Brigantia Unplugged? Getting off the grid

Much contemplation and cogitation this week about how to sever Brigantia from her increasing addiction to being plugged in. It hasn't been too much of a problem to date provided we get her on the pontoon at Fambridge overnight at the start (and preferably end as well) of a trip and get the battery charger cooking the batteries nicely overnight.

However, we have been on the verge of running the batteries down too far on more than one occasion and a lot of the time, whilst still powering the nav gear and lights OK, the voltage is too low to run the laptop. And therein lies the crucial clue to the problem ... we're tech head nerds and that's the way we like it! Chances are at any given moment in time there'll be at least two smartphones, one or two tablets and a small laptop all greedily chomping at the voles. Plus cabin lighting, GPS, VHF (base station and rechargeable hand held) and the big and small rechargeable flashlights.

Now you could say "do away with all that" and become minimalists. But why should we? I use my smartphone (or "phablet" as the big phones are coming to be called)  for a myriad of practical applications. It's my e-reader for one thing via the Kindle app, I've got tide and weather apps galore and it's the nearest thing we've currently got to a chart plotter (although one of those is on the shopping list in due course!).

Jane uses her tablet extensively as her entertainment centre both at home and when we're out and about. Games, her favourite magazines and (when there's a good enough data signal or wi-fi) TV on demand all keep her happily amused and why not?

The laptop generally serves a more practical purpose - it's an old slow one with the sole virtue of having a 12/240v PSU - being primarily used for passage planning and uploading / downloading data to and from the GPS. It does occasionally get pressed into service as a DVD player

Sooo ... if we want to get off the grid we need to minimise power usage where we can and make our own in sufficient quantities to meet our demanding technological needs. This could become mission critical for next year given the contemplated changes in mooring and usage patterns - weekends on board at the mooring with no mains available wil be battery killers.

Lighting

Currently, we've got two fluorescent strip lights in the main cabin and a round light in the heads. Provided people remember to switch it off, the heads light isn't critical. The cabin lights are probably 8W tubes so with both running they're pulling somewhat over an amp out of the batteries. In theory, each of our two batteries should be able to run the cabin lights for over 22 hours before reaching 50% discharge.

I can't see the cabin lights using much over 4 or 5 amp hours (a/h) a day, much less if we have an alternative means of general lighting and only use them when we need working light ...

If the input / output / cost benefit equation demands a reduction in power consumption on lighting, the two options are LED lighting and oil lighting. Now it has to be said I've been gagging to find somewhere to fit an cabin oil lamp ever since we bought Brigantia. I love the light from wick lamps (although I grant that it isn't good to read by ... but then we're all using e-readers these days anyway).. I've been struggling to decide where, if anywhere, it would be feasible to fit one and I think I've got the answer ...

I think one of these, with a height of 229mm and a projection from the bulkhead of 135mm, will fit neatly in the gap between the cabin windows, starboard side.

That will place it at the head of the starboard berths in the ideal position to be out of the way whilst providing light to the places people sit down below.

OK, so you won't get a huge amount of light from a single wick lamp like this but it's not light to work by, it's light to move around by and drink beer by and generally feel good by!

We could fit a second lamp in the same location on the port side above the galley but it would get in the way of the top shelf somewhat and I don't think it's necessary. For the relatively short periods lighting is needed over the galley, the strip lights serve the purpose better

£65.90 by the way, including the heat shield

Cockpit lighting, something we don't currently have as such, needs to be sorted too. We could do with an instant on electric light somewhere around the companionway for getting on and off the boat in the dark. As for sitting around in the cockpit lighting I favour a simple hurricane lamp and it so happens that we have two on board already - a very very rusty one in the cockpit locker which probably needs to go in the bin and a nice shiney unused one courtesy of a friend stowed away down below which needs to come out of hiding and replace the rusty one. The hurricane lamp is also our backup anchor light

And back to the strip lights ...

£39.95 each to replace the existing fluorescent lights with LED equivalents. The power saving isn't, however, all that massive given that the LED lights still draw about a quarter of an amp each. Given the £80 cost, my inclination would be to see how we get on with the existing lights using oil lamps to supplement them..

