Bow thruster with VSR charging conundrums

[William_H]

I would suggest a simple arrangement would be to connect the thruster/winch battery to the engine battery via decent but not huge cables. A hard parallel connection. Thus if engine is running it will charge up bow battery to that of engine battery. If thruster or winch is operated with engine running the alternator will supplement the bow battery with current dependent on size of cables. If engine is not running start battery will supplement bow battery when under load.
You do not need the isolation of VSR or B2B charger assuming that you will not deplete the engine start battery with thruster or winch with engine not running. In any case you should have provision for emergency starting from domestic battery.
Though actually I would advocate just heavy cables from engine battery and no bow battery. ol'will

 

[Macka1706]

I have had a bow thruster fitted (wired but not yet connected to batteries) and also intend to install a VSR. I am concerned that the bow thruster (Sleipner SE40, nominal current draw 315A) could potentially fry the VSR, especially if the domestic battery bank to which it is directly connected is depleted.

I currently (arf, arf) have a Paris-Rhone alternator of very modest output (can't find details just now, thought it was just 30A or 40A, but seen some listed as 60A), but likely to be eventually replacing this with something modern giving maybe c75A. Engine battery is c100Ah; Domestic batteries are 2 x c100Ah in parallel; all lead acid. For the purposes of the following lets assume the thruster is connected to the domestic batteries. (Whether it is preferable to connect to the engine battery and alternator is a different question!)

I have, but haven't yet fitted, a VSR and matching battery switches (starting, domestic and 'combine both'), to replace existing diode split-charging and old battery switches, which will all fit very neatly and conveniently in the available space near the existing battery and old battery switches wiring. The VSR, though, has a current capacity of 125A, so would be overloaded if the domestic batteries to which the thruster is wired are depleted, or quite likely even if they aren't.

I have mulled over at length the following thoughts (and now leaning with some trepidation towards Option 3b), and would be grateful for others' views and suggestions on the way forward.

OPTION 1) The (at first) 'obvious' answer would be to fit a high current VSR (e.g Victron i-400A), but this is both (a) very expensive - c£250 (and money is v. tight) - and (b) because of size/layout/style would need to be mounted in a aesthetically and operationally much less than ideal location, also some distance from the batteries, engine and existing & proposed) battery switches, requiring additional wiring and wire lengths and other downsides (when there is already a very long 'to do' list).

OPTION 2) In principle, one could always switch the 'combine both battery banks' closed before using the thruster. In practice, sooner or later it would be forgotten, and in any case I am not sure its operation would necessarily mean that the maximum current capacity of the VSR was never exceeded. (The current draw from engine battery nd alternator would presumably be split approximately in half by the between the two paths - VSR and 'combine both banks' switch.)

OPTION 3a) Fitting a normally closed 12V relay in series with the VSR, which would be operated (opened) by the power supply to the thruster, and therefore disconnect the VSR when the thruster is switched to 'ready to operate'. This (unless/until the really fails - the ones I've seen so far are unbranded and costs only about £5) should prevent any current flowing through the the VSR. If the manual 'combine batteries' switch is not also operated this will prevent the engine battery and alternator contributing to the thruster load, and if it is operated would connect the engine battery and alternator outputs to the thruster draw. The relay current capacity would need to accommodate the maximum charging current to the pair of domestic batteries.

OPTION 3b) I've belatedy thought of this - Fitting a normally open relay, again operated by the thruster power supply as per Option 3a above, in the thin negative wire between the VST and the negative busbar. With this wire open circuit the VSR won't 'see' the 13.7V necessary for it to cut in. (Note this will mean the VSR will have to start from scratch and re-sense whether 12v or 24v supply operation each time the thruster power supply is turned off.)

OPTION 4) Is there an option 4????

What does the team think?

Option 4.
60a Amp alt mounted on engine bed rail with adjustable hinge. Double pulley on crankshaft. Battery to suit. maybe wired into Instruments too, as a separate circuit.
Alt will keep Instr running battery topped up and you normally only run Thruster when in harbour. IE Donk running. That's what I had. 4 x house. 1 x Engine Start and bilge pumps, 1 x Thruster and backup for instruments.
6 Batt's at 110a. 2 x Alt. 4 x 85w Panels one wind Genny and one "oold" 15a Towing log. Even a decent tide or current kept that trickling when at anchor or quayside. Always over the side when moving
If a power boat. Shaft Alternators are a good option too. ANYthing rotating is a potential supply.
You modern lot are too fixated with your fancy electronics. Keep it basic at sea and you'll be a lot better off.
I can fix. Alter, Transfer supply and current flow from anywhere to anywhere with my eyes closed. Only electronics being Inverter to AC and Regulator to panels. Have spares for both wired in ready to sw over.

