At first glance HMPE
rope, available under a variety of names such as
Dyneema, Spectra, and Vectran would appear to have many qualities making it especially well-suited for use as
anchor rode.
High Strength and Low Weight- according to the
Dyneema website there can be as much as 80% weight reduction for an equal section with the same strength when compared to
steel.
Chafe Resistance- Per same diameter and same
rope construction, Dyneema is more chafe resistant than either nylon or polyester.
Floats- I have heard of polypropylene used in certain localities because it floats and is less likely to foul on the bottom. Likewise Dyneema enjoys the same quality and I think it could be argued it is therefor less likely to be subject to abrasion from bottom features such as
coral heads than nylon or polyester.
Low Stretch- Much like chain, HMPE rope has very low stretch resulting in less internal friction and
heating when compared to other rope.
Cost- Somewhere around twice nylon but half of chain. Here's some ballparks-
3/8" (G4) Chain 16,200lbs. Breaking Strength $6.09ft.
3/8" Amsteel HMPE 19,200lbs Breaking Strength $3.44ft.
3/4" 3-Strand Nylon 16,700lbs. Breaking Strength $2.01ft.
So what's the rub?
I've done some searching around and while Dyneema is growing in use for
offshore oil platform moorings for all of the above reasons, the problem with Dyneema for a yachtsman is that in addition to having very little stretch requiring the use of a snubber, it is notoriously slippery,which makes attaching a snubber challenging.
The
concept of using Dyneema for a
rode has been kicked around here on this forum, as well as elsewhere, and while the prevailing wisdom is that maybe using an icicle hitch or some other
knot might possibly
work, but that prospect seems dubious and I don't know of anyone who has tried it.
Recently, I ran across this knotless connector for tying with Spectra braid
fishing line and I wonder about it's suitability for attaching a snubber to a Dyneema rode.
Most of the knots used for tying Spectra are complicated and few offer close to breaking strength of the line, and the ones that do can never be undone. This connector on the other hand is stupid simple and easy to use by any blindfolded while having buckets of
water splashed in your face.
I think it's brilliant really. Perhaps a nearly ideal method of attachment and wonder if it wouldn't provide close to 100% of the breaking strength of the line? Having played around with it a bit I am quite certain that regardless of load this connection will be very easy to release.
I was able to find some prior art doing a number of Patent searches but couldn't find this one exactly so I am not really sure who to credit it to. For those who might think it too simple and somehow likely to unwind itself, keep in mind it's intended purpose is for tying lures and that many
fish are known to thrash about.
I have attached some photos of a connector I formed out of 1/4" mild
steel which I have paired with some 1/8" Amsteel as a proof of
concept. I figure it's small enough I can break it with a forklift to get a sense of whether it slips or not.
Assuming it works as expected I would like to go full-size and I wonder if anyone out there has access to the required testing
equipment who also wouldn't be interested in breaking some stuff?
I would be happy to provide samples.
Cheers