Navigation Gear

To a significant extent, this could arguably be ignored because when we are out navigation it's almost inevitable that we'll be running the engine sufficiently most days to put back into the batteries at least as much as we've taken out - the engine charging current is well over 5 amps at cruising speed.

Never the less, let's have a look at the gear ...

The GPS72H has negligible consumption - it's not even quoted in the spec! It'll run for many hours off a pair of AA batteries so it's hardly going to be noticed by one of our 60a/h main batteries

The depth/log uses 20mA (plus another 25mA if the display illumination is on). Even on a 12 hour sailing day that's barely a quarter of an amp/hour. Effectively double it at night. Wow! One fully charged battery could run the depth log continuously, day and night, for 40 days.

Okayyy ... the VHF. Here. life gets a little more complicated. On standby, it draws 0.4A. This rises to 1.5A when receiving and the same transmitting on low power then a whopping 5.5A transmitting on full power.

The tricky bit is that the amount of time the unit is receiving depends on how much chatter there is on the VHF. Usually, around our normal neck of the woods, there's very little going on. Down South it was virtually constant. Noticeably, during our last local excursion round into the Blackwater, there was quite a lot of irritating traffic on Ch.16 (I hope the East coast isn't turning into the new South Coast!)

I'm going to hazard a guess and reckon that on average the unit is receiving for 5% of the time it is on (this is probably wildly inaccurate on the high side but what the heck). Transmission times are so short, we rarely transmit and then only briefly and often use the hand held for the purpose anyway, that they can be ignored.

So on our 12 hour day at sea, the VHF will use roughly 5a/h (5.46 if you want the exact result of the calc)

So running the GPS, Depth/Log and VHF, in other words the essential navigation and safety gear, will use about 6a/h out of battery 1 on a 12 hour day.

And what about all that tech? ...

Well my smartphone has a (surprisingly large) 3.1a/h battery. Hmm. Jane's tablet has, apparently a 4a/h battery - not that much bigger. A Note 10.1 however has a whopping 7a/h jobby. Of course, most usefully one is not informed by Samsung of the battery voltage. A bit of googling elicited the vital information - 3.7v

Also discovered during the Google session is the information that the Note 10.1 (which I'll use as the defining standard for smart devices as it's the biggest thing we're likely to use) will charge at 250mA on a USB lead plugged into a computer, 500mA on a standard supply (almost certainly including 12v USB PSUs) and will only charge at the full 2A on a mains supply that meets the correct specification (high power type). I'm pretty well sure that Jane's 7" Tab2 does the same thing from experience

So assuming that both my phone and Jane's tablet need recharging from flat every day (and that, I'm afraid, is a reasonable asssumption!) at 0.5A each that's 7a/h a day. Plus there's use whilst plugged in which is often how my phablet is running which could easily add several more hours of use. Let's say 10a/h a day. Blimey.

As for the laptop ... well to be honest I'm inclined to leave it out of the equation. It's absolutely essential use is limited to downloading the daily track data from the GPS (it's the only device I've got on which this can be done) and any use beyond that can be deemed non-essential and thus only available if sufficient battery power is available. If I could solve the track download issue (say by being able to transfer the data to the phablet or tablet, the laptop wouldn't even get put into the car let alone on board the boat most of the time)

So the, perhaps not so, surprising result of this analysis is that by far the biggest consumer of amps on board is the personal toys at up to 10a/h a day. Lighting comes in at less than 5a/h a day and even then only on days where we spend the evening on board. Nav gear clocks about 6a/h a day when we're sailing, nothing when we're "in port"

What does that leave? Refrigeration is what.

Currently, we haven't got a cool box / fridge. It has been discussed and left for later consideration more than once. Given planned changes to operating patterns and taking into consideration the wishes of the distaff side of the crew, some form of cool locker or cool box has been specified as a requirement.

We've already got the space for it in the locker at the head of the starboard forward berth where the cool bag now resides. This locker is going to be built up to the height of the berth divider with a flat top and will contain an insulated box for items that need to be kept cool and a space for a bin bag (separated of course!) for the rubbish (something that's an ongoing issue).

