Electric Boats

[IanD]

1 hour ago, TNLI said:

 

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.

Group/bank switching like you describe means the batteries don't discharge equally, and also gives only a few fixed speeds. Very bad for canal boats...

 

It (with DC motors) was OK in "the old days" (U-boats!!!) before modern electronic speed controllers and PMAC motors -- which also allow variable speed/torque modes, current monitoring, protection, stall detection, motor temperature sensing and so on, so the "olden days" solution is actually less robust and idiot-proof than the modern one 😉

Edited March 18, 2022 by IanD

[Thames Bhaji]

2 hours ago, TNLI said:

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

I hope you’re never in close proximity to me! Just make sure you at least have a loud horn. 

[peterboat]

I am sticking with my system that has had a BSS, although I am fitting a new speed controller this year from 4QD which is allegedly better than my Curtis one. 

[TNLI]

2 hours ago, Tony Brooks said:

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.

They are used by drug smuggling surface runners and modern diesel electric submarines, they just consist of a stainless tube just below the waterline that has a lot of small holes drilled in it and an end cap fitted in such a way as it is easy to remove to allow an annual clean out of the pipe. The reason the drug smugglers and subs use them is to reduce their IR signature. The Columbian cartels found out the hard way by losing some of the boats, including full dive mini subs because their exhaust was far to easy to see on a basic IR camera. They initially fitted normal pipes but even those pipes could be detected by a passing AWACS or military satellite. 

[Alan de Enfield]

2 minutes ago, TNLI said:

They are used by drug smuggling surface runners and modern diesel electric submarines, they just consist of a stainless tube just below the waterline that has a lot of small holes drilled in it and an end cap fitted in such a way as it is easy to remove to allow an annual clean out of the pipe. The reason the drug smugglers and subs use them is to reduce their IR signature. The Columbian cartels found out the hard way by losing some of the boats, including full dive mini subs because their exhaust was far to easy to see on a basic IR camera. They initially fitted normal pipes but even those pipes could be detected by a passing AWACS or military satellite. 

 

 

Pretty much a piece of critical equipment for use by a Lifeboat on a canal. Wouldn't want to be giving off an IR signature would we.

 

Are you in a parallel universe  to the rest of us ?

[Tony Brooks]

5 minutes ago, Alan de Enfield said:

 

 

Pretty much a piece of critical equipment for use by a Lifeboat on a canal. Wouldn't want to be giving off an IR signature would we.

 

Are you in a parallel universe  to the rest of us ?

 

I suppose it might be a cheap way of doing a bit of exhaust silencing. As soon as the hot gas hits the cool water  the gas should contract to a degree. Sort of poor mans wet exhaust.

[TNLI]

2 hours ago, Thames Bhaji said:

I hope you’re never in close proximity to me! Just make sure you at least have a loud horn. 

I will have a very loud 12V air horn system, (It's in the parts room at present), and a small hand air horn, but a 27ft alloy boat does slow down fairly quickly and if it failed in full ahead, (Door jammed shut during crew mutiny),

  I'm real quick with the emergency stern anchor, (Small folding grapnel), as any boat owner should be, as engines of any type can fail. It takes far too long for a bow anchor to be of real use unless you have already partially lowered it and have a remote system or crew person ready to deploy it. A grapnel will hold with a 2:1, as will a traditional fisherman's anchor, whereas a Danforth or Bruce needs around 3:1 for it to function in mud, gravel or sand. The CQR might be the worlds best storm anchor, but it does need a 4:1 ratio to really dig in.

Red Folding Grapnel Anchor Kit 1.5kg for PWC/Kayaks/Jet Skis/Dinghys/RIB/Canoe | eBay

 

Rather expensive but I've seen a boat in the US that used one to prevent ice forming. The marinas around the great lakes and NE USA can provide a bubble pump that is placed under a boat, but they do charge extra for that service and the associated electric bill is significant if you need to leave it switched on all day to prevent ice forming.

2 X 3.5" STAINLESS STEEL EXHAUST PERFORATED TUBE 304 GRADE 6M LONG 3MM HOLE | eBay

 

Edited March 18, 2022 by TNLI

[TNLI]

3 hours ago, IanD said:

Group/bank switching like you describe means the batteries don't discharge equally, and also gives only a few fixed speeds. Very bad for canal boats...

 

It (with DC motors) was OK in "the old days" (U-boats!!!) before modern electronic speed controllers and PMAC motors -- which also allow variable speed/torque modes, current monitoring, protection, stall detection, motor temperature sensing and so on, so the "olden days" solution is actually less robust and idiot-proof than the modern one 😉

Yes that's true and you will need to fit split charge diodes to overcome the charge issue and zenner diodes to balance the bank. Not expensive if you make boxed up charge and balance boxes yourself. 

