Digital Instrument Display

I have twin 270 Crusader engines and my boat is going on 30 years old. Some of my gages are unreliable.
Since I will be replacing all gages and sensors in the near future, I was thinking of going to full digital display instead.

Since I am totally ignorant on this topic, what is actually involved. Do I just rip out all of the old wires and replace with one or small cables?


What would I need to buy in addition to a new digital display panel, things such as interface units?


What reasonably priced manufacturers would you recommend?

I am researching replacements for my TAMD Volvos

There seems to be a whole lot less info on the web than I would have expected.

Maretron is good place to start. This might give you some ideas Adventures of Tanglewood: Maretron monitoring.

There are adapters that will wire into the various sensors on your older engine and put the info on NMEA 2000 where it can then be displayed in many ways. You can do as little, or an much as you choose.

I found that the digital display often had the ability to tell the relative rate of temp, pressure or whatever. When tempeture is steady one can tell as the numbers are steady or nearly so. If the temp is rising rapidly the numbers will rapidly change quickly and almost constantly. With some measurements the rate of change is even more significant that the number itself. Say your coolant temp is 200 degrees. If it's steady it could be normal (mine usually reads 190) but if it's rising rapidly it's a big red flag and of great concern. You've got to stare at an analog display looking very closely and over a period of time to even tell if it's rising or falling. The rate of change is not very apparent.

I became aware of this flying ultralight aircraft and the cylinder head temp indicator almost needed a digital readout. Once discovered I always used a digital display as once cylinder head temp reached about 425 degrees (depending on the engine) it would dramatically quit. The piston becoming too big for the cylinder and the two acted like a brake. They called this "sticking" or seizing and in happened in much less than a minute w many engines.

However on a boat the need for very accurate monitoring of the rate of rise or fall of values is not so important or not important at all. The only digital display I have on my boat is the battery voltage indicator and it could easily be analog. No advantage to digital that I can see. I don't really see a useful advantage for digital indicators on our boats. Perhaps synchronizing twin engines would be easier w digital

However I do see a significant advantage for analog on the boats. With didgital display your mind needs to think the number through to get any idea of the value displayed at all. So a longer period of time is necessary to observe approximately what the value is. If you want to sacrifice that amount of time necessary to get the accuracy of the didgital display then didgital may be the preferred display. But for most values most of the time one's eyes can flash their eys over an analog display and get the information needed and pay attention to what is happening over the bow or wherever the action is. Airspeed display on my ultralight was an indicator where extreme accuracy wasn't needed ... or even wanted. A fairly good indication of speed while landing would show I was well above stall speed or not going too fast and that was required but nothing more. Seeing if I was 6" or 6' above the ground WAS important so keeping my eyes on the road (so to speak) was vastly more important than extreme accuracy of speed. So just a flashing glance at the airspeed indicator getting the information necessary and keeping my attention on the other more important stuff makes the analog display better. One can usually see that all is normal much faster w the analog display.

So for a boat syncing twins or perhaps a pyrometer display may give the advantage to didgital but I'd think most instruments on a boat would be better off analog.

Eric
Thanks for the thoughts. The reason I was thinking Digital Display was to be able to 're-arrange' the instruments the way I want and use them. Also I was thinking of changing out the 30 year old wiring. It would be so much easier to run a NEMA or USB cable than to run all new individual wires. Really tight space with lots of turns. I guess I could have a new brushed aluminum panel made up and put the instruments where I want them. Another note on the Digital Display: maybe I'm using the wrong term. I want the display to LOOK like analog, but actually be digital. I don't like looking at numbers. I have 2 multi-meters. My go to meter is the analog mostly because I am looking for shorts or opens. I can see the needle swing from weird body positioning. I may reconsider analog especially since there will be a big price differential.
I flew an Ultralight back in the early 1980's. I had a Rotec Rally 2B tail dragger. No instruments other than the cheap pitot tube with the little red floating disk. It was a fun toy. maybe someday I will get another one. If I ever do, it will be a two seater.
I know they came along way and licensing is getting easier.

I like your text Tony and no one ever found a better airspeed indicator than the dirt cheap Hall (brand) tube. My 2000hrs and 20 years flying was 100% with the Hall Brothers tube. If you fly again I'm sure you'll be using one.

If you are really thinking of flying again don't forget how much time it takes to stay on top of "your game". There's no casual flying in my book. For that reason I may look into a dirt cheap flying club. Small airplanes .. not ultralights. With an ultralight I'd need to be the only pilot and fly regularly. Very regularly.

