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Rough Water Downwind Vid
lori & beau whitehead
03/13/16 #18786
With the race cancelled, Alan, Eric, Mike L & myself shuttled Alan's OC4 to Wildcat for a dw run. It was setting up to be an all-time run when 1/2 mile in the carbon foot pedal on the rudder system broke whipping us sideways beam into the waves… Alan had to paddle 6-man style the rest of the way home but not having a true steering blade made it tricky. Still managed to catch a few good drops off post point.
Note to film editors; if you use Vimeo vs YouTube you can use any of your music & aren't forced to use YouTubes “approved” selection of soft-porn music…
Beau Whitehead
allipp01
03/13/16 #18787
The force exerted on a rudder, even the relatively small one I have on the OC-4 is extreme when on large waves moving at a high speed. With about 750 lbs of paddlers and 150 or so of canoe, that's 900 lbs total moving at nearly 20 mph on those screamers. Stomp on the rudder hard enough and with that kind of pressure and something will fail. In this case it was the carbon hinges on the Epic foot pedals (being designed and work admirably well - I might add - for a single surfski) that failed.
I think if I want a rudder system for big days, it's going to need to be a direct tiller system of some sort. Perhaps a shaft through the boat at the steersman's feet with a T-bar to steer with. You'd need a pretty big cotter pin to hold that in place due to all the torque exerted pushing on the rudder.
In the meantime, I'll head down to LFS and pick up some (strong) stainless steel hinges and should be good to go soon.
Reivers Dustin
03/13/16 #18788
good reminder to inspect your gear. On my X a few years ago Morris noticed that the carbon foot peddles were wearing through. I talked to Jude and found out there had been an upgraded design from that original S1-X. He sent me the new system and I replaced everything. I ended up adding stainless bolts to provide a strong-back to the peddles, just for that extra edge.
The force is not just the translated turning moment. On some of those nose-bleed drop-in waves you have to almost stand on your foot peddles to stay in your seat. There are times when I'm pushing against the back of the cockpit - so the force is approaching leg squat power.
The spectra line always seemed light duty to me vs. the stainless cables. In my reading I see that this material is quite strong. But there is a problem using knots or splices. The proper termination of spectra or dynema material is a tricky thing. Sharp bends are a no-no and the material is susceptible to abrasion. The loss of strength from an improper knot is startling.
I fussed with my stern leash running line for days (spectra) before realizing that this won't see much more than the 25 pounds of boat, some wind loading and of course impact of the stop - when it's in service. I had sized the line for 4,000 pound duty. It's probably ok if I tie a knot in it.
By the way, when the SeaRay guys were hauling Deb out, they had trouble saving her boat. They asked me if there was a bow anchor of some kind and I had to say no. There is nothing on the front of most boats for this. I've installed D-rings on front of two of mine, just so someone could clip a line on there. Maybe because they had trouble or were focused on getting Deb separated from her 'ski, they cut the spectra leash running line - so there's a little repair needed on that now.
rd
bill
03/13/16 #18789
My 2 bits.
I think you might be confusing spectra line with Kevlar line in respect with sharp bends. Spectra/dyneema is remarkable stuff and can handle tight bends just fine (within reason) where Kevlar has real issues with this. Spectra has a braking strength of about 2500lbs for 1/8th-3mm/ 1500 lbs for 2mm….so even with the 50% reduction in strength with most knots (more or less) it's still more than strong enough for rudder lines and then some. I use 1/4 inch for a runner just for handling reasons. It is also a lot more abrasion resistant than you might think. It is a spun version of UHMW known for its amazing abrasion resistance superior to stainless steel ( lots of caveats here). Dyneema is also used as chafe sleeves over other line in sailing. It's achilles heal is heat, heat and spectra=not good at all. It's also very UV stable to many people's surprise While stainless cable is strong and abrasion resistant it is not without a big issue. Crevice corrosion is real and very bad. The swedge fittings used with cable are not nearly as strong as you might think after just a few years. I think cable actuated rudders only benefit is feedback for better feeling steering ( not to be under valued) but nothing more than that. In the end all rudder lines should be replaced every 2-3 years if they need it other not for good measure.
Spectra or equivalent make that cheep and easy. A Bowline worked fine in spectra if you seize the bitter end to itself . So does a round turn and two half hitches if seizing the bitter end to the standing part or another part line, this is key.
There are better Dyneema variants for rudder lines than others. Some of the simple woven line hasn't been pre stretched or more correctly ' pre packed' and Isn't the best for rudders as it feels vague. There is some that is pre packed and treated to be stable unloaded and extra slippery like the 2mm “Ocean 3000 by Robline” that work well as rudder lines and feel more solid that generic Dyneema. You can also “pack” Dyneema yourself by pre loading it with several hundred lbs before installing it as rudder lines. It makes it feel better on the peddles and it also packs it smaller and makes it stiffer somewhat. Or just buy the Ocean 3000. The kite line that Think uses is nice as well but is a lot less strong at 600lbs before knots.
Knot strength for spectra in the right column.
http://www.neropes.com/Resources/sail_reprint.pdf
Bill Cirino
Nicholas Cryder 03/13/16 #18791
The spectra kite line is called Q-powerline, awesome stuff. I use it on my skis when replacement time comes (about every 2 years or so). Very easy to work with, zero stretch, highly abbraision resistant and easy to inspect for signs of wear. Ive tried stainless cables as an option, but had corrosion and abraision issues. Was also a PITA to work with. There might be higher quality SS suppliers out there, but I couldn't find them.
bill
03/13/16 #18794
I spoke with the Q- Powerline owner about his different lines a couple of years ago. He suggested the 2mm line they make for kite bridles. He said he would send me enough for a ski to try out but it never showed. Anyways, like the other line it's a parallel spectra core with a tightly woven spectra cover. Nice stuff I'd guess but I don't want to buy a 600' roll.
Nicholas Cryder
03/13/16 #18795
Yep, I bought a 600' roll. See me if you want to try some out.
