Surfski Knowledge Base

Discussion of Replacement:

Reivers Dustin
03/10/17 #20814

I'm riding R because rudder cable busted on the X.

But I'm glad you asked. ….

I found replacement stuff on McMaster Carr. Last time the rudder cable broke it was Jude's original design so all the kit had to be replaced: foot braces, etc. I was fussy about how to crimp these long barrell swage-eye fittings. The actual rolling press swage tool is about five grand plus another 600 bucks for the proper die. Not counting shipping of course. I found you can go to sail boat fitting yard in Seattle or Vancouver, BC and they will do it, but they will not let you near their tool. And, this means screwing around with your boat up on their table to get those last two crimps done and probably adding some dings to your boat.

So I used my handy-dandy vice grips. And of course I remembered all my materials science classes and my metallurgy classes and tried to avoid over-deformation which would work harden and introduce stress corrosion cell and also mess up the special tempering of the 18-8 SS swage eye.

I can see that the cable is what corroded, not the swage-eye fitting. So I bought marine-grade SS 1/16“ cable which is non-bendable (but this rudder cable design requires no bends). It is 316 grade SS. These new swage-eye are also 18-8 (probably only alloy of SS available). So. The best stuff I could find. The SS cables at Hardware Sales (which I've bought tons of) is 18-8 (so it's 301, 303 or 304 series - no moly).

Now to preserve function: I'm going to apply a special granular silicon gel used for assembly of graphite to graphite which provides “tooth” without dissimilar metal introduction. And no, Si don't bring SS into corrosion, but Carbon does.* I bought “TacX”, but I prefer Park Tool “SAC-2” used for seatpost assembly. For the crimping problem I'm going scrounge around for electric splice crimping tool that is close enough. I don't like the vice-grip idea so good. Not the best way to crimp so as to properly reduce the swage fitting I.D. and really grip the cable. The biggest headache I see coming is doing a really clean accurate cut of the SS cable. This is fixed footwell so a tiny error will haunt the steering.

any of you tool heads still reading parts list:

McMaster-Carr wire rope compression eye end fitting: p/n 3872T11 (bought 6 so I can screw up a couple)
McMaster-Carr 1/16 SS wire rope: p/n 8908T27 (bought 50 ft).
Park Tool SuperGrip Carbon and Alloy Assembly Compound: SAC-2 (4oz squeeze tube)
I'll probably find a crimp tool at Lowes or Hardware Sales. I have a couple but they don't look right.

I'll be down about $80 parts. Cost of labor: priceless.

rd engineering

*this is one reason to avoid Burndy “No-Ox”, Ideal brand or other zinc based corrosion inhibitor on your SS parts. Zinc or any carbon might be picked up by the SS and foster corrosion. And SS, like aluminum, is a non-linear corrosion process. There can be tunneling or other weird propagation. Not like carbon steel where you get progressive indication.

John Rybczyk
03/10/17 #20815

I bought the replacement cables from Jude at Huki and then crimped by asking big Medler to squeeze real hard with my pliers. But then, I'm not “retired.”

johnr

Larry Goolsby
03/10/17 #20816

Reivers…Thanks for posting this. I read it to my grand kids and they fell into a coma before the second paragraph. Good stuff - should keep them dormant for the next century.
LG

paul clement
03/11/17 #20817

If you know Mickey Bevans, he modified a pair of vice grips for this particular job. Very effective. I used them when I replaced the cables on my X with fixed footwell. Easy peasy. I also used a ss washer between the fitting and the carbon pedal to better distribute the load. Couldn't tell you what grade it was but it worked well.
pc

Jim Powers <j.powers@…>
03/11/17 #20818

Down near the bottom, you mention getting a clean, precise cut on the cable. I have used bike shop cable cutters on the stock Huki cables with success. You're probably already there on the bike cable tool, But mine are available if you don't want to buy some.

Larry Bussinger
03/12/17 #20823

I've used Boeshield T-9 waterproofing and lubricant on my cables and SS for years and have had minimal corrosion. Use it on both the kayaks and power boat.

Larry B

Waterman Larry
03/13/17 #20828

Are any of you switching out ruddle cables to from SS to Spectra to reduce weight and corrosion? Sailboats are switching at an increasing rate for both standing rigging and lifelines.

Perhaps the Spectra doesn't put up with the chafe?

Curious.

Larry

Nicholas Cryder
03/13/17 #20829

I use Dyneema kiting line. Zero stretch and excellent abrasion resistance. Easy to handle / install. Not sure if that can work on the Huki skis?

bill
03/13/17 #20830

My over caffeinated thoughts on this….

Dyneem/ Spectra has higher abrasion resistance on smooth surfaces than stainless rope but less on corse surfaces. It is very UV resistant and has less stretch than cable (under load). But, woven or braided construction has the disadvantage of weave compression to deal with. It's the braid in the Dyneema often seen in skis (12 strand hollow core) that causes a bit of a problem. It braided like a 'Chinese finger trap' and compresses under load and lengthening a bit. It will do this until it compacts but won't stay that way if it hasn't been loaded far heavier than rudder pedals will ever do, so you need to pre stretch/ compact it. If you don't every time you step on the peddles it has to compact down and will lengthen a little. It ends up feeling vague and dead. My Epics always felt like this.

