Do I need a generator (Honda 1kw), on a UK circumnavigation

[Robert Wilson]

As a numpty where electrics/electronics are concerned, I am in the dark (hopefully not literally!) regarding power consumption and re-charging.
My house-battery is 100Ahr, as is my starter battery. I shall be carrying a new spare 100Ahr house battery.
I shall also have a shore power lead, a trickle charger and mains light(s) when shore-power is available.

I will be running a Lowrance 7" plotter, and quite a lot of the time a PC laptop (with a portable inverter). I shall have an AIS transponder on much of the day. The VHF and remote mic will be on all day, and some evenings. I'll need to charge a tablet, smart-phone, hand-held GPS and from time to time a hand-held VHF.
In the dark hours I'll need some cabin lighting (new, LED cabin lights) and probably an anchor-light at times. Although from May to August the long light evenings are a bonus. Likewise, I don't anticipate needing navigation lights very much, especially as I hope not to do any night passages.
I'll cook by gas, have no fridge or heater and will while away the hours with a CD/radio (car type).

Will running my engine cope with this load? and for how long each day. The engine is a diesel Kubota 13HP. I fully anticipate that I shall need to use the engine quite a lot, and in addition for charging when necessary.

An inconvenient problem is that if I need a stand-by generator (which would consume circa 3 litres/6 to 8 hours) I'll need to carry/stow petrol; whereas the engine runs on diesel, which is safer to stow in the lazarette.
Diesel is readily available whereas supplies of petrol may not be so easy to obtain from marinas/harbours etc.

I would rather not have to buy a petrol genny if running my engine will suffice.

Advice, please, from much more experienced and knowledgeable folk.
Thanks in anticipation

RW

 

[RupertW]

I think a lot depends on how you plan to do it. If it is mostly day sails or single overnight sails with marinas in between then with your consumption requirements and 200 AH supply then I don't think you'll notice a problem. Still worth doing the Ah per day calculation. If you are planning to be on mooring buoys, using nav lights night after night or just get a lot of good wind sailing then you need to be self sufficient.

We tend to drop into marinas about once a week when cruising so its all about what the boat can generate. My own take is that running the engine is the easiest and best charger - simply for convenience. If doing real long cruises or liveaboard then I would move from engine driven fridge (our biggest consumption) to electric and solar power, but for now this is fine with 210 AH domestic, despite gadgets and using the autohelm almost all the time. When anchored then 2 hours engine a day max to keep the fridge cold and batteries charged - a bit more if we use the engine batteries to charge the electric outboard as an inverter is a very inefficent way of going from 12v to 240v to 9-12v.

My one recommendation is to use a USB tablet rather than a PC except when you really need one.

 

[VicS]

As a numpty where electrics/electronics are concerned, I am in the dark (hopefully not literally!) regarding power consumption and re-charging.
My house-battery is 100Ahr, as is my starter battery. I shall be carrying a new spare 100Ahr house battery.
I shall also have a shore power lead, a trickle charger and mains light(s) when shore-power is available.

I will be running a Lowrance 7" plotter, and quite a lot of the time a PC laptop (with a portable inverter). I shall have an AIS transponder on much of the day. The VHF and remote mic will be on all day, and some evenings. I'll need to charge a tablet, smart-phone, hand-held GPS and from time to time a hand-held VHF.
In the dark hours I'll need some cabin lighting (new, LED cabin lights) and probably an anchor-light at times. Although from May to August the long light evenings are a bonus. Likewise, I don't anticipate needing navigation lights very much, especially as I hope not to do any night passages.
I'll cook by gas, have no fridge or heater and will while away the hours with a CD/radio (car type).

Will running my engine cope with this load? and for how long each day. The engine is a diesel Kubota 13HP. I fully anticipate that I shall need to use the engine quite a lot, and in addition for charging when necessary.

An inconvenient problem is that if I need a stand-by generator (which would consume circa 3 litres/6 to 8 hours) I'll need to carry/stow petrol; whereas the engine runs on diesel, which is safer to stow in the lazarette.
Diesel is readily available whereas supplies of petrol may not be so easy to obtain from marinas/harbours etc.

I would rather not have to buy a petrol genny if running my engine will suffice.

