Matti Raustia wrote:

snip
By the way, how is the paddle wheel sensor fastened in the through-hull
housing? I couldn't find this out from the manual and as my boat is in the
water, I dont want to do enything that might sink my boat...


Most of them are round, have O-rings for sealing, and are pushed
straight down into a matching cylindrical hole. It will probably have a
notch or keyway to set the fore and aft alignment when all the way down
and is held in place by a cross pin that goes through the cylinder walls
and the top of the sensor. Or you may find a threaded collar that holds
the sensor in.

It should have come with a matching plug and you may find that stored
near or laying in the bilges by the through hull. Press a wadded up rag
or sponge over the hole as the sensor comes out, then put the plug in.
Some water will get in, depending on the depth of the fitting it can be
a fair stream. Plan on getting wet.

Airmar makes some through sensor through hulls that have a self closing
flapper valve that closes the hole as the sensor is pulled out. Those
do not give a 100 percent seal and you definitely want to put the plug
in place. Don't count on the self closing seal to keep the boat from
sinking!

A coating of a non-petroleum based O-ring lube on the outside of the
sensor will make fitting and removal easier.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)