Electric Boats

[IanD]

1 hour ago, peterboat said:

My boat has a DC motor 

There are still lots of (cheap) DC motors around, but for variable-speed drive purposes (including boats) they've almost all been replaced by PMAC motors for very good reasons -- higher efficiency, no brushes/commutator to wear, cheap digital variable-speed controllers easily available (e.g. Sevcon) complete with motor protection/sensing.

 

DC motors -- and primitive switched speed/field controllers -- had their day in milk floats and fork lifts (and cranes), just like steam engines did on the railways... 😉

[peterboat]

5 hours ago, IanD said:

There are still lots of (cheap) DC motors around, but for variable-speed drive purposes (including boats) they've almost all been replaced by PMAC motors for very good reasons -- higher efficiency, no brushes/commutator to wear, cheap digital variable-speed controllers easily available (e.g. Sevcon) complete with motor protection/sensing.

 

DC motors -- and primitive switched speed/field controllers -- had their day in milk floats and fork lifts (and cranes), just like steam engines did on the railways... 😉

Speed controllers are cheap for DC motors PWM works fine on them and are they really inefficient? Changing dc to AC costs power losses

[IanD]

39 minutes ago, peterboat said:

Speed controllers are cheap for DC motors PWM works fine on them and are they really inefficient? Changing dc to AC costs power losses

 

DC motors and controllers are less efficient than PMAC ones. Both PWM for DC motors and PMAC 3-phase controllers use exactly the same basic type of MOSFET switching circuit, but due to the way the currents and voltages and frequencies and DC field coils work an AC drive is actually more efficient.

Edited March 2, 2022 by IanD

[TNLI]

On 01/03/2022 at 23:03, IanD said:

I got a quote from Voltsport for the direct drive system and it was surprisingly reasonable given the cost of the components. It would be interesting to find out how much the belt-drive systems cost, I would expect less because the motor is much cheaper. 

  Any chance of copying the quote and which exact system it was for ??

Thanks for that, and their canal boat rig looks very interesting. 

[TNLI]

On 02/03/2022 at 08:29, peterboat said:

My boat has a DC motor 

Which exact model and type of generator and/or batteries ??

 

I plan to fit my BMC 1500D next week, BUT I need an Aux drive system for very light winds or canal use in particular. Looked at quite a number of 48V 5hp units so far.

[peterboat]

1 hour ago, TNLI said:

Which exact model and type of generator and/or batteries ??

 

I plan to fit my BMC 1500D next week, BUT I need an Aux drive system for very light winds or canal use in particular. Looked at quite a number of 48V 5hp units so far.

I have an Agni pancake motor, Cedric lynch designed them, I believe that The Thames electric Boat Company will be importing them. Mine runs at 72 volts nominal using LifePo4s from Valence I think I am pushing 30 odd HP it runs through a 3 to 1 belt drive gearbox if you want to talk PM me your phone number and I will give you a call 

[TNLI]

6 hours ago, peterboat said:

I have an Agni pancake motor, Cedric lynch designed them, I believe that The Thames electric Boat Company will be importing them. Mine runs at 72 volts nominal using LifePo4s from Valence I think I am pushing 30 odd HP it runs through a 3 to 1 belt drive gearbox if you want to talk PM me your phone number and I will give you a call 

Wow, that's a serious amount of power! It's enough to be used as a my main engine, as the BMC 1500D puts out 35HP max, BUT it's rather too big in generator terms.  A 30HP motor would require a 25kW generator, and that's a real big gen set for a small boat.

 

In battery terms you can use normal sealed Lead acid batteries connected in series correctly, BUT you do need to try and use the top end of the batteries capacity to be efficient, and never discharge them below 12V under low load, unless you buy more expensive deep cycle types. It also helps if you buy a real good high efficiency battery charger for the gen set. Some do have dual outputs, but the 12V part is not efficient or powerful enough. 

  Electric motors are a bit off in prop size terms, as bigger is better, although with a boat that has an enclosed prop location, you can't fit a bigger prop. Some type of belt drive is a must.

 

AGNI Motors  (Based in India) 

 

Server Rack LiFePO4 Solar Batteries - Mobile Solar Power Made Easy! (mobile-solarpower.com)  Very nice long life batteries available in a range of voltages and they last a very long time. Lots of different suppliers listed in Fleabay, Amazingzone and Gooogle.

Not so sure if the ten year warranty is a viable one, as unlike a 1 year guarantee, the buyer has to prove the battery is defective to get a refund.

Edited March 11, 2022 by TNLI

[TheBiscuits]

28 minutes ago, TNLI said:

Very nice long life batteries available in a range of voltages and they last a very long time.

 

The specific LiFePO4 batteries you linked to are useless for electric drive.  They are computer power backup modules so are set up for small currents over a long time, not for delivering serious power to a motor.

