Outboards and battery charging

[Tom Morgan]

Hello all.  A new member here, a non-boater at present.  I've been binge-reading the posts here and have learned a lot, especially about grp boats, which is the type I'm hoping to purchase.  Just entering "grp" in the search box has given me a virtual encyclopaedia of knowledge and experience to learn from.  So thanks for that.  My question is:

How does an outboard engine charge the batteries?  I assume it isn't as good as the big inboard engines I have seen in boating videos.  I'd be grateful for any answers.

[Alan de Enfield]

The simple answer is "it doesn't".

It has a very small alternator (around 7 amp is the usual size) which will charge / recharge the starter battery but is not enough to charge 'domestics' batteries.

You will need to have a solar-array or a generator to keep on top of the charging, unless you plan to live in 'electrical poverty', and not use lights, TV, phone charger, PC etc etc.

 

It can be done but you will need to have a very, very basic electrical system.

 

The other issue is that OBs are petrol powered, petrol is not commonly available on the canal network so you will need to plan your visits everyday to coincide with petrol-stations within walking distance of the canal - again it can be done but it is very restrictive.

 

The maximum legal amount of petrol you can have in cans on a boat is 30 litres so you will be looking for a petrol station most days.

 

The BSS (safety certificate) requirements for petrol engine boats are much higher than diesel engine boats because of the much higher risks involved.

 

If you ask for my opinion then if you want to 'go boating' then buy one with a diesel engine, if you want to spend hours planning routes to pass by petrol stations and hours walking along roads carrying petrol cans then buy a petrol powered boat.

 

Edit to add :

I am not against GRP boats (I currently have two of them) it is just that petrol powered boats are cheap for a reason - want the freedom of boating ? then get a diesel engine boat.

Edited September 3, 2018 by Alan de Enfield

[Tony Brooks]

A modern  outboard might charge at up to about 15 amps maximum so if you are very frugal with domestic electricity you might be able to make things work but taking things overall I tend to go with Alan.

 

Petrol is more available at the waterside on rivers where there are lots of petrol boars but it is getting rarer each year.

[Alan de Enfield]

14 minutes ago, Tony Brooks said:

A modern  outboard might charge at up to about 15 amps maximum so if you are very frugal with domestic electricity you might be able to make things work but taking things overall I tend to go with Alan.

 

Petrol is more available at the waterside on rivers where there are lots of petrol boars but it is getting rarer each year.

Big OBs certainly have bigger alternators :

Yamaha 50hp = 16 amps

Yamaha 70hp = 17 amps

 

But these are not commonly used on the canals - if the OP is planning on River usage they may be suitable

 

I know some 'small' engines now have bigger alternators so have had a quick look at one model I have seen used.

 

New Model 2018 Yamaha 9.9hp

Alternator output at WoT = 6 amps

 

Considering that it is unlikely that it will be used at WoT the output is likely to be a fair bit less than 6A

 

 

Engine Type	2 cyl
Displacement	212cc
Bore x Stroke	56 x 43mm (2.20 x 1.70 in.)
Prop Shaft Horsepower	9.9hp @ 5500rpm
Full Throttle RPM Range	5000 ~ 6000
Alternator Output at W.O.T.	6
Compression Ratio	9.4:1
Fuel Induction System	Carb
Weight*	39 kg (87 lbs) - 42 kg (93 lbs)
Recommended Fuel	Octane 87

Edited September 4, 2018 by Alan de Enfield

[doratheexplorer]

Tom, you should tell us about your planned use:  Liveaboard or recreation?  Extended cruising or short trips?  Home mooring?  Electric shoreline? 

 

The responses above are making a lot of assumptions about how you want to use the boat, but we don't know yet.

 

Lots of GRP boats are used recreationally from a home mooring and never do more than day trips (or the occassional overnight).  If so, get a solar panel to keep your domestic battery topped up and you'll be fine.  If your home mooring has mains electric then it's even easier.  The charged up domestic battery will be fine for short trips.  Bring a jerry can of petrol to the boat and top up the tank before setting off. 

 

The problem comes if you want to cruise for a few weeks at a time (or more).  Solar will look after you from about March to October but not in winter.  The easiest way to do it in winter is with a portable generator, but read up on the Carbon Monoxide risk with those and take precautions.  Both the genny and the outboard will need petrol, and as has been said, that's not the easiest to find.  Plenty of people manage though and there are apps now which will tell you where the petrol stations are.

9 hours ago, Alan de Enfield said:

The simple answer is "it doesn't".

It has a very small alternator (around 7 amp is the usual size) which will charge / recharge the starter battery but is not enough to charge 'domestics' batteries.

You will need to have a solar-array or a generator to keep on top of the charging, unless you plan to live in 'electrical poverty', and not use lights, TV, phone charger, PC etc etc.

