Backstay Failure

Apr 29, 2012
216
Beneteau 35s5 bristol ri
I demasted last week. When I got to the boat I noticed that the clevis pin in the backstay was gone. Could this have had anything to do with the fractional mainstay failure. I've been told that when in big swell on a mooring the mainstay can become slack and if the backstay is detached this could cause a shock effect causing this. Any feedback? I should get a hydraulic backstay tensioner
 

Joe

.
Jun 1, 2004
7,999
Catalina 27 Mission Bay, San Diego
Uh.... yes. That would be a problem. You need to get someone out to go through you boat and make sure there isn't anything else catastrophic waiting to happen. Check your through hulls.
 
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Oct 19, 2017
7,732
O'Day 19 Littleton, NH
When I got to the boat I noticed that the clevis pin in the backstay was gone. Could this have had anything to do with the fractional mainstay failure.
Just to get a better picture of the situation here.
You dismasted at the dock/mooring or under sail? You found the backstay disconnected, but the mast came down as a result of the forestay parting?

I'm imagining you found the boat dismasted at her mooring with the forestay parted and the whole and sound backstay disconnected. Your mast was being held up from tension on the sheet to boom and topping lift (boom to masthead), instead of the backstay.

In wind and waves, there would be stretch in these components that would allow the mast to snap backwards against the forestay with each gust and wave. The factional configuration would only compound the forces against the forestay. This is an example of why rig tuning is important.

What type of boat are we talking about?

-Will (Dragonfly)
 
Jan 11, 2014
11,321
Sabre 362 113 Fair Haven, NY
Like @Will Gilmore I"m a little confused about what happened.

There is no main stay on a boat. There is a forestay, a back stay, cap shrouds (or uppers), and lower shrouds.

If the forestay failed, the mast might well come down depending on the conditions. If the clevis pin in the backstay fell out, the combination of the the topping lift and mainsheet should support the mast well enough to keep the mast up if they mainsheet is tight enough.

If you have roller furling and the jib is in place the jib halyard and jib should support the mast.

If indeed the mast fell down, then before worrying about buying an expensive hydraulic backstay adjuster, the rig and mast need to be carefully inspected for damage as well as the deck and hull structure.

This is a good time to call your insurance company and inform them. They will help you assess the damage and determine the best course of action.

Dan at Rigging Only in Fairhaven MA is a knowledgeable rigger talking to him might also prove fruitful.
 
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May 29, 2018
457
Canel 25 foot Shiogama, japan
Did the mast fall forwards ( a backstay failure) or did it fall aftwards (a forestay failure)?

Gary
 

RoyS

.
Jun 3, 2012
1,739
Hunter 33 Steamboat Wharf, Hull, MA
The only way you can have a clevis pin fall out is if it was secured with a ring type cotter pin. These often work their way out. Critical clevis pin applications should have a properly sized split cotter pin. And, it goes without saying, never use a hairpin type which is for truck tail gates and the like. If someone used one of the ring types on the back stay, they probably put them on the other stays as well. Sorry for your troubles.
 
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Jan 1, 2006
7,039
Slickcraft 26 Sailfish
Huh? I used ring type cotter pins for decades and never saw any evidence of them working their way out. I preferred them to the jagged edges of the split cotter pins.
 
Jan 11, 2014
11,321
Sabre 362 113 Fair Haven, NY
Huh? I used ring type cotter pins for decades and never saw any evidence of them working their way out. I preferred them to the jagged edges of the split cotter pins.
Not all cotter rings/split rings are equal. The ones that are easy to install can work their way out. The ones that are harder to install are more secure.

For smaller boats, under 30 feet Scar Pins work well. these are cotter pins glued to velcro, insert the cotter pin, wrap the velcro around the turn buckle and your done. Easy, secure, and no taping the turn buckle.

 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
Huh? I used ring type cotter pins for decades and never saw any evidence of them working their way out. I preferred them to the jagged edges of the split cotter pins.
ALL of my rigging has the largest"SPLIT rings" possible in the turnbuckles. NOT the "cotter rings" where the end is curled inward. Makes it easy to look 360 and see if any are missing. In 14 years, none have failed. If you have clevis pins, make sure the "head" is on the uphill end. Upside down, the pin can just slide out from vibrations- which may well be why your rig failied? :yikes:.
 
