What’s with dummy lights?

[NorthernMac]

I’ve seen quite a few posts about people saying once the low oil pressure light came on.

Why don’t more people install and insist on having a oil pressure indicator?

I mean for me I feel odd not having CHT/EGT for each cylinder, but I get it, it’s a boat, still not having oil pressure to match against RPM and temp, plus the lack of folks who cut their oil filters and inspect the eminent on oil changes..

I’m all for adventurous, but dang

[rslifkin]

I've generally found sailboats and small powerboats to have poor engine instrumentation. Personally, I just have oil pressure and coolant temp gauges for the engines, plus a trans temp warning. More instrumentation probably wouldn't hurt, but I haven't really found it necessary. Exhaust temp / water flow can be monitored by watching the exhaust steam for changes.

[NorthernMac]

Originally Posted by rslifkin

I've generally found sailboats and small powerboats to have poor engine instrumentation. Personally, I just have oil pressure and coolant temp gauges for the engines, plus a trans temp warning. More instrumentation probably wouldn't hurt, but I haven't really found it necessary. Exhaust temp / water flow can be monitored by watching the exhaust steam for changes.

But you have to get well past the “green” to see that.

Having a trend and knowing where the engine is normally happy, and nipping things in the bud before you hit a yellow line, let alone red line.

Just seems having a baseline and nipping something on a way back to the dock seems better than having a dummy light and steam show as you enter a sporty inlet.

[rslifkin]

I find the steam to be a decent enough indicator on my engines, as they always steam some by their nature and exhaust system design. So it's easy to notice if one is steaming more than the other. And low water flow also shows up as a significant increase in exhaust noise with water lift mufflers.

[Cheechako]

Gauges are nice, albeit often very inaccurate. After 8 hours of motoring in a daze, the idiot alarm let's you know something's wrong!
But really, what is one going to do with a gauge? "Oh my oil pressure's lower than usual! I'll haul the boat, pull the engine, take it apart and see what's happening..."
On a boat I'd take an exhaust temp gauge, or buzzer, as a higher priority over an oil pressure gauge.

[Captn_Black]

Originally Posted by rslifkin

I've generally found sailboats and small powerboats to have poor engine instrumentation. Personally, I just have oil pressure and coolant temp gauges for the engines, plus a trans temp warning. More instrumentation probably wouldn't hurt, but I haven't really found it necessary. Exhaust temp / water flow can be monitored by watching the exhaust steam for changes.

Mine are pretty basic, but I survive.

[SV Bacchus]

Originally Posted by Cheechako

Gauges are nice, albeit often very inaccurate.

Two identical engines on my cat. For years now the Strbd oil pressure is straight up (where it should be) while water temp hangs on the bottom edge of the red. The port water temp is straight up (where it should be) but the oil pressure is low, down to about 20 lbs.

I’ve come to accept these readings as normal and consider the gauges as inaccurate.

Infrared thermometer reading show both engines running at same temps at multiple reading sites on both engines. Both engines are running at 80C or 180F. 80C is straight up on the gauges BTW. A quick glance should show all needles straight up, I believe that is their intent.

I don’t have mechanical oil pressure gauges as of yet to confirm those readings but they are on the “to do” list.

[a64pilot]

180F is pretty hot I believe, my thermostat is a 165 and that’s where it runs.
Gauges or not is a Motörhead thing. I have to have them, many sailors know pretty much nothing at all about a motor and that info doesn’t tell them anything, frankly they care very little, their plan is if it breaks you call someone.
Gauges allow you to see an event coming, allows you see trends in time hopefully to do something about it, before it becomes an emergency.
For example a slowly increasing temp gauge will alert you to your cooling system needs servicing, a lower than normal oil pressure can alert you to any number of possibilities from a stuck oil pressure relief valve to a clogged filter or even an oil leak.
Idiot lights or buzzers alert you that the event has already occurred, I.E. you have overheated and need to shutdown or you may seize the engine, pressure buzzer the same, shut down immediately or you may seize the engine.

