Typical install spot for a speed sensor thru-hull?

[noworries]

My boat doesn't have a working speed sensor.  I have a sensor on the boat that looks like a rat chewed through the wiring.  Where is the speed sensor thru hull typically located?  Under the aft cabin?  That's one of the few places I haven't looked yet (mainly because I'm too lazy to move all the stuff in there)

[Dave Spencer]

I think anywhere near or behind the keel would be a poor spot for the speed sensor.  Mine is located under the V-berth well forward of the keel.  Any disturbed water from the keel or the prop would adversely affect performance.  Have a look at the Raymarine website and there will be manuals for knot / logs there showing the best locations.  Good luck.

[scotty]

Mine is located in the aft, near the prop shaft. (1989, Mark I)

[Stu Jackson]

Aft would be odd, but we've seen some.  Usually either under the V berth or right in front of the mast, since those are the only two places, other than aft, that you could get to one.  Look for big black wires.

[Ron Hill]

No : You haven't mentioned the brand of Knot log that you have? 

Most speed transducers are thru the hull in a place the gets undisturbed water - near the bow of the boat.  Most C34s I seen, have them under the aft Vberth or more prevalent under the settee fwd of the mast.  Most speed transducers have a BNC connector between the transducer and the instrument - which is easy to connect/disconnect.

A few thoughts

[Ron Volk]

After I bought my boat I started looking for the knotmeter & depthsounder thru hulls.  I assumed that they were located on the aft portion under the v-berth but they weren't there.  I finally unscrewed the T & H sole in the v-berth and there they were.  You can't see the depthsounder thru hull but it is located just to starboard of the knotmeter and I have easy access to the holding nut.  This thru hull removes outward.  For safety purposes I wanted easier access to these so I had the fiberglass flooring cut out to a larger rectangle, had the screw down sole cut out and made a cut to fit piece of T & H to fit this.  See attached pictures.

[Ken Juul]

Nicely Done 

Easy access is important or it won't get pulled.  Mine is in under the vee berth.  Remove the cushions, access hatch, cover the control box for the a/c unit and then dive head first into the hole to pull it knowing full well I will get a face full of water each time the speedo head/plug is pulled.  As a result it gets cleaned on the haul out, when I scrub the prop and before extended cruises.  For the weekend trips I do without.

[Ted Pounds]

Easy access is even more important for safety reasons.  If it springs a leak you need to be able to plug it right away...

[Stu Jackson]

Very interesting, Ron, thanks for the details.  Ours is under the V berth, but one advantage we have is that the PO took the drawer out of the galley to install a microwave under the galley sink, so I put it in under the V berth which makes access somewhat easier.  If folks have them under the V berth, a drawer or even an access door underneath would help.  That fiberglass is massive and can take more holes, to which those who have installed drawers underneath and access panels on each side can attest.  http://www.c34.org/wiki/index.php?title=V_Berth_Louvered_Doors

[Ron Volk]

Stu,

I also got tired of having that large shelf under the v-berth because you couldn't stuff anything like sails down below, so as you can see from my pictures I followed that good wiki article you show by Dan Harrington and removed it and added four louvered doors like he did.  It's great to have a website like this to be able to go back and see detailed upgrades that can and have been done in the past.