Doug Merrill
Menlo Park, CA
Boat Name: Knot On Call
Model/Year: C22/1986
Hull No. 13394
Hailing Port: Lake Almanor, CA |
 06/20/2006 7:40 PM Pacific Time
Just recently purchased a 1986 Catalina 22 and have only been out a couple of times. I am getting a loud humming noise which seems to becoming from the main sail. I do not have a boom vang. Any suggestions? Doug |
Stefan Damstrom
Boat Name: Delfina sold!
Model/Year: C22mK2 / 1987
Hull No. 14306 sold :-(
Hailing Port: |
06/20/2006 11:30 PM Pacific Time
Doug this may actually be your keel cable. Trying experimenting with letting out slack or taking in just an inch or two. My '87 has a hum also near the front of the keel which may be trapped air or an aquatic gremlin :-) but slacking the keel cable seems to do the trick most times. If it's the main, maybe the luff needs to be tensioned?? |
Bilbo
Youngstown, Ohio
Boat Name: Sea Dog
Model/Year: Catalina 22 1987
Hull No. 13971
Hailing Port: Andover, Ohio |
07/10/2006 9:06 PM Pacific Time
Hi all, I think that I have a rational explaination why it sounds like the hum is comming from two places. 1)The cable and 2) the front mount points of the keel. Because It is.
As a musician, I know that the cable will hum or vibrate when under tension just as the string of any stringed instrument. As a matter of fact, the sound will change frequency and/or volume depending upon the speed of the boat. It vibrates in a similar way to the way a flag waves in the wind or (as I've seen an outside mast halyard slapping a mast when a boat is at anchor.) The vibrating cable will transfer the vibration (hum sound) to the places where it's mounted at either end. This is at the turning ball (an almost direct transference to a location that is nearest the cockpit.) but it will also transfer sound through the other attachment which is to the bottom rear of the keel and then through the keel to it's mounting at the keel pivot pin and the bolts. Yep, we can stop or change the vibration if we slacken the keel cable. I kind of like to hear it sometimes because I can get an audible feedback on speed from the sound. As the boat moves the hum begins and then as it moves faster, the hum may seem to change pitch and get louder. For the most part, the pitch of the sound and volume changes happen in steps and not gradually as in something like a slide whistle or someone sliding the slide of a trombone (called a glissando).
Theoretically the halyards, shrouds and downhauls (even the mast itself) can also vibrate if the lines are taught enough and there is enough wind but this may be happening at fairly higher wind velocities than one would like to have on the water while sailing.
Just my theories.
~Bilbo
N.E. Ohio |
Doug Merrill
Menlo Park, CA
Boat Name: Knot On Call
Model/Year: C22/1986
Hull No. 13394
Hailing Port: Lake Almanor, CA |
07/11/2006 7:14 PM Pacific Time
Thanks for all the help. I took last week off to sail for the first time since I posted the question. I added a boom vang, which I think helped a lot. Thought I had eliminated the hum until I got into a stiff wind at close haul. Thanks again Stefan and Bilbo. |
Bilbo
Youngstown, Ohio
Boat Name: Sea Dog
Model/Year: Catalina 22 1987
Hull No. 13971
Hailing Port: Andover, Ohio |
07/12/2006 4:32 AM Pacific Time
Well, the boom vang is good to effect a change in the sail twist and draft.
Both of us are assuming that you have a swing keel since a fixed keel boat won't hum. Is this correct?
If so, the only practical way to get rid of the hum is to unwinch the cable until the sound stops while the boat is moving. You could winch the keel up all the way while it's on a run downwind but I would not have the keel up on any other point of sail unless you know what you are doing.
~Bilbo
N.E. Ohio
|
Lynn Buchanan
Nevada City, CA
Boat Name: SAILYNN
Model/Year: SWING 1984
Hull No. 11994
Hailing Port: SCOTTS FLAT LAKE, CA |
07/14/2006 10:39 PM Pacific Time
If your keel cable is slack and you still have hum in a strong breeze, then it is most likely coming from your rigging. If you ever stay at anchor or in a slip during a good blow, you can hear the rigging sing. |
