Reply
 
Thread Tools Display Modes
 
Old 01-29-2015, 03:45 PM   #1
Veteran Member
 
Arcticspud's Avatar
 
City: Gig Harbor, WA
Country: USA
Vessel Name: Noeta
Vessel Model: Nordhavn 46
Join Date: Mar 2013
Posts: 99
Hobbs meter

I have install new hour meters on my boat. The old ones in the tach stopped working.

My question is: How to you wire them to the oil sending unit so the meters only run when the engine is running?

Mahalo
__________________
Advertisement

Arcticspud is offline   Reply With Quote
Old 01-29-2015, 03:56 PM   #2
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,525
Tou will need a T .

The oil pressure sending unit should not be messed with as its voltage shows as oil pressure.

Any NAPA will sell a pressure SWITCH that closes or opens a circuit when oil pressure is felt. Some are used to send an alarm if oil pressure is lost, you need the opposite.

Should be on the Cole Hersey site.

Lazy folks simply wire the meter to the key switch.
__________________

FF is offline   Reply With Quote
Old 01-29-2015, 06:20 PM   #3
Veteran Member
 
Arcticspud's Avatar
 
City: Gig Harbor, WA
Country: USA
Vessel Name: Noeta
Vessel Model: Nordhavn 46
Join Date: Mar 2013
Posts: 99
My key switches are hot so that will not work.
Arcticspud is offline   Reply With Quote
Old 01-29-2015, 10:09 PM   #4
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,886
Engine high temp/low oil press alarm circuit is hot with engine running, not hot off. You could use that to run your Hobbs.
Ski in NC is online now   Reply With Quote
Old 01-29-2015, 11:37 PM   #5
Veteran Member
 
Arcticspud's Avatar
 
City: Gig Harbor, WA
Country: USA
Vessel Name: Noeta
Vessel Model: Nordhavn 46
Join Date: Mar 2013
Posts: 99
It's a Cummins panel so are you suggesting I splice into the low oil pressure light?
Arcticspud is offline   Reply With Quote
Old 01-30-2015, 10:22 AM   #6
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,886
If you have the factory Cummins panel, you do not have traditional NC/NO temp and oil switches. But you do have an ignition switch that goes hot when you turn the key on. You can put the hobbs on that, it will clock when key is on. Or if you have no key, put it on the fuel shutdown solenoid on the injection pump. If it is power to stop, you can install a new oil pressure switch with NO contacts and power it through that. Depends on how your boat is wired.
Ski in NC is online now   Reply With Quote
Old 01-30-2015, 08:21 PM   #7
Veteran Member
 
Arcticspud's Avatar
 
City: Gig Harbor, WA
Country: USA
Vessel Name: Noeta
Vessel Model: Nordhavn 46
Join Date: Mar 2013
Posts: 99
I will have to check the key. I know one side is hot with the start battery on. I will check to see if the other side is cold until the key is turned. That would make things a lot simpler.
Arcticspud is offline   Reply With Quote
Old 01-30-2015, 10:41 PM   #8
Guru
 
C lectric's Avatar
 
City: Somewhere
Country: , Canada
Vessel Name: Island Pride
Vessel Model: Palmer sedan 32'
Join Date: Oct 2007
Posts: 1,870
If you have 'turn the key' switch to start it should have the one hot terminal as described when the battery sw. is on. There should be two more terminals for three total.
-One hot anytime when battery sw. is on. This is usually the ENGINE OFF.

-One will be hot with the FIRST TURNED key position which is the RUN position. This is the one you connect the hour meter to.

-One will be hot ONLY when actually cranking the engine and is the SECOND TURNED position. It will also be a momentary which is spring loaded to flip back to the RUN position when the key is released.
Note it is powered ONLY when you turn and hold the key to that position.
C lectric is offline   Reply With Quote
Old 01-30-2015, 11:17 PM   #9
Guru
 
AKDoug's Avatar
 
City: Kenai, Alaska
Country: USA
Vessel Name: Melanie Rose
Vessel Model: 1999 Willard PH
Join Date: Feb 2013
Posts: 570
Definitely the oil pressure sensor will not work, I tried that. Time to crawl around with a multimeter and poke a hole through the insulation if you can't find a connection to measure at.. The sensor sends out differing voltages as the oil pressure changes, so it won't power your Hobbs. It will probably either be red, or have a red stripe on it.
AKDoug is offline   Reply With Quote
Old 01-31-2015, 07:37 AM   #10
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 16,525
IF you wish there are marine ignition switches that work better than the off,start,run variety.

Like your car they have an accessory position .

This is very useful , as it would run your Hobbs , although a good use is to hook it to a merge solenoid ($18. at the RV place) and have the engine alt automatically charge the House batts , no thinking required , no switch position puzzles.

Wiring sensitive radio and other electronics is also a good idea (as in your car) should the starter fail to disengage , it becomes a DC generator , that can reach 50-100V easily.
FF is offline   Reply With Quote
Old 01-31-2015, 03:34 PM   #11
Veteran Member
 
Arcticspud's Avatar
 
City: Gig Harbor, WA
Country: USA
Vessel Name: Noeta
Vessel Model: Nordhavn 46
Join Date: Mar 2013
Posts: 99
I wired it to the "dead" post on the key and it now functions properly at least from the standpoint of the hour meter will run only with the key in the on position.

Thanks for the help.
Arcticspud is offline   Reply With Quote
Old 01-31-2015, 09:58 PM   #12
Guru
 
HopCar's Avatar


 
City: Miami Florida
Vessel Name: Possum
Vessel Model: Ellis 28
Join Date: Aug 2011
Posts: 3,505
I once had a pressure switch try to kill me.

I had landed my Cessna at Ft. Lauderdale to go through customs. When I went to leave, I started the engine, checked the gauges, and let it warm up while I listened to the airport information on the radio.

A fellow came up to my plane, tapped on the window, and pointed down. I shutdown the engine, got out and looked where he had pointed.

Oil was pouring out of the plane. It turned out that the diaphragm, on the pressure switch that controlled the Hobbs meter, had ruptured.

If it had failed ten minutes later I would have been looking at a stopped prop, trying to decide wether to ditch in the ocean or try to do a 180 and land downwind on the runway I'd just left.
__________________
Parks Masterson
www.hopkins-carter.com
HopCar is offline   Reply With Quote
Old 01-31-2015, 11:17 PM   #13
Guru
 
Forkliftt's Avatar
 
City: Biloxi Mississippi
Country: USA
Vessel Name: Patricia Louise II
Vessel Model: 1983 42' Present Sundeck
Join Date: Oct 2007
Posts: 2,433
Yow. Scary stuff!


1983 Present 42 Sundeck
Twin Lehman 135's
✌️
__________________
Steve Point Cadet/ Biloxi, Mississippi USA
*Present 42 twin 135 Lehmans
Forkliftt is offline   Reply With Quote
Old 02-02-2015, 07:10 PM   #14
Veteran Member
 
Arcticspud's Avatar
 
City: Gig Harbor, WA
Country: USA
Vessel Name: Noeta
Vessel Model: Nordhavn 46
Join Date: Mar 2013
Posts: 99
I met a guy who had something similar happen except he was in Dodds Narrows in BC when it happened. That would not be fun.
__________________

Arcticspud is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 10:21 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012