Humming Centerboard

Discussion in 'Capri/Catalina 14 Talk' started by DaveM, Jan 2, 2012.

  1. DaveM

    DaveM Charlabud #623

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    I had my 14.2 out on Lake Grapevine (TX) on New Year's Eve. Nice winds 10-15, bright and clear. Beautiful. As we accelerated the centerboard started to hum, and as our speed peaked the note actually pitched up a complete octave.

    I was wondering about the physics of the humming centerboard. It is a good thing?

    I use a mobile app on my phone called GPS Essentials and captured my top speed at 7 kts. Is that fast? It sure felt good.

    What is the fastest recorded speed you've seen in 14.2?

    The GPS app also captured the attached trace...
     
  2. gregwcoats

    gregwcoats Member

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    My best speed to date is 7.1 knots in about 12 knots of wind. We were really hiked out while sailing inside the harbor. Not sure I really want to push it past that, I am 65 years old and don't want to go swimming.....
     
  3. chemprof

    chemprof Member

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    DaveM,

    Several folks here at the forum have described various noises coming from the centerboard and/or the centerboard gasket. I've heard only the swishing sound of the water, and only if the centerboard was fully in the down position.

    It is highly unlikely, but I have to ask if you've inspected the centerboard for any snarls of fishing line! I "caught" a troller this past summer and there were certainly some interesting sounds (some of which came from the lady on the other end of the line!).
     
  4. Allatoona

    Allatoona Member

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    I like the hum, tells me when I am going fast. Although, I would imagine harmonics in the centerboard would probably slow the boat down somewhat. You can change the position of the centerboard by raising it up slightly and see if that

    I hit 10mph once on a good wind gust, and have been over 9mph many times solo and with crew. It's a real rush going that fast sailing solo. I have reefing points in my mainsail so I can keep some control while sailing solo.

    I broke 8mph in my Catalina 22 a couple weeks ago on the lake sailing downwind with my 150. One big wind gust my whisker pole folded in half. I was flying my 120 all day, then traded for my 150 for heading home going downwind. Switching to the 150 really wasn't a good idea after all.

    -Robert
     
  5. rkrebill

    rkrebill Member

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    Hum

    In good winds, I also get a hum from the centerboard area. Pretty sure it is the plastic in the gasket that kind of seals off the water from the cockpit. My gasket is old and has a few tears, which I think oscillate causing unwanted drag when trying to keep up with the fleet.. I see that Catalina Direct sells a replacement gasket, but suspect it is a bit hard to replace. Thinking about waiting till warm water-weather, then careen the boat on a sandy shoal so can more easily get to the boats bottom to make the repair. RK
     
  6. Capri Joe

    Capri Joe Member

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    Hummmm

    The Humming CB is normal and occurs at about 4.2 Kts. It is the board causing the noise and you can reduce it by lifting the board a few inches. The fastest my mod 3 has gone is 9.1 kts, per my GPS. Once I'm above 5 Kts I begin raising my CB about 10% for every knot above 5 kts which further excellerates the boat.
     
  7. fish89

    fish89 New Member

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    Hi Dave, I too have had a pretty good hum in my centerboard at about 7 kts., but I am pretty sure (at least on my boat in particular) that it is from a large crack in the foot of the board. Already ordered a new one from Catalina (about $340 or so), but have yet to install it to see if it fixes/solves the problem. Also had a fiberglass repair shop refinish and deepest my rudder, so I can't wait to get both new blades on the boat and give it a try. As long as you are running downwind though, pull the board up most of the way to both reduce drag and maybe eliminate the hum/vibration...just don't forget to lower it again when you jibe or you'll probably end up swimming. :p
     
  8. jerinaldi

    jerinaldi Member

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    Kinda like sweeping the wings on a supersonic jet!
     
  9. fan

    fan Member

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    The board hums because it is not "fair" or perfect in shape. This is like an out of balance tire on a car vibrating at certain speeds. Racing boat owners spend great somes of time and money to have the blades (keel, rudder) faired to remove the imperfections so the boat travels better through the water. Some owners fair the entire bottom of the hull too. Fairing removes the high and low spots in the blades and hull to create the perfect shape not found in manufacturing. Lots of filling and sanding.
     
  10. Gary Hannan

    Gary Hannan New Member

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    I like the humming- it lets us know that we are really starting to move......
     
  11. rkrebill

    rkrebill Member

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    Hum

    Cut off a small bit of the gasket that was torn, and now there is no hum on Tomato Sloop. RK
     

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