claverton said..
Being both an insomniac and addicted to a rowing machine, I love my podcasts and can recommend the website 59 degrees north (www.59-north.com/onthewind) as having some excellent sailing podcasts, and ones that are more directed towards offshore cruising.

One of interest is a two part interview with respected rigger Brion Toss, and specifically his opinion on the best place on the boom to mount a preventer, and thoughts on preventers vs boom brakes. This is covered in part 2 which can be found at 24.44 minutes into:

59-north.com/sailfeed/2014/10/1/podcast-master-rigger-brion-toss-part-2

Regards Claverton

Many thanks for the link Claverton this will fit into my time scheduled

I have experienced the benefits of a boom brake and now have it on my to do list for 2015 for fitting to my boat (a northshore 33). The main benefit is that a boom brake will still allow the boom to move although slower than in an uncontrolled boom movement. An uncontrolled boom swing can occur from an unintended gybe; or a mainsheet fitting failing; or being hit by a strong gust of wind. A boom brake will prevent the boom from swinging too wildly which can cause a person to be knocked overboard (that's happened t me) and can cause a goose neck fitting at the mast end of the boom to fail (that's happened t me). A preventer is fine to keep a boom in one position in relatively calm seas but is removed at the very times you really need to have some safety protection. The boom brake safety is there all the time. They are a cheap safety feature. Racing sailors who want to spin around and don't want the boom movement constrained by the brake can simply loosen the brake line for the duration of a race and re-tighten afterwards. On a recent trip to Lord Howe Island, the mainsheet block fitted to the end of the boom broke apart when hit with a strong gust just as we commenced the gybe. The boom swung out uncontrolled and the fitting on the other end of the booom that attaches to the goose neck broke. A boom brake would have prevented the uncontrolled swing of the boom and saved the goose neck fitting. A preventer would have done nothing as it would have already been removed in preparation for the gybe.

Both SydChris and HaveFun offer opinions totally opposite to those Brion Toss expresses in the podcast.

I was very much in the boom brake camp and have used one quite a lot offshore but after listening to Brion's podcast am now considering that a preventer mounted on aft end of the boom might be a much better alternative for long distance blue water.

The difficulty of an aft mounted preventer is that they are more complex to put together properly than a mid mounted preventer or boom brake...that is if you want one that you can adjust while the boom all the way out when running downwind. Brion describes how to set them up but I haven't quite got my head around this yet.

The crux of Brion's argument is that a mid boom mounted preventer is inferior because:
1) You are pulling down in the middle of an unsupported length so you get a lot more broken booms. The preventer forces at the end of the boom are supported.

2) mid mounted preventers don't provide nearly as much leverage as and of boom and have more of a vang action rather than a preventer action. The forces are acting down rather than aft, so you have to really crank them up to get them to do any preventing. And when the wind does get behind the sail the likelihood is that the boom will move aft making the situation worse.

He is even more critical of boom brakes but you'll need to listen to the podcast to find those out.
Regards Claverton

Crusoe said..

sydchris said..

A preventer is an excellent way to break a boom - indeed, one of the best ways yet devised. Don't ask me how I know.

I'll sail with a boom brake, but never again a preventer.

Come on sydchris, tell us more so we can learn what not to do. I use a preventer attached to the end of the boom with a loose foot main. All stress on the boom is compression. I'm interested to hear your story in case I have it wrong (again). Cheers

From experience, most people can handle running dead square in daylight in a light breeze with little swell or wave action, but these are hardly conditions in which you'd need anything to slow the boom down in an accidental gybe. Offshore in a blow with a big swell running and a tired helmsperson is another matter. I run symmetrical kites and sometimes the desired course leaves you no alternative but to go as square as you can, no matter what the conditions. The force of the boom coming across in an uncontrolled gybe, especially with a main with a long foot length, is significant; my humble opinion is that a boom brake if properly tensioned will slow down the inevitable whereas a preventer system isn't going to have any "give" in it. And therefore if the force is significant enough the next weakest link is going to fail; this will be either your boom or gooseneck. Or possibly your preventer mount, which then becomes an aft-directed missile. Of course it isn't just an unplanned gybe to be wary of; the boat can roll to leeward sufficiently to put the end of the boom in the water too.

That being said, I do use a form of preventer when reaching (very low chance of a gybe or putting the boom end into the drink) as otherwise even with a tight vang the boom tends to lift as a gust hits, losing the drive effect. But never with the wind aft of the beam - bitter experience (twice) leads me to believe that rigid preventers in that situation aren't worth the risk.

Of course, your mileage may vary. I don't think there is a right or wrong answer....except on board my boats, where I encourage the support of democracy rather than the actual practice of it.

Thanks for telling us a bit about your preventer experience sydchris. cheers

I always use my main sheet traveller to let the boom out, but once I start releasing the main sheet, I always attach the preventer. It is rigged to go from the end of the boom to a turning block on the toe rail just forward of the mast and then back to a winch. The preventer always has tension on it so in the case of wind loading the lee side of the main, the boom is unable to travel any significant distance. I've never had an accidental jibe (gybe) in my existing boat but in a previous cat, (30 years back) the guy on the helm turned the boat and I ended up in the water with gash requiring 6 stitches above the eye. Luckily, the Wujal Wujal Aboriginal community was just up the Bloomfield River where we were attempting to head and the repairs, to the said head, were done promptly. Probably why I'm a bit anal about using a preventer all the time. A recent 3 day/night ocean passage with the wind about 30 deg off the stern and reaching 30knts wasn't a problem.

When I purchased my existing boat, it came with a boom preventer (picky below) and the the rigger I got to check out the rigging said throw the preventer in the bin - so I did. I could see his point of view. For my boat with a loose footed main, the preventer comes into play when the boom is under consider compression stress. To have a preventer pull from the middle could easily cause the boom to flex and bend. A boom, like a mast, is not designed for sidewards flexing. The mast has spreaders and diamond stays to overcome this problem. But the boom has none of these. Would you load up your mast if a spreader was broken - I think not. This is what I think is best for my boat, but in the end you need a system that works for you and you are confident with. It's no use having preventers if you don't use them all the time or fail to set them properly.

Cheers

(just how do you spell gybe (GB) or is it jibe (US) or what) I just read an article about why half the world has green navigations lights to starboard for port/channel entry, then the rest have them on the port side of the channel for entry. Gee I hope we never get visited by Aliens, they'll think were a mob of idiots.

The Walder in the picture has grooves to hold the rope. I made a replica with a smooth drum and could not work out how to prevent overiding turns so I went crazy and spent $13 on a figure 8 decender.

I thought I had it sussed with satisfactory performance in moderate breezes, recently I gybed in fresh conditions and it's effect was minimal to say the least. I have it mounted well out on the boom with a strap around the boom. The theory being the arc would be greater and of course the friction greater. Next move is an extra pass through the ring.

Well that's four minutes I'll never get back. 8 knots of wind is obviously a lot different in the USA than here. Any boom brake will work in that breeze but his certainly didn't.

If the attachment point is abeam the mast on the tow rail or even ahead of the mast the length of rope variation in friction is minimalised.

For any comparison the wind needs to be at least 25 knots across the deck and the boom needs to actually be slowed as it passes over the cockpit. I have the rope through the figure 8 twice now and during the week I gybed in fresh conditions with both sides of the rig tensioned to apply friction. I doubt whether there was any appreciable slowing of the boom.

I like the idea behind the ABS system. Adjustable clutch and a system where there can be no overriding turns. Fairly easy to turn up on a lathe and I shall give it a go when I reduce the projects awaiting my attention.