A bad day up the mast - Page 5 - SailNet Community
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post #41 of Old 09-25-2011 Thread Starter
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Originally Posted by JonEisberg View Post
Well, while I may not care much for the look of that tang, how can you determine from those pics that the shackle post on that block does not swivel?
Jon - You have a good eye. When I replaced the block I looked carefully at the tang. It was clearly formed with the bend in it, probably so that the shackle wouldn't foul. When you are right up there it is clearly a formed bend and not a deformation. Both the original and new block (actually the shackles) are definitely clear +/- 120 degrees in azimuth and from 45 degrees above the horizontal down to mechanical interference of the block with the mast in elevation.

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post #42 of Old 09-25-2011
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Find something that doesn't have plastic. I haven't seen a block with anything but a composite sheave in a long time. Masthead sheaves are pretty much all composite. I think gross generalizations are short-sighted and not well informed.

Have a car? Lots of plastic parts you are trusting your life to. Oh by the way - that boat hull that keeps you safe? Plastic. Rudder? Plastic. Look around. Better stay off airplanes. Composites are a reality that in most cases are stronger and lighter than traditional materials. Instead of rusting they deteriorate in other ways.

That's why safeties and secondaries are a good idea.
No problem with composite sheaves...as long as they have a s.s. pin and bushing (which they do) or with plastic hulls, although I'd prefer one made from 316 s.s. Plastic is great for many things but not for any critical link in something holding me up in the air 50'! Actually, just had the plastic sheave crumble into sharp pieces in my main sheet fiddle block and am replacing with aluminum so I guess I do have an issue with plastic sheaves as well. Plastic is comparatively cheap to make and boosts profit margins for manufacturers who can then turn around and charge exorbitant prices to yachties. Racing boats have a reason for composites-weight. Do cruising boats REALLY have a need to save a couple of pounds and sacrifice the surety of a solid metal connection? I think not. It's like the idea of attaching a good piece of G4 anchor chain to a plastic pad eye. Plastic-bodied blocks just scare me.

The plastic technology in products like Dyneema, etc. is great for boats. I replaced my old s.s. lifelines with Dyneema. In that case I think the trade-off for using a lifeline subject to cuts and sun deterioration is outweighed by getting rid of all the swage failure points of s.s. wire. My jacklines are composite and not roll-under-foot wire. I guess many of these decisions are trade-offs but not in the block suspending me 50' up. The picture of that block is evidence enough, yikes!
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post #43 of Old 09-25-2011 Thread Starter
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You make some interesting points Murph (is that appropriate?) but your plastic lifelines are potentially a more significant safety item than a block. If my block had failed completely I would have fallen a max of six feet (still no fun). If your lifeline fails you go overboard. Plastic jacklines, plastic tethers, most likely a plastic harness.

I'm not poking at your choices -- I have made the same ones -- so much as pointing out that composites are everywhere in our lives and we trust our safety to them every day. Again, backups and safeties are important regardless.

That's why I'm nervous about going up on my wire-to-rope halyards and choose the fiber ones instead. That's why I tie my own bowline instead of using a shackle on the chair.

Oh - and I was 65' up. *grin*

sail fast and eat well, dave
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post #44 of Old 09-25-2011 Thread Starter
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Based on visual inspection under 10X magnification there is no question in my mind that the cheek failing was the proximate cause of the issue. The line jumping out of the sheave was a result of the cheek failure.

sail fast and eat well, dave
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post #45 of Old 09-25-2011
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Not to mention sails themselves---all plastic. Agree completely about not trusting wire-rope splices. I did away with the wire to rope splice last year and replaced it with wire, ended around a thimble with a halyard knot. The rope/knot really never needs to go over the sheave and when tensioned, there is only about 2' of Sta-Set left above the winch, virtually eliminating stretch. Has worked out really well. The topic of going over the side is always a hot one. I can travel stem to stern on jacklines without unclipping. The concern I always have is not so much whether the plastic is strong enough, it's knowing that I could easily go over the side in the right set of circumstances while attached to the jacklines. Getting back aboard could be difficult. Speaking of secondary safety lines, using the second tether to tie around the mast or clip into a pad-eye at the bow makes being tossed over nearly impossible from the work positions. It's traveling to them that can be a challenge.
Murph I am.

Last edited by smurphny; 09-25-2011 at 08:14 PM.
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post #46 of Old 09-26-2011
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Some of us like to get high

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post #47 of Old 09-26-2011
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Quote:
Originally Posted by SVAuspicious View Post
I believe that what happened was that the cheek of the block (which did and still does swivel incidentally) failed, probably from cumulative UV exposure. I suspect that when the alignment of the sheave axle shifted the line moved off axis and caught between the edge of the sheave and the cheek.

The line was not wedged or jammed. I pulled it out from between cheek and sheave with one hand.

The new block has stainless steel cheeks, and yes it swivels also.

I saved the broken block. I'll disassemble it and see what else can be learned.
For that sort of application, the Harken Hi-Load blocks are pretty nice, those cheeks are pretty solid, not much plastic there...

Here's my spinnaker halyard, the block at the masthead is the same, but with a becket...




I've really come to like having a 2:1 halyard, it's a very practical way to go for a cruising boat - especially if you're lifting a tender onto your foredeck, or hoisting it clear of the water overnight, or when not in use... Could really come in handy in an emergency situation like a MOB retrieval, for instance. Unless you're racing, and need a the speed of hoisting or dousing afforded by a regular halyard, a 2:1 is a really nice way to go, IMHO... and, if you're using a Code 0, you really need it to obtain sufficient luff tension...
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post #48 of Old 09-26-2011
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Some of us like to get high

Whoa, if I'm gonna get high, I'd sure rather see the guy cranking me up there take more than ONE wrap on the winch drum...

That's putting an awful lot of faith in the self-tailing mechanism, which are not really intended to retain a significant load...

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post #49 of Old 09-26-2011 Thread Starter
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Originally Posted by smurphny View Post
Getting back aboard could be difficult. Speaking of secondary safety lines, using the second tether to tie around the mast or clip into a pad-eye at the bow makes being tossed over nearly impossible from the work positions.
I agree there. I like the two-leg tether with a standard webbing wrapped around the mast and clipped back and the elastic one hooked to a padeye when things are particularly bumpy.

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Whoa, if I'm gonna get high, I'd sure rather see the guy cranking me up there take more than ONE wrap on the winch drum...
*grin* My first reaction was exactly the same.

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post #50 of Old 09-26-2011
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tough crowd!

that close up was shot after the fact. Nobody was in the air.

the video was purely meant as entertainment, not instructional.
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