 

Nothing wrong with LiFePO4 for driving an electric motor, but those particular ones won't do what you think they will.

 

 

[TNLI]

2 hours ago, TheBiscuits said:

 

The specific LiFePO4 batteries you linked to are useless for electric drive.  They are computer power backup modules so are set up for small currents over a long time, not for delivering serious power to a motor.

 

Nothing wrong with LiFePO4 for driving an electric motor, but those particular ones won't do what you think they will.

They make a whole range of different sizes and most do seem to be limited to 100A, but if you put a few in parallel they would work, but yes there are going to be cheaper better options like the Fleabay ones rated at 150A max output current and designed for motors rather than computer drives or servers:

4x 3.2V 50Ah 12V 640W Lithium iron LiFePO4 Deep Cycle Rechargeable Battery UK | eBay

I will just stick to using Bosch S4 car batteries, as that's the same type as I use for both start batteries, (Lifeboats need 2 start batteries if they do not have a manual start option). 

For 48V motors you would need 4 in series and if the motor draws more than 150A max, 2 sets of 4 in parallel. Seriously expensive as the net cost of that is 1760 quid!

 

2 hours ago, TheBiscuits said:

 

 

 

Edited March 12, 2022 by TNLI

[TNLI]

On 02/03/2022 at 16:06, IanD said:

 

DC motors and controllers are less efficient than PMAC ones. Both PWM for DC motors and PMAC 3-phase controllers use exactly the same basic type of MOSFET switching circuit, but due to the way the currents and voltages and frequencies and DC field coils work an AC drive is actually more efficient.

I was looking at forgetting the expensive batteries and inefficient control and charge units and just using a 230V AC tumble dryer motor with the same number of phases to match a cheap 230V 5 to 7.5kW max air cooled generator. Speed control like old diesel electric U boats, so group up and down to change voltage can be done with a 4 way battery selector. So 12 to 48V in stages. More efficient I think ??

 

This 5kW 48V DC motor is similar to a go cart motor available from the USA for about a grand delivered, the Alibaba source involves buying direct from the manufacturer in China, so if you add shipping and VAT, it will probably finish up costing around 750 quid:

 

Powerful 5kw Bldc Motor Electric Car Motor With High Efficiency - Buy 5kw Bldc Motor,E-motorbike Conversion Kit,E-car Conversion Kit Product on Alibaba.com

 

That motor does have a liquid cooling option, rather than a noisy forced air system. One blog for a similar motor said use 36V as max continuous if you don't like electrical fires.

 

For deep cycle 12V batteries, (4 in series), this type would be my choice, CCA stands for cold cranking amps and is often just listed as A for other 12V batteries. 

 

Bosch L5 Deep Cycle Leisure Battery L5075 12V 140Ah 800CCA Type 627 4047024776883 | eBay

 

PS: Avoid the buyer due poor rating, and you might find it cheaper if you can locate a direct source. Also much easier to return if they sold you a damaged one. Oddly enough both Volvo and Mercedes dealers stock very similar batteries, and the Volvo ones are often deep cycle versions.

Edited March 12, 2022 by TNLI

[TNLI]

How may folks fitting or looking at fitting a DC motor think an AC one might be worth looking at in terms of overall efficiency from generator fuel to HP output ??

A DC motor is more efficient than a 230V motor, BUT very few generators put out a significant amount of 12 or 24V output, so you need to use a transformer with all the loses involved. So the question is, is there a real difference to the final fuel to HP efficiency figures ??

[Thames Bhaji]

I have motors, battery and gen all at 48v, so no transformer / conversion losses for the propulsion. I never seriously looked at AC motor options (this was 15+ years ago) but have been happy with DC. 

[IanD]

Most electric/series hybrid boats being built today use brushless PMAC motors driven from a 3-phase AC controller which runs straight off the battery. This is the most efficient method and gives excellent control of motor speed and torque, and is quiet and zero maintenance (no commutator or brushes).

Edited March 18, 2022 by IanD

[TNLI]

53 minutes ago, Thames Bhaji said:

I have motors, battery and gen all at 48v, so no transformer / conversion losses for the propulsion. I never seriously looked at AC motor options (this was 15+ years ago) but have been happy with DC. 

Thanks for the reply. The issue I have is that the cheaper air cooled gen sets are designed to put out around 20A max of 12V power, and in the case of the Hyundai boxed gen set, 4.5kW max, and 3.5kW continuous of 230V, so I will need to use a heavy duty battery charger for the bank of NiCad's (48V total) to supply a 5HP max electric motor. 

