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Best Current sense option on a boat?

Discussion in 'General Electronics Chat' started by Little Ghostman, Apr 19, 2017.

  1. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Ok I get the idea now, what about a normal coil meter? Dosnt need batteries then :D.
    A slightly stupid question, when the switch is set to both, how much does it matter if the batteries are of different capacities but same Voltage? Just thinking I could get both in same place if I use a heavy duty car battery and the deep cycle one. Otherwise one would need to be underneath. I like to keep them well off the floor (2 foot).

    Battery to switch cable will be short anyway, I am using welding type cable at the moment. But I might replace that as well.
     
  2. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    I am going to use Cowboybob's switch to select either or both and I will low side current sense with a 50 or 100 amp DC shunt driving an everyday fool proof analog meter with a zero center so you have -50 - 0 - 50 Amps or 100 Amps. An analog meter will take a beating be more than accurate enough. I havent a clue what your charge rate is with the engine running or what the current draw is on a start? Anyway, I like crude and simple, especially on a boat.

    Give this a read.

    Ron
     
    • Like Like x 1
  3. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Cheers Ron, I could not think for the life of me the name!! Analogue meter!!!! That is what I was thinking of when I said coil meter! I could see the stupid thing but I dunno maybe all that EMF has fried some cells!! :D:D.

    I havnt a clue at the moment what the charge rate is or the draw on start up. Part of the reason for the rewire, the engine electrics were by passed by the last owner. You start the engine by the engine! But I cant get to anything safely to measure it from there. There is a large toothed flywheel on top, and where I would connect for taking a reading is a bit close for comfort. As for charging......... I havnt measured it to be honest. Apart from assumed start up current, I doubt the current draw is anywhere close to 50A. So that would be plenty, having said that I dont know what the hydraulic trim uses, again that is done remotely with a switch near the Engine at the moment.

    At least I got rough idea now what I am going to do with it. Thanks for the link I will read in the morning, well later this morning :D
     
  4. dave

    Dave New Member

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  5. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    The alternator's output is fed back to the battery through the starter relay to battery cable.

    You can measure the alternator's output (at the engine) by checking the voltage level, with the engine running, at the battery connection on the starter relay (using the engine block as your ground).

    For that matter, you could also get that value across the battery"s positive and negative terminals (again, engine running).

    You should see ≈12.5-14vdc, depending on electrical load and RPM.

    The above description is true for most (if not all) outboard engines with starters. And keep in mind that the valued observed does not necessarily indicate that the battery is taking the charge - it only indicates that the alternator is generating charge level voltages.
     
    Last edited: Apr 20, 2017
  6. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Cheers for that, I havnt messed with the engine. I need to track down a manual for it if one exists! It seems to run great, but I might try and get it serviced later in the year. We have a really good boat place not that far from me at Ardwell. The guy there seems to know his stuff and its only 40 mins away. They dont sell much (well not much I can afford :D), but he brought my small backup engine. So he has seen the boat and said he would service the engine and give it a good look for a pretty good price.

    I might try and get hold of the camera!! Then maybe you can point out which bit is the starter relay!! Seems to be more than one relay in the thing. Seems a pretty punchy engine but I dont normally push it.
     
  7. schmitt trigger

    schmitt trigger Active Member

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    I like that approach, or a similar module.
    Regardless if you purchase a module or roll your own, for marine use I would strongly advise all the electronic circuits to be completely potted.

    Anyways, good luck on your project! It seems like a good challenge and a lot of fun afterwards.
     
  8. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    I use those marine sealed boxs for connections and electronics. A balance between sealing and still be able to get to it.
     
  9. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    These guys seem to have one. I say "seem" because to get it, even though it's "free", they want a credit card #, etc.. Your call.
    Follow the positive battery cable into the engine. Ordinarily, it will (eventually) terminate at the starter relay, which should look like this:
    upload_2017-4-20_16-48-32.png with the the relay's tab (and one lead) attached to the engine block.