Advice, please, from much more experienced and knowledgeable folk.
Thanks in anticipation

RW

you need to list all the items of electrical equipment with their average current consumption ( some guesstimating may be necessary of an average for items that cycle between operating and standby) multiply the average current by the number of hours per day each will be in use. Total the products to arrive and a daily figure for your electricity consumption in amperehours (Ah).

Divide your total daily Ah figure by what you reckon is an average charging output from the engine alternator. The result is the number of hours per day you will have to run the engine. Rather inaccurate and very probably an underestimate but it will give you a rough idea. If you cannot or don't want to run the engine this much then additional charging will be necessary. Solar, wind, generator or shorepower.

Some people never ever need to resort to additional charging. The 35 amp engine alternator was the only source of electrical power on the boat I used to crew, year in year out!

 

[Mistroma]

Lots of stuff here and I won't have time to cover all in any detail.

Much of your kit (plotter, transponder etc.) will be running when you are likely to have the engine on and won't be off battery. Good chance it won't reduce your alternator output as battery acceptance rate is likely to be way below alternator output. You don't have a fridge and that can easily use 30-40Ah/day. You can also try to only charge laptop, phone, GPS etc. when engine is running and use their batteries at anchor. So that's good so far.

Now the bad stuff:
1) Batteries won't get to 100% charge even running the engine for 3 hours every day. If your charging system is old then there's a good chance you'll only ever reach 80%
2) If you only have a trickle charger then batteries won't even get to 100% after a few nights in a marina. Again, batteries will be undercharged most of the time
3) 200Ah domestic battery will only be giving about 60Ah usable capacity most of the time (try not to go below 50% depth of charge and unlikely to get above 80%)

It would help to have a better idea of your charging system, details of power use (list everything), alternator size etc. However, I'll make a stab in the dark and say you'll probably use in region of 50Ah/day and will need to put in more like 60Ah just to keep up. Assuming a standard alternator regulator, then 2-3 hours motoring every day might keep batteries at 80%. One hour a day is unlikely to be enough. Lots of guesswork here and I'm certain that someone will refine it when more information is available. Botto line, don't expect to manage with 1 hour/day on engine.

How will you charge from a small generator if you only have a trickle charger? Most small suitcase generators will also put out 6A-8A unregulated 12V and even running a trickle charger from 230V side would only give 10A-12A (assuming trickle charger doesn't reduce its output due to 12V from genny at same time). You'd need to run it for several hours in order to put back a decent amount.

I'm guessing that you will use the laptop a for longer than you'd expect and need to charge it from the boat battery at anchor.
If you don't have an LED anchor light then you could use 10Ah/day from that item by itself. Single biggest power saver on my boat.

 

[RupertW]

I think your facts are right Mistroma, especially about the small output from a generator (although my main beef is having to carry petrol, the extra space, and the noise), but I really don't get the "don't go below 50%" advice which so many people give. This was perfect advice 30 years ago when diesel and mooorings were cheap and batteries were expensive but now a 100AH battery is a tiny amount compared to the cost of keeping a boat - perhaps the cost of one or two unnecessary nights a year at a marina. I tend to treat batteries as disposable and wind them all the way down whenever that is needed. Oddly I find that they (any "deep cycle" battery) last 5 years or more without noticeable effect that way then deteriorate very rapidly.

Agree on the top 20% - I have a 20 Amp mains charger from Halfords which I have to leave on overnight to get in perhaps 10 of the last 20% - although it's very good until that point.

 

[RAI]

A couple of points. I would skip the suitcase generator. I have one. It works, but apart from the extra fuel issue, there are the mounting, noise and exhaust issues. The beast has to be outside and so exposed to the worst element it can see - salt water. Its noise and vibrations carry though your own boat and annoys others around. At anchorage, the exhaust fumes get back into the boat, no matter what you do, by a sort of devil's magic. They just don't smell, there's CO included and that kills.
Get some more battery capacity, I'd recommend 440 Ah if you can and a smart alternator controller of an alternator to battery smart charger. The smart charger will make best use of your engine's running time.
I found on my UK circumnavigation that such a combination combined with shore power opportunities keep all my gear working.

 

[EdWingfield]

When I did research for my round uk trip I learned that skippers used engine 50% of the time. I thought I would sail much more than that. I was wrong.

You'll learn self discipline ie. switch the gadgets off when essential work done. My domestic battery is 90ah.