  So I'm kind of thinking that I might forget about the dedicated battery bank and heavy duty charger and just go direct to the 230V, (EU is 230, UK is 240V), gen set supply. Although my lifeboat has a main BMC engine of 35HP max, that is far too much for use on a canal, I need a small gen set anyway, so I'm looking at AC gen sets more than DC ones. Obviously I will need to fit a top quality earth leakage breaker and fit the motor high enough to avoid salt water splash issues from the bilge area.

  I would note that a real marine electric motor that is salt water proof and has a warranty for 5 years costs around 7 grand, plus shipping and VAT for a 10HP 60V unit. Made in Austria by the Germans!

 

Hyundai DHY6000SE Diesel Generator | Generators-Direct

 

That cheapish gen set is reliable, BUT it is noisy in comparison with a more expensive water cooled Beta marine one. 

Edited March 18, 2022 by TNLI

[Alan de Enfield]

27 minutes ago, TNLI said:

The issue I have is that the cheaper air cooled gen sets are designed to put out around 20A max of 12V power, and in the case of the Hyundai boxed gen set, 4.5kW max, and 3.5kW continuous of 230V, so I will need to use a heavy duty battery charger for the bank of NiCad's (48V total) to supply a 5HP max electric motor. 

 

Where are you thinking of installing an air-cooled generator on your lifeboat ?

Would you be making some sort of exhaust system that would vent thru the hull, or are you thinking of strapping the Jennifer on the roof ?

[TNLI]

11 minutes ago, Alan de Enfield said:

 

Where are you thinking of installing an air-cooled generator on your lifeboat ?

Would you be making some sort of exhaust system that would vent thru the hull, or are you thinking of strapping the Jennifer on the roof ?

On the roof! Mine Gott, I already have a stainless chimney, but I'm kind of thinking about a bubble tube just below the water line adjacent to the gen set, as I might fit a diesel heater one day if the all electric system of used storage heater bricks and heat pads does not work out.

Any gen set has to go in the bow survivors cabin to avoid noise and potential exhaust system leak issues, (Makes fighting a fire easier as you can just flood the cabin as it is has a watertight bulkhead). Obviously there will be a CO & smoke alarm system in both the aft crew only cabin and forward cabin near the main engine and generator. In C of G terms I need to fit anything that needs to be bolted down to some place forward of my berth in the aft cabin, (It's right in the centre below the rescue/fishing deck area).

Edited March 18, 2022 by TNLI

[Alan de Enfield]

5 minutes ago, TNLI said:

On the roof! Mine Gott, I already have a stainless chimney, but I'm kind of thinking about a bubble tube just below the water line adjacent to the gen set, as I might fit a diesel heater one day if the all electric system of used storage heater bricks and heat pads does not work out.

Any gen set has to go in the bow survivors cabin to avoid noise and potential exhaust system leaks. Obviously there will be a CO & smoke alarm system in both the aft crew only cabin and forward cabin near the main engine and generator.

 

Just remember that portable Jennifers are not designed to have a fixed exhaust (ask the couple who died) and modifying the Jennifer would possibly / probably invalidate your insurance as it was not installed to manufacturers specification.

 

MAIB Report :

 

SYNOPSIS

On Monday 1 April 2013, the emergency services attended the motor cruiser Arniston on Windermere, Cumbria, where a mother and her daughter had been found unconscious. The two females were taken by air ambulance to Lancaster Royal Infirmary where they were pronounced deceased. A postmortem concluded that the cause of death was carbon monoxide poisoning. The subsequent MAIB investigation identified that:

• The carbon monoxide poisoning had resulted from the inhalation of fumes emitted from a portable generator installed in the boat’s engine bay.

• The external exhaust system fitted to the portable generator had been modified to incorporate a silencer that had become detached from both the generator and the outlet pipe to the vessel’s side.

• The portable generator’s engine exhaust fumes filled the engine bay and spread through gaps in an internal bulkhead into the aft cabin where the mother and daughter were asleep.

• The portable generator was not intended by its manufacturer to be installed into an enclosed space, nor was it intended to be modified in any way.

• The improvised exhaust system attached to the generator was constructed from materials and using methods that were not appropriate for this application

[TNLI]

1 hour ago, Alan de Enfield said:

 

Just remember that portable Jennifers are not designed to have a fixed exhaust (ask the couple who died) and modifying the Jennifer would possibly / probably invalidate your insurance as it was not installed to manufacturers specification.

 

MAIB Report :

 

SYNOPSIS

On Monday 1 April 2013, the emergency services attended the motor cruiser Arniston on Windermere, Cumbria, where a mother and her daughter had been found unconscious. The two females were taken by air ambulance to Lancaster Royal Infirmary where they were pronounced deceased. A postmortem concluded that the cause of death was carbon monoxide poisoning. The subsequent MAIB investigation identified that:

• The carbon monoxide poisoning had resulted from the inhalation of fumes emitted from a portable generator installed in the boat’s engine bay.

