I got a Sirius 21 this July and have been sailing it for half the summer. It sounds like the keel is humming, a vibration that kicks in at only certain speeds. The pitch shifts a little at faster speeds. Any idea how to fix this before it breaks into a full Wagner aria? I will be removing it from the lake in a couple of weeks for winterizing. Suggestions as to the cause? Thanks.
Keel hums
- Thread starter Gruvola
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I don't know your boat, but I bet it has a swing keel. If so, it is much like my Mac/Venture 25 in that the "humm" comes from the keel cable. I understand that if you loosen the cable (add slack), it will lessen the humm. Me? I love it when that boat is "in tune" especially at the higher frequencies - which means I am going faster 
The hum is called the song of the Sirius. It is the cable that retracts the keel vibrating as you move through the water. If you let the keel all the way out, with no sheering pin, the hum should go away. Mine hums nicely too, they all do.
my sirius hums as well. usually starts at 4.5 knots.
tonight was perfect conditions in port dalhousie. we headed out due west coming out of the pier and the boat took off. We were using a samsung phone "app" and measured 6.3 knots.
when we came back down wind we measured 6.5.
just to see how fast the boat went tonight, i used my merc 8hp and opened it to WOT with full sails and we reached 9.5.
fastest the boat has run. i did not hear the hum then.
my question: is this possible in this boat? i have never gone over what i calculated at 4.5 knots.
tonight was perfect conditions in port dalhousie. we headed out due west coming out of the pier and the boat took off. We were using a samsung phone "app" and measured 6.3 knots.
when we came back down wind we measured 6.5.
just to see how fast the boat went tonight, i used my merc 8hp and opened it to WOT with full sails and we reached 9.5.
fastest the boat has run. i did not hear the hum then.
my question: is this possible in this boat? i have never gone over what i calculated at 4.5 knots.
My S2 6.8 swing keel hums and I wonder whether there is some vibration damage/ware on the fitting which connects the cable to the the keel? If so, I would be inclined to keep the vibration to a minimum. Agree?
I had my boat flipped upside down last year, and keel removed. There was no damage to keel, or keel trunk. Only a couple of small stress cracks in hull around forward trunk. Nothing to worry about.
My Sirius has gone 7.8 mph (~7.4 kts) according to several readings on my GPS. This was with only my wife and I on board on a beam reach with fairly flat water and 15+ wind. I was on the cockpit rail using a tiller extension and my wife was (not happily) on cabin rail. Since it was past hull speed which is ~6.33 mph (1.2 X square root of water line), I'm assuming that we were planing. Wooo Weee!
It hums because it doesn't know the words. No seriously, it's the cable vibrating as it passes through the water. My old Balboa 20 did it. I kinda liked it and used it as a speed indicator.
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