Re: [Paddlewise] throw bag construction

I would worry about going to light on the line primarily because of a lack of
abrasion resistance.  It is very easy to cut or rub through a line that is say
1/4 thick or less.  If you have a fat line you can probably cut away 2/3 of it
and still have a solid towing system.  As for having tow rope loads of hundreds
of pounds I would avoid this at all costs!

 The average towing load is not likely to exceed the output of you paddling your
butt off.  Try hooking a spring scale on a tow line and then with the rope
taught paddling flat out and you will find that even 10 pounds of propulsion
force is pretty hard to maintain for a long time.  A head wind of about 25 knots
for example might add 8 pounds of force to push you the wrong way etc. etc.

Shock loading is the key and I am a strong proponant of having a bungie cord on
the end of tow line especially if you are going light on you line diameter.  To
answer the question do I want the tow line to snap while towing my friend in
rough conditions?  If  keeping the tow in place is going to pull on my body or
the rear deck ofmy kayak with hundreds of pounds of force I would pray for the
line to part before the back of my British heavy gets ripped open.

If you have a fairly long tow line rigged such as 30-50 feet the rope gives a
bit of stretch and takes up some of the shock loading.  However I had a friend
who towed someone for six miles in 15 foot seas without a shock cord on his tow
line.  When the boats decide to surf in different directions he described the
impact as like being rear-ended in an auto accident.  He was very lucky that
neither he or his boat were damaged, and he now uses a bungie to kill the worst
of the shock loading when towing in big waves.

Some folks tie a loop in the rope so that if the bungie breaks you still have a
solid tow line.  I just use a heavy enough bungie to take 3/8 inch single or as
a loop inspect it for wear often.  If the yank at the end of the rope can snap a
three foot length of double 3/8 bungie cord I want the towing line to part!

Philip Torrens wrote:

> >From: "Shawn W. Baker" <baker_at_montana.com>
>
> >Your math is figuring a static load--a 300 lb. load "hanging" on one end
> >of the rope.
>
> Douh! Right you are - I was thinking of the "fall factor" for climbing
> ropes, not the situation where the water supports much of the weight of the
> loads. That said, I still imagine that a jerk at either end of the tow line
> (referring, of course, to boats moving in opposite directions - not to the
> paddlers themselves-:) could exceed several hundred pounds. Glancing through
> a catalogue of commerical towlines (some sea kayak specific) I don't see
> anything weaker than 800lbs breaking strength.
> I think it was Dave K. in Oregon who did the detailed formulas. Dave, Dave,
> come in Dave, we need you.
>
> Philip Torrens
> N49°16' W123°06'
>
> ***************************************************************************
> PaddleWise Paddling Mailing List - All postings copyright the author and not
> to be reproduced outside PaddleWise without author's permission
> Submissions:     paddlewise_at_lists.intelenet.net
> Subscriptions:   paddlewise-request_at_lists.intelenet.net
> Website:         http://www.paddlewise.net/
> ***************************************************************************



***************************************************************************
PaddleWise Paddling Mailing List - All postings copyright the author and not
to be reproduced outside PaddleWise without author's permission
Submissions:     paddlewise_at_lists.intelenet.net
Subscriptions:   paddlewise-request_at_lists.intelenet.net
Website:         http://www.paddlewise.net/
***************************************************************************