The Offshore Voyaging Reference Site

Reducing Boom Dip Risk

While we were discussing preventers, a couple of members mentioned being worried about the boom end dipping in the water while restrained by the preventer, particularly if the preventer is attached somewhat inboard on the boom to oppose a centre boom mainsheet.

Certainly a rational worry.

Here’s what to do about it:


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Stein Varjord

“How often do you hear that from me?” 😀
Perhaps not in that sentence, but you try to help people overcome difficulties, dangers and fears, while showing it’s neither especially difficult nor dangerous, as the site name indicates: It’s attainable. That’s a pretty positive attitude, that shines through, and that I applaud! Thank you!

Eric Klem

Hi John,

Like you I have never dipped the boom on a typical cruising boat but also most of my offshore miles are on other types of vessels so I am not a great data point. One where dipping the boom is a real problem is some of the gaffers that have booms of like 60′ on beams closer to 20′. We did a couple of different things to deal with this issue although all of them are far from perfect. The common ones include:

  • Avoiding certain courses in some wind and sea conditions.
  • Sailing without a preventer with the best helmsman (these boats rarely have autopilots so there is a lot of practice here and usually there were 2 or more crew who were good).
  • Using sail combinations that didn’t include certain sails in certain conditions.
  • Oversheeting, particularly when the seas are bigger than the breeze.
  • Having a crewmember tailing the preventer with only a turn or 2 on with strict instructions on when to dump it works for shorter periods like a tidal race.
  • Having a crewmember whose only job is to stand by the preventer with an axe.

Your solution of reducing sail as needed and rocking the reefs combined with the typical geometry of a cruising boat is much better. Dipping the boom could be scary but I have never seen any actual issues with it on those boats. What worried me far more is that putting the boom in the water means you lose your ability to spill more wind and this was a contributing factor in multiple stability casualties.

Eric

Eric Klem

Hi John,

I always took comfort in knowing that a lot of these boats used to do stuff like fish on the banks in the middle of the winter prior to useful weather forecasting. The stuff that they used to endure was unbelievable and the boats were not always well maintained. Nowadays, when we hear of a vessel being caught in these conditions, it is considered negligence such as Robin’s decision on the Bounty. While an awful lot of lives and vessels were lost, the stories of the ones that survived made me realize just how much they could take if handled and maintained properly. To point number 6 of your latest article on boat and gear evaluation tips, with modern forecasting, modern design, modern materials, a well maintained boat and appropriate skills, an appropriate safety buffer can usually be built up so that it is not dangerous.

Eric

Matt Marsh

Two more sailors were killed last night, both by crash-gybing booms in the Sydney-Hobart race.
https://www.abc.net.au/news/2024-12-27/two-die-in-separate-incidents-in-sydney-hobart-yacht-race/104760416
Since it’s only been a few hours and there’s no report out yet, people are naturally speculating. And misinformation is rampant; stuff like “you shouldn’t use preventers in high wind because they do damage when they break; save them for light air only” is being upvoted on reddit etc.
Yes, we know that it is possible to engineer a safe and seamanlike system that will safely control that boom – but a worrying number of people seem to treat dipping the clew, crash-gybing, broaching, getting whacked on the head, etc. as just “things that happen”.

No, they don’t “just happen”. They’re the result of predictable physics, and we can design around them.

Carl Damm

When I sailed on Gaffers, we had “tripping reefs”. Basically a reef that only sets at the clew and lifts the boom end. On most cruising boats I favor a mainsail with a slightly cocked boom: like you said easier on the bimini and the crews heads.