 

It can be done but you will need to have a very, very basic electrical system.

 

The other issue is that OBs are petrol powered, petrol is not commonly available on the canal network so you will need to plan your visits everyday to coincide with petrol-stations within walking distance of the canal - again it can be done but it is very restrictive.

 

The maximum legal amount of petrol you can have in cans on a boat is 30 litres so you will be looking for a petrol station most days.

 

The BSS (safety certificate) requirements for petrol engine boats are much higher than diesel engine boats because of the much higher risks involved.

 

If you ask for my opinion then if you want to 'go boating' then buy one with a diesel engine, if you want to spend hours planning routes to pass by petrol stations and hours walking along roads carrying petrol cans then buy a petrol powered boat.

 

Edit to add :

I am not against GRP boats (I currently have two of them) it is just that petrol powered boats are cheap for a reason - want the freedom of boating ? then get a diesel engine boat.

How much petrol does a 10hp outboard burn in an hour then?

[Naughty Cal]

If your budget will allow find a GRP cruiser with an inboard diesel engine. It will make life much easier in the long run.

 

Not only will it properly charge your batteries and allow you to run more electrical items (think fridge, heating, etc.) but it will also provide you with hot water which an outboard will not.

 

It will probably be more expensive to buy but it will certainly hold it's money in the long run.

 

If you tell us how and where you plan to use the boat then we can probably find you some examples to compare.

[Tom Morgan]

Sorry for not giving much information - I never expected such detailed and considered replies.  I'm very grateful for them.

 

The GRP/petrol combination, is what I can afford so I must accept its limitations.  Family circumstances mean that my boating will be within these limitations, anyway, I think. I'm still in the very early stages of looking into it all and know nothing, but I was thinking of a marina when not cruising, with shoreline availability and recreational boating to begin with, only a night or two at a time. But I will look out for diesel boats too, and see how they compare price-wise.

Edited September 4, 2018 by Tom Morgan
To add final comment about diesels.

[rasputin]

I use my petrol powered grp boat for a month at a time in summer, I have a 100w solar for the fridge and a 30w solar for domestic, I am fairly frugal with electricity.

 

I have only had a problem once finding petrol, and I do not need to find it most days.

[doratheexplorer]

30 minutes ago, Tom Morgan said:

Sorry for not giving much information - I never expected such detailed and considered replies.  I'm very grateful for them.

 

The GRP/petrol combination, is what I can afford so I must accept its limitations.  Family circumstances mean that my boating will be within these limitations, anyway, I think. I'm still in the very early stages of looking into it all and know nothing, but I was thinking of a marina when not cruising, with shoreline availability and recreational boating to begin with, only a night or two at a time. But I will look out for diesel boats too, and see how they compare price-wise.

Consider this:  diesel inboard does bring a lot of benefits but this is reflected in the price.  So for your budget, you may be able to get a nice, well looked after petrol outboard grp or a knackered diesel inboard grp which needs a lot of work.  For the type of use you're proposing, I know which one I'd prefer.  I genuinely don't know what fuel consumption a typical petrol outboard has, but I'd be surprised if it was more than a litre an hour when pushing the boat along at canal speeds.  This means that if you turn up on your boat on a saturday morning and set off cruising for 5 hours a day,  you'd run out on thursday night/friday morning.  Typically little grp boats have a small 3-way fridge which will run off gas so all you need is a 100w panel which will charge a phone, laptop etc and run lights.  I used to have a camper van and I bought a 100w solar kit off ebay for just over £100 and it included a regular and all leads.  I just connected it straight to my battery and it gave me all the power I needed, much to the envy of other campers who kept having to run their engine to charge their batteries.

 

Do you mind saying what your budget is?

[Naughty Cal]

If you let us know where you plan to keep the boat and your budget we can find you examples of both Petrol and diesel boats in your budget.

[Alan de Enfield]

2 hours ago, doratheexplorer said:

Tom, you should tell us about your planned use:  Liveaboard or recreation?  Extended cruising or short trips?  Home mooring?  Electric shoreline? 

 

The responses above are making a lot of assumptions about how you want to use the boat, but we don't know yet.

 

Lots of GRP boats are used recreationally from a home mooring and never do more than day trips (or the occassional overnight).  If so, get a solar panel to keep your domestic battery topped up and you'll be fine.  If your home mooring has mains electric then it's even easier.  The charged up domestic battery will be fine for short trips.  Bring a jerry can of petrol to the boat and top up the tank before setting off. 

 

The problem comes if you want to cruise for a few weeks at a time (or more).  Solar will look after you from about March to October but not in winter.  The easiest way to do it in winter is with a portable generator, but read up on the Carbon Monoxide risk with those and take precautions.  Both the genny and the outboard will need petrol, and as has been said, that's not the easiest to find.  Plenty of people manage though and there are apps now which will tell you where the petrol stations are.

