Boom broke in half with a gust of wind

[KMP]

I wondered if anyone else has had this experience.

We were sailing yesterday in the San Francisco Bay in about 20 knots of SWS wind. I had just released the main sail for bearing away from a close reach to a deep broad reach. I cleated the main sheet. A guest of ours, also an experienced sailor, was at the helm. This is for a 1991 Hunter Vision 32 Sailboat. The mainsail was not reefed and the boat was handling the wind just fine without excessive heeling at a close reach. We had the fractional jib fully extended. (I had done the bearing away in stages. First releasing the mainsail to a beam reach, trimming the jib, and then releasing it to a deep broad reach.

A gust of wind came from around the east end of Angel Island. I am not sure how many knots because it was just a gust and did not sustain, but it was significantly more than the 20 knots we had previously. The sailor at the help kept the boat from rounding up or an accidental jibe, then there was a sudden crack and the boom sheared off just aft of the connection point on the boom for the rigid boom vang.

We just bought this boat used in December 2014. We have been in these wind conditions many times before, as it is often 20-25 knots in the afternoons in the SF Bay during the spring/summer months.

I am wondering if anyone else with a Hunter Vision 32 has ever had this happen to them? I am also open to comments from experienced sailors of any boats and those knowledgeable about boat design and stress factors. What do you think of this?

BTW. We took down the mainsail, rolled in the jib, and looped a line to the broken boom in the water (still attached to the sail) and brought it on the deck and lashed the sail and boom to the deck so it wouldn't go anywhere. then we motored back to the marina (about an hour trip) and brought the boat back to its berth. No one was hurt.

Karen L
Berkeley Yacht Club
Los Angeles Yacht Club

 

[Rick D]

I had the same boat for nine years and that's a plenty strong boom. I have to think it was a previously unnoticed fracture that finally let go. My two cents.

 

[KMP]

Thanks for your input.
Karen L.
Berkeley Yacht Club
Los Angeles Yacht Club

 

[Rick D]

Would suggest you check with the folks here at the Chandlery on this site for sourcing a replacement boom. I would think you just need the extrusion; I assume all the rest of the stuff is intact.

 

[KMP]

Would suggest you check with the folks here at the Chandlery on this site for sourcing a replacement boom. I would think you just need the extrusion; I assume all the rest of the stuff is intact.

Thank you for your suggestion.

 

[kloudie1]

Since the rigid vang was not part of the boat originally, I might suspect that the installer of the fitting on the boom for the vang to bear on might have made a mistake. Have people sat on the boom while being supported by the vang only?

 

[Rick D]

Stock

Since the rigid vang was not part of the boat originally, I might suspect that the installer of the fitting on the boom for the vang to bear on might have made a mistake. Have people sat on the boom while being supported by the vang only?

This model had a hard vang as factory. Having said that, you make a good point as to someone sitting on the boom, etc. I totally agree it sounds a lot like prior damage.

 

[Benny17441]

Either corrosion, a fracture or metal fatigue. It does not matter, that is an accidental occurrence. Report it to your insurance company and have them send an adjuster. A good insurer will pay for a replacement boom plus installation costs less the coverage deductible of course. This is no gimmick nor ruse, it is likely that your insurance premium includes the coverage of the risk of accidental equipment failure as long as the failure was not caused by negligence or abuse.

 

[Jackdaw]

One other input.... on all boat types combined, bearing away without easing the vang is the #1 way booms break.

 

[woodster]

One other input.... on all boat types combined, bearing away without easing the vang is the #1 way booms break.

that is good to know ...it now gives me one more thing to watch for when in operation thanks for pointing that out Jack

 

[tgrady]

Take a look at the fracture ends. It it has a flat area then it is fatigue. That would be interesing.

 

[jlp0217]

One other input.... on all boat types combined, bearing away without easing the vang is the #1 way booms break.

I thought the whole purpose of the vang was to keep the sail tight (reduce twist) when the boom was no longer above the traveler where the sheet controls tension.

 

[Jackdaw]

I thought the whole purpose of the vang was to keep the sail tight (reduce twist) when the boom was no longer above the traveler where the sheet controls tension.

Yes. The issue is the transition from upwind to reach. When you bear off, you really NEED twist.

When you bear off in a breeze, the load on the sail dramatically increases. In most cases you NEED to add twist so the sail is not overloaded. Now, if you just ease the main when you bear off, the sheet goes slack and ENTIRE load of the sail is on the vang, holding the boom near the middle.

When this happens, I've seen booms snap in half, vangs blow, or the fitting pulled from the mast.

 

[topcat0399]

Yes. The issue is the transition from upwind to reach. When you bear off, you really NEED twist.

When you bear off in a breeze, the load on the sail dramatically increases. In most cases you NEED to add twist so the sail is not overloaded. Now, if you just ease the main when you bear off, the sheet goes slack and ENTIRE load of the sail is on the vang, holding the boom near the middle.

When this happens, I've seen booms snap in half, vangs blow, or the fitting pulled from the mast.

Suddenly I'm not feeling so lowly for not having a vang...

 

[Jackdaw]

Suddenly I'm not feeling so lowly for not having a vang...

I think people often underestimate how easy/possible it is to break a boat while sailing in a breeze. When we race in 20+ knots, it is foremost in our minds. Stuff breaks, fittings pull out of the decks, blocks explode. The boom and vang are some of the most susceptible parts, due to the leverage on them. This is particularly true on factional boats is with big mainsails.

 

[Donnybrook]

Now, if you just ease the main when you bear off, the sheet goes slack and ENTIRE load of the sail is on the vang, holding the boom near the middle.

When the main is eased, the vang holds the boom down to control excessive twist. Should not hold the boom near the middle. Am I missing something here?

 

[Jackdaw]

When the main is eased, the vang holds the boom down to control excessive twist. Should not hold the boom near the middle. Am I missing something here?

Only missing something to the degree.

When the breeze is blowing hard, to be safe you HAVE to immediately add more twist to the main when you bear off. That means easing the vang. The amount of twist present in upwind mode is not enough to keep your gear safe on a reach. You have to spill more air. If you don't and a puff hits, stuff can break. Like what happened to the OP. Had they eased their vang, I am 99% sure they would not have broken their boom.

Again, the bigger the boat, the racier the boat, and fractional boats are at the biggest risk. Stout masthead cruisers are at less risk for breakage, but adding twist still helps control the sailplan.