Saturday, February 4, 2017

Boomerang Your Anchor

An Australian friend of mine developed an interesting open-source anchor turner he calls the Boomerang. It is also marketed by Anchor Right as the Anchor Flipper, and I believe there is a Canadian distributor, for those of you that don't have a bandsaw and drill press handy. What follows is my short description of what this devise does and how it is used. To get the the story straight from the horse, please visit How to Boomerang You Anchor Right Back at You.

If you align your chain properly between the anchor and the windlass, the anchor should come up straight virtually every time. I'm not much for swivels because I found a crack in my last stainless swivel. Of course, there are better ones out there, and it was install incorrectly, mounted directly to the anchor with intervening chain or even shackles to provide a hinge. Nonetheless, I don't need a swivel. All a swivel does is make the anchor easier to rotate. it also guarantees that the anchor will come up backwards 50% of the time, since the swivel will swivel and any careful alignment to the windlass will; be lost.

In addition to proper alignment, there are two other tricks to remember:
  1. Go Backwards. Most anchors and all new generation anchors line up with the water flow. If you are moving forward with the anchor in the water, it will be backwards. Stop or go astern.
  2. Rotate the Chain by Hand. Just give it a half twist while lowering a few feet. If a twist snuck over the 
  3. roller, it will go back. Don't do this while raising unless you want to loose a few fingers.

For larger chain, increase all dimensions in direct proportion to the chain diameter. For higher grade chain, increase all dimensions in proportion to the square root of the increase in chain strength.

But if you need a gadget, this is probably the best of the bunch. Although different shapes are certainly possible, theses are the critical factors:
  • Holes. The thickness and width of the metal surrounding the holes must exceed the dimensions of a common grade shackle. I have allowed additional material as a safety factor.
  • Steel Grade. Higher grade steel will allow reduced thickness. 
  • Bend. The bend must be sufficient to roll the chain. However, it must not be so large as to jam if it comes over the roller sideways. The reason for the asymmetry is to conserve width; if the short end is oriented toward the anchor, the chain has rolled by the time it gets there and additional length is unnecessary.  The asymmetry also reduces the bending stress on the bend.
  • Grove. If the roller has a groove the Boomerang should be either thinner or considerable thicker to prevent jamming.
  • Isolation Links. For best action, it should be isolated from the anchor by 5-9 chain links (an odd number insures the correct alignment). This allows the anchor to turn gently. If there is insufficient space, the Boomerang my be attached directly with one shackle, but the windlass much be paused at the correct moment. Although it looks thick and clunky, it is slender in the direction the chain is slicing down through the sand and should actually improve setting.

The bend in this example is slightly different but works just fine. Note the isolation links and that they are properly aligned. I'd like to a see a little more metal around the hole on the left.

 I think it nicely compliments the bridle plate. Compared to the shiny boat show stainless, they both look like stone age technology. But they work better and are strong as hell.

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