 

[dukeofted]

Just put 100amp fuses in both of the positive feeds to the VSR and then you don't need to worry. It's a good idea if those cables are fused as near to the batteries as possible anyway in case you get a short.

 

[Tranona]

Option 4.
60a Amp alt mounted on engine bed rail with adjustable hinge. Double pulley on crankshaft. Battery to suit. maybe wired into Instruments too, as a separate circuit.
Alt will keep Instr running battery topped up and you normally only run Thruster when in harbour. IE Donk running. That's what I had. 4 x house. 1 x Engine Start and bilge pumps, 1 x Thruster and backup for instruments.
6 Batt's at 110a. 2 x Alt. 4 x 85w Panels one wind Genny and one "oold" 15a Towing log. Even a decent tide or current kept that trickling when at anchor or quayside. Always over the side when moving
If a power boat. Shaft Alternators are a good option too. ANYthing rotating is a potential supply.
You modern lot are too fixated with your fancy electronics. Keep it basic at sea and you'll be a lot better off.
I can fix. Alter, Transfer supply and current flow from anywhere to anywhere with my eyes closed. Only electronics being Inverter to AC and Regulator to panels. Have spares for both wired in ready to sw over.

Pleased to see you think all that faff is "basic". The OP has a simple small coastal cruiser for which a simple electrical system is easy to devise and operate. The only complication arises because he has chosen to run his bow thruster from his house bank which is maybe 6 or 7m away from the thruster motor,

If he had adopted the now more common approach of having a dedicated battery for each major function this thread would never have been needed. I have a similar size boat and 3 battery banks, one for engine one for house (including instruments) and one in the bow for the thruster and windlass. Charging of the house and start is through a VSR and the bow battery through a B2B from the start battery. Simple, avoids running heavy cables and use of the thruster or windlass has no impact on any other of the boat's systems. You can of course add other means of charging to the independent banks such as mains, solar or wind if you wish.

 

[LittleSister]

Pleased to see you think all that faff is "basic". The OP has a simple small coastal cruiser for which a simple electrical system is easy to devise and operate.

I agree with the generality of that (if not the tone!) - Macka1706 is working at a whole different level of size and complexity (6 batteries in 3 banks and 2 alternators) that I have neither the space nor the money for, but might be of value to others reading the thread.

The only complication arises because he has chosen to run his bow thruster from his house bank which is maybe 6 or 7m away from the thruster motor,

The distance the house bank to the thruster (actually more like 5m) is not a 'complication' because I already have the cables installed. Ideally, I would like to put one of the house bank batteries in the bow, but mainly for weight distribution purposes (the boat is stern heavy), but the lockers in that area are rather shallow and awkward shaped for accommodating batteries, and keeping vented hydrogen away from the thruster motor is a concern to me.

If he had adopted the now more common approach of having a dedicated battery for each major function this thread would never have been needed. I have a similar size boat and 3 battery banks, one for engine one for house (including instruments) and one in the bow for the thruster and windlass. Charging of the house and start is through a VSR and the bow battery through a B2B from the start battery. Simple, avoids running heavy cables and use of the thruster or windlass has no impact on any other of the boat's systems. You can of course add other means of charging to the independent banks such as mains, solar or wind if you wish.

I think you are trying here to solve a different problem to the one I have. The question I originally posed was about how the VSR I have available would work with the set up I have in terms of current capacity, and people have clarified and put my mind at rest on that. I don't see a need for the cost and further installation work of a B2B charger for my current (arf, arf!) purposes, though your description of that arrangement may well be useful to someone else in a slightly different situation.

I am hoping to add some solar when time, money and energy is available (at the moment, just getting the boat back in the water after several years when unfortunate 'circumstances' have prevented it is the priority), but mainly for domestic demands. I'm not expecting my thruster use to require much in the way of amp-hours, just an awful lot of amps for very occasional, very brief periods

 

[Tranona]

As you say the "problem" is really not a big thing. The decision to use a bow battery is not straightforward as space is often an issue. My old Bavaria 37 for example simply did not have space because of the 150l water tank, whereas the later 33 I had was designed specifically to take a bow battery. The question of cabling also varies - again the Bavarias came with the cables already in place to suit all options available so like yours there is no advantage in using the smaller cables that a B2B allows. Not suggesting you use a B2B. it only has value if you want to install a bow battery. My installation started from a different point to yours - that is from nothing other than the bow battery already in place (originally charged from a solar panel, now removed) - so I designed it to be as simple as possible.

