[C320-list] Knotmeter knot working

[Bill Culbertson]

Bill,
Your colleague is right and you are right.  You will open a hole in the boat and let water in when you unscrew and remove the knotmeter.  It can be unnerving, especially the 1st time, but it doesn't amount to huge amounts of water after you've gotten the dummy plug installed.

Also Catalina makes this somewhat better by having installed a little rubber flapper across the hole to reduce water influx.  The flapper moves out of the way when you insert the speedo or dummy.  But when you remove it, the flapper closes as a result of the incoming water flow and reduces that flow when closed.  This is nice.  It also causes water behavior which is unintuitive if you don't know it is there.  That is, when you first remove the speedo or plug, water comes in at a pretty good clip UNTIL you finish removing it.  Then the ingress slows pretty noticeably.  So when water is coming in strongly, the best thing you can do is finish removing the speedo which will slow the water entry.  The reverse is true as well.  When you start to insert the dummy plug, water influx will increase until you get the dummy plug seated.  My previous boat didn't have the flapper.  Even without, there is not a huge amount of water if you don't take forever to insert
 the plug.  But the flapper does ensure that water doesn't spray up into your face when you most need to see what you are doing :)

Know that the thru-hull fitting is notched at the forward end with a slot and the speedo & plug are equipped with a tab.  This is to ensure the speedo paddlewheel faces forward when reinstalled rather than sideways.  So you MUST line up the notch/tab before screwing the retaining ring all the way down.  If you don't line them up and screw it in tightly anyway, you'll crush the notch in the thru-hull.  Lining up is not hard to do.  I put the speedo/plug into place to nearly stop the water influx and just rotate it a bit clockwise or counterclockwise until I feel it click into place.  You'll want to start with the plug/speedo in an orientation so that the tab is forward so its generally in the right position.  If I remember right, there is also a triangle shape on top of the speedo and plug to indicate the position of the tab to make lining up easier.

In my seven years with this boat, I've never had to clean the thru-hull hole itself of crud.  The crud whether it be slime, mussels, seaweed is always attached to the speedo itself.  So I remove it replacing with the dummy plug.  Then I do all the cleaning on the speedo taking my time because there is no hole in the boat.  I usually spray the paddlewheel with some SuperLube before reinstalling but I don't know if it helps or lasts very long.

Hope some of this info helps.

 -bill
 Harmony #859


----- Original Message ----
From: Bill Sloane <southsoundbill at gmail.com>
To: c320-list at catalina320.com
Sent: Tuesday, November 27, 2007 10:53:10 PM
Subject: [C320-list] Knotmeter knot working

Forum:

Having never owned a boat with a through hull knotmeter, I am not clear how
to fix one.  It was not working this past Sunday when I went out for a
chilly but beautiful sail. A colleague at work told me that I need to
unscrew the fitting in the V-berth sump, and immediately screw in the spare
fitting that is tethered there.  Is this in fact how you do
it? Isn't that opening a hole in the hull below the water line?

I am pretty sure a crustacean or other volunteer has made a home up in the
little fly wheel that needs to be dislodged. Can I do this by entering
through the sump?

Appreciate any advice.

Bill
C-320 'Endless Summer', No. 554
Olympia Washington


      ____________________________________________________________________________________
Never miss a thing.  Make Yahoo your home page. 
http://www.yahoo.com/r/hs