Page 58 - The Complete Rigger’s Apprentice

Also note in Figure 2-18 that as the angle of for even strain, low fatigue, and low friction. Make
incidence of a line to its block widens, the load on sure, in particular, that the block can articulate ade-
the block lessens. So fairlead blocks can be consid- quately for a fair lead coming into and out of the
erably smaller than blocks through which the rope block. If block angle changes depending on point of
takes a 180-degree turn. sail (a mainsheet deck block, for example), check
the lead at all possible angles.
Miscellaneous Practicalities Snatch blocks (Figure 2-19) can be stupen-
Cruisers, for whom a broken block can be more dously handy for impromptu fairleads and hoist-
than a simple inconvenience, should always use ing, but they do have their limitations. Avoid using

generously sized blocks, for a high safety factor. them on a line that is subject to violent flogging—
Reduced friction and prolonged rope life are other like Genoa sheets—as this can cause them to spring
consequences of prudent oversizing. open. There are many snatch block designs, so read
All sailors should bear in mind that swivel the maker’s literature closely for other limitations.
blocks fail most frequently; unfortunately, manu- Holding a snatch block up with a short bungee
facturing efficiencies have dictated that most of the cord will help hold it still while you open and close
blocks being made today are of a type that can be it, will keep it from clattering on the deck when the
either swiveling or non-swiveling; the conversion is load is off, and will help to dampen motion from a
usually made with a couple of set-screws. So if you flogging line.
don’t need a swivel, get solid bail blocks if you can, Nearly all snatch blocks available today come
and get high-quality, heavy-duty locking swivels if with a snapshackle attachment. So flogging or
you must. inattentive closing can result in not only the block
Poor lead is a major cause of block failure; be but also its snapshackle coming open. One form
sure that all lines lead fairly to and from all blocks, of snatch block, developed for mountain rescue, is
positive-locking (Figure 2-20). It’s a little slower to
Figure 2-19. Snatch blocks. The center illustration is a open and close, but you can trust it with your life.
soft shackle incorporated into one of Colligo’s sheave- It’s perfect for use as a turning block when hauling
less snatch blocks. Spectra slides readily through this someone aloft (see “Living Aloft,” Chapter 7).
block. (Middle drawing by Margaret Wilson-Briggs)

solid snatch block

screw pin
snapshackle shackle

block opens
here block opens
here

soft shackle

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