Simply put, your motoring along and your low oil pressure buzzer sounds off, what do you do? Shutdown and check oil level of course, it’s fine.
Next step? Call Seatow or Boat Us I guess, cause your dead in the water.
After that of course install a gauge and see if you really don’t have pressure, or change out the sender unit, hoping that’s it, and hoping the new one works.

I’d prefer if it goes off to quickly look at a gauge and confirm or deny the problem, I’ll know immediately if the switch went bad, without a gauge you won’t.

[tkeithlu]

Idiot lights serve idiots, who are boaters who do not do an instrument scan, which I guess covers about 97% of the people on boats. Idiot lights are cheaper than gauges for manufacturers. It's pretty simple to retain the same wiring, but add a sender at the engine end and a gauge at the panel end. Yes, likely inaccurate, but cheap from your local auto supply house. The gauge will show trends and suspicious changes, but if you ignore it, it will not wake you up until the engine seizes.

Hey, Bacchus, switch your leads between the two engines and discover whether your hypothesis is correct.

[Gaia]

Originally Posted by tkeithlu

Idiot lights serve idiots, who are boaters who do not do an instrument scan, which I guess covers about 97% of the people on boats. Idiot lights are cheaper than gauges for manufacturers. It's pretty simple to retain the same wiring, but add a sender at the engine end and a gauge at the panel end. Yes, likely inaccurate, but cheap from your local auto supply house. The gauge will show trends and suspicious changes, but if you ignore it, it will not wake you up until the engine seizes.

Hey, Bacchus, switch your leads between the two engines and discover whether your hypothesis is correct.

Am I reading this correctly? 97% of boaters are idiots? Seems a tad harsh. Glad I use gauges meaning at least in your eyes I am not an idiot on that metric.

We have met thousands of cruisers but very very few I would so judge.

Jim SV GAIA

[a64pilot]

Idiot lights got their name not from people being idiots, but because they display an ideogram. They way predate what I’d assume we would call today an icon.
They serve their purpose, especially the buzzers, to alert you, no one can continuously stare at gauges.
In more sophisticated aircraft we had a Master warning and a Master caution idiot light, then you would look at the warning / caution panel to see what system tripped the alarm, and often from there to the gauge or gauges that monitored that system.

However most cruisers, power or sail, don’t have more than a rudimentary understanding of the systems on a boat, but then only a very few people really understand what’s going on under the hood of their car too, and yet millions drive everyday, and the majority have never really read the owners manual either.
People just don’t care, they are far more interested in what so and so posted on social media.

However I believe almost all gauges are quite accurate, the accuracy of consumer “things” compared to what they were in the past never ceases to amaze me.
However just because there is a digital display doesn’t mean it’s a digital instrument, nor that it’s accurate to the last digit.
But we are primarily using gauges to spot trends, we usually aren’t so concerned if our oil pressure is 62 as opposed to 65 PSI, but more concerned that it appears to be dropping over time.

On edit it seems Wikipedia disagrees with the name source but does have a decent explanation.
https://en.wikipedia.org/wiki/Tell-tale_(automotive)

[Phyrcooler]

Just like what we saw in the automotive industry years ago. Fortunately, most now have temp gauges. But you’re hard pressed to find oil pressure gauges in anything less then commercial size vehicles. I prefer to monitor trends in both temp and oil pressure, so will be adding if not original once we find our next boat.

[thinwater]

Years of refinery work have taught me that within a few years, the only gauges that work are the ones the plant will not run without. The others are wrong.

[a64pilot]

ALL Miata’s even the Mazdaspeed have oil pressure gauges, but here’s the thing, they aren’t actually a gauge, anytime oil pressure is present, they go to one set position and never move from there, unless oil pressure drops almost to zero.
Seems that too many were concerned with oil pressure gauges that moved, so Mazda “fixed” that.
From a mechanical perspective, the average person is actually pretty stupid. I would have thought that with the easy access to information that now exists, that would change, but I think it’s actually worse now.
Average computer “expert” now knows no computer languages, can’t wire or read code, can’t de-bug, but they are an “expert” because they manipulate software. But as an example have not even a rudimentary idea of have a hard drive functions.

[a64pilot]

So why do boats have tachometers? Those of you that don’t want gauges, why do you want a tach?