Monday, November 23, 2015

Review: Fishbones - Gravity Hook (production)

Production on the left, prototype on the right
I covered the original release of the prototype Gravity Hook back in March, when the prototype was sent my way by the guys from FishBones. Not long ago the final production version of the Gravity Hook arrived, with some improvements.

The Gravity Hook is a combination grappling hook, and gravity claw. (Here's their promotional video...) By removing the middle cross-bar the more than serviceable grappling hook can be quickly converted into a claw-machine like grabbing claw. The clever design allows you to swap between these two features in just moments.
Production on the right, prototype on the left

The whole assembly weighs around 360g in its stainless steel configuration, a complete assembly includes 3 links, 3 "hammers", a cross hook, and hardware, in bolts and self-locking nuts.

One of the production improvements is the notches cut into the throat of the hammer, these allow the cross hook to seat much more securely that in the prototype, where it was held in place solely via the notch cut into top of the cross hooks. 

Production on the right, prototype on the left
The stainless Gravity Hook is made out of 1/8" thick 304 stainless steel and all of the Gravity Hooks hardware hardware is also stainless. When the hook is fully open, the 1.5" mouth will hold over 165lbs when biting into a 2x4.

When fitted, the cross hooks set in the jaws of the hammers, the Gravity Hook up as a quite effective grapple. The jaws are held in place and stopped from opening the by the twin o-rings which seat in a set of notches cut into the link pieces, and hold the jaws surprisingly tightly.

Production on the bottom, prototype on the top
 Given their design, any the pull on the tines of the hook only act to pull it further closed, the effect of the o-rings is really quite sufficient.

FishBones have suggested that an after market modification, drilling a hole in the middle of the hammer arms to fit a locking pin, for extra security, but so far, I haven't felt the need myself.

The bolts and locking nuts supplied with the production model are a much slimmer profile than the nuts and bolts I picked up at the hardware store, that was a big help.

The production version has nicely rounded notches cut into the links, where as the prototype version is rather a bit more rough making it rougher on and harder to remove the o-rings.
Production on the right, prototype on the left
One of the other backers of the Gravity hooks asked if they wanted to use it as a boat anchor for an inflatable lake boat, how they would dislodge it should it hook onto something on the bottom. Another backer suggested it could be set up with a failable style link like this  where if you pull hard enough the top link breaks and lets you pull the anchor from the bottom. A second way would be to use 2 ropes; one attached to the shackle, and the other looped through the claw to act as an emergency release in case the hook snags.

Here's me testing the grappling hook

Here's me testing the claw feature on a variety of dropped gear.

Two kinds of cross hook: plain and gear-tie batarang!
 You might ask "what makes it high performance?" well, this is probably a matter of its features:
  • It can be used either as a 2 or 4 pronged grappling hook.
  • In the claw mode it "bites" objects that might slip out of a grapnel.
  • Compact enough to be stowed on a back pack strap, by clamping the jaws over the strap and feeding the tail end through a loop
  • Can be dismantled into its base components for more compact storage. 
  • It's available in stainless steel, titanium or even non metalic Derlin.
There are also two options for the cross hooks, with the classic solid hook, as well as a version with cut-aways, both lightening the cross hook, and also offering a place to use it as a gear tie, not unlike the FishBones and Piranha gear ties these guys came to the front with. 

Ss, you have a very cool tool in the Gravity Hook, but what are its limits? Well, the Gravity Hook was specifically designed for retrieving. It has not been tested or certified to bear human weight. The makers strongly state that you should never use it in a situation where it's failure or dislodging might cause bodily harm or property damage. In a pinch though, it can certainly take a fairly hefty load: 
How do you get the Gravity Hook to release something whilst under tension?

Here's their testing underwater!

As well as being a really useful dropped-gear and treasure retrieving claw, and a sturdy and rugged grapple, the Gravity hook is also a really well made piece of engineering. I really appreciate its design and functionality. I've got a small CountyComm grapple, which is billed as a trip-wire clearer, but for bigger jobs, when you want to snag, yank and retrieve gear, or haul something you would do well with one of the FishBones Gravity hooks.

Better yet, the guys at FishBones have just launched a NEW project, the Gravity Hook XS, a pocket sized version, in just two-pronged format, on KickStarter. You should totally go check it out, and add some grabby, grapply goodness to your loadout.

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