Tony

I put in a Noland Engineering RS11 that converts my analog sensor outputs to NMEA 2000 and then display it on many different devices, Lowrance LMF 400 gauge, Lowrance MFD, and in Coastal Explorer. Actisense and Maretron both make similar devices. The interesting thing about these is you can use an external sensor to calibrate the output. For example, my temp sensor reads about 5 degrees high compared to a IR thermometer. I can adjust the reading on the RS11 to make them the same. The other thing with using NMEA 2000 gauges, is they allow you to set different warning thresholds. Where as the typical oil pressure alarm might set off the red light at 15 psi, you can tell the gauge to alarm at 20 psi.

Tom

I would look at the Actisense EMU, and an arrangement of Maretron displays.

Eric


I'd like to think about another UltraLight but I don't see it ever happening. We are full time cruisers and will be settling in somewhere different every 6 to 9 months. No way to tow it along. LOL.
I lost mine while in a hanger that got wiped out by a tornado. I did love it when I flew it. I never forget my first flight - totally unanticipated.

Thanks Tom.


Can it be configured to look like an analog gauge or is it all just numbers?

Maretrons can be configured to look just like the existing analog gauges.
One thing you really need to consider is what you do when the system fails. Yes it will fail in some way,shape or form. It is an after market adaptation you are talking about. You need to be very careful about who's system you select. You will not be happy if you need support in 5years and the company is no longer in the business.
You should also consider relocating your old gauges to another location (engine room) in case yo do have a failure you can always go look at a gauge to confirm if you have a problem.

Sent from my Nexus 7 using Trawler

In reality unless your wiring from the engine(s) to the helm has been physically damaged, there is almost certainly nothing wrong with it.

You could replace your instruments and even your senders with modern ones that would be functional and look sharp.

While a dilly digital display might seem like a cool idea, is the reward worth the hassle?

I'm an electronics person, and have a history of engine automation in the generator world. That said, when I repowered I went with new separate instruments. To me the hassle and the risk was not worth the reward.

Thanks Kev and everyone else.
My original thinking was that I could replace my gages and with digital. I could also replace a pile of 30 year old wires with a small USB or NMEA cable. Now you guys are making me rethink the whole idea. Pulling old wires is still a nightmare but putting in new ones is even worse. So now I have another question or two.

How long do old wires last without getting brittle or corroding too badly. I'm sure a lot depends on exposure to moisture and other contaminants. Should I have to replace 30 year old wiring?

Tony B said:

How long do old wires last without getting brittle or corroding too badly. I'm sure a lot depends on exposure to moisture and other contaminants. Should I have to replace 30 year old wiring?

Click to expand...

In general wiring doesn't just go bad.

Most issues are with the ends of the wire, which are easy to replace.

A method I've used allot is to leave wire in place but cut it off and terminate it at a terminal strip on both ends. Then you can wire from the terminal strip to the devices on each end.

If you really want to replace the wire, you can also use multi strand wire. I've used wire with as many as sixteen 12 awg conductors. Its pretty common stuff in the instrumentation world. You really do not need that many conductors for an engine. 8-10 wires will generally be enough for an engine instrument package depending on how you wire it.

I installed Glowshift gauges , which are single auto style.Electric powered .

They offer BOTH analog and a good sized digital readout on the same gauge face.

NOT >marine< so the price is not bad , and best the EGT units can have plain wire extensions ! as required.

For an offshore boat I would use Murphy Switch Gauges for their adjustable alarm feature (24/7 is a long time to watch gauges).

Anytime

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We replaced our analog tachs with digital tachs from Aetna Engineering.

CruzPro offers a full suite of digital displays CruzPro electronic boat instruments, alarms, digital gauges and monitors

Both solutions use the original senders, assuming original senders are or can be compatible with modern stuff.

The 4" Aetna tachs were a drop-in installation in the existing holes. Looks like the CruzPro 2" gauges will drop into existing holes to replace our smaller gauges. (Their 2" tach would have connected, but wouldn't have fit our existing holes.) No necessary changes to wiring or senders.

I'm thinking of replacing the rest of our engine gauges, mostly because the analogs aren't displaying all that accurately anyway. Just like the original tachs weren't displaying all that accurately across the full RPM range.

I know our temp displays aren't correct, wouldn't mind more accurate fuel tankage display, etc. This assuming the senders are transmitting accurately and the analog displays are actually the problem.

-Chris

I too have replaced my analog gauges with Glow Shift digital and tach with the Aetna digital. I had to change out the old sending unit but was able to use the existing wiring. The replacement was done in the pilothouse and not the flybridge.

One of the issues I need to address this spring is changing out the FB gauges. An issue that concerns me is: Do the new digital sensor work in a dual station application? I guess that Atena and Glow Shift can address. So...off to work we go!

Question:
Do the sensors have to be matched to the gauges by manufacturer or are they all pretty much standard? I ask this question because I see a lot of Gauge packages i.e. 6 gauge sets, but I have not seen any sensor packages. Looks like they have to be ordered individually. If I replace the old gauges, it would make sense to me to replace all the 30 year old sensors also.