So now the plan is to dismantle an old 12v cool box and use the peltier plate and fan from it to actively cool the insulated compartment in this new locker (I am assuming here that I won't be able to find just the right size of coolbox with the fan in the right place to just drop into the locker ... because I'll lay odds I won't be able to find just the right size etc.)

Now if we take the smallest of the suitable and available 12v cool boxes, say the Waeco U26, we're looking at a power consumption of 47 watts on DC ... whilst the cooler is running of course. That's as near as makes no odds 4 amps. Given that the cool locker isn't bad at keeping things moderately cool anyway, we won't need to run the electrical cooler 24/7, a couple of hours a day should generally be enough although in hot weather that could easily double (and the weather is proving right now that it can get hot in England in the summer ... for the first time in several years!)

So if we estimate 10a/h a day as a minimum for the coolbox we'll probably not be too far out

Demanding the demand ...

Blimey ... it's a whopping 25-30a/h a day or to put it another way the entire capacity of one of our two batteries every day (that, by the way, jives with experience 'cos without the addition of a cool box we seem to get about two days out of battery 2 before it starts to get a bit low voltage and that's the battery that powers everything but the lighting when we're in port)

So where to find power without a bit of string

There's three ways and whilst it may be stating the obvious they are ...

Solar Panels
Wind Generator
Petrol Generator

Let's look at each in turn and see what it could deliver for us

Solar Panels

We should be able to find somewhere to install 20W of solar panel either as a single 20W panel or two smaller 10W panels. We might be able to find room for as much as 30W at a pinch and at some significant additional expense.

So how much power would a 20W solar panel actually produce? Well there's a handy calculator from the EC Joint Research Centre at http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php and using this with a bit of common sense generates the following table of data ...

Month Ed Em Hd Hm
Jan 0.01 0.337 0.73 22.7
Feb 0.02 0.612 1.38 38.6
Mar 0.04 1.27 2.53 78.5
Apr 0.07 2.01 4.23 127
May 0.08 2.40 5.01 155
Jun 0.08 2.46 5.40 162
Jul 0.08 2.39 5.11 158
Aug 0.06 1.99 4.23 131
Sep 0.05 1.48 3.19 95.7
Oct 0.03 0.893 1.85 57.5
Nov 0.01 0.447 0.99 29.8
Dec 0.00 0.264 0.60 18.5

Ed: Average daily electricity production from the given system (kWh) Em: Average monthly electricity production from the given system (kWh) Hd: Average daily sum of global irradiation per square meter received by the modules of the given system (kWh/m2) Hm: Average sum of global irradiation per square meter received by the modules of the given system (kWh/m2)

So at peak output in May, June and July a 20W panel might reasonably be expected to produce 0.08 kilowatt/hours of electricity. That's 80 watt/hours or, and here's the crunch number, just over 6 amp/hours a day.

In March and October, at the nether ends of the sailing season, the output is going to be about half that.

Of course, this does assume normal (i.e. average) weather conditions although it doesn't mean the sun actually has to shine! Photovoltaic arrays work in daylight, not sunlight. Very cold weather, on the other hand, can murder the output levels of a PV panel.

Given an average 10 day gap between visits to the boat (on the basis of planning to be, as much as possible, on the boat every other weekend next season) a 20W solar installation will put back between 30 and 60 a/h between visits. In other words, one batteries worth (at best)

Wind

Here we would be looking without a shadow of doubt at a Rutland 504 ...

Neat enough unit, about 20" in diameter and measuring about 18" front to back.

I've seen ones you could hardly hear and heard ones you couldn't ignore from several boat lengths away so I guess much depends on the age and condition of the unit and, of course, how windy it is.

The noise levels might also depend on how much load is on the generator I guess.

It'd have to be mounted on the stern deck or taff rail so it'd be whirring around right above the cockpit which could get irritating especially for me with my hyper-sensitive hearing (although that is inevitably declining as age starts to take its toll)

Of course, there is a solution to the noise - put a sock over it! Seriously, if we install one I will make up a bag to go over the turbine so it can be put to sleep when it isn't needed or when we want to shut it up.

Now as for how much power one would produce, this is where it gets perhaps a little disappointing. According to Marlec's own figures, it starts working with 5kts of breeze and in a 10kt breeze will churn out a mighty 3 watts! Bottom end of an F6 will see the generator kicking out an amp. Yep, just one amp. In an F6.

