Thursday 21 May,  2015

North Atlantic Ocean 29 31.5N  71 50.6W

Today's Blog by David  (Time zone: BST -5.0; UTC -4.0)

“Be Prepared”. it’s what Baden-Powell espoused, and in sailing terms it is also good advice. One is constantly thinking about what might go wrong and taking steps to prevent it from happening …..  or minimising its consequences when it does. Whether it be doing one’s best to eliminate chafe or scheduling routine tasks to be done at one’s best convenience, there is a continual programme of preventative maintenance.  So it was in planning for this Atlantic Passage (Oh, we have set off for Bermuda, by the way). 

The experience of 42,000 miles sailing Serendipity has told us a fair amount about what can go wrong and given us experience of what fixing it at sea can be like, thus reinforcing the benefit of preventative maintenance.  And so in planning for this passage we  undertook a number of routine checks and maintenance tasks before we set off .

Now, we know that from time to time the impeller which drives  the genny’s raw water cooling system fails: bits (paddles)  fall off the ‘paddle wheel’ reducing the efficiency of the wheel and at the same time the ‘bits’ block the flow of water through the raw water circuit; eventually the generator shuts down because it isn’t getting enough water to cool the engine.  The generator lives under the floor of the main saloon.  Any maintenance or repair task involves lying on the saloon floor and reaching at full stretch  downwards below your head to twiddle with  whatever needs twiddling.  This is much easier when the boat is stable, at anchor,  than when we are at sea - with her bucking around like a bronco at a rodeo and your tools and the nuts bolts etc.  rushing around like bagatelle balls.  So if it is time for it to be done, better to do it before we go.

Impellers last from about 70 -180 hours in our experience so with the prospect of a month at sea and the generator having now run uneventfully  for 230 hours (sic)  since her last service,  it was time to do it – on a flat surface -  before we left.  A full service is a time consuming exercise, particularly when you re-fit things  (as I did) back to front,  but the service was duly completed last Friday and the genny ran for about 8 hours in the next couple of days to allow washing to be done and water to be made.  Job done!

The first time we came to use the generator to top up the batteries after we left the Bahamas – on the 23.00 watch change – it shut down after about five minutes – deepest joy!  The digital display offerred the intelligence: “High Exhaust Temperature – Fault Code 38”. This is different from the code we normally get when the impeller has failed  (“Loss of Raw Water Flow - Fault Code 7”).  Hmmmm!   We were now at sea, bucking around, hard on the wind, so we decided to sleep upon it.

There have been other simple issues with the genny around cavitation in the raw water intake causing air in the raw water strainer – the engine then runs on air and shuts down (Fault Code 7).  So at the 05.00 watch change it was with worthwhile optimism, if misplaced being  faced with a “Fault Code 38”  that  Peter tried to start the Genny.   And surprisingly it didn’t work;  so SOMETHING had to be done -- particularly so because we had contrived to set off with only about 250 litres of fresh water in the tanks  (We need to run the genny to make water). So riding the bucking bronco it was, as Peter and I sought the cause of the problem. 

As it happened, the initial cause proved pretty obvious; the new impeller had shed a bit of a paddle after the 8 hours use and that bit had lodged itself across the outflow from the impeller housing and radically restricting water flow.  The Fault Code 38 thus diagnosed, and crew so relieved, we replaced the impeller and then reassembled everything and  started the engine to test it.  Job done!.  However, within a second or two the engine stopped; Fault Code 7 appeared suggesting we were no faced with a different problem.

This time when we dismantled the genny – all the time riding the bucking bronco bareback – there was no evident source of fault.   We took  it all apart, we consulted the manual, and because we were dealing with raw water flow – and because I happened to have a spare – we decided to replace the heat exchanger.  Integral to this is a replacement “raw water flow sensor switch.”   While this seemed a simple process, it transpired assembly was not simply a reversal of dismantling it; it took nearly an hour to get a single clip re-fastened working at full stretch into a cramped space while hanging on for dear life!   However, through perseverance and some inspired thinking from Peter we did eventually get it back together.

As we turned it on, we observed that in all of this we had not determined the cause of either: (i) the loss of the paddle in the first shut down nor (ii) the cause of the Fault Code 7 in the last  and thus had little confidence in it working.  But it did – and has run for a couple of hours since without hiccup. So the jury is out – the longer it keeps working the more confident we will feel. Particularly when (OK, if)  we get past 20 hours operation…. Watch this space. 

We are mow at sea – probably half way to Bermuda.  The wind is light from aft and we are having to motor quite a lot to try to keep up with our schedule to get there before the weather changes;   so we are not using the genny – nor sadly are we  making water.  When we are not motoring we have been flying  the Frog – a welcome sight.

Finally, an update on the weather.  It is very hot when the sun is out during the day.  At night though there is a developing nip in the air.  Shorts and ‘T’ Shirts are still the order of the day but I foresee the day when one of our number will be resorting to his thermals.  Let it not first be me!