Adding an Hour Meter

[colb218]

Hello -

I would like to ad an hour meter to my Yanmar 3HM35F. It seems that the two options for this are to either wire it to an oil pressure switch or to the ignition switch. I am planning on wiring to my ignition switch as my low oil pressure alarm goes off quickly if I kill the engine and leave the ignition on so I doubt I will be in a position to leave the key in/on and the engine off. My process is slightly complicated in that I would like to install the hour meter inside rather than in the cockpit. I don't really have a spot for it on my instrument panel and I have an old toggle switch that was abandoned at some point that I can pull out, enlarge the hole and should be able to slot the hour meter into.

I took a photo of the back of my instrument panel. I have located the blue wire marked with an M near where I want to place the hour meter. Can I splice into this wire? Or should I run an entirely new wire from the instrument panel all the way back? My concern is that with 3 wires already on the ignition post I am worried I will run out of room. Also, if I am being honest it seems a lot easier to spice into a wire rather than fish one through everything. There is a ground bus bar that I will be able to use nearby to complete the circuit.

 

[Benny17441]

You can drill a hole close to the instrument panel and install the hour meter. Weather and water leaks should not be a factor if a good gauge is properly installed. The reason I recommend it on the cockpit is because it has a functionality there. It is used to calculate available fuel left and in conjunction with speed and position instruments serves to calculate range and the all important decision whether to press on or divert course for refueling. It can still be used to schedule maintenance functions. Connect the (+) terminal to the wire that is energized when the key switch is turned On and the (-) terminal to a Negative lead.

 

[Stu Jackson]

The meter "needs" to be neither at the cockpit control panel or on the electrical panel down below. Using 1/2 to 1 gph of fuel is not something that requires immediacy. I motored for 165 engine hours from SF to BC in 2016 and looked at the hour meter once a day, only to be able to calculate fuel to next fuel station. Once a day!

Put it where it is easy to see, but doesn't have to be in a panel at all.

Put it where it is easiest for you to wire it up.

Good luck, all the best.

 

[dmax]

If you end up splicing into the wire, the best way is to use one of these heat-shrink 3-way connectors:

 

[Ralph Johnstone]

As @Stu Jackson say, it can go anywhere you desire on the boat. Seeing as how you want it down below, the easiest thing to do is to take a 12V supply from your engine when it is running. The easiest thing I've found for near infinite resistance devices (like hour meters) is the line to your oil pressure switch.

The below drawing is ripped from a wiring diagram which starts and powers my engine blower when the engine starts. Just be sure this matches the wiring on your boat before going ahead. Running a wire from the deck is also a bugger on my boat.

The current draw is so small on the blower electronic relay, it doesn't bother the low pressure alarm.

 

[Charles Erwin]

Yes to the key switch. Easy to do at the key switch itself (the non- battery side) or the push-to-start switch (the key switch side.) The wire color is white.

When I bought my boat the hour meter was spliced into the dash illumination lamps circuit. Only recorded motor hours at night so the hours shown were pretty understated.

Charles

ps I assume you have the Yanmar wiring diagram - if not I can send it.

 

[Stu Jackson]

If you end up splicing into the wire, the best way is to use one of these heat-shrink 3-way connectors:

View attachment 202035

Actually one of the worst things. The reliance on the center hole to maintain continuity has been suspect for quite some time, and Maine Sail warns against using them. Find another way to do a 3 way splice...easy enough to do.

 

[dmax]

I stand corrected, thought they were the way but never used one myself. Though it sure beats the splices I've seen where people cut into the wire and tape it up.

 

[Ralph Johnstone]

Only recorded motor hours at night so the hours shown were pretty understated.

But think of the resale value with low hours like that .

 

[colb218]

Thanks all! I am not particularly worried about having the display in the cockpit. I have a fuel gauge down below which helps with monitoring fuel levels.

I have previously used a vampire clip for splicing wires in car stereos. I assume that would not be an acceptable splicing method, yet I see they sell 'marine grade' versions?

 

[Ralph Johnstone]

I have used crimp butt connectors which have a different diameter (and colour) at each end to accommodate the single wire in one end and the same wire plus the spliced wire on the other end. Quick, easy, and strong.

 

[jssailem]

Do it once, do it right. Is my mantra when dealing with marine electrical.
Get some proper lengths of wire. Use proper ring connections. Install a small terminal block if necessary.

Then you can put the number of wires needed for this connection safely.
They make terminal blocks in many sizes.