    A similar device is probably used for the trim motor.
     
    Last edited: Apr 20, 2017
    • Thanks Thanks x 1
  10. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Thanks for that, I will grab a pic. There is what I think are 4 relays!! Really hard to tell and difficult to reach with the boat on the trailer. The other bad news is the seal around the engine case, looks like I squashed it last time I had the engine cover off and the engine protector leaked over winter, so some rusty bits inside! Looks mainly to be things like the relay tabs. I am not too bothered, I can get a seal and I will change relays when I get it serviced.

    I dont have a credit card, and not sure I trust anything free that needs one! Dont know over there, but here if you give the number out, its seen as authorising the use. Normally there is a hidden membership somewhere when they ask for one. I will do some digging around :D.
     
  11. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Actually I think that cant be the engine, it says 1999-204, I am pretty sure the engine is older than that :D.
     
  12. dr pepper

    dr pepper Well-Known Member

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    Hey ghostie, I used to have a norman, a 26' centre cockpit job, I loved it.

    Making your own canopy canvas is not a job for the feint hearted, start with one without windows as you need a special gizmo and skills to do that.
    As for heating, electric probably isnt a good idea unless you have shore power, the outboard probably wont generate enough power for that, they tend to be only around 100 watts.

    As for load sensing, either make a shunt from some copper bar or something like that, or get one o those really cheap power usage indicators off china ebay, some have an rs232 port, all you need is then supplied as a string, current, voltage, power, amp hours in, amp hours out etc.
     
  13. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    How about this one (1980). Once you get under the hood you can compare the pieces parts to the schematics/graphics.

    Pretty simple, which the engine's electrics, of that vintage, were. And I saw elsewhere (roaming) that, as you'd expect, a model would cover a span of years.

    Nor sure why the need for 4 relays. When you get some pix, I'd love to see them.
     
  14. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Yeah I intend to wrangle the camera from my mums hands this weekend!!! Its that time of year for her to work, so she uses the camera alot. Well most photographers do :D.
     
  15. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Hi, I ditched the canopy!! It was a PITA at sea:D. the windows I am replacing are the front ones at the very front of the boat. Mine is classed as the Norman 20, but its actually 22' long :confused:, draft is booked at 1.5' but again mine is around 2'.

    The cockpit top wind-shield was a real wind catcher, made it horrific at sea. Got rid of that and now its just abit bobby, but I dont mind that, With the 65 engine it rides up really nice if you want it too. Normally though I trim it down a fair bit if I am giving it any kind of welly! The heater I will do a write up on, what I have in mind isnt the norm :D.

    Looking at the Transom area I need to get some marine ply and fibre glass out, if I am doing that then I might as well alter the wheelhouse door etc. I also want to refit it inside, nothing special but a few things really bug me. Alot of people mock it for a sea boat, but I have sen an old cine film of one with a 120hp outboard on being raced at sea!!! Man it shifted. The film was from 1974! Compared to some the modern boats it has a pretty thick hull on it, Overall I like it alot. The guys with Shetlands are surprised when I pass them going up the Loch, but then again I really like the engine trimmer on it. Its quick but not too quick, the semi D at the back end dosnt start until past the wheel house bit, so you dont get motion sick on it (or I dont), I do get sea sick on Shetalnds.

    But one day...................... http://www.ebay.co.uk/itm/Cutlass-2...486155?hash=item25d4a6b94b:g:ZfQAAOSwDKtY1V8s

    Or

    http://www.ebay.co.uk/itm/Hurley-Si...962325?hash=item3f7a4f6195:g:mSsAAOSwN6JY9RUA

    I have my gas chromatograph for sale, if I can sell it quick enough I would buy the Hurley in a flash!!! I also really like the Cutless. I really fancy a couple of years practice then off on it for a year. Kill or Cure :D.
     
