Many messages have recently traversed the
SailNet Chrysler discussion group regarding "cable hum". Hoppy from Florida
developed the survey and gathered the resonses, and, given the nature of this
information, it only made sense to repost it to this site. This information
is applicable to C-20, C-22 and C-26 swing-keel classes.
The first section contains results from an informal survey of C-22 owners
with regards to "cable hum".
The second section contains a collection of e-mail messages relating to
"cable hum" sent directly to me, or gathered through the SailNet discussion
The first section contains results from an informal survey of C-22 owners with regards to "cable hum".
The second section contains a collection of e-mail messages relating to "cable hum" sent directly to me, or gathered through the SailNet discussion group.
"A survey was conducted of some 30 C22 owners on the subject of cable humming. As I see the question has come up again, I'll post the results again."
Subject: C22 CABLE HUMMING
Thanks for your responses! Here are the results. It looks like humming is here to stay.
Keel Cable Material:
Of those surveyed, here are the keel cable materials they cited:
Of those surveyed, here are their reports based on the cable material they used:
I have found a way to virtually eliminate the vibration hum given off by the keel winch cable. I can't believe with all the engineering sailors out there that no one has thought of this. At the risk of giving away a priceless idea, here goes. I should really show a drawing regarding this but don't know this computer stuff so well yet.
What I did was run a length of 1/8" nylon cord though a 3/16 hole in the top of the keel trunk as far forward as possible. Then, it runs down through a pad-eye that I screwed to the curved front end of the keel (drilled and tapped), then it gets tied to a 1" x 3/16 ring that gets the keel cable run through it. Back inside the cabin, there is a small cleat on the side of the keel trunk near the exit of the cord. The thinking here was that if I could change the angle of attack, I might lose the water resistance hitting the cable straight on.
It works pretty dang good. Just a couple notes: It does nothing for keel bang in heavy seas and you have to remember to release the cord before you raise the keel. Also, you need enough keel winch cable slack length for it to be pulled forward enough."
Any questions? I'm at Box 216, Kiel, WI 53042. E-mail: firstname.lastname@example.org
One owner reported: "Objectionable hum, reduced by grounding/fairing keel, mounted wood board between winch and bilgeway as vibration isolator.
One owner reported: "My personal decision on a keel cable was 5/32", 7x19, stainless steel, marine grade type 302/304 wire. At 2400# breaking strength, it should yield a 5:1 safety margin."
One owner asked; "Please answer - have you experienced the keel banging up and down in large waves. There seems to be no way to lock the keel, and in 6 to 12 foot seas, the keel can thump pretty hard."
One owner reported pulley problems: "I used to raise my keel from full down up a turn until it ripped the pulley off the frame work in heavy waves. Now I let it all the way down to keep tension off of the cable."
One owner moved his winch: "I installed a new winch under and forward of the starboard seat. There is an opening on the side of the seat for a handle to be inserted. This is a much better location, but not as good of a gear ratio."
One owner reported: "My C-20 hums too. The C-20 has a different setup (shoal keel with centerboard in the middle) but I think the way the cable is attached must be the same. My theory is that a small length of the cable is exposed to the water "rushing" past as the boat moves through the water. It's all part of the charm of owning a Chrysler, I guess..."
One owner reported: "Ah the hum.... not to worry (I'm pretty sure) the hum tells us we are in the 3 kt and up range. Actually, I like it for that reason. I do think it is the cable. I can put my hand on the cable down in the cabin and feel the hum. Probably does take something off the speed but, then, you didn't think you were going racing did you?"
One owner reported: "From my experience with the C-22, that hum is from the keel cable and cannot be "stopped" without some extraordinary efforts (like putting a collapsible foil over the cable, or somehow locking the keel in place an loosening the cable itself, or never sailing with the keel down).
Mainly, I have found the hum to be a good guide for how fast I am going. Now that I use a GPS, it only confirms the estimated speeds I came up with based on the hum. While there have been times when I have wished that hum away (normally a romantic moment when you want only the sound of slapping waves and wind through the rigging :-) ), but I have come to connect that hum as part of the mystique of C-22 onwership. When I take sailors out and get Miss Molly kicking her heels and humming along (pun intended), the question is always asked and I tell them "Oh, I forgot to shut down the other engine".
One last thing, until the GPS, I could use that hum as a tool to help in racing. It told me whether one tack was better then another, if I was slowing or speeding, and confuse my competitors with just the sound itself (If we were close enough). In the end, that hum is your boat talking to you. Enjoy listening!"
One owner reported: "My C-22 is quiet as a mouse with regard to hum from below decks. However, my centerboard is connected with a nylon rope rather than a cable (long term - a maintenance problem, as it needs to be replaced regularly). The good news is that I have found the boat sails a little better with about five turns on the crank. This has the advantage that the nylon acts as a shock absorber in choppy wave conditions going up wind and keeps the centerboard from banging, which has to be destructive."
One owner reported: "Cable hum was addressed in an early Trailer Sailor article entitled "Clipper Snips". If you are not a member of TSA (shame on you), I will try to dig it out of my archives for you. As I recall, it involved attaching a "fish" to the cable (it really looked like a small fish)."
One owner reported: "Didn't someone somewhere have a cure for cable hum that I saw on line (Trailer Sailor's page) or in a magazine. It was in the form of a small wooden wedge threaded onto the cable and kept from floating to the top by a piece of fishing line. As the rig passed thru the water it trailed along on the cable, preventing the vibration from getting to a high enough frequency to cause the hum. I've never seen it in use, but I've heard it works with some experimentation."
Another owner wrote: "The solution to cable humming problems is actually quite simple. It surprises me that none of you popeyes out there have never figured it out. Keel cables hum for one reason and one reason only. They simply don't know the words!!"
If you have any questions about any of the
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button in the left frame.