Holding Tank Level Inspection Window

I have a holding tank gauge with sender unit for some years now, but have never enjoyed removing the tank sender unit for a clean from time to time. Even when the unit is especially designed for black water, it would eventually clog up and need to be cleaned. My aft holding tank was easily accessible, so I decided to put a view port in so as to "see" the level of the tank. You can view the old sender unit here at WEMAUSA. It is the one on the right.
First, I had to design my window and decided for simplicity sake, to use a beckson hatch with a clear screw lid. These have a "O" rind for sealing. To this I mounted it on a half inch piece of ply cut to shape and given 3-4 coats of clear epoxy. Screws were mounted so as not to protrude through the other side. I also didn't want screws to go through into the holding tank and the mounting wooden plate adds some stiffness to the tank. Why wood instead of GRP? I like the idea of being able to reverse anything I do and the wooden base plate would (no pun intended) be easier to cut off.

After removing the sender unit, which was now showing signs of corrosion, I had to remove the screw in adaptor. This had a "C" shaped backing plate, so I lassoed it with a cable tie before undoing the last screw which held it there. I was then able to remove the backing plate with some ease.

I marked out the location of the new base plate, takeing out the old hole. But it was somewhat off centre, so to help with the hole saw, I screwed on a scape piece of wood and held it in place with screws through the piece of GRP that was going to be discarded.

To the right you can see how easy it is to drill a new hole where an old hole already exists.

Next, I sanded the paint off with a Rolok sanding disk.

The back of the backing plate was also sanded. Then I mixed up some epoxy with a silica type "Glue" additive to give a peanut butter viscosity. This was applied to the tank and then the backing plate pressed into the mix. Some squeezed out to the inside and I was able to get this before it fell into the tank. (wearing rubber gloves). The out side was smooth filleted with just a finger and left to harden overnight.

Finally the beckson hatch was bedded with 3M 4200 to the base plate.
And the finished inspection/view hatch to the left. It helps to shine a small flashlight up to one side of the clear hatch to get a better view of the level. Plus, now if I want to, I can put a hose in the tank to give it a wash out from time to time.

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.

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.

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

406 EPIRB with User Replaceable Battery

I wrote recently about the poor product support for EPIRB's over 10 years of age. Most of the manufacturers won't do it. You can read about that here.
Today, while in a Chandlery, I came across an EPIRB with stated "user replaceable battery". I have blogged about that one with the manufacturers details here and there is another manufacturer purporting a user replacement here.
Here's the blurb from Kannad Marine about their Safelink EPIRB (with GPS).

This ultra compact and stylish 406 MHz EPIRB comes with a built in high accuracy GPS as standard, for enhanced position location and a user replaceable battery* with a 6 year life.
Meeting the demands of both commercial mariners and recreational boaters, the new Safelink EPIRB heralds the arrival of the next generation in EPIRB technology. The Safelink EPIRB range offers two models, one features a manual deployment bracket and the other an automatic deployment housing which also includes a hydrostatic release unit.
This ultra compact and stylish 406 MHz EPIRB comes with a built in high accuracy GPS as standard, for enhanced position location and a user replaceable battery* with a 6 year life.
The Safelink EPIRB range offers two models, one features a manual deployment bracket and the other an automatic deployment housing which also includes a hydrostatic release unit. The Safelink 406 MHz EPIRB is designed to operate with the COSPAS-SARSAT international search and rescue system. The unit can be activated automatically by immersion in water, or manually by following the activation instructions printed on the unit.
The built in GPS receiver ensures that an accurate position of a casualty is relayed to the rescue services. This in turn improves the speed of recovery by updating the position of the beacon at regular intervals.

Key Features:

• FCC approved
• Internationally approved
• Ultra compact and stylish
• Transmits on 406 and 121.5 MHz
• Integral 20 channel GPS
• User replaceable battery* (leisure users only)
• High brightness LED flashing locator light
• 72 comprehensive diagnostic and self-tests during battery life
• Once activated, will transmit for a minimum of 48 hours
• 6 year battery life
• 5 year warranty
• Non hazardous battery for safe and easy transportation

[download a full spec sheet]