hobie humm

I sail with a lot of older hobies and when they run hard they Hum. My 72 16 has no hum. My question is what causes the humming and why is mine silent? Also, does anyone have any input on 16 wings?

IIRC the rudder blades are causing the hum. Hobie has some old instructions how you could modify the original Lexan blades so that the humming might quiet down some. The instructions recommend to shave some material of the trailing edge of your blades using a pair of scissors. Do not attempt this with EPO's or other aftermarket composite blades. Shimming and good alignment of the blades might resolve some of the hum as well.

Patrick

The reason Hobie's Hum is that they forgot the words...

Ok, sorry, - I'll go away now

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The fact that this windy world is largely covered in water obviously means that man was meant to sail.

Patrick is correct. If your friends want it to stop have them ook on the support page under rudders for the instructions on how to fair the trailing edge of thier PLASTIC rudder blades.

The hum is caused by the blades cavitating. I will spare everyone the fluid dymanics lecture as to why.

Your blades may be already faired or are composite.

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Nick

Current Boat
In the market
Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO

I have the EPO rudders and they hum as well. It appears to be leading/trailing edge condition and not alignment. They will hum individually if either one is up.

Not neglecting the speed loss that may be associated, the biggest problem is "sneaking" up on the boat in front!

If we're out sailing with newbies on board we tell them we have reached "terminal velocity" which just adds to their excitement!

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H16 #88638

This is probably the memory that stands out the most for me from sailing with my dad as a kid. When the rudders were humming, we were haulin' butt, and everyone on the pond we sailed in (College Pond in the Miles Standish State Forest in Mass.) would look and wonder what was going on. There were no stink boats allowed on the lake and we were accused of using a motor and that the noise was proof. Ha, it was cool to say, nope, that is the power of wind my friends.

On a line along with a post earlier, does it really cost that much speed when they start to vibrate like that?

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Raizin' Hull
#638
CCMQ6749M82H

My 1980 H16 with the old style rudders would hum pretty loud when you really got going in a good breeze.

Over the winter I had filed an sanded per instructions a forum post. I wish I hadn't because I really miss the sound. You could really tell when the boat was at top speed the rudders would really scream.

It's a good thing you stopped the rudder hum, because of a little know fact about rudder hum.

If you get going fast enough, the hum gets VERY loud and violent --then the rudders can literally explode! The schrapnel from the explosion can fly 50 feet in the air.

The worst story I heard about this was some guy in Florida that liked to race with his pet parrot. The parrot got so used to the humming, the bird actually imitated the humming whenever it saw the sailboat. One really fast day of sailing, the rudders were loudly humming, then one exploded. A piece of the rudder came flying out of the water and decapitated the parrot. The grief stricken owner of the parrot sued Hobie for $600,000.00. The Hobie Company offered to buy a new parrot, but refused to settle for anything more than the cost of the parrot. Hobie lost in the initial trial, but has appealed to the Federal Appeals court, where the case is still pending.

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Jeff Peterson
H-16 Sail #23721
Big Marine Lake, MN

Jeff,

Any more details on this "exploding rudder balde" story. Were they nylon or EPO or carbon? Old brittle blades or new ones?

Does anyone know the resonate frequency of the different blades? Then, does anyone know the frequency or range of frequencies of the hum?

This just sounds unlikely. I don't men to knit-pick, but I too enjoy the hum and since I don't race I don't care about any speed loss because of it. I just want know if I will be decapitating any small passengers I take out on my boat.

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Nick

Current Boat
In the market
Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO

I guess the emphasis here is on the "worst story" - but quiet entertaining... Patrick

This sounds more like a fish story than a parrot story.

Exploding rudders?

If you want to be SURE yours don't have this problem...

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Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)