I installed a simple Hobbs meter in the engine compartment. Every time I start the engine, I check the oil level, coolant level, and the Engine Hours. Record them in the boats log. All the data in one place.

 

[Benny17441]

The meter "needs" to be neither at the cockpit control panel or on the electrical panel down below. Using 1/2 to 1 gph of fuel is not something that requires immediacy. I motored for 165 engine hours from SF to BC in 2016 and looked at the hour meter once a day, only to be able to calculate fuel to next fuel station. Once a day!

Put it where it is easy to see, but doesn't have to be in a panel at all.

Put it where it is easiest for you to wire it up.

Good luck, all the best.

Stu, in most cases that is true, but as you well know depending on conditions fuel range can significantly change from hour to hour and when you might be 50+ miles from shore in a passage it pays to keep track of your fuel capacity more often than once a day. I guess it all depends on how the boat owner use their boat.

 

[Stu Jackson]

Stu, in most cases that is true, but as you well know depending on conditions fuel range can significantly change from hour to hour and when you might be 50+ miles from shore in a passage it pays to keep track of your fuel capacity more often than once a day. I guess it all depends on how the boat owner use their boat.

Benny, I read this and said to myself: "I agree and kinda don't, both at the same time."
Here's why:
--- it all depends on how the boat owner use their boat - agree completely
--- fuel range can significantly change from hour to hour - disagree. I have not had a working fuel gauge for over 20 years. Knowing that the sender needed to be replaced, in many cases on a somewhat regular every few years basis, I started to keep meticulous records of my fuel use, and I know what my engine uses (0.496 gph over almost 25 years). Sure, fuel use will change a bit if you compare idling for hours to running at 70% throttle (say normal use) but how many people do that? I contend that "significant hour to hour change" just doesn't happen for any given engine in any given boat. Take it even further: if you slow down to reduce consumption it just takes you longer to get there so you end up using about the same amount of fuel. Benny, in my experience, it just doesn't happen. The other point often made by others (not you) is that you use more fuel if you hare working again headwind and/or currents. Nope, your engine doesn't know what's going on outside your boat, all it knows is that it is running at any given rpm for X number of hours. Against wind/current it just has to work longer to get from A to B. It does not change the engine gph, it just increases the "h".
Significant consumption differences are most usually associated with generators, where the eletrical load upon them can change drastically over time and affect it, so it is not the same as propulsion engines.

 

[jssailem]

The other point often made by others (not you) is that you use more fuel if you hare working again headwind and/or currents. Nope, your engine doesn't know what's going on outside your boat, all it knows is that it is running at any given rpm for X number of hours. Against wind/current it just has to work longer to get from A to B. It does not change the engine gph, it just increases the "h".

Thank you for making that statement.

 

[MikeHoncho]

I put my fuel gauge next to my hour meter which is on the bulkhead that makes up the engine compartment (in the cabin). Seemed logical and works fine.

 

[Benny17441]

When I say fuel range can vary from hour to hour I meant that you could leave port and be running at one speed and half way on your trip a change in weather conditions can reduce that speed to lets say half of what you were doing. The fact that it will take you longer to get to your destination determines that you will burn more fuel to get there. The burn rate is constant but if you have to run the engine twice the time it will burn twice the fuel on the average to the same destination . I don't contest the fact that we usually do not check the hour meter more than once or twice during a trip but I say that is because 1) we learn to tell by our speed and distance travelled that our numbers are close to what is anticipated (learned intuition) 2) we also tend to sit out adverse weather conditions that would significantly alter calculations of range. To be honest in my years of sailing I have only encountered conditions that would raise concerns about range to a refueling port only about 3 or 4 times and only once did I choose to divert course to a down weather alternate destination as a prudent measure. Pushing 1.5 knots for hours without no sign of respite is no picnic. The USCG vessels when out to sea they plot their position in a dead reckoning track every hour on the hour and mark distance travelled and average speed. That is in case they loose any of their instruments. Worst case scenario it is good to know your heading, your position, your speed and your fuel availability with no more than an hour's lag. Needless to say I do not trust fuel gauges to give me accurate results other than you have fuel or not. Regarding location of the hour meter I have not found a good reason that would dictate there is a better place to locate it than in the cockpit. Nothing happens fast in a sailboat, but when shorthanded every little bit can count.

 

[Roland5048]

Nothing happens fast in a sailboat

Until it does. That's when a spare pair of britches come in handy.