How much petrol does a 10hp outboard burn in an hour then?

We have a 5hp 2T on our tender and it uses roughly 2 litres per hour with 4 PoB

[ditchcrawler]

Just found this but may be those American gallons 

 

I ran a consumption test last fall on my 1998 Honda BF8 8HP outboard to get an idea of how much fuel I would need for my Havre De Grace trip in the spring.Test parameters: Boat - 27', 7000 lb 3'9" draft Hunter. Also the boat has an inboard diesel, so there is a big three blade prop underneath slowing the boat down. I intentionally filled my water tank and left my fenders on. My BF8 has the standard prop - three blade roughly 9.25" x 8.6" - not the powerthrust prop. I can get to about 2/3 throttle with the prop, the boat just doesn't go any faster if I give it more gas, the engine just bogs down. I filled my spare 3 gallon tank with exactly half a gallon at the gas station. I left my marina using my normal 6 gallon tank and headed out to the river. I disconnected the 6 gallon tank, waited until the engine was about to die and plugged the hose into the 3 gallon tank and immediately set the throttle at about the 2/3 setting. I ran exactly 35 minutes when the engine died.I found later back at the marina that the 3 gallon tank still had at least four or five ounces left in the tank that the pickup tube couldn't reach.I'd venture a guess and say you would get even better results with your boat, maybe 3/4 gallon/hour going at a good clip, but to be safe budget 1 gallon/hr.Mannyedited to add - I forgot to mention it's a four stroke

[doratheexplorer]

24 minutes ago, Alan de Enfield said:

We have a 5hp 2T on our tender and it uses roughly 2 litres per hour with 4 PoB

What's 4 PoB? Remember the original poster is entirely new to this.  It's helpful to avoid jargon and acronyms.  You used the acronym WOT earlier, I have no clue what that means either.

If you have a tender then that's not canal use, so not really the same thing.  I'm picturing a little boat zipping across a harbour at full throttle.

[Naughty Cal]

4 persons on board.

Wide open throttle.

[doratheexplorer]

20 minutes ago, ditchcrawler said:

Just found this but may be those American gallons 

 

I ran a consumption test last fall on my 1998 Honda BF8 8HP outboard to get an idea of how much fuel I would need for my Havre De Grace trip in the spring.Test parameters: Boat - 27', 7000 lb 3'9" draft Hunter. Also the boat has an inboard diesel, so there is a big three blade prop underneath slowing the boat down. I intentionally filled my water tank and left my fenders on. My BF8 has the standard prop - three blade roughly 9.25" x 8.6" - not the powerthrust prop. I can get to about 2/3 throttle with the prop, the boat just doesn't go any faster if I give it more gas, the engine just bogs down. I filled my spare 3 gallon tank with exactly half a gallon at the gas station. I left my marina using my normal 6 gallon tank and headed out to the river. I disconnected the 6 gallon tank, waited until the engine was about to die and plugged the hose into the 3 gallon tank and immediately set the throttle at about the 2/3 setting. I ran exactly 35 minutes when the engine died.I found later back at the marina that the 3 gallon tank still had at least four or five ounces left in the tank that the pickup tube couldn't reach.I'd venture a guess and say you would get even better results with your boat, maybe 3/4 gallon/hour going at a good clip, but to be safe budget 1 gallon/hr.Mannyedited to add - I forgot to mention it's a four stroke

3'9" draft sounds like a very different thing.

1 minute ago, Naughty Cal said:

4 persons on board.

Wide open throttle.

aha!  Does anyone have any real world experience of consumption on a canal from a typical small grp like a Norman 25?

[Naughty Cal]

Our little 2.3 Honda uses 1.1 litres per hour at full throttle. In practise it is never on full throttle so uses a lot less.

 

On our venture up the Chesterfield Canal we were out for six hours and it used a little over three litres. (Easy to calculate as the integral tank holds 1.1 litres)

 

Our 6hp Mariner uses considerably more but we tend to be messing about on the plane with that one rather then pottering around.

[sal garfi]

I'm just about to leave for Sawley from where my wife and I are going to take our Norman 22, with 15hp outboard, all the way cross country to Maesbury on the Wales-England border. We won't leave until the middle or end of next week and we've planned our journey, plotting petrol stations etc. Once we're settled in, in our new mooring, we can let you all know how we got on, though this will probably be in early October. Re petrol consumption, I'm presuming ca 1.5 ltrs per hour, and we envisage travelling no more than ca five hours a day. No matter what, it should be fun!

[MtB]

2 stroke engines are inherently more thirsty than four strokes, small blades are inherently less efficient than big blades, and petrol is less energy-dense than diesel.