The thruster was professionally installed. As the photo shows very neatly. The battery is the other side of the bulkhead and the windlass is immediately above. There is an isolator on the berth front on the left. This means all the heavy cabling runs are very short. The charging cables are not installed at this point, but now run along the left hand side before going through the bulkhead to the battery.



My response to the new post was really to comment on how inappropriate it was in relation to your original question, or even the ensuing discussions. As you say a completely different level of complication unsuited to your requirements, or indeed most other small coastal cruising boats.

 

[Macka1706]

Sorry. Old Fart I was thinking my 32ft Pugh. My old Nicholson 27 timber girl I had my 2 x Battery's under forward berths for ballast With ring main wired in (me. Water tank midships and single pot Bukh under cockpit Solar on frame over rear cockpot and wind genny on centre stern to get airflow from main. Port or Stbd Tack..
28ft by 8ft 4in Beam with 4ft 8in draught with around 4 ft sitting headroom.
Moulded lead keel to suit. Sailed llike a witch. Stable as. and wet as too, over 20 knots.
Lovely heavy weather boat. As long as you kept up with the cotton and oiled putty in Underwater seams chuckle.
Always single sailor, so no extra ballast and baggage (people) plenty of room for me and pet.
Most boats with inboard on rails will have room for a double pulley and bracket on bed rails. Find an older model car alt. they tend to activate and generate at lower rev's.
Anything is possible. One mate made up 2 x waterproof boxes and kept his battery's in them in forward sect of cockpit. Shortened the seating "in" area. (not floor)Directly above eng. Battery's above. But no power winch or thruster. Hand hauled pick, and big rudder. Small boats shouldn't need Them?. I hand hauled my 8mm chain and 35 lb plough for yrs. Then fitted a Simpson Lawrence Manual anchor winch for 60th B,Day. Still Hand hoisted my 35ft luff 17ft6in foot , 9oz Tan Full battens Main to top though. Keeps you fit.

 

[Tranona]

Sorry. Old Fart I was thinking my 32ft Pugh. My old Nicholson 27 timber girl I had my 2 x Battery's under forward berths for ballast With ring main wired in (me. Water tank midships and single pot Bukh under cockpit Solar on frame over rear cockpot and wind genny on centre stern to get airflow from main. Port or Stbd Tack..
28ft by 8ft 4in Beam with 4ft 8in draught with around 4 ft sitting headroom.
Moulded lead keel to suit. Sailed llike a witch. Stable as. and wet as too, over 20 knots.
Lovely heavy weather boat. As long as you kept up with the cotton and oiled putty in Underwater seams chuckle.
Always single sailor, so no extra ballast and baggage (people) plenty of room for me and pet.
Most boats with inboard on rails will have room for a double pulley and bracket on bed rails. Find an older model car alt. they tend to activate and generate at lower rev's.
Anything is possible. One mate made up 2 x waterproof boxes and kept his battery's in them in forward sect of cockpit. Shortened the seating "in" area. (not floor)Directly above eng. Battery's above. But no power winch or thruster. Hand hauled pick, and big rudder. Small boats shouldn't need Them?. I hand hauled my 8mm chain and 35 lb plough for yrs. Then fitted a Simpson Lawrence Manual anchor winch for 60th B,Day. Still Hand hoisted my 35ft luff 17ft6in foot , 9oz Tan Full battens Main to top though. Keeps you fit.

All very interesting, but largely irrelevant for most people with modern cruising boats and modern engines that have high output alternators and good battery management systems. While it is quite possible to handle modestly sized boats with no mechanical or electrical aids, you will find that as you get older and rely on berthing in marinas rather than wandering around the open seas you will find such things increasingly attractive. Fitting them extends your sailing life and helps keep you safe and secure. Plenty of other ways of keeping fit that are better than hauling a heavy old poor anchor like a CQR and heavy chain that you do not need, or raising the mainsail when you can fit low friction slides and battens then take the halyard back to a powerful winch that you can operate while still in the cockpit.

As for birthday presents, good start to buy a manual windlass at 60, but for me that is a distant memory and over 15 years on I expect much better things. Indeed for my 70th I bought myself a new boat, with all the aids fitted and enjoyed 5 years of simple fuss free sailing before moving onto another challenge.

 

[Macka1706]

All very interesting, but largely irrelevant for most people with modern cruising boats and modern engines that have high output alternators and good battery management systems. While it is quite possible to handle modestly sized boats with no mechanical or electrical aids, you will find that as you get older and rely on berthing in marinas rather than wandering around the open seas you will find such things increasingly attractive. Fitting them extends your sailing life and helps keep you safe and secure. Plenty of other ways of keeping fit that are better than hauling a heavy old poor anchor like a CQR and heavy chain that you do not need, or raising the mainsail when you can fit low friction slides and battens then take the halyard back to a powerful winch that you can operate while still in the cockpit.