  16. dr pepper

    dr pepper Well-Known Member

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    Yes the 22' was earlier than the 20', and the inside layout is different, maybe thats why you dont get on with it.

    The 20' and most of the norman range (which were previously callumcraft and postly atlanta) were meant for inland cruising, and a lot were not built for high power high thrust motors, but some were, those have a couple of I beams running along the keel to stiffen the hull quite a bit, yours will (or it better with a 65hp o/b) have something like this, otherwise the outboard will end up in the cabin.

    The draught depending on who quotes it can be without the prop, the bottom of the keel maybe 18" but the bottom of the prop could well be 24", the n20 is a displacement hull so its meant to have a deeper draught to increase load carrying and be easy to pilot, a planing hull would have much less draught and will only be just in the water at the front, if you want to go like a dont know what the n20 isnt the right bucket, it will go reasonably quick but if you push it with 120hp without any hull mods you'd just push the back end under the water.

    Shouldnt take long to save some readies for one of those sailors, they arent really my thing, I like to turn a key and go, sod the wind.
     
  17. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Yeah but yachts are going cheap at the moment, motor boats are not. Besides no reason to not use the inboard engine on them :D. Apparently most are getting sold because of mooring fees, thankfully that is one problem I dont have. the Norman is great on the Loch, and not as restricted speed wise like a river. Near coast and the local bays I have fished, she is a great boat.

    Not sure I would want to do much more than coast hug in it though. I would love to sail around the UK for my 18th Birthday on my own. I saw the boat the other day, I dont want to sell the GC, but If I do sell it before the yacht is sold then I would get it. if I dont then I will remove the GC from sale. The other one is great, but no chance of getting that for a while.
    I wouldnt sell the Norman though, but it does need doing up a fair bit!! Done some great fishing on it :D.
     
  18. dr pepper

    dr pepper Well-Known Member

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    Your lucky to own such a thing at your age ghostie, make the most of it, when your old & grey you can reflect on good times.
    Normans are a good bucket and they sell well too, she'll do you fine if you maintain her.

    I havent sailed around the uk, but i have around scotland via the caledonian, there are some treacherous passages on the north west side, also there are some magnetic anomalies and gps isnt 100%, and scapa flow is an experience if you go that far north, I wouldnt advise you sail on your own at sea without at least a couple of years of experience and crew, better though with a 65hp motor on a smaller boat, I didnt have the power, a pair of perkins 4108 diesels & J boxes, but it was a 40' bucket loaded up.
    I did my skippers offshore and it came in handy.
    Dont forget gizmo's like dsc radio(which upu need a licence for), epirb, hand held vhf & gps, I kept mine in the oven.
     
    Last edited: Apr 21, 2017 at 4:29 PM
  19. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    The Norman my dad got the first week we moved here, we were going to restore her together. Then he died and the boat didnt get much done to it, I decided this winter I would finally do it, took a while to feel comfortable to do stuff to it. I didnt want to touch it because it was as he got it, I am getting used to him not being here now. but taken a long time and I miss him alot.
     
  20. dr pepper

    dr pepper Well-Known Member

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    Yes its tough that, I had a similar thing with my mam.
    At the end of the day though matey its just a boat, do with the old girl what you want.
    I've had lots of fun on boats, in fact pretty much the first time for everything happened on a boat.
    Being out in the open, learning skills, such as restoration and navigation will do you a lot more good than an x box, oops sounded like yer old man used to there a bit.
     
  21. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    Truth be known I believe my oldest daughter was conceived on my 1963 Cris Craft Cavalier Express. :) Those were my much younger days but we sure did enjoy they boat. I am sure my wife would be OK with it if I wanted to buy another boat, all I have to do is sell my Harley and that is not going to happen. :)

    Lil' Ghostman your dad was really a good guy and taken too soon but sometimes we only get to play the hand we are dealt. You have done just fine and I miss my dad too and I had much more time with my dad than you have.

    Ron
     

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