Snatch Block & Pulley Winching Guide: Double-Line Pulls and Redirects

A snatch block is a pulley housed in a steel or aluminum shell with a hinged side plate that allows you to insert the winch line without threading it through the end. This "snatch" feature is what gives it its name: you snatch the line open and drop the cable or rope in, rather than unspooling the entire line and re-threading it through a closed pulley.

When used in a double-line configuration, the snatch block creates a mechanical advantage that effectively doubles the winch's pulling power while halving the line speed. A 10,000-pound winch pulling through a snatch block becomes a 20,000-pound system. The physics are straightforward: the load is distributed across two legs of the line instead of one, so each leg bears half the total force.

This mechanical advantage comes with two tradeoffs. First, line speed drops by half because the winch has to pull twice as much line for the same vehicle movement. Second, the anchor point bears the full combined load of both line legs (roughly equal to the winch's rated capacity times two), so the anchor must be rated accordingly. A tree that can handle a direct 10,000-pound pull might not survive a double-line pull where the anchor sees 20,000 pounds of force.

Run the winch line from your vehicle to the anchor point, then pass it through the snatch block. Attach the snatch block to the anchor using a rated D-ring shackle and tree saver strap. Run the free end of the winch line back to your vehicle and attach it to a second recovery point using another rated shackle.

This creates a V-shaped line path: from the winch drum, out to the snatch block at the anchor, and back to the vehicle. The load is shared between the two legs of the line, each bearing half the pulling force. The snatch block's sheave (the pulley wheel) must be rated for the total load it will see, which equals the winch's rated pulling capacity.

Critical detail: the returning leg of the line must attach to a separate recovery point on the vehicle, not back to the winch drum or the same mounting point. Attaching both legs to the same point defeats the purpose by concentrating all the load at one location. Use one D-ring mount on the bumper for the winch line and a second D-ring mount for the return leg.

Ensure the snatch block's sheave is properly sized for your winch line diameter. A snatch block designed for 3/8-inch cable won't work safely with 1/2-inch rope, and vice versa. The line should sit in the sheave groove without pinching or riding up over the edges.

Not every recovery happens in a straight line between the stuck vehicle and the anchor. Obstacles like boulders, trees, or terrain features may block the direct path. A snatch block attached to an intermediate anchor point allows you to redirect the pull direction around these obstacles.

For a redirect pull, run the winch line from the vehicle to a snatch block attached to a midpoint anchor, then continue the line from the snatch block to the final anchor point. The vehicle will be pulled toward the midpoint anchor, then the line redirects the force toward the final anchor. This doesn't provide the double-line mechanical advantage (since the line isn't returning to the vehicle), but it enables recovery paths that would otherwise be impossible.

Angle matters in redirect pulls. The forces on the midpoint anchor increase as the redirect angle becomes more acute. At a gentle 30-degree redirect, the midpoint anchor sees roughly 50 percent of the winch load. At a sharp 90-degree redirect, the midpoint anchor sees about 140 percent of the winch load due to the vector forces. At 180 degrees (a complete reversal), the anchor sees the full double load. Plan your redirect angles to keep loads within safe limits for your anchor points.

You can also combine redirect and double-line techniques by running a double-line through a redirect snatch block. This requires two snatch blocks: one at the redirect point and one at the final anchor, with the line returning to the vehicle. This configuration provides both doubled pulling power and a direction change.

Every component in a snatch block rigging must be rated for the expected load. Chain the ratings: winch capacity, snatch block WLL, shackle WLL, tree saver strap WLL, and recovery point capacity. The system is only as strong as its weakest component. A 20,000-pound snatch block is useless if it's connected with a 9,000-pound shackle.

Inspect the snatch block before every use. The sheave should spin freely without grinding or wobbling. The hinge pin should be straight and fully seated. The side plate should close completely and latch securely. Any deformation, cracking, or rough sheave action means the block should be retired.

Always use a winch line damper on each leg of the line during double-line pulls. If either leg fails, the stored energy will cause the line to whip. Two dampers, one on each leg, provide redundant energy absorption. Keep all bystanders clear of the entire rigging area, not just behind the vehicles. Failed lines and shackles can travel in unexpected directions when a double-line setup releases.

Never shock-load a snatch block. The winch should pull smoothly and steadily, never in jerks or surges. Shock loading can exceed the rated capacity of the block, shackles, and anchor points even if the steady-state load is well within limits.