You'd need over 30 knots of wind to get enough out of the 504 to power the planned fridge installation directly and that's pretty much a gale!

Now looking at the Dept. of Engergy's own mean wind speed map for the UK, we can expect on average around 6 to 7 m/s of wind down in our favoured corner of Essex (and pretty much anywhere else around the coast for that matter). That's an F4 or moderate breeze to put it another way. 

So on average, based on the above and our experience of wind conditions over the last two and a half years, the 504 could be expected to churn out between a quarter and three quarters of an amp most days. There will be days when it's doing nothing useful of course but taken over the 10 day between visit period we could reasonably expect the 504 to push at least 60a/h and perhaps as much as 120a/h into the batteries - and we've only got 120a/h of battery capacity!

In a single day, left running for the full 24 hours, the 504 would knock out between 6a/h and 12a/h or enough to run the cool box for between 1.5 and 3 hours. Feather it for the evening and night and you've halved that of course ... but since we would probably only do that, if it all, in windier conditions to curb the noise it's probably not an issue.

Generator

This is a tempting option it has to be said because we've got two generators sitting in a cupboard at home. Unfortunately, they're both dead and they're both noisy and they're both too big (although the smaller of the two could probably be squeezed in to one of the stern lockers if we took the carrying handle of it)

The critical issue is that they are both rather noisy though. And did I mention that neither of them works?! So a replacement might be in order I guess and the really cheapo bit of kit is something like ...

Ok so it's 2 stroke and it's not fabulously quiet (65dBa at 7m isn't terrible but you wouldn't want it running for long periods on the boat next door to you) but it churns out 650W continuous, will fit in the space vacated in the port cockpit locker by ditching the jerry can and it costs less than £100

That cost is quite crucial because it's a last ditch backup option in the first place and very vulnerable to getting stolen - it wouldn't be left on board for starters!

If it did get nicked, at that price we'd grumble but not be devastated

OK, given that it can take the charger up to 8 hours to recharge one of the two batteries, it's not likely we'd be too keen to do that with the generator but we wouldn't have to because the solar or the wind would be in the mix. The real question is actually whether or not we would need the backup of a generator at all.

(Actually, I'm really kicking myself now that I economised when I bought the new battery charger and bought the 7A model for just under a hundred quid. I should have spent the extra forty quid or so on the 15A model which would halve the charging time to a more reasonable four hours. Hey ho).

Anyway, as things stand, it's more likely that the generator would be pressed into service to recharge the laptop battery for navigation use or to pick up the batteries in order to maintain the essential safety gear (VHF etc.) in the (admittedly unlikely) event that neither wind nor solar was producing enough juice.

Costs

Cabin oil lamp and heat shield £  69.90

20W Solar Panel               £129.95

Rutland 504 Wind Charger  £299.95

Rutland 504 Mounting Kit  £105.95

Rutland HRDi Controller    £144.95

Clarke 720W Generator    £  95.99

                                         --------

                                         £846.69

I must admit that the total caused a sudden intake of breath. I wasn't quite ready for it to come to quite that much - £500 or £600 maybe. However, all is not lost. 

First things first, I want to have a damn good look at how much solar I can find space for because I think that's the most effective charging solution for our normal everyday needs. If we could double the solar we could reasonably hope to do away with the wind generator (and I'm not wildly keen on the wind generator to start with because of the noise they make)

An option that has just occurred to me is to locate one or more solar panels in places where we wouldn't want them whilst the boat is in use to charge the batteries between trips. Of course, then we'd have the problem of finding somewhere to put them when we were on board!

Then, even if we can't get enough solar capacity for the whole scheme, I would be very much inclined to construct the cool locker with the capability to add electrical cooling to it but wait and see how things go

Because it's a relatively expensive option with relatively poor returns (averaged out), the wind generator would be a purchase of last resort in my view. It's certainly not worth spending over £500 until we've worked out whether or not we need it. (We would have to buy a basic solar charge regulator but a two battery one of them can be had for under £25)

So the initial shopping list is going to be the oil lamp and as many solar panels as we can find space for plus a basic solar regulator.