Tuesday, March 13, 2012

A Lesson in Troubleshooting

I'm writing this up after almost a year after the incident. I never wrote it up originally because I was some what embarrassed about it all, but after reading an article by sail-delmarva, I have thought it my be of use to some of you "troubleshooters" out there.

Last year we installed a class "B" AIS transponder and after some issues with it not working, we left Picton, New Zealand and eventually made Fiji. The unit worked fine and we loved seeing the targets on our MFD. (Furuno AIS and Furuno MFD). The original reason it didn't work was because the unit was set to "USA" instead of "International". Something to do with the frequencies AIS works on.  I checked the installers manual and all the frequencies are the same, except for about two. I couldn't understand why that setting made a difference, but it did. Perhaps somebody out there can tell me why.

Anyway, in Fiji, I noticed we were no longer picking up ships which should be displaying as an AIS target on our MFD. So, I check the AIS unit and notice the power light is now flashing green and none of the other LED's were on. I said to my wife, "I'm sure that Green LED used to be a solid Green".
I checked the manual and couldn't find anything about a flashing Green power light, but figured that with the other LED's not lighting up there was something wrong with the unit. I also hooked up my computer to it, because it has a self test, and you can change the settings with the computer, but was unable to get a connection.

So, as per sail-delmarva suggestions in "Lessons in Electrical Troubleshooting", I took out my multimeter and checked the voltage supply. The batteries were a little down but I showed 13.2 volts. Almost the same as what was showing on my house bank monitor.

My wife was making a quick trip back to New Zealand (by plane), so I had her take the whole unit back to Auckland NZ for a test etc. To my surprise, I get a phone call from NZ to say the unit tests out OK. Fine, bring the unit back.

Now this is where it gets interesting. Sail-Delmarva says 
  1. Never assume the previous owner didn't set you up. He did.
  2. Always trace the wiring

I reinstall the unit, and that dammed light is just flashing back at me again. Damm! I check the voltage again. 13.4 volts. What could be wrong?

I  take the unit out and now hook it straight to the battery. Yes, it works!!!
Put it back in place  and the light is flashing again. Voltage fine. Hmmmmmm
Check circuit breaker voltage. Fine. BUT now I have a little alarm go off in my head.

I vaguely recall having switched out a circuit breaker some time back because one had been playing up. At the time I switched it with one that wasn't being used, and I remember thinking, I'll change that faulty circuit breaker sometime when I can get into my spares.

I change the circuit breaker, and all is solved. I don't know why the circuit breaker seemed to test out fine with the multimeter, but there was something the AIS unit "picked up" and wouldn't work due to the fault in the circuit breaker. Can anybody tell me why this might be?

The issue was, when I had installed the the AIS, I put it to one of the remaining circuit breakers that was not in use. This was of course, the faulty one, and unknowing to myself at the time, set myself up.

So, my lesson is, if at first everything checks out fine with the multimeter, try hooking the device straight to battery to see if it works. It seems the electronics of today are getting so much smarter and can detect issues on an electrical supply and turn themselves off to protect their circuits.

They do say " a stitch in time saves nine". I should have replaced that circuit breaker at the time of the fault, or put a note on it.

Monday, March 12, 2012

Clean cuts on Plywood

Mark Corke has shown us a wonderful tip for cutting ply. Go on over to his web site to get the full blurb.

Mark says.....  The picture shows some cuts that I made in half inch thick marine ply and as you can see they are perfect straight from the saw. The blades that I use for this type of cut is the Bosch 101AO, which have needle teeth not too dissimilar to those found on Japanese pull saws. With the pendulum action turned off they really are the nuts with almost no tear out even when cutting against the grain on the face laminate. A quick trawl of the internet shows these blades can be had for around $8 for a pack of five which considering the little cleaning up you have to do once you have cut out the component is money well spent.

Sunday, March 11, 2012

Aye for Ayetides

Here is an app I recently downloaded to my iPod touch. In traveling around the world, I wanted a tide app that is easy to use and work with iNavX in the iPad. Ayetides XL does that, and I'm using it's little brother, Ayetides, available for the iPhone and iPod Touch for $9.99.

Here is a standard tide table screen from AyeTides, one of the best standalone tide apps for sailors traveling around the world. In addition to high and low tides, it shows sun and moon rise and setting times. Near the top you see the water height at the present moment and the arrow indicating a falling tide. Scroll sideways to move days forward or backward.

Most important for choosing a tide app is its specificity for your area. This app is purported to have over 9,900 tide stations in it's list, however, you may do better for your local area by purchasing an app specific for your area.

Importantly, AyeTides stores all data on your device - you don’t need connectivity on the boat to have all tide areas at your fingertips.

Here is AyeTides’ graph of today’s tides, the clear circle at the top showing the present moment. You can tap or drag the circle around to see the water level at different times.

The app has been designed for ease and speed of use. To toggle between the standard table and the graph shown here, just rotate your iPhone or iPod Touch and the accelerometer makes the change for you.

Touching the little "i" located in the top right of my first picture, flips the page and shows the tide station location with a lat and long.

In the finding a station window, you can find by, Alphabet, Geographic, Nearest Station, and Recently Opened. You can also save a tide station as a favorite and that has it's own list window. There are some preferences to change to your liking.

There are two types of stations in AyeTides, currents (tidal streams) and tides. You don't see the depth at a current station and you don't see the current at a tide station. To see the nearest current station, tap on the info button (the 'i'), select "Find Nearby Stations" and look for the first station that's in bold. Alternatively, go to the main view's Find a Station menu and in the Alphabetical list, tap the search button and enter the word "Current". This will show you all the current stations in AyeTides.

A significant benefit of the current data is that boaters can easily and immediately correct the common erroneous assumption that the ebb current begins at high tide and the flood current at low tide. In reality, there is a time lag before the current reverses and starts up again that depending on local factors can be longer than an hour. If you’re guessing about tidal current changes based on high and low tide times, you can be surprised and perhaps caught unaware.

Accuracy? Pretty close!! I checked it against two different tide charts available off the internet for Gladstone, Australia. The Ayetides showed a High Tide at 11.48am at 3.74 Meters.
The other tide tables from the internet, showed 11.54@3.8M  and 11.44@3.77M . I could be happy with that. I'd give it 8.5 out of 10