If you are seeking out the truly remote places there is no diesel, no hotel, no shop, no population. Marvellous in our crowded little island.

I carried a couple of 5L diesel containers should I need to walk far. Never had to, but I did sneak them on to a local bus disguised as supermarket shopping.

Top tip. Isle of Lewis. Don't expect shops or pubs to open on Sundays - they don't.

Carry anti-midge product and/or headnet. Centre and north of Crinan Canal were badly affected mid June last year.

Have a great trip.

ps. Instruct friends/family that you will be 'off air' much of the time. They should not panic if they cannot reach you.

 

[William_H]

You don't need a petrol generator.
The spare 100AH battery should be wired permanently in parallel with existing 100AH battery. You might like to buy an engine battery smaller and cheaper and wire that for quarantine engine only. Then add the "engine" 100AH in parallel with the other 2x 100AH. So you should have 300AH for discharge and still be able to start the engine from, engine battery. This 300AH will ensure that any engine running will get a decent charge from the alternator for much of the engine running time.
At a given stage of charge If the engine alternator puts 5 amps into one battery it will essentially put 15 amps into 3 batteries provided the total does not approach the rating and ability of the alternator. (The ability depends on engine speed.) It will simply self limit the total current if the ability of the alternator is reached.
Sure a smart charger would give even more charge for the engine run time but perhaps not necessary and still limited by the alternator capability.

You should have an amp meter showing charge into the batteries so that you can check and also see the point where engine run is of less value ie amps versus noise.
I think a cumulative AH meter might be of value but really a volt meter will tell you when you have used too much domestic capacity and should either run the engine to charge use a shore power charger or simply cut down on usage. In any case the first few days of the voyage should see you with some sort of pattern and you can buy whatever you need enroute. Including gnerator or batteries. good luck on voyage olewill

 

[exMNSailor]

My only lengthy experience of sailing the UK Coast was a six 6 month stint.
I had NO ELECTRICITY during that time, (except for a shore cable when in marinas).
I survived.

I had no nav lights or computery nav systems. My laptop and cameras were charged when in marinas.
I survived.

The boats with electricity had washing machines, hot air hand dryers and underfloor heating.

For tens of thousands of years man sailed the 7 seas, (as I have done) Without Electricity.
For Electricity may I suggest https://www.ssepd.co.uk/Connections/

 

[Kwik Decision]

We're planing a similar trip to you this summer, and I hadn't even considered a generator. We have 150 Ah of house batteries, and a similar amount of electrical kit as you have, plus a Webasto heater. I really wouldn't bother. You may like to consider a small solar panel. We have a 10 w one, and it stops the batteries from self discharging over winter, and will put back what the instruments use on a sunny day. That plus motoring in and out of harbours etc provides all the electricity we need.

 

[AngusMcDoon]

I sailed for 4 months last summer in Scottish and Irish waters with just an outboard engine and a 30W solar panel for electricity supply and had no problem at all, including running a compressor coolbox continuously. An alternative way to do it is to minimize consumption - switch off the AIS transponder unless there are ships around, same with VHF, chartplotters don't need to be on all the time, nor GPS, nor phones. Portable battery powered radios use less power than car type ones. All LED lights. The Samsung NC110 is the best solution for low consumption computing with low charging power and long battery life. Do you need a laptop, smartphone and tablet? Cheap phone only type phones use much less power. If you really can't sail without all that gadgetry on all the time then you will have to lug a noisy smelly generator around, but you don't have to.

 

[charles_reed]

I'd suggest you first work out your daily usage - the "power budget" - you'll probably find that the two biggest power consumers are the fridge and the laptop.

From that you can determine your minimum battery capacity which, IMHO, needs, at a minimum, to be x2 your daily budget.

You can then work out how to recharge your batteries - engine, PV panels, shorepower mains charger, wind generator or petrol generator.
I'd agree with most of the opinions that the last thing to look at is a petrol generator.

I spend 6/12 on a boat in the Med and find 328 watts of PV panel quite adequate for my needs, without starting the engine or using shorepower, but then my 24-hr budget is about 80ah.
I'm truly amazed by those who can get by on 1 x 30 watt PV panel.

 

[Iliade]

Check out the electrical generating capability of your Kubota. My Nanni (also a kubota) has a microscopic alternator fitted. Fitting a more powerful, or second, alternator would be my preference over an additional generator. I know that GP Barnes in Southwick have a big Lucas Marine alternator that has been sitting on the shelf for the best part of twenty years...