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Sep 25, 2008
7,075
Alden 50 Sarasota, Florida
I’ve often thought of suggesting we have a forum topic here labeled “routine maintenance” or “inspection” items every boater should do. Unfortunately, we often read here the stories about what happens when people don’t...
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
I’ve often thought of suggesting we have a forum topic here labeled “routine maintenance” or “inspection” items every boater should do. Unfortunately, we often read here the stories about what happens when people don’t...
Not actually a bad idea, but there ARE dozens of books on the subject... and Christmas is coming !
 
Sep 25, 2008
7,075
Alden 50 Sarasota, Florida
Not actually a bad idea, but there ARE dozens of books on the subject... and Christmas is coming !
I know but can’t help wonder if the folks who don’t do the work would buy the books describing what they don’t do.
 
Jul 27, 2011
4,989
Bavaria 38E Alamitos Bay
Use ones like this. They do not fall out. The Bavaria came with this type of ring cotter on the life lines, but slightly more elaborate: Z-shaped inside the ring.

 
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Jul 27, 2011
4,989
Bavaria 38E Alamitos Bay
I demasted last week. When I got to the boat I noticed that the clevis pin in the backstay was gone. Could this have had anything to do with the fractional mainstay failure. I've been told that when in big swell on a mooring the mainstay can become slack and if the backstay is detached this could cause a shock effect causing this. Any feedback? I should get a hydraulic backstay tensioner
So, your boat is on a mooring or in a slip and when you came that day the mast had fallen down, forward? You evidently do not have swept-back spreaders. So, if not then yes. if the backstay is loosed, the mast might fall forward although the lower shrouds should resist it.
 
Jun 25, 2004
1,108
Corsair F24 Mk1 003 San Francisco Bay, CA

All rings need to be covered with self amalgamating rigging tape. That short end can of wire that sticks out be caught by a flailing sheet and pulled out. I’ve personally seen it happen.

Split rings without straight sections can be easily deformed by flailing sheets, and can be pulled out too.

in short, rings are more likely to be damaged than cotter pins, and require more frequent inspections and taping to remain safe.
 
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Jul 27, 2011
4,989
Bavaria 38E Alamitos Bay

All rings need to be covered with selfamalgamating rigging tape. That short end can of wire that sticks out be caught by a flailing sheet and pulled out. I’ve personally seen it happen.

Split rings without straight sections can be easily deformed by flailing sheets, and can be pulled out .

in short, rings are more likely to be damaged than cotter pins, and require more frequent inspections and taping to remain safe.
Yes. The SA rigging tape covers my pins on the shroud turnbuckles. But there I have the straight cotter pins. The ring pins are on the lifelines but those are not taped. :what: The ones on the Bavaria a little different on the straight part; more secure. Can’t find them here.
 
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Jun 25, 2004
1,108
Corsair F24 Mk1 003 San Francisco Bay, CA
Any attempt to describe the mode of failure is pure conjecture at this time, given the paucity of information.
 
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Oct 26, 2008
6,044
Catalina 320 Barnegat, NJ
I know but can’t help wonder if the folks who don’t do the work would buy the books describing what they don’t do.
Good point. I follow up on a lot of stuff I read in here. I haven't looked for a maintenance book in who knows how long! I prefer rings over pins, too. I've read all the pros and cons and just don't like sharp points. The rings I use are hell on the space between my fingernail and the flesh, though. It can be a week of irritation after I've installed them. :banghead:
 
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Jan 11, 2014
11,321
Sabre 362 113 Fair Haven, NY
The rings I use are hell on the space between my fingernail and the flesh, though. It can be a week of irritation after I've installed them. :banghead:
Use a small screwdriver to open them up. Sometimes it is a bit tricky to get the ring into the pin, but it is much easier on the finger nails.
 
Oct 26, 2008
6,044
Catalina 320 Barnegat, NJ
I'm often too lazy to get up to find a tool. I've been known to use my fingernail as a screwdriver. It usually doesn't work but that doesn't stop me from trying! :confused: Actually, my preferred tool for the ring dings is a needle-nose plier to grip & twist. I can use it for cotter pins, too. I usually look for tools only after I tear up my fingernails. :facepalm: