bail?
Just wondering if that would work.
My searches found some interesting threads on split main sheets, various methods of using the boom vang, and installing a boom brake...but I couldn't find a thread on using the Jib Blocks.
Appreciate any feedback.
Thanks,
Jim
T minus 20 days and counting....
Re: Boom Preventer using Jib Blocks
Posted: Sat Nov 29, 2008 11:37 am
by Matt19020
I have Bill's EZ Cleats and you do not have to use the blocks on the cockpit Genoa tracks. It does take a little more muscle to sheet the Geneo in a stiff breeze 12+ knots but I would think you would start furling in a little at that point anyway and should not be an issue. I think using the EZ cleats eliminate the need for the winches and is a lot more conveniant when you are single handed.
I have used them for one season and they held up perfectly in up to about 15 knots before furling in.
I do not use a preventor so I can not speak on that but if I did I would prabably start by connecting the boomvang as a preventor to the bail where the mainsheet attaches to the boom.
I am not sure how you would rig a preventor from the tracks on the cabin top. I believe you would need to me more forward then that.

Re: Boom Preventer using Jib Blocks
Posted: Sat Nov 29, 2008 12:14 pm
by c130king
For those that use the boom vang where do you connect the base to in order to use it as a boom preventer? To the forward stanchion where the baby stays go on an

?
I was looking at some pics and it seems as if the cabin top tracks go as far forward as that stanchion. But maybe they are too far inboard to get a good angle? I think I will play with this over Christmas and see what if I can get it to work...I have an old halyard that will work fine for this application.
Jim
Re: Boom Preventer using Jib Blocks
Posted: Sat Nov 29, 2008 2:07 pm
by bscott
Accidental gybes can be very damaging and can jerk a swivel apart or possibly break the base of a life line stantion. Using the mast base will not doo much to prevent the boom from sweeping the cockpit.
I rigged a second boom bail near the end of my boom. It is attached via a 4:1 vang to a spinnaker car on the combing genny track. I use the vang so as to tack and still keep the preventer in place. Once I physically bring the boom to center line I remove the vang from the old leeward rail and fix it to the new one, ready for the new tack. This also helps me control my broad reaching sail shape by reducing boom lift on a reach (something your traveller and boom vang are supposed to do).
Bob
Re: Boom Preventer using Jib Blocks
Posted: Sat Nov 29, 2008 11:52 pm
by Chinook
I'm a great believer in preventers, having experienced a few accidental gybes that luckily caused no damage. I set my preventer lines up before leaving the dock, now, so they're handy and easy to use whenever sailing with the wind. I use my two 50 foot dock lines for the purpose. I run the lines from the cockpit, forward to the pulpit along both starbard and port side decks, pass them through pulpit rails on both sides, and then lead them back to the stern cleats. I tie snap shackles to the bare ends of each line. I cleat off the looped end of each line to the stern cleat, and snap the shackles to the stainless fitting that holds the lifeline in place, at the stern. This keeps both lines out of the way, and yet handy for use without having to go forward while underway. If I want to rig a preventer, I unclip the shackle from the rear stanchion/lifeline loop and snap it onto an eyelet which is mounted on the aft end of the boom. I can then tension the preventer by pulling on the looped end of the line, and then cleating it off. The rig would work a little better if I had a pair of snatch blocks rigged up at the pulpit, but I haven't spent the money for them yet. There's a little friction with the lines running around the pulpit stanchion, but I can still set the proper tension. The key for me is having the preventer lines set up in advance, so it's quick and easy to hook up whenever needed.
Re: Boom Preventer using Jib Blocks
Posted: Sun Nov 30, 2008 12:14 am
by c130king
Chinook,
That is exactly what I was thinking about doing, except instead of taking the line around the pulpit I was thinking of attaching a block to the base of the forward most stanchion on top of the cabin or putting the jib block/cars on the track on top of the cabin and running the line through the block.
I imagine one must yank down pretty hard on the vang to keep the top of the sail from rubbing on the spreaders. But I also doubt I will be doing any long-term running that way.
I will give it a try on December 20 when I unwrap my boat and report back here with results.
T minus 20 days and counting.
Thanks,
Jim
Re: Boom Preventer using Jib Blocks
Posted: Sun Nov 30, 2008 4:33 am
by John Christian
For those that use the boom vang where do you connect the base to in order to use it as a boom preventer? To the forward stanchion where the baby stays go on an ?
exactly Jim, it works great. I doubt its worth purchasing an aditional vang though. Lots of cheaper solutions here. I installed a rigid vang last season so the original was available for the job. I also would like some type of quick connect to make set up a little easier.
Re: Boom Preventer using Jib Blocks
Posted: Sun Nov 30, 2008 10:12 am
by tangentair
Yes as perviously mentioned just move the "base" of the vang over to one of the life line stanchions, but I have been wondering if a small block attached there with a line run back to the cockpit, and the other end running over to the boom where it would go through some sort of twisting or compression device and then on to the other sides stanchion would save climbing up to the mast to connect the preventer or would it be just be more lines on the deck to trip on? On a long run downwind, going up to the mast is no big deal but when manuvering and requiring regular jibs, it might be a convienence.
Re: Boom Preventer using Jib Blocks
Posted: Sun Nov 30, 2008 10:26 am
by c130king
So does anyone think that the jib cars on the cabin top track would NOT be strong enough to work as a preventer? Would it be possible to pull that car out of its track if you accidentaly gybed?
Jim
Re: Boom Preventer using Jib Blocks
Posted: Sun Nov 30, 2008 10:45 am
by tangentair
I think it would be strong enough to prevent it from jibbing, and that is the key, once that boom snaps across it really would not matter much unless you tried to stop it with the preventer before it hit the stays and you should have been pulling on the traveler at that point.
Re: Boom Preventer using Jib Blocks
Posted: Sun Nov 30, 2008 5:42 pm
by bscott
I don't think the cabin top jib track/genoa car will hold up as the boom really has alot of momentum once it passes over the car.
All the accidental gybes I've encountered were so fast that you barely have time to duck out of the way.
Bob
Re: Boom Preventer using Jib Blocks
Posted: Mon Dec 01, 2008 12:01 am
by c130king
Bob,
Maybe I don't quite understand how a boom preventer is supposed to work. I thought that once the boom was out where you wanted for sailing downwind you would pull the boom preventer tight. Thus the wind is pulling the main sheet tight and the captain will pull the preventer tight. Thus there is is no slack so there is no movement and no accidental gybe. The boom won't move...I think.
Is this not the way that a boom preventer is used? To be honest, I have never seen one, just read about them here and in a few sailing books.
Also, as to your statement:
I don't think the cabin top jib track/genoa car will hold up as the boom really has alot of momentum once it passes over the car
If using the Jib Car track on top of the cabin (at the forward most position next to the stanchion), the boom will always be aft of that point never get "in front" of the jib car thus it will never "pass over the car" or build up any momentum.
But even with the main and the preventer tight, it would still be possible to get the main back-winded, especially if sailing "by the lee" or if the skipper wasn't paying attention (but we all know that never happens with any of us...