Giving more load to the engine would also be a good thing rather than running it light when being used as a generator.

You might also consider a removable drive belt system (uses a weighted idler to apply tension and thus seconds to remove the belt)

 

[Robert Wilson]

As I said, I'm a numpty with these things!
Anyway, thanks for all of the above.
I sort of understand the technical bits, but do understand the advice to reduce/use power only when essential.

Distilling thoughts from the advice given I think I'd rather spend the £800+ on a good PV charger than the genny.
The "man with the tool bag" who will be fitting the new VHF and AIS is a qualified and experienced marine electrical engineer - so I'll get him to calculate the loadings etc.

A new LED auto anchor-light is on order.

Just one point, if the laptop is switched-off then it won't be recording track data etc, so it's a case of ON or OFF - no half-way measure?

Thanks one and all.
If anyone has anything further to add, please feels free to do so!!! :encouragement:

 

[NickRobinson]

Hi Robert

I bought a genny when I had a mooring on remote saltings but it now stays at home.

You should be fine with your batteries if you swap out lamps to LEDs. My seven cabin lights went from nearly 10A to 1A.
The laptop is your weak point, drawing 2/4A I guess through the inverter? My laptop is used to upload routes to the ancient Garmin and my tablet then shut down. The 10" tablet has transformed my power usage under sail, the current draw on a 12v lead is c. .5A and it'll keep going for 7/8 hours with no power. It lives clamped to the saloon table and I drive it from the cockpit with a £3.00 blue tooth mouse.

It continues to track even if you choose to let the screen auto shut down.

 

[Cantata]

Teenager we knew became the youngest UK solo circumnavigator a few years back, he certainly didn't have a generator on his Coribee, nor an inboard engine for that matter....

 

[Robert Wilson]

Hi Robert

I bought a genny when I had a mooring on remote saltings but it now stays at home.

You should be fine with your batteries if you swap out lamps to LEDs. My seven cabin lights went from nearly 10A to 1A.
The laptop is your weak point, drawing 2/4A I guess through the inverter? My laptop is used to upload routes to the ancient Garmin and my tablet then shut down. The 10" tablet has transformed my power usage under sail, the current draw on a 12v lead is c. .5A and it'll keep going for 7/8 hours with no power. It lives clamped to the saloon table and I drive it from the cockpit with a £3.00 blue tooth mouse.

It continues to track even if you choose to let the screen auto shut down.

That's reassuring. I had a feeling I had "gone over-board" with the idea of Plotter and Laptop.
I'll still use the Laptop for "domestic use", e.g. uploading photos from camera/phone, writing my novel rolleyes and luxury route-planning and use my Plotter as main nav work; and Tablet as back-up/cockpit quick reference - or whatever.
I will use the AIS a lot, I think.

Hopefully it will be sunshine and fair winds all the way with 30 miles visibility so I'll be able to navigate by sight

 

[michael_w]

Increase battery capacity, add a smart controller for the alternator (Adverc, etc) Job done.

For the laptop, alter the power settings so when you close the lid it does nothing rather than go to stand by/shut down. This setting will shut down the screen, but keeps everything else working. Cuts the power consumption dramatically, yet the lappie springs into life as soon as you lift the lid.

 

[KellysEye]

Web had a smart charger for the batteries both on the engine and shore power which should do the trick.

 

[Kwik Decision]

That's reassuring. I had a feeling I had "gone over-board" with the idea of Plotter and Laptop.
I'll still use the Laptop for "domestic use", e.g. uploading photos from camera/phone, writing my novel rolleyes and luxury route-planning and use my Plotter as main nav work; and Tablet as back-up/cockpit quick reference - or whatever.
I will use the AIS a lot, I think.

Hopefully it will be sunshine and fair winds all the way with 30 miles visibility so I'll be able to navigate by sight

Are you taking and using paper charts? If yes, you really don't need the plotter and laptop running all the time. Even with plotter and tablet, you have 2 independent electronic means of nav - which (I understand) is what the commercial ships use now.

We find AIS receiver very useful going across channel, but it gets far less use during coastal sailing. I suspect if the fog were to come in, it would become very valuable though (no radar).