Knot meter

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Sep 1, 2014
93
Beneteau 37DK Alameda
I sail a Beneteau 37. When I remove the sending unit for the knot meter for cleaning The gush of water is big compared to the B323 I used to sail. It makes a mess! The 323 had a flapper which reduced the flow and made removing the unit an easy and clean job. The 37 has a clear though hole that is explosive when opened. Did Beneteau change this unit on newer boats or is mine damaged in some way?
 
May 17, 2004
5,693
Beneteau Oceanis 37 Havre de Grace
Our 2014 37 had the type with the flapper. The flapper broke off the second time we tried to replace the transducer. The dealer helped us out and replaced it, but the new one broke again on the first replacement. Seems like it's just a fragile design.
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Those Airmar flaps are prone to damage. By design the have to be very thin. If one breaks, you get a water cannon ever time you pull the transducer.
 

DougM

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Jul 24, 2005
2,242
Beneteau 323 Manistee, MI
If my 323 had a "flapper", I never did see it . Consequently, I got fairly good at pulling the paddlewheel and replacing it with the dummy plug. A towel on the bilge floor was enough to contain the small amount of incoming water. I have to admit, the first time I tried it was rather scary.
 
Feb 26, 2004
23,050
Catalina 34 224 Maple Bay, BC, Canada
I used to take ours out with my right hand and try to install the plug with my left. Finally realized being right handed should come in useful: so I used my left to remove it and right to install. Much less water. Even the old way, though, a towel kept it down to a negligbnle amount to deal with.
 
May 24, 2004
7,174
CC 30 South Florida
Like Napoleon asked his butler "Help me get dressed slowly because I'm in a hurry". Just set up in an efficient matter with rags and the plug securely within reach. . I hold a rag on my left hand around the transducer and as soon as I pull it with the right hand I will stuff and hold the rag in the opening. With the water stopped I will release the transducer and pick up the plug making sure I have it in a proper convenient hold. I have plenty of time to get ready to insert the plug . I will get it close to the opening and as I remove the rag I will move the plug into place in one sure motion. It does not pay to try and do things quickly as anxiety builds in and it may cause a fumble of the plug. I find that stuffing a rag is quicker and easier in controlling water flow allowing me time to do things slowly with minimum water intrusion.
 
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arf145

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Nov 4, 2010
495
Beneteau 331 Deale, MD
I had to replace my flapper and the collar it hinges on after my transducer got jammed on it. The part is available from Airmar and is easily done when you're on the hard. To DougM and others, you may not see it, but if you aren't getting a huge gush, it's probably there. The flapper is down in the thruhull and doesn't show at the opening inside.
 

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Sep 1, 2014
93
Beneteau 37DK Alameda
That is good info arf145. I will fix next bottom job. I was thinking we would have to do a complete thru-hull. Thanks Richard
 

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Sep 1, 2014
93
Beneteau 37DK Alameda
The part cost is $33 from iMarine #33-510-01. Must be out of the water to replace.:dancing: