Moderated Discussion Areas
ContinuousWave: Small Boat Electrical
|Author||Topic: Electronic Malfunctions|
posted 08-04-2008 09:02 PM ET (US)
Recently we were aboard our boat for a week, and we were underway several hours a day. This gave me a chance to put some of my (modest) vessel electronics to use, and, in general, they all worked well. However, I did experience several malfunctions, which I will share with you.
Self-induced GPS Errors
My GPS receiver has an external antenna, and I have mounted it on the stern deck of the boat. This puts the GPS position close to the SONAR transducer, so that any depth recorded by the SONAR is nearly coincident with the GPS position. My reasoning was that one day I might have a data recorder and would be able to log depth soundings and positions, and in that way I would be able to gather data which might be more useful.
In general, the GPS receiver antenna has a totally unobstructed view of the sky. However, at one point in my voyage I was engaged in taking some pictures. To put the camera to better advantage I stood on the rear deck of the boat while taking some pictures. At that time we were in an area of many shoals, and we were relying on the GPS to give us a position relative to all those shoals as they were shown on the accompanying digital cartography in the chart plotter.
Much to my surprise, when I returned to the helm after taking pictures from the stern deck, I found that the boat's position was suddenly about 500 feet away--so far off that I was in another portion of the waterway. Initially I was confused by this, and I looked around to verify that the boat was actually where I thought it was, not where the chart plotter had it plotted. It took me a moment to realize what had just happened: by standing over the rear deck I had blocked the GPS antenna, and the GPS receiver has lost its lock. The GPS position was now inaccurate. And I was the cause.
Fuel Flow Error
In the course of a week of boating we had a few stretches where we had to make way upwind and into some head seas. The seas where not terrible, about 2-feet to 4-feet high, but the boat was in a lot of motion. I imagine that there was some sloshing of the fuel in the tank. Further, we had just taken on some new fuel. Due to a somewhat awkward orientation of the fuel fill inlet and the very high deck height at the dock, the fuel was introduced rather slowly. I think there might have been some aeration of the fuel as it was coming in. In any case, I believe these two factors combined to produce a sudden error in the fuel flow metering.
We were making our westing into these head seas when I noticed that the instantaneous fuel economy calculation began to climb. Soon were were making 20-MPG, then 35-MPG, and then the numbers displayed went crazy, showing F014-MPG or something like that. I switched the NAVMAN 3100 FUEL instrument over to the flow rate setting, and I found the measured fuel flow was now 0.1-GPH and dropping.
Not having accurate fuel flow measurement and calculated MPG was quite a loss for me, as over the past three years I have become accustomed to continually monitoring those parameters. The engine seemed to be running fine, but without appropriate fuel flow data I was suspect. Was I on the verge of leaning out the engine? A few moments later the fuel flow returned to normal, and the MPG readings returned to their normal (and dismally low) figures.
Sometime during the voyage, my DSC radio appeared to spontaneously loose its programmed marine mobile service identity (MMSI). Without an MMSI, the radio stopped supporting its DSC function, although it continued to transmit and receive properly. However, the radio would not permit an MMSI to be entered, as it had reached its limit (of one) MMSI programming.
Today I called the manufacturer and described what happened. The technician with whom I spoke had not previously heard of such a problem with the particular model radio. The radio has been sent in to be reset, and it will be shipped back to me in about two weeks at no charge.
About the only factors which I can associate with the lost MMSI are:
--the radio was in the CANADIAN channel mode; perhaps the software has not been as thoroughly tested in that situation as in the USA mode;
--the radio had received an ALL STATIONS ALERT from the Coast Guard some time earlier.
--the radio is powered by the engine starting battery, although the engine had been started many times previously without any apparent affect on the radio operation.
As a result of these three malfunctions, I am giving some consideration to making a few changes. I may move the GPS antenna, since I often use the stern deck as a place to stand while taking pictures. I may separate the boat electrical system so that the electronics are fed from an isolated battery to prevent any possible engine starting transients from affecting them. As for the fuel flow transducer error, I don't have any ideas, other than to perhaps re-prime the fuel system after taking on new fuel.
posted 08-04-2008 09:22 PM ET (US)
Experience any thunderstorms along the way? Maybe a close hit threw high voltage spike on the buss feeder.