If you use Spectra line like Q-Power kite line its parallel core with a very tightly braided cover that's not under tension and only there to protect the parallel core. Since the core is not braided there is nothing to compact so there is no dead vague feel (or at least a lot less). It is handy as well as it's stiff and you can just feed it down the rudder tubes unlike the very soft Dyneema. Dyneema is a lot better if you buying the pre stretched and coated kind like Robline Ocean 3000 or similar but it's as expensive as kite line and doesn't work as nicely. Or you can stretch your own. Just take it and load it with something like 1/3 the braking strength (so about 500lbs for 2mm line) with a come-along or throw it over something , tie a loop in both ends and step in one side while some one steps in the other. The line will compact and stay there. I switched all my skis to Q-power line and I'm more than happy. Much better feel, feels slicker in the tubes, easer to deal with and comes in pretty colors

Wire does have one really big advantage though…. feel.

Spectra/ Dyneema has enormous strength under tension but has nothing under compression. There in no push-pull with Spectra/ Dyneema and the line does not telegraph the what going on with the rudder nearly as well. I often wish I could feel the rudder more than I can with soft line. The Q- power kite line is better at it than the braided Dyneema but it still feels more remote than it should. There is a reason why both Fenn and Huki are praised for rudder control and feel and I'm guessing it's mostly to do with using wire…. ( thats my hypothesis and I'm sticking to it!). I have been thinking of going from line to wire on at least one ski to see how much it makes a difference it really makes. I imagine it like going from power steering back to straight rack and pinion… ok not a perfect analogy but I do like the road feel from non assisted steering and i think it's something wire is more likely to give you than soft line. Shouldn't be hard just to do an easy rig up just to check it out…….. bla, bla, bla. Way too much coffee this morning.

Bill

Reivers Dustin
03/13/17 #20831

That's a great topic. Spectra is European name for Dyneema. There's some kind of patent thing or merger thing or something or other about this name deal.

The problem I ran into is how to secure it. The guys at Sampson rope and the local rigging shops tell me that there are certifications for splicing these lines. When I looked it up I found that the main problem is that it can't deal with tight radius bends. Of course it can be tied, but the bend and inherent low friction dramatically reduce the strength.

There's some issues around overheating, but corrosion, weight and strength are really great.

I have to stop now or people will think I had a chocolate bar for breakfast. Which I did not. Yet.

Really, I just get excited about techie stuff. The Larry's understand. Their techie. But you can tell they have a human side because they pitch me a lot of crap. Bet they both have pocket protectors they wear at home when they do their taxes.

rd

bill
03/13/17 #20832

Spectra/Dyneema does have its issues. It's very susceptible to heat but at around 300°+ so unless you are worried about your rudder integrity while your ski is on fire it's not an issue.

Much of Dyneema/spectra lines issues with knots can be dealt with by seizing the bitter end of the knot to the load line. Or in the case of branded line feeding the bitter end back threw the braided line when it's slack and tying an overhand knot. When under tension it will pinch the bitter end keeping it from slipping, if it does the knot will stop it. The Q-power line is easer to tie and an anchor bend with a seized bitter end should be more than enough. Q-power has a waxed coating hat helps a bit with knot holding. Dyneema is slippery but the same anchor bend and seizing should be fine. If you are really paranoid about slipping under these kinds of loads then pull out some threads of Dyneema from some excess line, thread a needle and 'lock' the knot by stitching back and forth threw it. Spectra/Dyneema does much better than most other synthetic line over tight bents, MUCH better than Kevlar.

This shouldn't be an issue on a ski unless what you are tying too is actually sharp. The loads we put the line threw are nowhere near threatening there structural integrity over less than optimal bends or getting near there braking strength, even with bad knots. Plus all the potential problem areas are readily inspectable. This is a real advantage of spectra / Dyneema over stainless wire rope. Wire rope is notorious for giving little warning before braking at the swage. There is a reason why sailors change there wire rigging on a schedule (or should) or take it in to be X-rayed. With Spectra line wear is visually evident. Even when screaming down the biggest wave and stomping on the rudder we only put 20-30 lbs of pressure (pulled that number out of my ass) and no were even close to the 600lbs braking strength of the Q-power line even if the knot compromises it by 50% and the line is worn half way threw…… let alone the 2mm Dyneema so commonly used (1600 lbs braking strength). I see no issues with Spectra other than it's inherent issues with compression strength and braid construction…. at least in a surfski rudder application.

If you want to spend the winter perfecting the best eye splice for Dyneema 12 strand, here is the appropriate splice. It's called the Modious Brummal Eye splice and is just weird, plus good luck doing this in 1.5-2mm Dyneema.
https://www.riggingdoctor.com/life-aboard/2015/12/24/mobius-brummel-eye-splice

Bill

Michael Gregory
03/13/17 #20833

I have been using Spectra line on my Epics for years. Stretching has not been an issue at all. Of course, there should be very little loading running Spectra from the pedals to the rudder yoke. Good news is all that is needed at pedals and yoke are simple knots to secure the ends. “Splicing” is not required. MG

Reivers Dustin
03/13/17 #20835

Wish I woulda seen this last year. I did the eight inch feed with taper cut. Did not know about the mobius trick. I used a stainless eye to provide bend radius and snugged it all up. For good measure I used wax whipping to make it look nice.

This is on some 1/4” dyneema I used for the running line for my stern leash. So as you mention William, this is stupid overkill. If the boat doesn't break then I will. Not to mention that I spent hours on this. Kinda fun. I learned some stuff. And I got to indulge my alphabet syndromes: OCD, ADHD, Delusion of PhD, all that other type stuff.

You must also be in the pocket protector club. In case some of you normal people don't get that, it's the little plastic sleeve that you put your colored pens and pencils in when you go to engineering club meetings. You know, where all the guys look related to Urkle.

rd

Steve Scoggins
03/13/17 #20836

I vote that we collectively send Reivers and Bill on Dennis's surf vacation to further this dialogue while Dennis tries to relax.

Steve