Newcastle Departure

Left Newcastle Yacht Club at 13:30 this afternoon for Mooloolaba. Lovely sunny conditions and westerly breezes.

I checked out the Sydney weather this morning on the SMH Website (as you do on a Monday morning…). The site gives a nice snapshot of the forecast as well as historical statistics. As I cast my eye over the week’s forecast maximum temperatures (24°C, 26°C, 23°C, 21°C, 21°C, 22°C, 22°C) I was pleased by the mild weather. I then noticed the “Average Max” statistic for May: 19.4°C. A quick calc produced an average maximum temperature of 23.7°C for the next seven days! Hardly rigorous scientitific analysis, I admit, but still…

Needing any credible excuse to avoid starting the work week, I went off to Google to find long term temperature statistics for Sydney, which, as you would expect these days, are available on the WWW. Even more impressive, you can get it off the BOM’s “Climate Data Online” website. The oldest official data was recorded at Sydney’s Observatory Hill weather station and dates back to 1859 – only 150 years of data unfortunately. The first land-based observations were made by William Dawes, who arrived with the First Fleet in 1788. He built an observatory at Sydney Cove and for the next three years kept daily records of the wind, temperature, pressure and rainfall, but that’s another story…

Mean Maximum Daytime Temperature, Sydney 1859 to 2009

Mean Maximum Daytime Temperature

I wanted to do a bit more than just look at average maximums for the month, so I downloaded and analysed:

I calculated the mean, maximum and minimum temperatures for winter (May to August) and summer (November to February the following year) and added a trend line to each data set to show the 10-year moving average.

The daily maximum temperatures (lowest and highest for the month) aren’t all that useful, because they really are the outliers and, while the trend may be usefull, the scatter makes interpretation difficult. The monthly mean maximum temperatures shown above are very interesting though, particularly the maximums for winter.

There is no doubt it’s been getting steadily warmer over the last 150 years. The mean winter daytime maximum temperature is probably the most significant indicator and winters are definitely a lot milder now (10 year moving average of 19.2°C) than in the 19th century (16.7°C) . While there is a noticable “kick” upwards in the graph in the last decade, the rate of increase (2.5°C in 150 years or 0.017°C/per annum) appears to have been pretty steady though and I can’t really see an acceleration in the temperature rise during the past three of four decades (when greenhouse gas emissions were meant to have become the main contributing factor). In fact, if Sydney-siders had been paying attention to the climate instead of worrying about the Great Depression and WW1, they’d have been pretty anxious about the temperature increase during the period 1901 to 1927, when 10-year moving average maximum temperatures in winter increased by 2.3°C, from 16.0°C to 18.3°C.

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Windlass Overhaul: Part II (Mod)

I’m now thoroughly bored with trying to fix the windlass

Having cleaned it out and re-fitted the windlass earlier, it worked perfectly, twice! I’ve now had a further two attempts and think I have it licked. This is what I ended up doing:

  • I fitted a sealed bearing to the top of the electric motor (replacing the original, shielded bearing) the part number for this bearing is 6201LLU/2AS. Read an explanation of the difference between open, shielded and sealed bearings if you’re into that sort of thing… This should hopefully prevent a recurrence of the inside of the electric motor being coated with grease. This was the only way of solving this issue as there is simply no room to fit a separate lip seal. You do have to wonder whether a sealed bearing might have been fitted in the first place?
  • I machined the old, worn bronze bush that is meant to support the windlass’ output shaft’s bottom end (and probably the most highly stressed part of the windlass…) to take a HK1512-B drawn cup needle roller bearing insert (I kid you not!). The output shaft was also machined down to 15mm diameter (from 16mm) to suit the new bearing. Once you measure something for machining, you really get a feel for the workmanship that went into it. It was a bit disappointing to find that the accuracy of the machining is not great, with the output shaft top bearing having an interference fit while the drive gear’s fit on the same shaft is a bit “loose”, to say the least.
  • I replaced the electric motor brushes and re-wired the brush holder. This bit really annoyed me, as it required a third removal of the windlass when it only turned about three revolutions under load… It would appear that the brushes had absorbed grease and, under load, the heat of the current flowing through the brushes would cause a film of grease to be deposited on the commutator – end of windlass! Further frustration was caused by the fact that South Pacific wouldn’t sell me the brushes. I was told to send the windlass in for a quote and repair (yeah, right, throw good money after bad?). When I showed the electric motor to my local auto-electrician (Paul Bagnalls in Mona Vale), he was not impressed with the small brushes, given that they had to carry higher currents than your average starter motor. He reluctantly sold me a set of starter motor brushes (thought I was wasting my time and money), which I then sanded down to the correct size using a belt-sander, holding the brushes in the vice! Not elegant, I grant you, but it worked! The brush holder was also re-wired with heavier guage wire.
Sealed bearing fitted to windlass with old bearing for comparison

Sealed Bearing Fitted

Bush machined to take new roller bearing

Machined Bush and Bearing to Suit

New bearing cartridge fitted to gearbox

New Bearing Fitted to Gearbox

Replaced the electric motor brushes and re-wired the brush holder

Brush Holder and (modified) Brushes

Fortunately, it appears the windlass has now had a new lease on life, having picked up the anchor three times on the weekend. My next move was going to be replacement. The modification of the output shaft has removed all the slop and wobble from the capstan – let’s hope it lasts a bit longer than the original!

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Not something you see every day!

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