Dyneema wishbone help

[lawstraljan16]

I'm replacing my stock Tahitian wishbone to home made dyneema wishbones and after looking on google and youtube I can't find what kind of knot is used to tie the wishbone itself. I knot a constrictor knot is used so the insertion wont come out, but what about the knot used for the wishbone itself?

I've checked out videos but they're all unclear.

Thanks

 

[foxfish]

I use a simple overhand loop , just a basic knot & blob it with super glue.
Some folk thread on a bead if you are using very thine dyneema.
I use 2.5mm or 3mm but this is matched to a shark fin spear, if you are using a notched spear then you will need thinner material & in which case you might need a bead but it is still the same basic knot & glue.

 

[jonnyhl]

I use a simple overhand loop , just a basic knot & blob it with super glue.
Some folk thread on a bead if you are using very thine dyneema.
I use 2.5mm or 3mm but this is matched to a shark fin spear, if you are using a notched spear then you will need thinner material & in witch case you might need a bead but it is still the same basic knot & glue.

Foxfish where do you buy your dyneema from? Is the stuff from eBay acceptable or does it need to be treated etc etc? Apnea and Scubastore don't say much in their wishbone sections but have it for sale by breaking strain. Any idea what mm diameter the breaking strains refer to?
https://www.apnea.co.uk/product_info.php?products_id=1003

 

[foxfish]

Not really but I could guesse at 1.8mm 2.mm & 2.5mm?
I buy mine from a locale boat chandler, they sell in for sail boat rigging from 1.5mm to about 10mm.

 

[scallywag]

I get mine from fleabay. If I remember rightly it was 2mm advertised for sail rigging. Medfish hints and tips is a good source of info, think I used a sheet bend, works fine, well into its second season with no signs of wear. Just make sure that the notches in your spear are well polished and smooth.

 

[lawstraljan16]

Is 1.5mm dyneema good for the wishbone? I have a 95cm Beuchat Marlin Elite with a 125cmlong, 6.75mm shaft. Also will be putting on 2 16mm bands (dark red natural latex).


Sent from my iPhone 4 using Tapatalk

 

[scallywag]

To be honest, I wouldn't use less than 2mm but I'm no expert.

 

[martin366]

Im using 1.5mm Beuchat Pure Dyneema (300kg)
Its very good and right size

 

[Bill McIntyre]

I use 3 mm Spectra, and a simple overhand knot works fine.

 

[jonnyhl]

Got 2.5mm dyneema off eBay. What cord do you use for the constrictor knot at the end of the band?

 

[Mr. X]

I got mine from spearitco.com in the USA - they have everything you need, they sell on ebay too. There rubber was very fresh too.

I use nylon Rob Allen beads - metal seems like unnecessary mass & therefore inertia. For my screw on wishbone (on the Omer XXV), I use the same stopper knot that RA use (I believe) - I would call it a Double Overhand Knot or Surgeons Overhand Knot (I sometimes replace the word "Overhand" with "Thumb" - but I think "overhand" is clearer). Basically tie a simple overhand knot, then pass the end through one more time. When pulled tight the knot looks quite neat and tidy, with a rather cylindrical appearance (reminiscent of half of a double overhand knot ). I guess the idea is that it is a little bigger and more secure than a simple overhand knot (although modern Alpinists use the simple overhand knot in some life-dependent uses, for example to join ropes for rappelling/abseiling - scary but it does work and is arguably the best way).

 

[Mr. X]

RE. size, bear in mind the Bill is likely using huge "woodie" spearguns with shark-fin spears.

Check the spearitco.com website, they also offer thinner braid (1.9mm I think) suitable for use with euro-style spearguns.

If switching from a metal wishbone to dyneema, you will likely need to smooth out the wishbone grooves on your spear(s) to avoid damaging the dyneema. There is a thread on this but something like a Dremel drill with grinding rod piece and/or cheap, slim, round diamond files followed by a grinding paste (such as Autosolv chrome cleaner). Regular round files aren't really up to filing stainless steel spears in my experience.