Crane SS cable fail with dinghy 15 feet up

[Streff]

In August of last year, the techs installed a new Warn dc1000 hoist in my crane arm. They rigged about 25feet of 5/16” SS cabling to lift the dinghy up 18feet or so to the upper deck. I asked for Dynema or such, they indicated that the hoist is not designed for synthetic rope and they were worried about chafing inside the Nick Jackson arm.

Initially things worked fine, other the crunching of the SS cable as it wraps & unwraps around the drum and the odd slip of the cable on its down or up. There is nothing to keep the cable tight against the drum so it coils in a disorganized way so its a mess. We try to put pressure on the cable when rolling it in without a load to keep it organized on the drum but nothing really did the job.

Yesterday morning, we are pulling the dinghy up and when its about 15 feet high (almost high enough to pull over the deck), the SS cable snapped and the dinghy made a perfect splash in the water below. Holy smokes ?. No one was hurt and the dinghy seems fine. Wow, a bit troubling. The cable snapped in an segment that does not normally spend much time on the drum.

I took off the remaining cable and rigged the hoist with Dynema as thats the only thing I had onboard. Hoping to try again today and then either use galvanized steel cables or find a hoist that is dynema-compatible.

We all heard the gory stories of cables snapping so we consider ourselves lucky.

Just thought I would share and invite any comments.

Streff

 

[Juliet 15]

Guess i should probably quit having my dog ride the dinghy up and down...



JK...

 

[OldDan1943]

They replaced the cable with Dynema not because the cable was worn out but because there were LOTS of prickles to grab your skink. So far, no complaints.
Remember to make the cable/Dynema long enough that you can lower the dingy to the ground when you are on the hard.

 

[Comodave]

The cable certainly didn’t last very long. Good heads up for others.

 

[High Wire]

>>>The cable snapped in an segment that does not normally spend much time on the drum.

Look at the ends of the cable where it broke. Fatigue fracture? Corrosion? Put pictures on here. That should never ever happen.

 

[twistedtree]

Holy Smokes is right. Yikes.


Understanding the break seems very important. That just shouldn't happen with a new cable.


How heavy is the dinghy, and what is the load rating for the 5/16" cable?

 

[jungpeter]

In August of last year, the techs installed a new Warn dc1000 hoist in my crane arm. They rigged about 25feet of 5/16” SS cabling to lift the dinghy up 18feet or so to the upper deck. I asked for Dynema or such, they indicated that the hoist is not designed for synthetic rope and they were worried about chafing inside the Nick Jackson arm.

Initially things worked fine, other the crunching of the SS cable as it wraps & unwraps around the drum and the odd slip of the cable on its down or up. There is nothing to keep the cable tight against the drum so it coils in a disorganized way so its a mess. We try to put pressure on the cable when rolling it in without a load to keep it organized on the drum but nothing really did the job.

Streff

Hi Streff,

Wow, something's REAL fishy about this installation. To my knowledge, there is no such thing as "....the hoist (WARN dc1000, now discontinued) not designed..." for synthetic hoist cable. And if your techs were worried about chafe inside the Nick Jackson hoist, I bet Nick Jackson would be VERY surprised. And if the synthetic chafes, why wouldn't the wire chafe as well? Sounds suspiciously like a botched initial installation to me, particularly if you heard "crunching" of the SS wire as it spooled on the drum.

True that neither wire rope nor synthetic will reliably spool without overrides, unless a constant load is placed on the hoist cable. Furthermore, I sincerely hope your techs rigged your hoist with more than 25' of hoist cable for an 18' hoist! When I rig a hoist, I insist on one full drum layer at maximum hoist height to ensure adequate drum friction to lift full load. Often times this limits the maximum hoist height, as the drum cannot overfill before the lift is complete, but that's all part of the design equation.

Nick Jackson is one of the premier hoist manufacturers in the marine marketplace. Have you contacted them with details of this incident? I strongly suggest you do so, as a failed dinghy hoist is EXTREMELY dangerous.

 

[Streff]

Pics of cable fail

Thanks for the comments. I have attached 2pics of the cable at the break. We were on a mooring buoy (getting ready to head to a marina) when this happened. It was a real happening that surprised folks around.

We were able to lift the boat with quick rigging with my the Dynema I had onboard.

