Bill Tuthill wrote:
Jeremy wrote:

http://www.nrsweb.com/shop/product_list.asp?deptid=1039

I have one of the 1/4 inch polypro lines, which I concluded recently
is NOT suitable for pulling things off of rocks.

Thanks for all your poste, Jeremy.

I have a 1/4 inch Spectra line, which has almost 3x the tensile strength
of polypro, but doesn't throw or coil as easily. It feels too stiff.
Whereas the 3/8" Spectra line handles more like a real rescue rope.
But the 1/4 Spectra was able to unwrap this boat without snapping, using
the (Boy-scoutless) "Ten Boy Scouts" method:

That's useful feedback. I was considering replacing my polypro line with the
equivalent width spectra. The polypro started out nearly bath towel soft,
and is probably almost as strong. Have you found a better dual-use line
suitable for carrying in a kayak?

http://cacreeks.com/photos/antelop5.jpg

Our little situation wasn't nearly as submerged, but had the added benefit
of oars and frame to lock it down.

Bill Tuthill wrote:
In rec.boats.paddle Brian Nystrom wrote:

In case anyone actually cares, Spectra is the name of product Allied
Signal manufactures in the US under licence from Hoescht-Celanese in
Germany, the manufacturer of Dyneema. They are identical fibers, though
they can be made into a variety of products that may differ widely.

According to the Dyneema website, they are a Dutch company.

http://www.dsm.com/en_US/html/hpf/home_dyneema.htm

Spectra and Dyneema are both made of polyethylene, but is that evidence
to indicate they are really "the same thing"?

I've always consedered Dynema and Spectra to be essentially the same
thing and look at other properties of a line when deciding what to buy.
Does it float? Can I splice it? How much does it cost? Is it grippy
or smooth? How much does it stretch or creep? There may be slight
differences between Dynema and Spectra (or not) but whatever they may be
they're overshadowed by other considerations.


Specs indicate Dyneema-core ropes have slightly higher tensile strength
than Spectra and some marketing blurbs indicate they have a softer feel.

Remember that two lines of the same diameter may have quite different
core diameters - a thick cover vs a thin cover. Look at non-blended
single braids for a better apples-to-apples comparrison.



//Walt

Bill Tuthill wrote:
In rec.boats.paddle Brian Nystrom wrote:
In case anyone actually cares, Spectra is the name of product Allied
Signal manufactures in the US under licence from Hoescht-Celanese in
Germany, the manufacturer of Dyneema. They are identical fibers, though
they can be made into a variety of products that may differ widely.

According to the Dyneema website, they are a Dutch company.

http://www.dsm.com/en_US/html/hpf/home_dyneema.htm

Spectra and Dyneema are both made of polyethylene, but is that evidence
to indicate they are really "the same thing"?

Specs indicate Dyneema-core ropes have slightly higher tensile strength
than Spectra and some marketing blurbs indicate they have a softer feel.

Hee-hee, at least something useful to whitewater boaters is made in the
Netherlands! :-)

Now if only that stuff was for sale in the throwbags that we can buy
here. Haven't found that yet in the paddling stores in the Netherlands. :-(

--
Wilko van den Bergh wilkoa t)dse(d o tnl
Eindhoven The Netherlands Europe
---Look at the possibilities, don't worry about the limitations.---
http://kayaker.nl/

On 8-May-2006, Bill Tuthill wrote:

Spectra and Dyneema are both made of polyethylene, but is that evidence
to indicate they are really "the same thing"?

At the fiber level, yes, since one is simply licensed from the other. At the finished
product level - they may be different, since the manufacturer of the rope will put
in his spec which may be different - different core, different sheath etc. These
things will affect the stretch (static vs dynamic), hand etc.

Sort of like comparing two GoreTex jackets - the GoreTex is the same, but the
jackets can be very different - even the fabric onto which the GoreTex is bonded
can be different.

Mike

Jeremy wrote:

That's useful feedback. I was considering replacing my polypro line with the
equivalent width spectra. The polypro started out nearly bath towel soft,
and is probably almost as strong. Have you found a better dual-use line
suitable for carrying in a kayak?

Based on specs below, I am going to buy 50' of Yale Conception 6mm (1/4")
to replace the braided Polypro that came with my $27 Kayaker's Throwbag.
http://theboatpeople.com/atr_safety.html#throwbags
The 50' of braided 5/16" Polypro will become the new bowline for my raft.
I'll report back after initial use. NRS Spectra might be Blue Line.

tensile cost/ft #/100ft handling
NRS Spectra 6mm 2500# $.80 1.6# stiff and abrasive
Yale Conception 6mm 2500# $.62 1.4# soft hand?
Yale Conception 8mm 4100# $.95 2.0# soft hand?
Bluewater Polypro 8mm 1900# $.56 3.0# core, but handles well
NRS Spectra 10mm 4966# $.99 3.4# semi stiff, not bad
Yale Conception 10mm 5500# $1.32 3.5# soft hand?

What makes Yale Conception unusual (easier handling characteristics)
is that the Dyneema is braided together with Polypro. This makes it
lightweight, soft, and unitary. Blue Line(?) Spectra has an inner core
that makes it very stiff, and the Polypro sheath behaves differently,
and comes apart from, the Spectra core. This is OK in a 10mm (3/8")
line, but I just don't like it in a 6mm (1/4") line.

typed
I'm not a whitewater boater, so take what I say with the right degree of
skepticism, but I would think that for a rescue line you want a bit of
stretch. For instance, climbing ropes always have a bit of stretch
(made out of nylon usually). The Yale and Samson lines in question are
intended for use as halyards, sheets, and control lines on a sailboat
and are intentionally made to have as little stretch as is possible.
I'm not sure that ultra low stretch is what you want in a throw line.