Tony B said:

Question:
Do the sensors have to be matched to the gauges by manufacturer or are they all pretty much standard? I ask this question because I see a lot of Gauge packages i.e. 6 gauge sets, but I have not seen any sensor packages. Looks like they have to be ordered individually. If I replace the old gauges, it would make sense to me to replace all the 30 year old sensors also.

Click to expand...

Coolant temp and oil temp are the ones that need to be matched to the sender. Also remember that if you have flying bridge gauges then you need senders that take into account the added resistance of the second gauge.

Switch type senders are generally closed when "good" For example an oil pressure sensor generally is open when the engine is not running and closed when oil pressure is above the set point. This can also vary based on how they wired the engine.

Tony,

Most NMEA 2000 gauges and MFDs can show engine data as numbers (digital) or as an analog gauge with a moving pointer. At least that has been my experience with Lowrance. The main reason I went with the RS11 was to get engine data to the upper helm. All we had up there was idiot lights and buzzers. Once I had the NMEA 2000 conversion done at the lower helm, I was done as I already had the NMEA 2000 network at the upper helm running into a Lowrance MFD. Putting in the LMF-400 gauge was simply a hole, a NMEA T connector and a short NMEA 2000 cable. The gauge is powered off the NMEA 2000 network.

Tom

Tony B said:

Question:
Do the sensors have to be matched to the gauges by manufacturer or are they all pretty much standard?

Click to expand...

CruzPro told me their oil pressure, water temp, and fuel tankage gauges use changes in resistance (Ohms) as transmitted by the original senders. (That's the same way our WEMA fresh water and holding tank gauges work, too.) Apparently resistances at various display points are standardized across the industry? (That's the story with WEMA water, holding, and fuel tank gauges.) I don't exactly understand how resistance works with oil pressure and water temperature sensors/senders, but... they said it (e-mail) with conviction, so it must be true.



The Aetna gauges can be paired to at least a couple different types of sensors/senders, in our case magnetic (which were standard on our engines), but apparently most engines already use one of the types that will work with the Aetnas.

-Chris

I think this stuff is too rapidly obsolete. Mbevins got it right. Just look at the junk electronics you find in the used stores. You never find a working Cummins or Stewart Warner tach in there, they rarely fail. Digital is zoomy and interesting but an analogue gauge can be interpreted in a glance when you do your scan. Stick to steam-powered gauges for a boat!

Another point I just thought of, try synchronizing dual 8.3 Cummins with digital tachs. There is too much detail and with the sensitivity of the power levers and the "supposed" accuracy of the tachs, you spend way too much time trying to synch 1132 rpms (really?) when you should do it by ear and be looking out the window. I have driven a Symbol with same, give me analogue anytime.

Xsbank said:

I think this stuff is too rapidly obsolete. Mbevins got it right. Just look at the junk electronics you find in the used stores. You never find a working Cummins or Stewart Warner tach in there, they rarely fail. Digital is zoomy and interesting but an analogue gauge can be interpreted in a glance when you do your scan. Stick to steam-powered gauges for a boat!

Another point I just thought of, try synchronizing dual 8.3 Cummins with digital tachs. There is too much detail and with the sensitivity of the power levers and the "supposed" accuracy of the tachs, you spend way too much time trying to synch 1132 rpms (really?) when you should do it by ear and be looking out the window. I have driven a Symbol with same, give me analogue anytime.

Click to expand...

Our analog tachs failed. The others work OK, but the temp gauge displays are simply wrong. And the fuel tank gauge displays only a mere suggestion.

I'm not arguing that digital is better per se, but OTOH, I also don't like wrist watches that require me to do all the work (big hand is on the..., little hand is on the... I should interpret that to mean the time is...). I prefer a gauge (or a wrist watch) that simply tells me the number.

Syncing is indeed a hoot, though. With the digital tacks, I reckon when both engines are running anywhere plus/minus 10 RPMs of each other -- around a given target RPM level -- it's close enough for me. But yes, that's best done mostly by feel, ear, a visual on the wake, etc. Usually if I'm shooting for running at approx. 2100 RPMs, where ever I get them synced plus/minus 25 RPMs to that is fine by me. The displayed value on the tach becomes a check on average RPMs (to compare to speed, fuel consumption, etc.) more than a sync tool.

-Chris

Thanks everyone for the help.
It looks like I will be ordering Teleflex Lido Pro Series (fog proof) gauges.
I spoke to someone at partman.com and he told me that when I get ready to order the sensors, give him my engine serial numbers and he will make sure everything is compatible.

One huge advantage of steam gauges is you can paint green , yellow or red marks on their face ,

and a person standing watch only needs to observe if everything is in the Green , and call if anything changes.