Mustang Sally
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The Hull is Popping the Hull is Popping

It started in Paradise Cove in Malibu California.  "Snap, crackle, pop".  Sharon heard it first and the sound was barely audible.  She asked me to listen.  I heard nothing.  "You are hallucinating " I said.  "It is just your brain cell rattling around in your head". 

Late that night the surf calmed down and the loud exuberant disco party people on shore called it a night.  A blanket of quiet lay over the cove.  It was the first night at a new anchorage.  I lay in bed, sleeping lightly, waking frequently.  I was enjoying the feeling of the gentle rocking motion of the boat, checking our position often and confirming the anchor gently tugging against the current.

Then I heard it too.  "Snap, crackle, pop".  I gave my head a shake and listened again.  Am I dreaming? I roll over and try to sleep.  Snap, crackle pop sounds - just like Kellogg's Rice Krispies coming from down low in the boat. 

My half dozing mind ticked off a list of possibilities:  Cock roaches? Water flowing into the boat?  I'm dreaming?  The boat is disintegrating? Somebody eating Rice Krispies?  Evil creatures from the planet Zarrcon?

I always investigate evil Zarrconians.  So I get up.  It is 4:00 AM.  The boat feels and floats normally.  There is no water in the bilges.  The sound stops.  Back to bed and worry about it tomorrow.  There it is again!  "Snap crackle pop".

Next morning I wake up to snap crackle pops.  Louder now and more consistent. Sharon is awake too. We both listen and wonder.  What the heck can it be?

"Come on Sharon,  we will check under all the floorboards".  I get the flashlight as Sharon sleepily sits up, a wide eyed expression of wonder on her face.  What is that sound?  Sharon sits on the bed watching as I slowly and dramatically lift the first floor board and cautiously shine the flashlight into the dark spaces underneath.  I loudly slam the board back down,  jumping back and shouting CRITTERS!

Sharon jumps a foot then shouts - "Quit goofing off you idiot!"   We both laugh nervously.

A search under all the floor boards reveals nothing but the sound continues.  We remember a story a Betsy, George and Lucas told us about when they were in Central America.  They heard strange sounds on the bottom of their boat and attributed it to a fouled and dirty hull attracting some sort of parasite that made the noise. 

Dive gear pulled out and put on.  Over the side I go with a soft brush.  Our hull has a coat of brown and grey soft growth.  It easily brushes off.  I've noticed that if the boat speed goes above about 8 knots for an hour or two the motion of the water against the hull automatically cleans the crud off.  So I had been a bit lazy about bottom cleaning, waiting for a good breeze to do the job.

But the last few weeks have seen only light winds and lower boat speeds allowing the crud to accumulate.  An hour and a half later the whole hull is shiny blue like a new bottom paint job.  In southern California's crystal clear waters it looks great!  We depart quickly as this unplanned work delays a rendezvous in Marina Del Rey.

Mustang Sally slides smartly over the water, the smooth, slippery bottom making a noticeable speed improvement.  We gain an extra 3/4 knot,  the clean bottom and flat seas allow us to easily motor at 6.0 knots with the twin diesels spinning at 1900 RPM.  A favorable breeze springs up and we raise the sails and gain another knot and a half.  The boat feels unencumbered and it is a pleasant and quick sail to our destination.

Into Marina Del Rey and Sharon grabs the hand cart and heads for the grocery store to stock up for guests - Alice and Roger.  The marina is busy and noisy and I hear nothing from the bottom of the boat.  I clean up and prepare for our guests.

That very night the snap crackle and pop begins again.  Roger and Alice can hear it clearly.  This is embarrassing.  Boats should not go snap crackle pop!

Frustrated,  I fire up an Internet web browser to do some research.  Seems this is a known problem,  with a lot of talk in various nautical forums but little fact.  I locate a site maintained by a biologist.  She claims the sound is made by a species of snapping shrimp that have claws like a crab.  The shrimp snap their big claw, when hunting prey, to communicate or when threatened.   When this species of shrimp are in the water near you boat, you hear them. 

And so solved was the mystery of the boat that goes "snap crackle pop".


These links describe the Snapping Shrimp:  Susan Scott, Science Daily, Ocean Link