Knowing your electrical and maintenance capabilities, I doubt it was a loose connection
posted 08-05-2008 12:07 AM ET (US)
It may be of interest to see if you get a new version of software in you radio when it is returned.
The super cap or battery for your memory may have failed, But I am somewhat suprised that the tech support didn't give you the button sequence to reset it. this leads me to wonder about the software.
On your GPS, you may have induced a significant amount of multi-path as well as blockage, sending the unit into Dead Reckon mode. This mode, if initiated at the moment of a fast roll, may have given the unit a false velocity and direction. The result could have given you the 500 Ft error.
This high roll rate is why I have generally tried to mount GPS antennas low on the small boats. Granted it is always a trade off with the blockage vs pitch/roll decision. Even a 110' tug can have wild fluctuations in its positions in rough weather. This can be very interesting to watch on ARPA radars and Electronic Charting systems. On ARPA radars that are referenced to the GPS for Speed and Position, the targets Speed and Heading Vectors will appear to gyrate all over the place. This will be out of time with the actual motion of you vessel due to the filtering of the position in the GPS and the filtering of the Radars as well. Electronic Charts will move and dance due to the same factors, and some times overwhelm the computing hardware's ability to refresh.
Since there is a new Satellite, SV 32, some GPS manufaturers have had to update thier software to work properly. This happened some months ago but some recreational boaters may not have been out to test thier gear.
Just some thoughts.
posted 08-05-2008 12:13 AM ET (US)
Do you have any AC on the battery leads when the engine is running? I have had batteries fail and the charger induced a chainsaw sounding hum in the vhf. Your flow meter may be the most sensitive to something like this.
Just more thoughts.
posted 08-05-2008 08:30 AM ET (US)
Two of these problems were somewhat coincident: the fuel flow error and the radio MMSI reset occurred about the same time. This made me suspicious that the same thing caused them both. About the only likely event would have been an engine start. However, I don't think that was the case.
Thinking back to that situation we were in when the fuel flow went haywire, I recall that we had stopped down for a few minutes to let one of the boats in our flotilla catch up. I think I shut off the engine (to save gasoline) and we were just bobbing around in the waves. This might have sloshed up the fuel. The flow transducer is downstream of a RACOR 10-micron filter, so it should have been protected against debris. I think foamy fuel might have been the problem.
The MMSI problem might also have been self-induced. As I mentioned, that same day or time frame we got an ALL STATIONS call from the Coast Guard (about a missing or overdue boat). This seemed to have set some sort of alarm, and there was something odd about the display on the radio. I think the DSC icon was flashing. When we got into the next harbor, I looked more closely at the radio to see what it was trying to tell me. I navigated through the menus looking for some sort of reset. It is not clear in my memory if the radio was flashing the DSC icon because it had already lost its MMSI, or if perhaps I inadvertently caused the MMSI to be lost by some action I took in the menus trying to reset what I thought was an alarm. The radio is already packed and shipped off, so I will have to see if the manual sheds any light on this.
In any case, the software would be somewhat stupid if it allowed me to erase the MMSI and then prohibited me from entering a new MMSI. That seems like a very one-way path, and the outcome is not of much value. It leads only to having to send the radio back to the manufacturer for a reset. By the way, the technician assured me there was no field reset possible, although perhaps there is a secret key sequence which they just do not want to reveal to the public.
The most revealing thing about all these events was how suddenly deprived I felt when I was not getting fuel flow data. I have come to really rely on that instrument. When it began to give me bad data I was very disturbed.
The loss of the DSC radio was also upsetting. Even though the radio still worked perfectly well as a radio, not having the DSC and MMSI programmed into it was mildly upsetting. It started me thinking about perhaps installing a second radio. A small VHF radio is so inexpensive these days that the cost is hardly a consideration. It is very common on larger vessels to have at least two radios, with one dedicated to monitor CH-16.
