VHF Interference from Autopilot

I noticed in the web log stats that someone had searched for “VHF interference tiller pilot”. This reminded me that I had a problem which occurred soon after the new electrical panel was wired: whenever I turned on the autopilot, there was a constant buzzing interference audible on all VHF channels.

The source was as I had expected: an earthing problem. I used the Seatalk cable to connect to a NMEA multiplexer and the NMEA input to connect to my chartplotter, both of which were earthed, but the primary power input negative (earth) was not connected (d’oh!). The resulting high currents on the signal earths for Seatalk and NMEA caused RFI which was picked up by the VHF antenna.

Many years ago I built an audio (hi-fi) amplifier which had earth loops because of multiple return paths to earth – the AC mains hum was unbearable! Fortunately I remembered that lesson.

The best strategy is always to run all earths (and power supply grounds) to a single earthing point such as the main negative terminal on your electrical distribution panel.

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Of cooking and fires at sea…

While at anchor at Whitehaven Beach in the Whitsundays, we had the misfortune of our alcohol stove catching fire, nearly burning us down to the waterline. If we weren’t actually watching the stove at the time, it could have easily turned out a nightmare. Here’s what happened…

Sunny Spells is fitted with a MaxiMarine alcohol stove (two burner with grill) of fairly recent vintage, installed on gimbals. I’ve always been uncomfortable with the procedure for lighting the stove, which feels a bit like starting a barely controlled fire. A little methylated spirit (metho) is dripped into a tray around the burner and lit. This liquid metho burns and heats up the burner itself. Once the burner is hot enough to vaporize the metho, the alcohol flow is turned on again and the metho vaporizes and burns cleanly, a bit like a propane stove.

Our MaxiMarine alcohol stove

Getting just enough metho into the tray initially is a bit tricky, and you either don’t have enough or the alcohol burns quite vigorously while you watch it (very nervously).

On this occasion, we had all three burners going, including the grill. For some reason which I still can’t determine, the metho started pouring out of one of the burners (I suspect the grill), flooding the bottom of the stove and then running onto the cabin sole. When this caught alight, it was seconds before we had a roaring fire!

Fortunately, the fire blanket was close to hand and this was quickly thrown over the fire and I then closed all the control knobs on the stove. Unfortunately, the fire was still burning and getting out of control. I then grabbed the fire extinguisher, took a couple of seconds to remove the safety pin and work out which way to point it, and then discharged it into the fire under the fire blanket… The fire went out instantaneously – to our combined relief! The fire blanket had helped to slow down the fire, but in future I’ll be grabbing the fire extinguisher at the same time!

To say we were all a bit shaken, if not stirred, is an understatement. In the seconds before using the extinguisher I was about to urge everyone to abandon ship, it was that close…

The inside of the boat was covered in powder, a substance we found pretty difficult to clean up. We took the stove outside, cleaned it and then started the two burners (not the grill) on deck, where it operated flawlessly. The stove was reinstalled and used for the rest of the trip without any incident.

The problem now, of course, is that I don’t trust the devil…

I’ve learned a lot from the experience though:

  • In my initial safety briefing I concentrated on sea safety (MOB procedures, harnesses etc..) but we didn’t cover the fire-extinguishers, which I left for a later briefing which never happened. When I briefed the crew on the use of the stove I eplained the use of the fire-blanket, but the most experienced crew member, who had used an alcohol stove before, was on the helm at the time. Of course, she was the one doing the cooking when the stove decided to go up in flames!

    Lesson 1: make sure the crew is briefed on fire fighting and that they all get the opportunity to handle the fire blanket and fire extinguishers.

  • I was intrigued by my subconscious resistance to firing a $20 fire extinguisher while the boat was going up in flames…

    Lesson 2: Be mentally prepared to use the fire extinguisher.

  • I fumbled with the fire extinguisher: first I couldn’t get it out of its bracket, then I had trouble getting the safety pin out and, finally, I had to force myself to loook at it carefully to find the trigger and make sure the nozzle was pointing the right way (while having a very urgent, flaming distraction in front of me).

    Lesson3: Familiarize yourself and the crew with the fire extinguishers so you can use them with your eyes shut.

It does raise the old question again about cooking on board: propane vs alcohol? I don’t know the answer to this one. I do feel a bit biased against the alcohol stove now though, but is an explosion better than a fire?

Finding Good Help…

While I’m quite happy sailing Sunny Spells on my own, doing so 24/7 is probably not the most sensible thing to do. So I advertised on FindACrew.net. The passage from Mooloolaba to Hamilton Island would take place during the school holidays, which must have suited a lot of people, because I was inundated with interest. Let’s face it, sailing the Whitsundays is not an unattractive prospect either! I was spoilt for choice, so I could select what I thought would be a good mix: one experienced sailor, who could be watch captain, and two competent crew, to be… competent crew! I also tried to match the ages, so they ended up all being in their late twenties.

My crew for the passage from Mooloolaba to Hamilton Island

Matching the personalities was harder to do. While I spoke with all of them on the phone, trying to judge their sailing experience, it is impossible to really assess personalities on the phone. All I can say is that it’s worked out great! Sarah, George and Vicky got on really well with each other and it’s been fun watching them work and play.

Everyone has participated one hundred percent and it has been great to see them settle into the boat and start working together as a team. The cooking has been fabulous and we have lived like kings. Even more remarkable has been the willingness with which everyone has pulled his/her weight when it came to cleaning up. The dishes always seemed to wash themselves and whenever we anchored the crew immediately, and without prompting, started cleaning and tidying the boat before relaxing. Very impressive!

Sarah scrubbing the decks

I’ve obviously been very lucky, but finding these people certainly has restored some of my faith in humanity. It’s marvelous what you can find on the internet these days…

Scawfell Island

After a very rolly night at Middle Percy Island, we set sail for Scawfell Island at 0645 on Saturday 5 February 2008. The forecast promised 20 to 25 knot south-eaterlies so we played it safe: poled-out no.2 genoa and main by the lee. The wind averaged around 15 knots all day and we managed a consistent 6 to 7 knots boat speed. By 1630 we were dropping the hook in Refuge Bay, Scawfell Island.

Crew paddling out to snorkel in Refuge Bay, Scawfell Island

We spent a lazy day at anchor, snorkelling and fishing (I should say angling because we caught nothing…). In the evening we played a game of monopoly, which the skipper won despite the collaborative best efforts of the crew to prevent him by any means, however devious – sorry guys!

Monopoly in Refuge Bay!