The Electric Hobbit

  • 01 Oct 2020 23:53
    Reply # 9277852 on 8732915

    Yes, but not from one metre, when you are sitting in the cockpit!

    As you know, I adore brightwork and I don't mind giving it a light sand and recoating once a year.  The latest two-part polyurethane finishes make it all quite painless and flow out nicely.  The Carbothane that I am using is actually designed to go over coloured paint to prevent fading and wear! 

    Personally I think Cetol is ugly.  Either use a clear finish or genuine paint.  It is, as you have said, possible to find a red-brown that looks like wood from a distance (or a gold-brown for spars).

    As I am in the middle of spreading various finishes over Fanshi at the moment - and enjoying it - my mind is full of thoughts of paint and varnish!

  • 27 Sep 2020 08:31
    Reply # 9267482 on 9267221
    Deleted user
    Jim wrote:

    . He was one of those laconic, traditional boat builds whose name was associated with boat building on the South Shore. Without a hint of a smile or irony, he said, "Paint it." I didn't need to ask why. So, I sealed it with one coat of epoxy and painted it with one part polyurethane Brightside "Rustic Red" (no longer available). It could be mistaken for mahogany at 20 ft. It never cracked or peeled. I just needed to cover it every few years with a thinned coating of the same. I had energy left over to grag.

    One alternative I've read about, for painting teak furniture, says: Remove any coatings. let the wood weather to grey. Sand lightly. Paint with an oil-based primer. Cover with polyurethane. I'd try to find a colour that would match the golden hue of freshly Cetoled teak. (Now, let me take cover before passing judgement, please.) 

    P.S. No launching this year. 


    Good to hear you are making progress of a sort. Re your trim timber. I agree, paint it! I have just fitted the belting strips of timber around the gunwhale area of my new catamaran. The intention was to varnish the timber so I had some beautiful brightwork, just to set off the boat. After several days of thought I came to the same conclusion: paint it! I will use some timber coloured paint which I know will last for several years, stand up to a lot of abuse, and will only need a recoat of thinned down product to make it look absolutely fantastic from a couple of meters distance. 
  • 27 Sep 2020 01:54
    Reply # 9267221 on 8732915

    Progress report:

    The motor, batteries and all associated equipment has been trial fitted or permanently fitted and tested. All systems work fine. My techy did a marvelous job of tidying up the engine room wiring. He's delighted to be part of the project, the first of its kind so far for him.

    The bad news is the shaft coupling on the motor does not quite fit the Yanmar coupling. I thought it did but.... Not to self: It doesn't hurt to be obsessive about these things. Anyway, I got a matching coupling from the distributor of the motor's coupling. The old one had to soak in lubricating fluid for a day before it would come off, using a gear puller from the Halifax Tool Library. Same story for the stuffing box, to check the packing. The propeller shaft is showing considerable wear in way of the cutlass bearing, caused by calcium deposits? There was a lot of that in the system. So, we are getting a new Cutlass bearing, stuffing box hose and propeller shaft. Fortunately, the brother in law of a friend will do the shaft turning for free. Ah well... I won't have to worry about those things any more. The stuffing box will get a nice wash in muriatic acid.

    The rudder is fastened to the boat, gudgeon/gudgeon to a 3/4" bronze rod, heavily worn. The SS gudgeons wore down the rod quite a bit. Two trips to the Caribbean would contribute to that. They were not aligned as well as they should. I've fixed that. I bought a 3/4" SS replacement. The price was surprisingly low.  The rudder rebuild has been set aside until I get the hull painted.

    Painted the starboard side of the hull today. The working conditions this year have been fabulous. last year this time was too late already. Tomorrow, in the late AM, the Port side. Dark green, like Marco Polo/Teleport. Goes well with the grey teak decks and Cetol coated trim.

    About Cetol on teak. An abomination. It's like putting nicotine in candy. When I was building Marco Polo, I asked an old timer what system I should use on my mahogany trim. He was one of those laconic, traditional boat builds whose name was associated with boat building on the South Shore. Without a hint of a smile or irony, he said, "Paint it." I didn't need to ask why. So, I sealed it with one coat of epoxy and painted it with one part polyurethane Brightside "Rustic Red" (no longer available). It could be mistaken for mahogany at 20 ft. It never cracked or peeled. I just needed to cover it every few years with a thinned coating of the same. I had energy left over to grag.

    One alternative I've read about, for painting teak furniture, says: Remove any coatings. let the wood weather to grey. Sand lightly. Paint with an oil-based primer. Cover with polyurethane. I'd try to find a colour that would match the golden hue of freshly Cetoled teak. (Now, let me take cover before passing judgement, please.) 