When we got home from the cruise we found ourselves quite fatigued, so much so that on Sunday I could hardly muster energy to investigate the electrical system for a loose connection. I will make a thorough inspection of all the primary battery distribution connections, including those under the cowling of the engine, to verify that they are all tight. However, the engine starting was flawless, and once the engine was warm a re-start occurred immediately with barely any cranking.
posted 08-05-2008 03:27 PM ET (US)
all in all you gained some more knowledge and some times its just a burp and that's the end of it
posted 08-05-2008 06:30 PM ET (US)
The limited number of MMSI settings is to prevent people from
playing games and using MMSIs they don't own. If you can
only change it once or twice, you aren't going to play games.
posted 08-05-2008 08:01 PM ET (US)
Yes, there is no problem in understanding the WHY of the MMSI reset limitation, It makes perfect sense. I don't have any argument with that. But when the radio appears to reset itself, it is an annoyance. I'll be two weeks or more without a radio.
And if the radio's software provides for a user-initiated reset, then what is the point? Why have a reset if the radio can't be reprogrammed in the field?
I don't think I reset the MMSI, but I am not sure. I think the radio reset it by itself. Software is a funny thing, and you can't foresee all the possible situations. Maybe the weird combination of CANADIAN settings and an ALL STATIONS DSC call provoked some unanticipated result.
posted 08-05-2008 08:32 PM ET (US)
roloaddict--Thanks for your comments regarding the error in the GPS position that I induced by blocking its antenna. Yes, I was surprised to find how far off the GPS position jumped after just a moment of blocking the satellite view of its antenna. As they always say, the prudent mariner does not rely on a single source of information for deducing his position.
posted 08-05-2008 11:37 PM ET (US)
Your comments on the software are spot on. I have developed a mind set that if nothing makes sense, then it must be the software. Twenty years of denials from manufacturers, only to have new versions magically show up at strangely key times have left me a bit jaded I suppose. I am not bitter, just seen It enough. Most all of our tools/toys are software animals and as such should be troubleshot with this in mind. When you open up these boxes, you see fewer components and bigger processors. The Land Mobile market is going to the Software Defined Radio. Program your Frequency HF,VHF,UHF and you're on the air.
All the commercial DSC radios are programmible in the field. Mmost with keystrokes. This is because commercial vessels are commonly reflagged on the fly. Reflagging requires new numbers to be programmed in to all the radios. The tech who goes out assist or do the inspection for the new flag authority, will also do the programming.
Repairs on the non commercial radios, even programming may not be worth it if your tech is charging the customer 140+ an hour. It may be the hamster that doesn't go to the vet, if you know what I mean.
posted 08-06-2008 09:59 AM ET (US)
IIRC, you have a Standard Horizon Matrix GX3000, right?
Same radio I have. I just searched through the PDF of the
manual for MMSI, and there's no documented MMSI reset
function. So don't blame yourself.
posted 08-06-2008 08:19 PM ET (US)
I received an email reply to my inquiry with the radio's manufacturer regarding the MMSI reset. They confirm that there is no facility in the menu structure that permits the user to reset the MMSI. The loss of the MMSI by the radio was due to some malfunction in the radio, and they will investigate it when they receive the radio for repair.
Chuck--The radio is a Standard Horizon GX1500S, but I believe it is very similar to the GX3000S. The instruction manual sometimes confuses the two.
posted 08-06-2008 10:52 PM ET (US)
I would be surprised if the MMSI code were stored in a memory device which required a super cap or battery. Functionality in an emergency situation is critical and a good design should not require a power source for data retention. The MMSI code is much more likely to be stored in an EEPROM which does not require battery back up. A small 128 bit EEPROM is quite inexpensive in the volume a radio manufacturer would procure, <$0.15/ea. It is more cost effective and more reliable than an on board power source.
It would be interesting to know what is used to retain the code.
posted 08-20-2008 08:38 PM ET (US)
I shipped the radio back to the manufacturer on Monday, August 4. It went by ground UPS, also known as slow boat. The manufacturer got it on the following Friday, August 8. They promised a two-week turnaround. It looks like they shipped it out late on August 14, just six days after they got it. I received the radio today, August 20, again a rather slow trip from California to Michigan. The manufacturer shipped it THREE-DAY service, but the package was misrouted in transit and took six days to be delivered.
I haven't checked it out, but I imagine they've fixed it. There was no charge.
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