Keel Saver

[Diarmuid]

Could attach a gas shock to the keel, like the lifting cylinders on a hatchback. They only move so fast -- a slow, steady extension wouldn't be affected, but a rapid descent would be cushioned. Heh. I thought for awhile of removing the winch altogether & putting a hydraulic ram on the front or back of the compression post. That would give a soft up/down with limits and could be operated from the helm.

I'm also partial to non-wire winch cable. Amsteel Blue is inexpensive, chafe-resistant, dead easy to splice, and at least as strong as galvanized wire of equal diameter. It's the new default material on most ATV winches. I use a 1/4" Technora-core, poly sheath halyard line on our winch. It's knotted rather than spliced at the terminal end, which somewhat compromises its strength -- but it's also about 5x stronger than needed for this application (8000 lb). No meat hooks, no corrosion, no catastrophic fatigue failures. Something like this:

http://www.samsonrope.com/index.cfm?ind ... 148&inst=1

[San Juan Sailboats]

What does it take to replace the sheave on top of the keel with one big enough for the rope?

[Diarmuid]

What does it take to replace the sheave on top of the keel with one big enough for the rope?

Didn't at all. 1/4" hi-tech line runs perfectly in the stock sheaves, as long as they don't have burrs on the rim. Most Dyneema/Technora/Spectra/Vectran lines are okay with wire sheaves; indeed, some manufacturers specify wire blocks for their cord. Good stuff. I like the polyester cover, just to reduce chafe & give it some tooth (our keel 'cable' is a halyard remnant); but you'd almost certainly be fine with bare 12-strand Amsteel. Slippery stuff -- don't try to knot it! -- so you''d need some kind of back splice or toggle to hold it in the winch clamp. Your HDPE materials tend to creep slightly if left under heavy load (as in 25% or more of breaking strength) for long periods. Not an issue with our keels.

I did add a bushing to the bolt where the keel cable's bitter end is fixed; increasing its diameter makes the knotted rope stronger. The old bolt was all bent up, anyhow. Some day I will have to learn how to do a core-to-core splice. Side note: hi-tech cordage often runs slightly under its nominal dimension, while double-braid polyester or nylon ropes are often fat for their size. Same is true for climbing ropes: I've had 10mm lead ropes that consistently calipered at 10.6 or 10.8mm. Lets them advertise greater strength & fall-holding numbers. Aramid cord is so darn strong, and the materials so expensive, they tend to shave things a bit.

[San Juan Sailboats]

This may be a good topic for a DIY article.
I have seen many boats break their keel cables. This could be a good solution.
I am convinced the reason why they break is due to over straining the cable by either continuing to crank the winch after the keel is all the way up, or having one of the sheeves frozen.
Cables have less stretch than most hi-tech lines. Without a window on the keel trunk inspection cover, you have to go by feel to know when to stop. Even so, there is some flexibility that must put great stress on the cable, sheeves, and and keel head. I wonder how a line with its greater stretch would effect these parts.

[Diarmuid]

Actually, Technora, Vectran, Dyneema, and the like have stretch characteristics pretty close to those of wire rope. Half a percent elongation at 25% breaking strength, versus 10% for polyester and up to 30% for nylon. You should not use them in applications where hard dynamic loads may be expected, including mainsheets, unless you want to blow up blocks or snap your boom. Halyards, reefing lines, and standing rigging: they are fabulous for that. When we buy our big boat, I plan to replace all the stays with synthetic line. Stronger than steel at one-seventh the weight -- you can save 40-50 lbs aloft on a stoutly-rigged boat.

I think most cable failures stem from fatigue and corrosion. Our keel cables make a 180 turn and a 90 degree turn around ~1" radius sheaves, then suffer multiple turns around the winch drum. Cycle that a few hundred times, add the weakening effects of internal corrosion, and you have an accident waiting to happen. Synthetic line has become favored for winching applications because it doesn't rust and it doesn't easily fatigue. But it does have its own issues. Uncovered aramid cordage can lose substantial strength with intense UV exposure; and while it's a devil to cut while splicing, it will part easily when under high tension if it contacts a sharp edge. That's two reasons the powers that be are still leery of its use for lifelines.

My recommendation for anyone considering a synthetic winch line would be 3/16" Amsteel Blue (a 12-strand, HDPE line with 5400 lbs breaking strength) with (optional) an inexpensive polyester sheath pulled over it to make a sub-1/4" line. You can buy a similar combo ready made, or you can make your own by stripping the cover off a double-braid polyester line. The core will carry all the load. In fact, you can buy ATV winch lines already eye-spliced with a thimble for the bitter end (they sell 12' lengths for ATV snowplow blades):

http://motors.shop.ebay.com/i.html?_fro ... etic+Winch
http://cgi.ebay.com/ebaymotors/Syntheti ... 4cf7a24f7a

Or buy by the foot at Redden Marine, who have the best prices & service around:

http://www.reddenmarine.com/marine-supp ... -blue.html

The stuff is laughably easy to splice. Whether using naked Amsteel or covered, I'd advise leaving a good 5-6 turns around the winch at keel-full-down. That's good policy whether your winch cable is rope or wire. Replacing the keel cable was the very first improvement we made on this boat. After three seasons of use, often raising and lowering the keel as many as four times a day, the cord looks good as new.

[Wildcat]

Resurrecting this old thread here. Are there any discussions/instructions around on how to replace the cable? I'm gearing up to rebuild the horn on a Mk I and am going to replace the cable as part of the effort.

[kuriti]

I'd say Diarmuid's advice stands. I have used Dyneema sold as an ATV cable on mine for 2 years now and am much more confident with it than wire rope. I even knotted it despite his warnings, but be sure to google dyneema knots as only a few are sufficient given it's slippery nature. If you don't have a crank up/crank down winch, replace it. On my most recent trip I ran aground on the way into Albemarle sound and had to crank up the keel. I brought it down a bit afterward, but accidently sailed 23 miles with it under load with no problem. I don't advise this and am going to replace the line this year just because, but the point is, that shit is tough. Inspect your sheaves, knot appropriately and go sailing!

[Wildcat]

Think I've figured this out. Leaves the winch, goes under a metal sheave under the winch, enters the keel well and goes up to a block attached to the horn of the keel, and exits the keel well under the winch and around a bolt to where it's tied off. Or that is the way mine seems to be configured.