 

So I would be inclined to suggest these three factors broadly offset the lighter weight of a GRP boat to push along and I'd estimate fuel consumption will still be about 1 litre an hour, the same as a bigger steel diesel boat. 

 

 

[Alan de Enfield]

49 minutes ago, doratheexplorer said:

aha!  Does anyone have any real world experience of consumption on a canal from a typical small grp like a Norman 25?

Probably because of the small number of Petrol engines boats, sub-divided into OB powered boats, sub-divided into canal users, sub divided into CWDF members there are probably are not more than one or two who have seen the question and could reply.

[MtB]

7 minutes ago, Alan de Enfield said:

Probably because of the small number of Petrol engines boats, sub-divided into OB powered boats, sub-divided into canal users, sub divided into CWDF members there are probably are not more than one or two who have seen the question and could reply.

 

And of those who could reply, probably only one in a hundred will, as most members here never post. 

[Naughty Cal]

Some examples of cheaper diesel powered cruisers.

 

But really we could do with an idea of your budget and where you will keep the boat as these might not be suitable, i.e too wide, for some waters.

 

https://www.watersidemarinesales.co.uk/boats-for-sale/seamaster-813-break-in-the-clouds.html

 

https://www.watersidemarinesales.co.uk/boats-for-sale/hampton-25-omadawn.html

 

https://www.nya.co.uk/boats-for-sale/birchwood-25-executive-6/

 

https://www.nya.co.uk/boats-for-sale/freeman-22-mkii-3/

 

https://www.nya.co.uk/boats-for-sale/royall-rapier-20/

 

http://www.newark-marina.co.uk/used-boats/seamaster-23-2/

 

http://www.jonesboatyard.co.uk/boat-sales/elysian-27-boat-for-sale-6856.html

 

http://www.jonesboatyard.co.uk/boat-sales/seamaster-725-boat-for-sale-6787.html

 

And I know of a narrowbeam Freeman 22 with a little 2 cylinder diesel that is looking for a new home if you are willing to put in a bit of work.

[doratheexplorer]

1 hour ago, Naughty Cal said:

Some examples of cheaper diesel powered cruisers.

 

But really we could do with an idea of your budget and where you will keep the boat as these might not be suitable, i.e too wide, for some waters.

 

https://www.watersidemarinesales.co.uk/boats-for-sale/seamaster-813-break-in-the-clouds.html

 

https://www.watersidemarinesales.co.uk/boats-for-sale/hampton-25-omadawn.html

 

https://www.nya.co.uk/boats-for-sale/birchwood-25-executive-6/

 

https://www.nya.co.uk/boats-for-sale/freeman-22-mkii-3/

 

https://www.nya.co.uk/boats-for-sale/royall-rapier-20/

 

http://www.newark-marina.co.uk/used-boats/seamaster-23-2/

 

http://www.jonesboatyard.co.uk/boat-sales/elysian-27-boat-for-sale-6856.html

 

http://www.jonesboatyard.co.uk/boat-sales/seamaster-725-boat-for-sale-6787.html

 

And I know of a narrowbeam Freeman 22 with a little 2 cylinder diesel that is looking for a new home if you are willing to put in a bit of work.

The OP is based in the West Midlands where these won't go.  Would be a real shame to miss out on the nicest canals in the country for the sake of 2 feet.

2 hours ago, Mike the Boilerman said:

2 stroke engines are inherently more thirsty than four strokes, small blades are inherently less efficient than big blades, and petrol is less energy-dense than diesel.

 

So I would be inclined to suggest these three factors broadly offset the lighter weight of a GRP boat to push along and I'd estimate fuel consumption will still be about 1 litre an hour, the same as a bigger steel diesel boat. 

 

 

I'd go along with that.  There are such things as 4 stroke outboards aren't there?  Are there diesel outboards too?

[rasputin]

Ok as the only person qualified to reply, I use about 1L per hour.

 

15hp 4 stroke pushing an 18.5 foot skip

Edited September 4, 2018 by rasputin

[doratheexplorer]

Just now, rasputin said:

Ok as the only person qualified to reply, I use about 1L per hour

So going back to my original query.  If you can store 30 litres of petrol on board you definitely don't have to go and collect more petrol everyday, which was what was begin said with a view to putting the OP off a petrol boat.

[sal garfi]

14 minutes ago, doratheexplorer said:

So going back to my original query.  If you can store 30 litres of petrol on board you definitely don't have to go and collect more petrol everyday, which was what was begin said with a view to putting the OP off a petrol boat.

Too true!! I, for instance, can collect 20 litres in two 10 litr jerry cans, with a trolley, whenever it's required.

Edited September 4, 2018 by sal garfi