I spoke to another rigger today and they have ways to make the drum dynema-compatible. And they indicated they have a standard of putting 5 layers of dyne material due to slipperiness, regardless of desired length.

I will be taking the boat to them on Monday. So hopefully, installing a new bigger hoist and improving on the rigging.

Streff

 

[Comodave]

I don’t see any photos…

 

[Streff]

Attaching pics again. Dinghy weighs 735, I measured cable and it’s 3/16”.. I was told WL over 1100, breaking load over 3500.

 

[Streff]

I am going from a 1000# warn hoist to the much beefer 1200# commercial hoist. The opening in the arm will need to be widened a bit and adaptor plate lowered to allow for the new hoist, with loosing the arms integrity.

 

[SeaDogAK]

My winch has a weight on the cable above the hook so that the cable rolls on smoothly when rolling it in without the dinghy attached.

 

[Streff]

I do have a heavy SS donut (removed to take photo) that puts weight when rolling cable in but it still does not pack tight. I has a Rule winch which has a spring on the drum to keep the cable in place.

I took it off to install a hoist to avoid the exact thing that happened.

Streff

 

[Nordlys]

Almost same thing

My Nick Jackson davit had also been remotored and new dynema line just before we bought Nordlys in January of this year. The boat was also in the PNW. (Near Tacoma)—I mention this as “perhaps it was the same outfit that re-rigged yours?)
I did end up talking to NickJackson directly and he was very clear. Our dinghy was dropping perhaps 12 inches with a horrible bang and wobble as we hoisted it. Scared the bejeebers out of us as this was our first crane—previously we had NJ stern Davits. Our crane had been rigged with a Warren Winch and dynema but the diameter that was 1/8 inch larger than what Nick recommended. Bigger was not better. We installed the thinner line (dental floss for an elephant??). Idon’t want to say the actual size as each situation is unique (again—“talk to Nick J).

With the thicker line even with a 10 lb SS weight it didn’t lay right on the drum. So far the correct size line is working well (at least the three times we have hoisted the dinghy).

 

[Streff]

Thank you for the input Nordlys. Our first 4000# warn winch always had 1-2 drops of the dinghy 4-8” with a loud bang. We got used to it. I installed a 3600# Rule winch.. same thing happened and it struggled to pull the dinghy. I agree with you, no matter how heavy a donut was added, the cable or dynema never spooled perfectly.

Talked and exchanged emails with Nick and also with Warn winches. Warn advised against a winch for lifting (Nick said that it should be fine).. Warn directed me to a hoist. The techs installed the warn hoist and it has similar dinghy loud drops but less often. Only 3 cable drum wrap layers can be installed on the hoist to allow it to have the power to lift the dinghy at max height. This had functioned ok for a year but the crunching sound and the odd drop were always present.

I will have a new outfit to do the rigging this time and see.

Streff

 

[twistedtree]

This says the WLL for 3/16" stainless is only 713lbs. Breaking strength is 3500lbs, but still...


https://www.e-rigging.com/three-sixteenths-X-200-foot-Grade-316-Stainless-Cable

 

[AlanT]

I switched from SS to Dynema on my last boat (Bayliner 4788). I disassembled the crane and cleaned up and faired the wheel as it was not very smooth from having SS grinding on it for 20+ years. Dynema performed perfectly and I was careful to examine for chafe every season. No signs.

My current boat has a Jack Nickolson crane with SS wire. There are no fishhooks on the wire, and other than the occasional slight slip when a coil reseats I have had no problems. First sign of fishhooks on the SS and I will switch to Dynema after fairing the wheel.
~A

 

[SteveK]

Query. Did the cable ever jump the pulley and get pinched? something started that break.

 

[slowgoesit]

You first mentioned that the wire was 5/16", then stated in another post you measured it at 3/16". . . . which was it? And does you invoice state 5/16"? If so, they owe you a refund. 3/16" is way too small IMHO . . .

 

[Streff]

Finally spoke to the rigging outfit. Their records show that they planned on installing 7/32” cable. The max recommended for the hoist but rigged 3/16” instead. Now, I can see that 3/16” is not near enough. Glad it happened where and when it happened.

 

[SteveK]

6/32 installed, not 7/32. Sorry but I am not feeling much difference.
Still leaning to it jumped the pulley and damage was done to the cable.

