Speed transducer

[Andrew Dickson]

The speed transducer was not installed into the 'through hull' when we took delivery of our boat. She is now in the water. How do I install the transducer without getting water in the boat?

[Stu Jackson]

You simply don't.  There is no way.  Seems like you have a plug in now and want to install the transducer.  This is why they invented towels, and folks who say: "Swap 'em out quickly."   

[TonyP]

On Moonshadow we recently had installed Raymarine ST60+ speed transducer replacing an old one.
It has gates that close as you pull it out to lessen the amount of water flow. I do remove it and insert the screw in plug whilst cleaning it as small barnacles stop it from working if left for too long.I should actually remove it when the boat is not being used and leaving the plug in till the speedo is required again.
Yes it can be done but don't muck about and as Stu said have towels ready
Cheers
Tony

[DarthOccam]

This is what bilge pumps and sponges are for.  I leave mine out most of the time to prevent growth from clogging it, and put it in when I'm doing more than just a daysail.  You get good at swapping it quickly.

Michael

[Andrew Dickson]

Ok...thanks for the feedback. I'll give it a crack tomorrow...with sponges/towels in hand.

[Kevin Henderson]

It's really not as scary of a procedure as it it appears.  When you first pull the lug out a fair amount of water comes in and spills to the bilge.  After the pressure realeases a bit, you simply take your time and reinsert the speed transducer into the hole.  Twist it down tight and clean up.. done!!
I take my transducer out if I'm not going to be sailing for a couple of weeks, just to keep the crude off it. 
Your diver should also be cleaning it as well if  you do keep it installed.   

[Jim Hardesty]

A thought,  as you didn't remove the sensor, check that the o-rings are in place and in good condition on the speed transducer before you start the swap.

[Andrew Dickson]

I did the deed and, you're right, Kevin, it is quite an easy procedure...just a bit of a daunting thought of pulling a plug on the bottom of the boat. Regardless, it all is fine and the seal is holding well. All is good and I'll now know how fast I'm going. Thanks all for the comments! 

[Ron Hill]

AD : Your KnotLog (boat speed) instrument should have come with a thru hull fitting that has to be permanently mounted in the hull when the boat is out of the water. Depending where it's mounted in the hull (usually near the keel center and just fwd or aft of the Vberth bulkhead) it may require a piece of 1/4" plywood on the inside of the hull along with the caulking.

The instrument should also have a plug for when the transducer is removed.  Silicone grease works well on the "O" rings (gaskets) for both the plug and the transducer.

I've had great success with spraying the transducer wheel with Petit Outdrive paint - as compared to using special transducer paint which the slime and critters seem to really like!! 

A few thoughts

[Stu Jackson]

I agree with Ron.  It can't hurt to put something on the little paddlewheel.  I usually wheedle some antifouling paint from the nearby boatyard.