Rivets

[blackbeard]

The topping lift on my boat passes over a block at the masthead, the block is supported from near the masthead by two pop rivets (about 4.5 mm dia) in shear.
As a topping lift, it seems fine. However:
a. the topping lift is the obvious thing to use as a safety line when going up the mast using the main halyard (it's a fractional rig so the jib and spinnaker halyards don't lead from far enough up). Is the "safety" real or illusory, ie would the rivets shear if they had to take my weight (as a shock load, of course!). (Not that much of a shock, I'm about 78 kg but my crew is about 50!). Do I need a safety line anyway, a tangle of safety precautions seems to attract unwanted events!
b. One possible answer to the man overboard recovery problem is to hang a 4 part purchase from about half-way along the boom. The boom thus supports the weight of a waterlogged person who could be a lot more than 78 kg; but the topping lift will only see about half this weight as it leads to the outboard end of the boom. Would the rivets be strong enough for this? or do I need another solution to the problem?

 

[nigelhudson]

a) The block mounting does sound rather flimsy. I use the topping lift as an extra line but I attach it to a spare sail slide in the mast groove by means of a shackle. I then thread a webbing strop through the shackle which I use as a foot rest. By this means I can distribute my weight between the chair and the footrest which makes for comfortable working at height. Once above the spreaders I put a safety line round the mast so, in the very unlikely event that everything fails, I will only slide down the mast to the next set of spreaders.

b) Why not use the main halyard? Bring it back to support the boom at the point the 4-part tackle is fixed - that way there is no bending force on the boom and the topping lift is relegated to back-up.

 

[William_H]

When ascending a mast it is very useful to have a second line from something like your topping lift with a loop that you put a foot in. 2 is better. If you take some of your weight on your foot in the strop it can make it a lot easier for the man on the winch to pull up the bosuns chair.
Once the chair has gone up a little you take the weight off your foot so that line can be tightened.

However if you have doubts about the strength of the topping lift attachment you should improve it simply because your confidence is important. You might want to use the topper as a main halyard some day also. olewill

 

[roly_voya]

I definatly would not use it as a safety line which means if your main halyard ever jams you have no safe way of climbing the mast to fix it. Next time the mast is down I would look at adding either a bolted or welded tang to the mast crane