The gas bottle that would not go empty

We are now in Sneek (or actually 'Snits' in Frisian). One of the 11 Frisian cities and one of our favourites for an extended stay as its quite lively, there is good shopping nearby and the view from our favourite spot is nice, the 'Waterpoort" is the trade mark of the city:





But nice as that may be, today's main topic is more unusual. Let me explain:

On Onbekommerd, we use bottled gas for cooking and for hot water, both in the galley and in the bathroom. Gas is in two 'bottles', of 10.5 Kgs of propane gas each. Normally, a bottle lasts about 7 weeks (49 days) before we have to change it. No problem, we just uncouple one and connect the other. They sit in a gas bin at the back of the boat, all very safe: if a bottle or it's connection would leak, the gas escapes out of the back and does not form a danger on board. Changing the bottle takes no more than 5 minutes. Gas is also not very expensive, a 10.5 Kg bottle costs €30 (you hand in the empty one and get a full one, so you only pay for the gas, not for the bottle).
There is one problem for us though..... In spite of the EU being responsible for everything (including saving the Greek economy), every country has its own design of gas bottle and it's own connections. So you can't exchange an empty Dutch bottle for a full Danish one! So what to do if you ever want to be away for more than 14 weeks (two bottles at 7 weeks each)? As cooking on board is sort of a given (eating out every night is not only unaffordable but not much fun either), we had to look at hot water usage. Now in almost every harbour there are good shower facilities on shore. Sometimes even free, but often you pay €0.50 or in Denmark 5 Kroner for a 4 or 5 minute shower. So we made sure we had 2 full bottles when we left Delfzijl, our last Dutch port of call at the end of May and dutifully showered 'on shore'. It's really no big deal. And we were extremely curious how long a bottle would last. If it was going to be 75 days or more, we would be happy: our future trips are unlikely to take us out of the country for more than 5 months, 'two gas bottles worth'.
We got back into the Netherlands on 27 August, exactly 90 days after we left. And the gas was still going strong! As the problem was solved: showering on shore gives us the required 'range' and moreover shore facilities in the Netherlands are - on average, there certainly are exceptions - much inferior to either German or (especially) Danish harbours - we decided to shower on board again. Of course we expected that now at any time the bottle would go empty. Just when you have a head full of shampoo and it's raining outside....
But no, today, on day 113, just as we were ready to start cooking, the gas went out. What luck, it was not even raining when I changed the bottle:






So there you have it: cooking takes very little gas, compared to showering. I now have two equations with two variables, so I can work out exactly how much cooking takes and how much showering.

We'll stay in Sneek for a few days. Then on to Leeuwarden and finally to Franeker to put Onbekommerd to bed for the winter on Thursday next week.

Location:Geeuwkade,Sneek,The Netherlands