We took Privateer out today just to check all the systems after a 2000 hour service and a change of all her oils and fluids. All that went fine.
The area just north of Newport can be pretty crowded so occasionally someone shows up near us that I didnt see coming. In the picture below you can see Big Blue on AIS coming by. She is a 45′ cabin cruiser doing 25 knots.
So I look out the side and see nothing. I get up and go to the door, nothing. Then a minute later she disappears from the screen as well. I search the screen and she reappears about a mile north, where she really is.
My assumption is, there was a malfunction in either her transmission or my reception. More likely her transmission. I have seen AIS return for boats showing them going backwards or sideways, a transmission error that I could sort of comprehend, but this is the first time I have ever seen a boat displaced by more than a mile. The ramifications are quite disturbing.
We also have received inaccurate AIS reports, both a vessel reporting that it is much closer that it really is, or more frequently, a vessel that is close showing that it is farther away, or not at all. I assume that all these erroneous reports are from class B transponders. I have never noticed similar anomalies from large commercial ships which are required to have class A units. The difference is that class A transmits at 12 watts every 2 to 5 seconds, vs class B 2 watts every 30 seconds.
But even though there are sometimes inaccuracies, AIS is still useful in showing vessels that radar can’t see, such as a boat that may be on the other side of an island, around a bend in a river, or on the other side of a rain squall.
Richard Ross
Yep, we love AIS. That day there were so many boats transmitting that it could have been network contention. Like you say, IAS Class B is every 30 sec. And carrier sense TDMA. SO it is possible that in my case Big Blue was blocked from transmitting for the 4-5 minutes it would have taken him to get from where he was on my chart to where he was in real time.
Class B+ is now available. 5W instead of two, SOTDMA, and much more frequent transmissions. I am all Furuno so will wait till Furuno offers the upgrade. I have already committed my entire upgrade budget for this year anyway.
What are the particulars about your water heater?
It is a Raritan 2o gallon model. It was 120v till I swapped out a 220V coil and re-wired my panel. Things are better now
I imagine that 20 gallons is sufficient for most of your needs, or is it?
I suspect that the re heat performance is greatly improved with 220 volts.
Just two of us, so we never run out of hot water. But w 4 on board, sometimes it got warm. But we were not replacing hot water or re-heating, except once a day with the genset.
The 220V should help quite a bit during genset driven water heating.