 

[markpj23]

This grabbed my attention.... I just received my Warn DC1000 hoist and will do the installation next week. Owners manual specifies at least 5 wraps on the drum be maintained to prevent slippage.Warn tech support advised that 7/32 synthetic is the max diameter for this hoist. Hoping that using the synthetic line will not cause a big slippage problem.

Highly unusual for a new cable to part as yours did - have you ruled out a faulty roller or that the cable may have jumped the roller?
Glad no injuries - it must have been quite the experience!

 

[Blissboat]

Streff: Thanks for sharing that experience, which must have been freaky. Until your last post I was about to offer the thought that the crunching of the cable on uptake is routine, in my experience at least, as the incoming wraps seat themselves under load. The photos you showed did seem alarming, in terms of the capacity of that relatively thin-looking cable to sustain the load, but then I am often surprised at the stated load capacity of rope and cable. Everything always looks to me as though it ought to be thicker.

Vey glad no injuries and no damage. Good lessons learned.

 

[boatnbump]

I had a boat with 2 warn winches. They work fine but you do need to be right there guiding the cable on the spool. If not the bouncing can be violent. Even if you guide it on perfect the crackle ling and chafing is bad. I suspect the jerking from the cable not being on the spool correct caused the problem. When that dingy drops a few inches is a hell of a lot of force.
The other thing I found with cable is if you pay it all the way out the corrosion on the spool and cable down in where it doesn't get used is scary.
I have dynemia on my new boat I wouldn't use any thing else.

 

[Streff]

Thank you all for the recent comments. When the techs and I spoke with Warn, they indicated that at beyond the 3rd layer of cable, the dc1000 will not be able to lift the 730lbs dinghy for the last few feet. This is also documented in the manual. The dc1000 has the 1000# hoisting capability at the 1st layer and it drops from there. When the techs initially had 45feet of cable, the hoist struggled to lift the last 3-4 to the upper deck.

Warn advised to shorten the cable so that only 3 layers are on the drum. They indicated that fewer layers also reduce the probability of cable tangling and reseating. Reducing the cable length actually worked fine for the first 10 times then the crunching and more slippage started to happen until it the cable failed.

My mistake was to buy a 1000 hoist, I needed a 1200 hoist. The 1200 hoist would require more modification of the crane arm. The 1000 a lot less.

In retrospect, I should have stayed with a 4000# winch instead of a hoist, but warn always advised against a winch. I was trying to do the safe thing.

Streff

 

[Nick F]

Since the discussion has included Warn winches, I would like to share my recent experience in case anyone has similar experience.

I have a 500# Nick Jackson davit on a GB42. It had a Rule T42 winch with Dyneema line and the dinghy weighs about 350#. I bought the boat 2 months ago and it seemed to be working fine but then started to emit a real howling sound under load. I assumed that the gear reduction was about to fail. Rule is now out of the winch business and the winch manual says "sealed for life", so no way to add grease. After contact with Jackson I bought a Warn DC800. Installation was easy, but it also screeches!

I have only used it once so far, and plan to call Warn tech support.

Nick

 

[SteveK]

The dc1000 has the 1000# hoisting capability at the 1st layer and it drops from there.

Now that is some statement, probably true but who thinks about it. The rating is based on an empty reel and as you bring in the cable the rating diminishes rapidly. The last 2-4 feet the winch had trouble with 730#. Too bad ratings are not based on a full reel making this 1000# winch actual only good for 700#.

Still, the cable broke with 730# on the end. Would it break if the dink was left hanging a foot off the water?

 

[bowball]

My steelhead came with amsteel cable.

 

[Stout]

Our Steelhead came with Amsteel line also, but we have the hydraulic cylinder and pulley style winch that is more expensive but does away with the drum style winch issues.

 

[gsholz]

When I bought our last boat, the cable on the davit was all messed up. There were kinks and loops under the first very uneven layer of cable. I don't understand how the previous owner was able to use the davit.

It took me 4 hours with a grinder to cut away the old cable. Installed the new SS cable making sure it was cleanly wound and never had a problem again.

It is really key to keep a constant load on the cable when releasing the dinghy. If you lift up on the hook, you will tangle the cable on the winch and then you are on borrowed time unless you carefully rewind the cable from scratch.

If you go with synthetic line, make sure the end is not constantly exposed to the sun. They make protective sleeves for that purpose.