    P.S. No launching this year. 


  • 27 Sep 2020 00:42
    Reply # 9267171 on 8748722
    Is there much current – river or tidal – where you spend your time? There are some interesting water turbines these days.

    Shemaya

    No. I don't know anyone who is using a water turbine from a boat in these parts.
  • 09 Jun 2020 04:29
    Reply # 9024355 on 8732915

    Hello Jim & All,

    I don't think this has been mentioned here:

    If the boat's battery charger is one which can operate as a power supply (not all can) then the generator can be run while motoring under way.

    A 600W charger, for instance, would have my 6.3m 'minim,' for instance, going about 3 knots in a calm (or we'd be sailing.) Going slower than that, the excess power would charge the batteries. Done routinely -> less generator noise in anchorages.

    Your 2kW generator could handle a 1kW+ charger for your bigger boat, so I'd consider your situation in the same practicality ballpark. 

    'minim' and 'mehitabel' do without generators, requiring compromises many people wouldn't like. I got rid of the 1.3kW DC generator I put together for 'mehitabel' and I haven't missed it.

    Darren Bos's words describe it well: "Without a generator I think you'd need to sail like you didn't have a motor, and then use the electric at low power levels for extremely pleasant motor-sailing, or for the convenience of getting in and out of anchorages." 

    [... or up and down canals & rivers, or anywhere - slowly...]

    Cheers, Kurt

  • 06 Jun 2020 00:13
    Reply # 9018220 on 8732915

    Thanks for that factful reply. I'll study it carefully. I'm better informed than I was yesterday. Now I have more questions for my technician.

    I had wondered about a floating ground. My system is pretty simple. It may be a good way to go.

    I'll get back with more detail to match with your information.

  • 04 Jun 2020 17:57
    Reply # 9015346 on 8732915

    I'll take a shot at this with the disclaimer that I'm not a trained professional and that some of the decisions involved here could lead to life threatening circumstances that anyone reading this needs to take personal responsibility for.  Also, criticism and comments are welcome, I've written this to try and help, but it is just as true that writing something out and having it criticised  makes plain any gaps in ones knowledge.

    Looking at how long this post turned out, I've come back to the beginning to add that if your boat had no corrosion problems before, the simplest solution is to choose a new single point to "ground" your negative bus.  This might be easiest done by using a metal through-hull, but in that case I would also use the motor disconnect mentioned at the end of the post.

    The word ground is a bit abused in recreational marine quarters.  It tends to be used to describe both electrically connecting the negative bus to seawater (which should only be done at one point, usually the engine), and it is also used to describe the AC ground which is usually necessary if you have shorepower.  Although both of these are often the same physical connection (a single point on the engine), they actually serve different purposes.  The  AC ground is as you would normally expect in a house, it provides a safe path to ground for dangerous AC current should a fault arise in a live conductor.  The DC "ground" can also serve this purpose, should a live AC wire come into contact with a DC wire, but it also has the purpose of providing a low resistance path that a DC fault can travel so as to minimize corrosion.  Without it, if you had two faults in your DC ground wire, lets say one to a seacock near the bow and another to the engine shaft, they are unlikely to be at the exact same voltage because or resistance in the wiring.  This voltage difference is very much like you took a very low voltage battery, perhaps a fraction of a volt to a volt, attached the positive to the motor and the negative to the forward seacock.  The result will be electrolysis, and can lead to erosion of metal.  If you look at a galvanic table, zinc has a value of about -1, while 316 stainless is about 0.  So, you can actually make the stainless dissolve rather than the zinc if you apply a voltage of greater than one volt and overcome the protection provided by the zinc.

    As for solutions, lets start with safety first.  If you have an AC shorepower connection, you really need an AC ground or an isolation transformer.  The main reason for this is if you have AC and don't connect the ground, then a fault means you could leak current into the surrounding water.  Particularly in freshwater, if a swimmer (or hull cleaner) is in the water they can offer a path of less resistance than the water and die of electrocution.  Even in "saltwater" the places where we moor our boats are often brackish or even have a freshwater lens floating on the surface so that it could be dangerous for swimmers.  An isolation transformer gets around this by breaking the connection with the shore, in it there are two parallel but isolated coils of wire, the magnetic field from one coil creates electric current in the second coil and there is no physical connection with the shore.  Thus if a fault exist, it doesn't try to go back to the shore ground because there is now no connection to it.  Swimmers are safe.  Follow the instructions that come with the isolation transformer to keep people on the boat safe from AC faults.