BATTERY SPLIT CHARGE DIODE 6-36V 70AMP 1 ALT 2 BANK like Sterling | eBay

Alas you might need 2 more of those for a 48V system.

 

What is a Zener diode and how does it work? - Tutorials | CircuitBread

Be careful when buying off the shelf charge or output balance boxes as it's very easy to buy the wrong type. A box with heavy duty Zenner diodes is a balance output one, the split charge systems are just for recharging contain normal diodes. Both have heat sinks and you will need to use the more expensive variety to avoid a voltage drop. 

 

The Zener Diode Resistive Balancer - Endless Sphere (endless-sphere.com)

Interesting but the poster is using Zenners that look too small and lack a heat sink.

Edited March 18, 2022 by TNLI

[TNLI]

1 hour ago, Alan de Enfield said:

 

 

Pretty much a piece of critical equipment for use by a Lifeboat on a canal. Wouldn't want to be giving off an IR signature would we.

 

Are you in a parallel universe  to the rest of us ?

Yes I'm in a parallel universe most of the time. It used to be one in Trinidad, but I might be moving across the universe to a place where they seem to be using IR missiles on bath sides of the river, unless President Putrid recalls his badly mauled Army and what is left of his air force. 

 

Underwater exhaust systems are far better in orrible fumes terms, and also reduce the noise, although I'm still going to fit a silencer box for the main engine. They work well for preventing ice if you don't drill too many holes but do require a series of attachment points that need to be done correctly to avoid leaks etc. Big reduction in that terrible suck and spit sound, BUT are only a sensible option if you have the good sense to have a keel cooled diesel. 

[Alan de Enfield]

30 minutes ago, TNLI said:

Underwater exhaust systems are far better in orrible fumes terms, and also reduce the noise,

 

Just so you know, one of my boats has two six-litre / six-cylinder engines. They both have 3" exhausts that exit underwater.

I am aware of the pros & cons of  'underwater exhausts'

[TNLI]

5 hours ago, Alan de Enfield said:

 

Just so you know, one of my boats has two six-litre / six-cylinder engines. They both have 3" exhausts that exit underwater.

I am aware of the pros & cons of  'underwater exhausts'

What type of main engines do you have, as two 6 litre diesels would drink a fair amount of go juice, on what looks like a semi displacement hull. Did you get an issue with white tube worms blocking up the holes when the engine was not run often enough ??

 

[Alan de Enfield]

6 hours ago, TNLI said:

What type of main engines do you have, as two 6 litre diesels would drink a fair amount of go juice

 

2x Ford 2765E

5 litres per hour each at 5 knots at around 1400 rpm

 

2700 litre fuel tank ensures sufficient range.

 

Edited March 19, 2022 by Alan de Enfield

[TNLI]

5 hours ago, Alan de Enfield said:

 

2x Ford 2765E

5 litres per hour each at 5 knots at around 1400 rpm

 

2700 litre fuel tank ensures sufficient range.

 

Thanks, and do you use one engine at a time on trips to the best fishing area in the Atlantic, which is often in the Doldrums about 300 nm SW of the Cape Verdes. That area is very popular with large seine netters and you can off load to Isle Du Sal, which is about the only tourist resort in the Cape Verdes. They have a good airport, so fresh provisions are supposed to be fairly OK. The area I used to fish is infested with FAD's (Fish Attracting Devices) surrounded with mostly small to medium Tuna (No Bluefin), Dorado's, assorted sharks and blue or black Marlin. I even saw a rare offshore Grouper under one pallet set. Easy to fill the water tanks from heavy thunderstorms. Longest leg is about 750nm to Gran Cannery, Azores and then Cornwall. If you time it right and troll there is a chance of a few big tuna or a white Marlin, (Sold as Swordfish), almost all the way.

[Mad Harold]

18 hours ago, TNLI said:

 

 

Big reduction in that terrible suck and spit sound, 

Agree, boat moored next door has a BMC 1500 with suck and spit.

Suck seems to be quiet but the spit sounds to me like a group of drunks having a vomitting contest. 😰

[Alan de Enfield]

18 minutes ago, TNLI said:

Thanks, and do you use one engine at a time on trips to the best fishing area

 

No it has too much prop-walk on a single and is hard work to steer for the auto-pilot, it has 'opposite' (LH & RH) rotating props, makes it much easier to steer.

[TNLI]

6 hours ago, Mad Harold said:

Agree, boat moored next door has a BMC 1500 with suck and spit.

