MOB Recovery Question

[Ken W]

My R31S has the “hardtop” cockpit cover with an u-bolt (with backing plate) located in the center of the stern end. It is presently used with a pulley system to raise and lower the davit-mounted dinghy. Is the u-bolt strong enough to use with a 5:1 Lifesling block and tackle?

 

[JamesTXSD]

My R31S has the “hardtop” cockpit cover with an u-bolt (with backing plate) located in the center of the stern end. It is presently used with a pulley system to raise and lower the davit-mounted dinghy. Is the u-bolt strong enough to use with a 5:1 Lifesling block and tackle?

Real world 200 pound man being lifted by a 5:1 block and tackle should be about 40 pounds of force needed to lift. That said, the weight on that U-bolt as someone is being lifted is still 200 pounds. Without seeing the install, it would be hard to say, but you could put your weight on it to see if there is any deflection of the hard top.

 

[NorthernFocus]

Real world 200 pound man being lifted by a 5:1 block and tackle should be about 40 pounds of force needed to lift. That said, the weight on that U-bolt as someone is being lifted is still 200 pounds. Without seeing the install, it would be hard to say, but you could put your weight on it to see if there is any deflection of the hard top.

Load on the attachment point is the static weight of the person plus the tension on the tail end of the block/tackle. Also friction plays a part so depending on the quality of the 5x1 rigging the force needed to lift 200# is likely more like 50-60#. Then if you're making the lift with any sort of sea running there is a dynamic component that is hard to calculate but could easily be greater than the static weight. IOW depending on conditions the attachment point could easily see twice the load of the person's weight.

It's bad enough having someone overboard. Getting them half way back aboard and having something break and all come crashing down would really be a fiasco.