As for birthday presents, good start to buy a manual windlass at 60, but for me that is a distant memory and over 15 years on I expect much better things. Indeed for my 70th I bought myself a new boat, with all the aids fitted and enjoyed 5 years of simple fuss free sailing before moving onto another challenge.

""

""Plenty of other ways of keeping fit that are better than hauling a heavy old poor anchor like a CQR and heavy chain that you do not need, or raising the mainsail when you can fit low friction slides and battens then take the halyard back to a powerful winch that you can operate while still in the cockpit."">>>>

Basically no matter what size shape your boat YOU should be able to put her. Park here Wherever needed with no trouble. It's called practice. And the iod BUkhs etc are not mdern. they older than you. I'm 81.
32ft 8 1/2 ton of steel you NEED the 35lb and 8mm chain. Had electric one on 42ft 17 tonner though. 10mm BBB and 60lb picks.
The 32fter main HAD a winch on mast and slugs. It was quicker and easier to hoist and set by hand. Plus it "felt" good. Kept me fit and muscles working under load. My last 25ish yrs were basically coastal around Australia Tassie and a few hops to N.Z.
Problems with Aortic Valve. Hereditary. Another reason I was solo. NO responsibility for/to anybody if things went upside down.
Even coastal I rarely went out under 20knots of breeze. and we got a fair %age of up to 40 and more down South of Australia.
Good sailing, not puffing around. Hence my bigger, heavier boats. Horses for courses.
My first boat was using a 16ft rower in Middleton Harbour at 9 yrs old. Learned sailing in a GP14 sailing dinghy at 11yrs. and deckie on North Sea Trawlers at 13 yrs. Army with Nuclear Missiles 17 to 21.
Sailing is sailing. Feeling her straining to the wind and talking to you. Not pushing buttons on machinery. That's for factory hands.
My old Nich. Double reefed small jib. Gunnels under. Wet as a shag. I would be steering with tiller while pumping bilge pump with other as it poured in through the above waterline seams. THAT's Sailing Enjoy, I did,
Off to watch footy (Rugby) now.

 

[Tranona]

All very interesting - but I think I have got to the age (and 50 years experience) when I can make my own decisions about what I want out of my boat so don't need to be told by you.

I am not in Australia but in sleepy Poole on the south coast of England and just about to go out for a little potter around the harbour to try out my new anchor when I stop for a spot of lunch.

 

[Macka1706]

All very interesting - but I think I have got to the age (and 50 years experience) when I can make my own decisions about what I want out of my boat so don't need to be told by you.

I am not in Australia but in sleepy Poole on the south coast of England and just about to go out for a little potter around the harbour to try out my new anchor when I stop for a spot of lunch.

Hey. Not Telling you anything lad. It's just horses for courses.
You putter putter around in calmer weather than us, in general.. We get weather direct from Antarctica. NO islands in between down South. And the TradeWinds plus cyclones seasons from middle up.
It gets blowy then some. Specially in Cyclone season. We average 4 per yr mostly.
You should come over here sometime. It's great sailing most times. When wee get the "trades" here. mostly keep all boats under 30ft in for months. No fishing boats for near 7 months a few yrs ago. A few boat/tackle dealers retired.
The 35+lb picks and 8mm 110m chains are Necessary for normal sailing in 30/35ft range unless lightweight toys.. We are basically open coastline with a few bays and man made hidey holes. We have thousands of km's of coastline. Mostly UNinhabited.
34,000km's not counting the offshore islands. I've sailed round in 1 1/3 times. Ridden 600ccdirt bike around and across it (desert). Caravanned it over 30 yrs of that. Seen about 1/2% of what we have over the 50+yrs I bin here.
PS. Pity you didn't come to Aust all those yrs ago. Nothing for kids there in those days. Here Mine all working, 2 businesses one retired at 55. Grandkids 10 plus one boy 6 in the mines. 2, Shift Supervisors others Operators. That's good money. I retired from operating full time at 49/50yrs. Part time (cash) after that.
That's the difference moving to Aust made to me/us.Financially I was good but nozzing for kids growing up (8/6/3yrs)
In UK early '70's. Motorways and 36in Gas pipelines finished. Only the rigs left for us dumb old labourers.
(I know what i Am/was.) We all different. Rough/gruff old colliery born git.