Suck seems to be quiet but the spit sounds to me like a group of drunks having a vomiting contest. 😰

 

Sounds like your neighbour is daft enough to use a non close tolerance or common rail diesel as a battery charger. One daft idea unless you stick to a strict schedule of 30 mins at max continuous under load every 10 hours as I always did when slow trolling live bails, (2 kts max), on one engine at around 1300 RPM, or fast trolling lures, (6 to 7kts), on both at around 1500 RPM. That routine is still not as good as correct use, but was recommended by a Perkins R&D engineer as a way of reducing upper cylinder deposits, (Mostly Carbon), that cause significant additional wear of the rings, valve seats and valve guide oil seals. Boron Nitride additives in nearly all major brand diesel engine oils and a high level of Calcium Sulphate detergent does help, but only partly. 

  If you need to charge batteries, fit solar panels and/or a cheap air cooled generator, as they cost around a grand, which is about the same as the bottom end rebuild my BMC is having done. 400 for parts and 600 for labour, although that includes regrinding the crankshaft. The top end overhaul would cost less at around 500 quid for parts and labour IF done correctly. Low power canal use tends to result in far more upper cylinder wear than the more expensive crankshaft and main bearing wear. 

  Running a fridge or freezer seems to be the big culprit on live aboard or fishing boats, as LED lights seem to have reduced both anchor or navigation lights combined with below decks lighting to a far lower power consumption than the old incandescent days. I've just been making some dual cream and red lights, (2 way switch), up from old used stern or steaming light holders. 25W of light for 5W of power from cheap LED's. 

[TNLI]

6 hours ago, Alan de Enfield said:

 

No it has too much prop-walk on a single and is hard work to steer for the auto-pilot, it has 'opposite' (LH & RH) rotating props, makes it much easier to steer.

Sounds like one of the engines needs moving to the side in location terms, although that is one real big job. I would be inclined to fit a drag tab just above or to the side on the stern that can be adjusted to make the boat steer hands free. You might think about seeing if there are any off the shelf used trim tabs from a similar size boat.

  I would also check the gearbox manual to see if it's OK to let the prop spin after an engine is shutdown, as it's not good for some hydraulic boxes due dry sump issues. All of the BMC boxes are OK but many larger hydraulic boxes require shaft locks to make sure the box output bearing does not start to wear out. Shaft locks or brakes are a pain if the crew forget one is on, so it might be possible to fit a small electric feed pump in the hydraulic fluid circulating system.

  Not mad keen on auto pilots on fishing boats, as the crew need a way of staying awake or they tend to run over their own gear, or worse still hit the rocks as one local boat did near me one night, (Sank after reaching port in the slipway due to caved in bow section and no collision bulkhead).

 

[Alan de Enfield]

4 minutes ago, TNLI said:

Not mad keen on auto pilots on fishing boats,

 

No problem there - its not a fishing boat, its a liveaboard cruiser.

 

Don't worry about the gearbox 'freewheeling' it is designed for it. It is not a 'lightweight toy' it weighs in at almost 200lbs and rated for continuous commercial activities.

 

 

 

[TNLI]

9 hours ago, Alan de Enfield said:

 

No problem there - its not a fishing boat, its a liveaboard cruiser.

 

Don't worry about the gearbox 'freewheeling' it is designed for it. It is not a 'lightweight toy' it weighs in at almost 200lbs and rated for continuous commercial activities.

 

 

 

That's interesting as I said in my last post that the PRM 100 in my boat is OK for freewheeling. Oddly enough there is still a case for using a simple shaft brake, as the drag from a free spinning prop is higher than it is from a stationary one. This is due to the increased angle of attack the spinning prop has when compared to the angle when locked. I used to be able to draw the vector diagram to prove that and to show which engine is critical when you have 2 engines in terms of requiring slightly more rudder angle. 

If you have the dosh there are  quite a number of companies making self pitching props that nearly feather when the engine is shut down. Those props cost about three times as much as a normal bronze prop. Autoprop were the original company, but nearly every major company in the marine propulsion game copied their basic design. They do reduce fuel consumption even in a normal boat, but the real difference is when you motor sail or have a big sea running. My last yacht for example had a normal 3 bladed prop and if you used the engine when sailing at 5 kts, it only made 1 kt difference at moderate power, whereas other owners said it doubled the speed under sail due to the low load causing the springs to increase the props pitch angle.

