How to monitor your 12v battery

June 15, 2014 at 11:41 am

Now I’ve got some progress with Duet’s interior refit, my focus is starting to move towards her electrical systems.

She currently (no pun intended!) has one 70AH leisure battery fitted, which was new last year as I fried the predecessor charging my phone and using the autopilot one sunny afternoon, totally discharging the battery and it wouldn’t re-charge.  I learnt a lesson there, and am keen to make sure that it doesn’t happen again… mainly because batteries are expensive!

I have already done a quick calculation of what power I need for cruising and have recently bought a 20w solar kit to replace the knackered 10w panel I removed earlier in the year.  However, because I’m not really sure how much juice I need I’ve gone for just a 20w panel, and I still suspect that I might need another battery but haven’t decided where I will put the bank as there’s currently only space for one.  I have no experience of boat 12v electrics so I’m just going to try it and see where we get…

Anyway, all this needs careful monitoring as if you discharge a battery below 40% it will fry it (or at least shorten its life).  I’ve been looking at the NASA BM-1 which retails at about £90 though it does show the battery draw when something is turned on (which helps with calculating power needs I suppose) and it shows the current voltage and percent charge.  However, like I said, it’s £90 which is more than the cost of a(nother) new battery, and it needs wiring in which is a bit intimidating as to be honest I’ve never done electrics.

However, there is a drastically cheaper alternative: I’ve bought a plug in 12v voltage meter, on eBay for about £4 delivered.  It looks like this:

12v Voltage Meter hurley 22 duet

Really easy to use, you just plug it into the cigarette lighter and it tells you what the current voltage is, by which you can work out the percent charge of the battery.  Couple of caveats though; always test batteries when they have stood without charge or use for at least 30 minutes. Batteries just taken off charge will have significantly higher voltage until the surface charge decays over 30 mins or so.

I have done a chart on what the voltage means, that I will be printing off and laminating for the boat.  It’s pretty self-explanatory… basically try not to discharge below 12.42v (80%) and never discharge it below 12.06 (50%). Please help yourself to the image if it would be useful to you too!

12v Voltage Charge table hurley 22


Beautiful Beaulieu…

April 28, 2014 at 5:35 pm

Well, I actually traded at Beaulieu Boat Jumble this weekend… (With my clothing business, not with actual boat bits.)  I got there at 6 o’clock on Saturday evening to set up, and literally within 5 minutes of getting out the van I had bought a spinnaker pole with no ends for £6.  (I subsequently found one end to fit on another stall which I exchanged for one golden nugget (£1) – so it’s very nearly even useful!)

Boat Jumbles are like that; If you think they are busy when the first boiler suited and be-oilied public rampage through the gates then you should see the 2 hours before the gates actually open.  It builds up like a crescendo of Arthur Daley types all just running about swapping outboards and propellers from one stall to another if they think they can turn a profit.

Beaulieu Boat Jumble 2014

Little do they know, most of the propellers and outboards have already changed hands 3 times by now…
(Photo stolen from

Then of course there’s the poor trunk traders who generally are less accustomed to the ways of ‘The Hustle’.  By the time they arrive, the keenest traders have been round everywhere 3 times for the best ‘deals’ and are waiting ready to pounce on the gentle folk, who just want to get a few quid for their old bits and clear a bit of space in the garage, as they open their estate cars and set up their wobbly paste tables on the grass.

So, it pretty much rained all Saturday night, and was forecast to rain pretty much all Sunday morning!  Beaulieu is amazing for bargains though and I had a big list of stuff to buy (paint was a biggie, I need epoxy, and primer, and antifoul).  Except of course I went and left the list in the van, so there were a few deviations that I couldn’t help.

Also, I was kinda supposed to be on my stall, selling my stuff… Though I had bought a spare ticket to take a mate, in the end, what with the weather I decided to go alone…  And to open my stall up late after I’d been round for my bits and pieces. Amazingly though,  a lady from the Moody Owners Association who had bought from me last year, and follows my Facebook group, actually offered to man my stall while I went shopping!  I’m not sure she expected to be left so long, and with the dog, but thank you Annie!!

