Standing rigging wire diameter
- Thread starter lipets
- Start date
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Is this a larger steady sail mast with boom and topping lift or a winch or just a short signal lighting spar ? If the later I’d just go with 1/8” 7x19 stainless wire often called aircraft cable with Nicopress crimp terminals. Plenty strong, readily available and easy to install.
Rick
Rick
Lostsailor13
Senior Member
Did my cables this past summer used 3/16 with swageless fittings,don’t scimp out you’ll just have to them over sooner
With a sail and running rigging to lift your tender this changes the equation quite a bit. Questions like is there a headstay running forward or just shrouds port and starboard ? Then how are the shrouds and stay secured, are there plates ( chainplates ) or just through deck pad eyes do the terminate at the mast head or below. Not trying to make this overly complicated but with hoisting a tender this is now a dynamic load and accidents can happen that can put a heavy shock load on the mast and boom. I wonder what was the wire size originally and did it fail ? So at minimum I’d go no lighter than 3/16” wire ( with a safety factor of 4-5:1. I don’t believe you need stiff 1x19 wire so flexible 7x19 wire will work. Your hoist line should be matched to your boom sheave it may be larger. Without seeing your set up I’d honestly suggest going out and checking other similar boats with your type of rig. Sorry for not helping more but sometimes a little scouting is best.
Rick
Rick
jungpeter
Guru
Hi Rick. All excellent points. And you're NOT trying to make this issue more complicated-it IS more complicated. By a bunch. ASAP the Original Poster lets on that he's using the mast to launch and retrieve a dinghy, even a tiny one at 100lbs., this issue becomes a very real safety issue. Many, many people have become injured (and some killed) by attempting to launch a live load off a boat with substandard hoisting gear. And unfortunately, this includes not only the mast and boom, but all the associated hoisting tackle as well. NOT items that a scientific wild-assed guess without knowledgeable boots and eyes on the scene can specify. lots of leverage through many parts and pieces anchored to the deck in who knows what fashion for wild assed guesses on wire size! And just because the OEM built the boat in that fashion is no guarantee that rigging is satisfactory for hoisting much of anything.
I'm pretty sure it was Archimedes that said "give me a lever long enough, and a fulcrum strong enough, and I can move the world". I bet he was trying to launch a dinghy from a trireme when a wave came along when he uttered those words. Immediately after shouting "Oh Ship!"...
Color me cautious,
Pete
Pete my gut tells me you have some technical depth and experience on this subject and probably capable of dragging me into deep water. Only kidding, I think, but your advise is solid. I won’t add anything more to the OP’s question because there are way too many variables but as a old worn out surveyor I can offer this particular loss case.
Insured’s vessel was moored at Avalon harbor at Catalina Island which is a popular destination about 25 miles off LA or Long Beach, CA . They had lowered their Avon inflatable with outboard off the upper deck and left it hanging about 8-12” above the surface, as I was told. They went below for lunch etc. ( nooner ? ) and felt the boat being hit by what was apparently a good size wake. He ran up to cuss out the perp when the mast and boom came came down on the upper deck. Investigation and conclusion revealed the wake hit the hull and flipped the inboard rail upwards on the back splash against the hull allowing it to fill with water and the secondary wake wash pulled the mast and rig down. Losses of this type are covered as fortuitous, some may say stupid
Rick
Insured’s vessel was moored at Avalon harbor at Catalina Island which is a popular destination about 25 miles off LA or Long Beach, CA . They had lowered their Avon inflatable with outboard off the upper deck and left it hanging about 8-12” above the surface, as I was told. They went below for lunch etc. ( nooner ? ) and felt the boat being hit by what was apparently a good size wake. He ran up to cuss out the perp when the mast and boom came came down on the upper deck. Investigation and conclusion revealed the wake hit the hull and flipped the inboard rail upwards on the back splash against the hull allowing it to fill with water and the secondary wake wash pulled the mast and rig down. Losses of this type are covered as fortuitous, some may say stupid
Rick
OP
OP
lipets
Senior Member
I think some of you are over thinking this, two or four 3/16" wire has the combined breaking strength of 6-8,000lbs +
To my knowledge no Beneteau mast has failed some with the motor on the raft
I think I'll go with 3/16" 7x19
The secondary key is the lines hoisting the load, much easier to find the minimum requirements
To my knowledge no Beneteau mast has failed some with the motor on the raft
I think I'll go with 3/16" 7x19
The secondary key is the lines hoisting the load, much easier to find the minimum requirements
jungpeter
Guru
Hi Rick,
And another loss case: I was cruising in concert with a good friend in SEAK in 2016. As my fellow cruiser began to hoist his tender aboard the boat deck on his OA54, and the tender was about rail-high on the boat deck, a splice failed in his hoist gear. The tender hit the boat deck rail and overturned, then fell ~10 feet back overboard. Fortunately, as he is a VERY experienced owner/operator, he was not standing under the boat, so his only loss was about $8K for a new outboard, about $1K in onboard electronics, and another $2K in camera gear. Scared the bejessus out of all concerned.
And another: I was rafted alongside a friend at Opening Day in Seattle three years ago. We were all gathered on my boat for the festivities. Out of the blue, with no one aboard, my friend's dinghy hoist winch began to reel in his hoist cable, which was dead-ended to a padeye on his boat deck. I was the first to hear the winch spooling, and realized that something was amiss. Several of us jumped aboard and scrambled to find his main battery switch, and his hoist controller. Before we could sort it out, the winch cable overcame the hydraulic boom hoist cylinder, causing the boom to fail violently and crash into his boat deck. Again, fortuitous that no one was in the way, but it did do several thousands of dollars in damage to the hoist and his boat deck.
Yeah, I've been around this particular rodeo multiple times in both my professional and recreational maritime careers. And learned enough to definitely "over think" all things associated with hoisting aboard a boat.
To the Original Poster: I wish you all the best. PLEASE, PLEASE don't stand under your tender when launching or retrieving the thing. If you take the care to actually calculate the loads in all parts of your standing rigging, and apply an industry standard margin of safety to the rig, you'll find the safe working load of your wire rope diminishes in a hurry. And it is almost never the weak point in a dinghy hoist.
Regards,
Pete