  

Shaft generators work very well once you are sailing or motoring on one engine at more than 3 kts. I used to use a towed water generator offshore that would produce 20A of 12V power at 5kts with a shunt regulator that buzzed enough to let you know when the battery bank was fully charged. Those alternators, or even simple starter motors can be belt driven, although it makes sense to fit a more expensive freewheel clutch as used on better car or truck alternators. 

 

All of the boats I've owned or skippered could be used for liveaboard applications, although some were converted by adding freezers that were removed in port after off loading, although the best ones had real ice makers all whole sets of large Coleman cool boxes if the fishing trip was less than a week. I used to put them all in a row and then put a mattress on top of them in port. Daily fight with the cockroaches was all part of the job, as most boats down South get them as unwanted visitors. Roach traps near the sinks or fridge drains, bleach wiped around other dubious areas and the occasional use of a surprise attack with fly spray rated for crawling inspects. Ants could be an issue when hauled out, but never had any rats get onboard cos the cut off bottle ends on the docking lines prevented that serious problem, as cats are bad luck on a fishing boat.

BOAT PROPELLER - FOLDING - 3 Blade Bruntons  H5 Autoprop  | eBay

 

I've nearly lost 2 boats to serious net and FAD tangles, with one off the Cape Verdes and another turn back and expensive dive team net cut off job off Gran Cannery Island, (They can mostly skipjack Tuna and sometime air freight to New York white tuna). That is one foul up that I will never let happen again, so looking at a few prop guard designs, like this one:

 Custom Made Metal Prop Guard To Fit Mariner Tohatsu 24 30 hp - ex RNLI | eBay

 

Boat Outboard Engine Propeller Guard, Size: 13" (Blue), fits 40HP - 65HP | eBay

That one is more interesting as it might fit either side of my prop, although I do not like buying parts overseas.

 

Edited March 20, 2022 by TNLI

[ditchcrawler]

Someone just pointed out this blog to me with some numbers on it Stats for April 2022 – Narrowboat Firecrest (nb-firecrest.co.uk)

[IanD]

18 minutes ago, ditchcrawler said:

Someone just pointed out this blog to me with some numbers on it Stats for April 2022 – Narrowboat Firecrest (nb-firecrest.co.uk)

 

Elsewhere on the blog is a graph showing measured power vs. speed -- at typical real cruising speed of 3mph power is 3kW which is exactly what I used in my power audit but was told by several people was too high... 😉

 

The really fast rise in power above this (faster than speed^3) is presumably due to canal width/depth and the boat "digging in" at the stern, where a lot more power gives a lot more wash but little extra speed.

Edited May 20, 2022 by IanD

[TNLI]

10 hours ago, IanD said:

 

Elsewhere on the blog is a graph showing measured power vs. speed -- at typical real cruising speed of 3mph power is 3kW which is exactly what I used in my power audit but was told by several people was too high... 😉

 

The really fast rise in power above this (faster than speed^3) is presumably due to canal width/depth and the boat "digging in" at the stern, where a lot more power gives a lot more wash but little extra speed.

Umm, it will only take twice as much power to do 3.5 rather than 3mph if the hull speed is around 4 mph. The last 20 odd percent to hull speed is real bad news in fuel economy terms.

Hull speed in kts is 1.35 times square root of the waterline length in feet.

Edited May 21, 2022 by TNLI

[MtB]

11 minutes ago, TNLI said:

Umm, it will only take twice as much power to do 3.5 rather than 3mph if the hull speed is around 4 mph. The last 20 odd percent to hull speed is real bad news in fuel economy terms.

Hull speed in kts is 1.35 times square root of the waterline length in feet.

 

Isn't that for deep water?

 

Hulls in shallow water and a narrow channel, behave very differently.

 

 

[TNLI]

13 minutes ago, MtB said:

 

Isn't that for deep water?

 

Hulls in shallow water and a narrow channel, behave very differently.

 

 

Only if the boat is an almost exact fit in a very narrow channel. Oddly enough the actual draught does reduce in a significant manner in shallow water at speed. That's why the QE2 ran aground once.

A boat does need more power in shallow water, but the hull speed remains the same. This is noticeable in a flat bottomed canal boat hull but not a yacht.

Edited May 21, 2022 by TNLI

[LadyG]

I'm not one to butt in ( ho ho ho), but there is another factor not mentioned, and that is the surface of the hull.

Last year I put on three coats of jotamastic 90 which provided a smooth shiny surface, and for a few months the boat was transformed in to a superboat, very much faster, now back to normal steady but sure, courtesy of a coating of green stuff.

Racing boats and gliders are very aware of the benefits of polished surfaces, it's not a thing for narrowboats, but it's something to think about, it would save fuel, save money, would it save the planet?

Edited May 21, 2022 by LadyG