Mac 25 HUmming sound/ keel check

[Ryan]

Can any one explain the sound that comes from the boat while underway? It gets louder as speed increases. Also How can I check my keel to make sure it,s secure? Also there is some kind of string that runs down the mainsail in a sleeve. can any one tell me what to replace it with? Size, length' etc. Thanks so much. Ryan.

[arknoah]

Where does it seem like the sound is coming from? I have kind of a humming sound that I think is coming from the rigging, but I'm not sure what it is. Maybe we have the same sound.

[THE CUSCUS]

The humming sound is coming from the keel cable (it vibrates as the water rushes past it). I use it as a speed indicator. When it starts humming loudly (we're moving fast), my wife says, "the boat is happy now, the keel is humming"

[Freedom77]

If you don't like the HUMMMM just loosen the keel cable a little bit. We always enjoy "humming along" Fair Winds and Full Sails....

[Ryan]

well I guess the humm is normal then. How about a keel check? I've heard of guys losing keels. I want to be sure mine is gonna stay on. I dont have a manual and I am new to this. Anybody have any info? Thanks folks!

[Hamin' X]

Macgregor 25 Manual

~Rich

[arknoah]

The humming sound is coming from the keel cable (it vibrates as the water rushes past it). I use it as a speed indicator. When it starts humming loudly (we're moving fast), my wife says, "the boat is happy now, the keel is humming"

That makes sense. I first noticed the sound both when going a little faster, and after I deployed the keel all the way down.

[snotnosetommy]

As long as it's humming, you know your keel is still there.
And yep, you should take a look sometime at the pivot bolt and the surrounding fiberglass. Also the stainless cable attached to the lower end of keel. Also the winch. Also the plastic tubing and its clamp where the cable goes thru the bottom of the hull. If that comes loose it could sink you. Just sayin.
Happy sailing.

[tomchitecture]

I have had a few swing keels that hum and one fixed keel that does. My Mac 26s hums when I am in a nice upwind groove. A hum means the stress on the keel verses the hydrostatic pressure from the water are constantly equalizing at a resonating frequency that is audible. The higher the speed, the more taught the keel, (like a guitar string) and the higher the frequency of the hum. In my boat I hear it going upwind. We were in the Race to Macinac last weekend and I heard it once we reached 13 knots in a Tartan 10 downwind at 150 apparent. THAT was fun.

It is my understanding that the keel itself, not the downhaul, is humming. If you loosen the daown-haul, you lesson the resistance and de-power the keel, thereby reducing the resonating frequency below audible range.

That's what I think.

[RickD]

No offense to the OP but this made me laugh.

The first day we took out our Venture 25 we had returned the week before from our lessons. The boat we'd learned to sail in was a 30' Catalina with a fixed keel. I knew there were differences in the Venture and Catalina, but when we hit nearly 6 knots cross the lake and this weird HUMMMMMMMMM came from the boat I started to wonder what the heck was wrong.

Took me a couple of trips down below to finally figure it out. Loosening the cable caused it to go away.

The boat was singing to us as she was happy!

Yeah, it's your keel cable.

[Ryan]

Thanks so much guys. But how do you actually check the keel bolt? Do you have to remove it? Thanx,Ryan.

[snotnosetommy]

You want to see the condition of the fiberglass around the pivot bolt. For instance, if a PO has snagged the keel on something while in reverse, it could severely damage the keel trunk. That condition will also make the rubber bolt gaskets useless, causing a leak.
In my opinion, if it looks good and seals good, it's good. No reason to mess with it.

[Ryan]

thank you everybody for your help, I am truly greatful !! I live on a small island without much resources and your input has helped me greatly. This is a great website! Mahalo!

[Catigale]

It should hum at A 440 Hz

You take it to a rig tuner if its out of tune.

[eliduc]

Mine hums "mi" do, ray, mi.... The 25 manual tell you to back off on the cable a little to get rid of the hum.