Snatch Blocks
Versatile snatch blocks have many uses on boats.
Blocks are one of the foundations of sailboat rigging. They are used to change the direction of lines on a boat—either to guide them to a particular location, or to increase the purchase of a tackle.
What is a block?
A block is a pulley, consisting of a sheave (around which the line turns) suspended between two sides (cheeks) and turning either on a pin or ball bearing races.
What is a snatch block?
Snatch blocks are a special kind of block which has many uses on boats. Snatch blocks have a side gate that opens and closes for easy line insertion. The design of snatch blocks gives them the ability to accept lines through the cheeks without reeving the bitter end of the line through. Most snatch blocks include a snap shackle which enables you to remove and quickly reattach them most anywhere. Many snatch blocks also include a trunnion which is a pivoting axis that allows the block to pivot on two planes to maintain correct load orientation where shackle movement is restricted such as on a perforated toe rail.
Recently, a new type of snatch block has emerged called a “loop block”. These blocks use flexible loops, usually made from Dyneema, to take the loads directly through the center of the sheave. They’re quite popular on larger performance racing boats, but work equally well for cruisers.
Snatch Block Applications
Snatch blocks are commonly employed as jib fairleads and spinnaker sheet blocks. They are also sometimes used as a guide for anchor rodes. For example, if you have a boat with a large bow pulpit, you can attach a snatch block to the lower rail and lead the anchor rode through it to keep the line off the deck.
Snatch blocks should not be used as turning blocks because they are not intended to take heavy loads.
Brands of Snatch Blocks
West Marine carries snatch blocks made by Antal, Harken, Holt, Lewmar and Ronstan.