Helm Blower Switch

[Les Noble]

I would think a take-off from either either the oil pressure line or ignition switch would be more "automatic" and one less thing to think about when leaving the dock. Attached is a wiring diagram for the fan I installed in mine a few years ago. I chose to take the signal off the oil pressure switch just to reduce the electrical load (all of 4 amps) on the battery at start up. Never can tell when you might need it. The electronic relay is necessary or otherwise the low oil pressure alarm will always be sounding. The voltage regulator is required to keep the fan from launching itself out the window when the alternator output hits 14.7V.

I am trying to figure out how to use relays for the blower, fuel pump and fuel filter water alarms. Looks like you are using an auto relay AND a SSR. My electrical knowledge is not at a level I can comprehend your diagram...yet. One thing I don't get is where is the low voltage for the relay coil coming from? Do instrument panels have a transformer for 5v for LEDs, sensors etc? I hooked up an auto relay to 12v and fried it. Unfortunately, my boat is 2000 miles away and can't run out and measure voltage when knowledge happens, like ignition terminals or oil pressure terminal. I am also investigating relays for bilge alarms. You can pick up water level sensors pretty cheap, but they only need 1.5A max.
http://www.ebay.com/itm/Double-Stai...585507?hash=item5d60b752a3:g:XBwAAOSwayZXjMSr
What am I missing?

 

[lehighsail]

Just finished the installation of the switch with a little electrical advice about the relay from a dock neighbor. Right next to the small blower fan along side the stuffing box under the back berth was a relay.
I ran a 16AWG wire from the relay up to the instrument panel on the side of the cockpit, inserted a 7.5A fuse, and put in a 1" round switch with a blue light just above the access for the starter fuse. Ran the wire back down to the other contact on the relay. Then attached the ground on the switch to a ground in the panel box. The switch is accessible from an existing small hole in the clear plexiglass cover that is used if the ignition fuse needs to be changed. Seems to work fine.