There was a recent thread on "halyard snare" a bit ago. I have been posting in the "How much is too much" thread & thought to add what I did to alleviate this halyard jamming on my C30.
My boat neighbor has his halyard jammed between his sheave, pinched between the sheave, his shaft & the inside of mast crane casting. Well, this is how it happens most often.
You're boat is hobby horsing in head seas. You've probably just lowered your main but, something happened & you let the external halyard have too much slack in it. This slack causes the halyard to whip loops vertically up the mast causing the line to pop off the sheave. Now the harder you pull, the more jammed the halyard becomes. The following are some posts I wrote in the "How much" thread that got me to thinking about this & begat my fix.
My first post:
Someone mention on this thread of weight strain on the sheaves in the mast crane.
Speaking of this, I had a scare I found myself in. I used my Top Climber 4 times one weekend doing steaming light changeout, spreader boots & Windex/antenna changeout a few years back. On my 4th. trip up, I discovered that my cast aluminum crane had a vertical full top-to-bottom crack along where one sheave shaft 1/4 to 5/16"" dia. was attached w/cotter pin.
There I was, almost 50 feet up & my crane had failed. Oh let me tell ya, it was a scary trip back down. After dropping the mast, I discovered the shaft had also bent. Now, I only weigh in @ 150# & yet, my crane had failed. Could this cause me to fall, I don't know. Was there a chance of this happening?
I assume I was not the only one to climb the mast, as I had a rigger go up before. But, this is just something to think about.
About rope & tensile strength, here's a link to various charts that may help.
https://www.google.com/search?q=rope...w=1106&bih=509
============================================
My second post:
Thin,
Yea, I agree with you pal.
My story here in thinking, here's what I thought could have happened to me with the cracked crane.
The initial crack happened at the front sheave. What if the crane now being stressed, developed the same type of crack along the rear sheave? Remember this is cast aluminum, not the strongest material against structural failure.
With external halyards, had the whole side failed, there was a distinct possibility of the halyard rolling off the sheaves & now nothing to stop the rope from falling to the deck, with me attached.
People are killed every year with going up the mast, both experts & owners as you had described. I still think that folks new to mast climbing, should have experienced people to show them the "Ropes" first & then go in stages while they are learning.
Sheaves & shafts are designed to raise sails, maybe not the more weighted people.
=======================================
So, when I installed the new crane w/internal halyards, I tackled two issues. The first was the mast crane was open top. This allowed rain to sit inside my mast at the deck. Over the years, My core got wet & the decking sagged. So, this problem was fixed.
The second part was how to close-off the top of the crane from rainwater & at the same time insure that my halyards didn't jump the sheaves. Now, I should not have halyard jumping problems but, those with external halyards might.
I did my own new crane install while my mast was down at the boatyard. I cut a removable top plate to cover the open top crane & screwed down. To ensure my halyard stayed in the sheaves, I epoxied a PVC filler piece to the underside of the cover. I used a thickness that left a 3/16" gap between the sheave & the PVC. This will stop the halyard from jumping the sheave.
I now have minimal rainwater intrusion to my mast base. I also redid my wiring penetrations at the mast base, added air venting & deck draining to ensure no intrusion to the coring.
Here are some pics of the top plate & mast base to give you an idea. Sorry, but no pics of the PVC spacer piece underneath. Two pics of the cover & one pic that shows a circular vent on the mast. I have another on the opposite side to allow for rainwater drying. This is the same principle of those large concrete cooling towers with steam coming out the tops. They remove vapor using pressure differences & suction created by air moving across the tops. My crane cover is not a full seal thus the effect is the same. I remove the vent fitting from time to time for checking any water buildup inside the mast base. It's always dry.
If you drop your mast in the future & have an open top crane, this may be a fix for some.
CR
My boat neighbor has his halyard jammed between his sheave, pinched between the sheave, his shaft & the inside of mast crane casting. Well, this is how it happens most often.
You're boat is hobby horsing in head seas. You've probably just lowered your main but, something happened & you let the external halyard have too much slack in it. This slack causes the halyard to whip loops vertically up the mast causing the line to pop off the sheave. Now the harder you pull, the more jammed the halyard becomes. The following are some posts I wrote in the "How much" thread that got me to thinking about this & begat my fix.
My first post:
Someone mention on this thread of weight strain on the sheaves in the mast crane.
Speaking of this, I had a scare I found myself in. I used my Top Climber 4 times one weekend doing steaming light changeout, spreader boots & Windex/antenna changeout a few years back. On my 4th. trip up, I discovered that my cast aluminum crane had a vertical full top-to-bottom crack along where one sheave shaft 1/4 to 5/16"" dia. was attached w/cotter pin.
There I was, almost 50 feet up & my crane had failed. Oh let me tell ya, it was a scary trip back down. After dropping the mast, I discovered the shaft had also bent. Now, I only weigh in @ 150# & yet, my crane had failed. Could this cause me to fall, I don't know. Was there a chance of this happening?
I assume I was not the only one to climb the mast, as I had a rigger go up before. But, this is just something to think about.
About rope & tensile strength, here's a link to various charts that may help.
https://www.google.com/search?q=rope...w=1106&bih=509
============================================
My second post:
Thin,
Yea, I agree with you pal.
My story here in thinking, here's what I thought could have happened to me with the cracked crane.
The initial crack happened at the front sheave. What if the crane now being stressed, developed the same type of crack along the rear sheave? Remember this is cast aluminum, not the strongest material against structural failure.
With external halyards, had the whole side failed, there was a distinct possibility of the halyard rolling off the sheaves & now nothing to stop the rope from falling to the deck, with me attached.
People are killed every year with going up the mast, both experts & owners as you had described. I still think that folks new to mast climbing, should have experienced people to show them the "Ropes" first & then go in stages while they are learning.
Sheaves & shafts are designed to raise sails, maybe not the more weighted people.
=======================================
So, when I installed the new crane w/internal halyards, I tackled two issues. The first was the mast crane was open top. This allowed rain to sit inside my mast at the deck. Over the years, My core got wet & the decking sagged. So, this problem was fixed.
The second part was how to close-off the top of the crane from rainwater & at the same time insure that my halyards didn't jump the sheaves. Now, I should not have halyard jumping problems but, those with external halyards might.
I did my own new crane install while my mast was down at the boatyard. I cut a removable top plate to cover the open top crane & screwed down. To ensure my halyard stayed in the sheaves, I epoxied a PVC filler piece to the underside of the cover. I used a thickness that left a 3/16" gap between the sheave & the PVC. This will stop the halyard from jumping the sheave.
I now have minimal rainwater intrusion to my mast base. I also redid my wiring penetrations at the mast base, added air venting & deck draining to ensure no intrusion to the coring.
Here are some pics of the top plate & mast base to give you an idea. Sorry, but no pics of the PVC spacer piece underneath. Two pics of the cover & one pic that shows a circular vent on the mast. I have another on the opposite side to allow for rainwater drying. This is the same principle of those large concrete cooling towers with steam coming out the tops. They remove vapor using pressure differences & suction created by air moving across the tops. My crane cover is not a full seal thus the effect is the same. I remove the vent fitting from time to time for checking any water buildup inside the mast base. It's always dry.
If you drop your mast in the future & have an open top crane, this may be a fix for some.
CR