). So what would happen in this case? I don't know, never done that...my guess is the boat would try to round up into the wind??? But if the main and preventer were tight the boom would not swing across...and that is the point isn't it?
Or am I way off-base here?
Thanks,
Jim
Re: Boom Preventer using Jib Blocks
Posted: Mon Dec 01, 2008 9:58 am
by delevi
I use the jib tracks and the vang bail. Works perfectly. On each jib track, most forward hole, I have a large padeye on a track attachement (same type as jib cars but instead of a car, it's a large padeye.) Vang connects to the mast base via large snap shackle. Disconnect snap shackle and connect to the eye on the jib track. Pull in hard via 4:1 block and tackle of the vang. Works great. I sail "by the lee" a lot, wing on wing slight angle.. approx 170 degerees with the genoa on the leeward side to keep her full. The main still draws, but is prone to gybe w/o preventer. I set up the preventer before sailing this angle. Saved my A$$ many times. The attachments appear plenty strong. Stancions are plenty strong too. I have 5 lines on each side with blocks mounted to the stancions and they do a great job. Just have to mount no higher than the eye for the baby stays. This is one of the stronger parts of the boat and the stancion plates are as beefy as you're going to get. I feel good about the jib car tracks too, since they're designed to handle large loads.
As for the EZ cleats, I contend that there is no way you will sheet the genoa properly for a close hauled tack without the winch unless the wind is very light. I have them. I used them once for the headsail and that was that. For a while, I used them for my running backstays, but I no longer use those, so the ez cleats now reside in my box of spare parts.
Leon
Re: Boom Preventer using Jib Blocks
Posted: Mon Dec 01, 2008 10:45 am
by Paul S
I went with a boom brake to control/prevent jybing. Works quite well..works automatically. The only issue is you have to lock the mast in place on an M, for it to work properly. The dutchman boom brake is not cheap...but installs easily..and can save your life!
The EZ cleats are great. But I do find hard/impossible to release under load. Letting off the wind a bit will allow it to release. But sometimes things happen fast and you want your crew to release it, but they can't.
Jury is still out.. but I think the general ease of use outweigh any downside.
Re: Boom Preventer using Jib Blocks
Posted: Mon Dec 01, 2008 11:08 am
by parrothead
My practice is similar to Leon's, except that I clip the vang snap shackle to the base of the stanchion. I don't find going forward to the mast to do so to be inconvenient, becasue if I will be on a run for any length of time I use a whisker pole to wing out the jib. The vang-as-preventer does a great job of removing the danger of an uncontrolled jibe.
Paul, If you are using EZ cleats for your jib or genoa, try replacing the provided cam cleats with alloy-pawl Harken 150s. They are much easier to release [and to secure] under load. At this point, I've installed them everywhere there was one of those cleats with the black plastic pawls - except on my boom vang, which hasn't really been an issue. Since setting up my crossover rig that brings the jib sheets to the winch on the "high" side of the boat, my EZ cleats are now used only for the spinnaker sheets.
Doug