• The external exhaust system fitted to the portable generator had been modified to incorporate a silencer that had become detached from both the generator and the outlet pipe to the vessel’s side.

• The portable generator’s engine exhaust fumes filled the engine bay and spread through gaps in an internal bulkhead into the aft cabin where the mother and daughter were asleep.

• The portable generator was not intended by its manufacturer to be installed into an enclosed space, nor was it intended to be modified in any way.

• The improvised exhaust system attached to the generator was constructed from materials and using methods that were not appropriate for this application

As I said before the gen set will be in a sealed cabin, not the main cabin and that cabin will not be occupied by anyone when it's running, partly because of the noise and heat.

The gen set I plan to fit is not a portable and is fully enclosed.

I do not intend to fit an additional silencer.

Not sure what mistake was made with the exhaust installation, and that report does not say if the engine room had a CO monitor fitted. In reality there should be two, one near the potential source and another near where the captain sleeps. 

[Alan de Enfield]

14 minutes ago, TNLI said:

As I said before the gen set will be in a sealed cabin, not the main cabin and that cabin will not be occupied by anyone when it's running, partly because of the noise and heat.

The gen set I plan to fit is not a portable and is fully enclosed.

I do not intend to fit an additional silencer.

 

Am I reading this correctly.

You are going to put a generator in a sealed room.

You are not going to fit an exhaust sytem.

 

Where is it going to get its air supply from & where are the exhaust fumes going to go ?

[TNLI]

2 hours ago, Alan de Enfield said:

 

Am I reading this correctly.

You are going to put a generator in a sealed room.

You are not going to fit an exhaust system.

 

Where is it going to get its air supply from & where are the exhaust fumes going to go ?

No it's a watertight cabin which does have small vents and 2 reverse loop drains and anchor chain entry loop, so there will be enough air for a small generator. The exhaust is out of an existing chimney with a flexible stainless hose, OR a bubble pipe if I buy another heater that needs an exhaust. 

 

I've also purchased a small stainless steel wood or charcoal stove/heater that says it was designed for cooking or heating a small tent. I'm not going to fit in a permanent manner as any surveyor would have a fit about the CO or direct fire risk. So I plan to use it in the central rescue deck area when beached, in a marina or becalmed only. The less said about CO risks from charcoal in particular the better. 

 

One final word for any safety orientated boater, never sleep with a generator or main engine running unless you really have no choice. Part of the reason is CO risk, but the overheat alarm or broken fuel return line fire risks should not be underestimated. The cook got fired on an Oyster 69 I was first officer on for a few years for sleeping with an old Onan generator running whilst at anchor. She had had her ear seriously bent for failing to clip on before leaving the centre cockpit when sailing offshore after I specifically warned her, so in safety terms it was a second offence. The funny thing was that she was a real good cook and the skippers girlfriend, but he was an old school professional sailor, so I was not surprised when she got the order of the boot.

Edited March 18, 2022 by TNLI

[MtB]

8 minutes ago, TNLI said:

No it's a watertight cabin which does have small vents and 2 reverse loop drains and anchor chain entry loop, so there will be enough air for a small generator. The exhaust is out of an existing chimney with a flexible stainless hose, OR a bubble pipe if I buy another heater that needs an exhaust. 

 

 

You can see why we have to endure the BSS, from posts like this.

 

 

[TNLI]

On 02/03/2022 at 10:13, IanD said:

There are still lots of (cheap) DC motors around, but for variable-speed drive purposes (including boats) they've almost all been replaced by PMAC motors for very good reasons -- higher efficiency, no brushes/commutator to wear, cheap digital variable-speed controllers easily available (e.g. Sevcon) complete with motor protection/sensing.

 

DC motors -- and primitive switched speed/field controllers -- had their day in milk floats and fork lifts (and cranes), just like steam engines did on the railways... 😉

 

I agree with you about the motors, but the old diesel electric U boats used group up and down methods if varying speed by switching in more or less batteries as required. Very cheap and reliable in wiring terms:

Idle: One battery

Slow ahead: 2 

Half ahead: 3

Full ahead: 4 batteries in series, so 48V. 

No real need for reverse on small boats. It can be done but does rather complicate the wiring to the point of buying a real control box and e throttle lever unit.

[Stilllearning]

Is this bloke for real?

No need for reverse....

[ditchcrawler]

2 minutes ago, Stilllearning said:

Is this bloke for real?

No need for reverse....

Reading recent posts I am starting to wonder

[Tony Brooks]

I am still trying to work out what a bubble pipe exhaust is, unless he just means an ordinary wet exhaust. I know that you can get attachments for car exhausts that make the blow bubbles but I don't think he wants clouds of bubbles blowing out of his generator exhaust, but maybe he does.