I got some cracking bargains, even after opening time…  (* denotes not on list but yet irresistible):

Brand new £350 (mrp)  Gill Ocean Jacket (like this) for £40, yes £40! (Gill were selling off samples – shows you their markup!)*
2 x 2.5 litres of Hempel Gel Protect SFE200 for £50 (would have been £150 full price)
2.5 litres Hempel Tiger Xtra Antifoul for £45 (£60 full price – if you shop around)
10l water carrier £3*
5l water carrier £2*
2 stainless steel hinges for the cooker lid I have yet to make £1
A harness (so I don’t always have to wear my lifejacket) £3*
A small pressure cooker (will fit on boat stove) £8*
Big Mainsheet shackle £3*
Yellow ‘Q’ flag and French courtesy flag £8
Irish courtesy flag £2
Set of softwood bungs £4*
Small pointy wire brush drill attachment for crevices £1
Bunch of galvanised shackles £1.50*
Brass bulkhead clock £2
Brass barometer (though it turns out it doesn’t work!) £2
Stainless steel collar which *might* do for the rudder £1.50*
Storage box for screws (or something) £1*
Bundle of teak strips (ex decking lengths) £5*
5m routed teak trim for hatch £9
North Brittany Pilot from late ’90s £2 (the rocks don’t move)*
Lundy and Irish Sea Pilot (current), and South and West Coast of Ireland Sailing Directions (2008) £10*
2 lengths of 8mm Dyneema (used but useful condition) £4*
1 length of 10mm Braid on Braid (used but useful condition) £2*
6ft? bare spinnaker pole (ie no ends) £6*
1 Spinnaker pole end £1*
and, a Proctor complete whisker pole  (6ft?) £10 (bargain!)*

(Also picked up a free copy of next month’s Practical Boat Owner :-)

So, I did spend £200.  But I got a lot for it I think.  And I did sell the old paraffin stove that came with Duet to my sharkey looking neighbour for £20.  He then promptly told me he would get 80 quid for it (from the right person) …but to be honest I just wanted something towards a new alcohol stove and to clear a bit of space in the garage (and I also think ‘the right person’ for a paraffin boat stove is a rare specimen).

Rain stopped play really, and by midday the site was a quagmire.  There were a lot of empty pitches, but still clearly bargains to be had.

Verdict: A grand day of fundamental economics (and mud).

Next weekend I will be back to the interior scraping over on Portland…

Cardiff Boat Jumble

March 2, 2014 at 3:55 pm

Just back from Cardiff Boat Jumble, which was in the drizzly grey car park of Cardiff Football Stadium.

To be honest it was pretty disappointing… Most were traders, I think there were no more than 3 or 4 private individuals including the 2 dinghy’s on trailers for sale.  I’ve been to a few boat jumbles and there were the usual load of old boys in yellow high-vis waterproof jackets getting excited about buckets of bolts and haggling determinedly over lumps of rusty metal (I just don’t get it?).  Weather was rubbish; I was there an hour tops.

Some of the “bargains” to be found there included a broken Plastimo Mini 100 compass for £50, and 7kg white painted home-made looking Danforth type anchor for £20 (you can buy a new one that isn’t going to make a mess of your forward deck online for £35?).

Disappointingly, though, I narrowly missed out on a 5hp Mariner sail drive with fuel tank and line which had just gone for £200…. But I still managed to come away with this little haul:

Just Back From Cardiff Boat Jumble

37m x 12mm Anchor rode – £30
25m x 8mm Braid on Braid (for new main halyard) – £20
Tin Hempel Boot Top paint – £10
Heavy Weather Sailing – £2.50
The Commanding Sea by Clare Francis – 50p
Around Alone by Emma Richards – 30p

Top Tip #1: Make a list, and look up the best online prices of your list items before you go .  Then you will know if it’s a bargain (or not…)

Top Tip #2: Always stick to your list.

I think I will try Dorset Boat Jumble at the end of the month.  There’s still a lot left on my list…

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