    There may be a third solution, perhaps some of the European members could comment on.  I think the use of ground fault interrupts are more common there on dock pedestals and in boats.  This could also provide protection, but I don't know enough to say any more. 

    For the DC side, you can have a completely floating (no connection to "ground") negative bus if you like.  However, this requires a great deal of care.  You must have no faults in your wiring.  Neither positive nor negative wires may contact any metallic bits of the boat.  This may be harder than you think, lots of electronics ground the negative to the case, a mast-top antenna might have its mount connected to DC neg, etc....  Because we have an aluminum hull we've gone to the trouble of installing a floating DC ground.  However, the first thing I installed was a tester that can be used with a push of a button to check that there is no connection at all to the hull.  Every time new equipment goes in, I have to check that we've maintained isolation.  Even something like corrosion on a connector might lead to a high resistance fault.  Chasing these faults is really difficult if you have typical DC breakers that only break the positive lead in the circuit.  We went to the trouble to install double pole breakers that interrupt both the positive and negative branch of every circuit.  This makes hunting down faults much easier.  With a metal hull, our case is more difficult to isolate completely then if you have a wood or fiberglass hull.

    If your boat has a simple wiring system, a floating DC system might be possible.  I would disconnect the battery and all the known grounds and then use a multimeter set to the resistance or continuity setting to test to see if any unknown leaks exist.  Test between the Negative bus and every bit of metal on the hull, same for the positive bus.  If there are no leaks a floating DC system is possible.  Because internal combustion motors are so difficult to fully isolate (due to using the block as a DC negative ground) and keep isolated, we have an isolation switch for the motor.  The one we chose is double pole again, so that when it is off both the negative and positive are disconnected from the motor.  You could do the same if you like and then the path for corrosion to the shaft is disconnected except for the relatively small percent of time you run the motor.  This is also nice to have if you want to work on the motor and make sure it is not energized, and if placed discretely is a pretty good anti-theft mechanism.  In this case, you should have a zinc on the prop or the shaft, especially if you have something like a stainless shaft and a bronze prop.


  • 04 Jun 2020 15:32
    Reply # 9014804 on 8732915

    Attached is a simple sketch of Hobbit's wiring system.

    (No solar panels of wind generators yet.)

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  • 04 Jun 2020 15:23
    Reply # 9014788 on 8732915

    I have a conundrum. 

    I am nearly ready to connect my batteries and motor. The wiring diagram shows a negative bus to which all negative leads are connected. It reads: SINGLE POINT GROUND CONNECTED TO BOAT SYSTEM.

    At present, I have no boat grounding system when at sea. It is grounded when the boat is connected to shore power. Before, the diesel motor was my ground. I asked the manufacturer to clarify. Could I use the new motor, which is connected to seawater as my ground? They replied that there are so many theories about this subject that they cannot advise me. I have a friend who installed one of this manufacturer's motors years ago and he remembers the same discussion but he can't remember what they did in the end.

    One of our members who seems to have a sound knowledge of electricity warned me that if I use the motor, current will pass from motor shaft-bearing to shaft causing pitting of both. (See what I mean?)

    There are objections to hull grounding plates. I don't know what they are.

    The two mast lightning conductors are attached to the steel fin keel via two keel bolts. One doesn't use those locations.

    Any suggestions? 

  • 07 Apr 2020 20:35
    Reply # 8884325 on 8883693
    Deleted user
    Jim wrote:

    Meanwhile, its an opportunity to tidy up one's life and find other doable projects, including things necessary for the boat. New seats for the Porta-Bote, for example. I'm sharing a workshop with some friends, one user at a time, so I have a place to go.


    It seems Jim that everyone's lives are being turned upside down at present, which includes some disappointments such as cancelled holidays, (me!), and deferred projects such as yours. But something has got to be done to bring this pandemic under control and minimise the tragic loss of life. I really hope you get a chance to complete your project and try it out during your coming summer. But as you say a good chance to tidy up ones life. I am relishing my forced month at home. There is massive progress on my catamaran build, and I am finally getting around to various property maintenance items which I just never had time for previously. 

    Here in NZ we are only halfway through the one month lock down, but at this stage the country seems to have control of the virus with cases diminishing by the day. We are not sure what happens at the end of the month, the Government is still working on that. Hopefully there will be a gradual return to the new 'normal'.

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    Last modified: 07 Apr 2020 23:12 | Deleted user
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