For my throwable lines, I just use garden variety 3/8 inch 25 cents a
foot polypro - I don't see the need for ultra low stretch or ultra high
strength in a throwable. And for docklines, you really don't want low
stretch - I've seen boats with damaged hulls because the owner recycled
his old sheets as docklines. Let the line absorb the shock, not the boat.


Since I'm one of the rescue geeks, I'll take a swing at this one.

a dynamic line like poly is fine for a throwrope to recover swimmers
since it has a bit of give when that 200 lb boater and kayak full of
water hits the end of the line, but since we normally don't have the
option to carrying two ropes, you are better of using a static line
that can double for your mechanical advantage systems. If you are
trying to pull a boat off the a rock while on a steep river bank, the
less stretch you have the better.

Just as a note, you hardly ever use dynamic lines in vertical rescues.
These type of rappelling lines have minimal stretch and very high
working loads.

BTW, I like the new Rescue Line by Bluewater, cheaper than Spectra and
with a decent working load. And it's available in a 5/16" line that
packs much better than the 3/8" and still can double as a working line
in a mechanical advantage system.

"Larry C" wrote in
oups.com:

BTW, I like the new Rescue Line by Bluewater, cheaper than Spectra and
with a decent working load. And it's available in a 5/16" line that
packs much better than the 3/8" and still can double as a working
line in a mechanical advantage system.

....and that won't cut your hands to ribbons, either.

In rec.boats.paddle Larry C wrote:

a dynamic line like poly is fine for a throwrope to recover swimmers
since it has a bit of give when that 200 lb boater and kayak full of
water hits the end of the line, but since we normally don't have the
option to carrying two ropes, you are better of using a static line
that can double for your mechanical advantage systems. If you are
trying to pull a boat off the a rock while on a steep river bank, the
less stretch you have the better.

The only thing I have to add is that nylon climbing rope, polyester
rappel rope, or Kevlar stranded rope (I've seen it) are all terrible
as a throwline, because they sink.

It was enervating once watching a swimmer unable to grab a sinking line,
then wash over a waterfalls. Fortunately he was only mildly injured.

I won't divulge who had the idea of putting Kevlar rope in a throwbag.
It was for strength I guess, in the days before Spectra.

Bill Tuthill wrote:

Jeremy wrote:

That's useful feedback. I was considering replacing my polypro line with the
equivalent width spectra. The polypro started out nearly bath towel soft,
and is probably almost as strong. Have you found a better dual-use line
suitable for carrying in a kayak?

Based on specs below, I am going to buy 50' of Yale Conception 6mm (1/4")
to replace the braided Polypro that came with my $27 Kayaker's Throwbag.
http://theboatpeople.com/atr_safety.html#throwbags
The 50' of braided 5/16" Polypro will become the new bowline for my raft.
I'll report back after initial use. NRS Spectra might be Blue Line.

tensile cost/ft #/100ft handling
NRS Spectra 6mm 2500# $.80 1.6# stiff and abrasive
Yale Conception 6mm 2500# $.62 1.4# soft hand?
Yale Conception 8mm 4100# $.95 2.0# soft hand?
Bluewater Polypro 8mm 1900# $.56 3.0# core, but handles well
NRS Spectra 10mm 4966# $.99 3.4# semi stiff, not bad
Yale Conception 10mm 5500# $1.32 3.5# soft hand?

What makes Yale Conception unusual (easier handling characteristics)
is that the Dyneema is braided together with Polypro. This makes it
lightweight, soft, and unitary. Blue Line(?) Spectra has an inner core
that makes it very stiff, and the Polypro sheath behaves differently,
and comes apart from, the Spectra core. This is OK in a 10mm (3/8")
line, but I just don't like it in a 6mm (1/4") line.

I think you'll like the Yale Conception. It is quite soft, not at all
stiff, very lightweight and pretty grippy. I've been using it as a
mainsheet for two seasons of hard use, and it's held up pretty well.
Note that it runs a bit fat and tends to flatten out when cleated, but
that's probably not an issue for your intended usage.

I respectfully withdraw my concerns about ultra low stretch lines as
throwables, other than the increased cost. Of course, if you are ever
in a situation where it really makes a difference the extra $50 is
pretty darned irrelevant in the greater scheme of things.

//Walt

Bill Tuthill wrote:
In rec.boats.paddle Brian Nystrom wrote:

In case anyone actually cares, Spectra is the name of product Allied
Signal manufactures in the US under licence from Hoescht-Celanese in
Germany, the manufacturer of Dyneema. They are identical fibers, though
they can be made into a variety of products that may differ widely.


According to the Dyneema website, they are a Dutch company.

http://www.dsm.com/en_US/html/hpf/home_dyneema.htm

My mistake.

Spectra and Dyneema are both made of polyethylene, but is that evidence
to indicate they are really "the same thing"?

As I said, it's the same product manufactured in different places.

Specs indicate Dyneema-core ropes have slightly higher tensile strength
than Spectra and some marketing blurbs indicate they have a softer feel.

That's due to the construction of the specific ropes, not to any
difference in the fibers.