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Jonathan

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Jonathan last won the day on October 10 2015

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  1. Jonathan

    Independence - Updates | Maintenance & Care

    Robin, The ZF manual says (Page 97) "10.2.1 Control Head The primary function of the Control Head is to send out a variable DC voltage to the Processor. This DC voltage is representative of the Control Head’s present lever position.", so it is not a digital system it is analogue from the control levers to the processor box. On page 105 it says "the command signal is between approximately 0.8 VDC at Full Astern to 4.10 VDC at Full Ahead.", so it looks like the total range is 3.3V or about 1.67V either side of the neutral position. If "full throttle" corresponds to 3000 rpm, then there is only about 0.06 Volts change per 100 rpm (less if max' rpm is higher), so the engine variations you have experienced may have been caused by very small voltage changes. Given the long cable runs, the various joints and connectors, proximity of radios, radar, fridges, D.C. motors for pumps etc. I'm surprised it works at all! Grendel has already suggested a noisy potentiometer (variable resistor) may be the problem (like the "scratchy" volume controls on old radios and televisions). If it is possible to clean it, as he suggested, and then the situation might improve, but it should be possible to see the voltage change at the processor as the throttle(s) is/are moved. If it is not smooth then you have found the problem (rapidly cycling the lever end-to-end, with the power off can help sometimes too!). I think that other "noise" in the circuit from other electrical/electronic devices could be a problem, particularly if there is any hint of corrosion or moisture at the joints. It would be very difficult for you to know if the erratic engine behaviour correlated with something else running (e.g. bilge pump), but it's worth a thought. The ZF MARINE web site says: "We have established a reputation for reliable, responsive control systems" So you may get some help from them if you tell them how unreliable it is, particularly if you know that this system has not been installed for very long (from http://www.allboatservices.co.uk and the boat's paperwork). Good luck with the investigations. I don't know where I would even start.
  2. Jonathan

    Independence - Updates | Maintenance & Care

    I agree! Add to that that many extinguishers are almost useless against a fire that has already got a hold and as Jayfire has already said, they can really only help you to get to the exit. I suspect that what Robin has in mind is a fixed engine room installation. He has the ability to close the external vents remotely and if he could then "flood" the close engine room to suppress a fire it might be effective if the extinguisher is big enough (he said "commercial sized version "). On a slight tangent. My experience with "dry powder" extinguishers is that they are effective at stopping a petrol fire, but the powder is quite corrosive, and damages electrical installations.
  3. Jonathan

    Independence - Updates | Maintenance & Care

    I have refreshed the "MarineTraffic" site a few times in the last few minutes. They are only showing 7 or 8 kts with wildly different headings each time, so I'm guessing it's rough out there! I'm also guessing that the 4.5 hrs is going to be more accurate for the remaining time.
  4. Jonathan

    Independence - Updates | Maintenance & Care

    Robin, Just a thought, which I think you mentioned yourself some time ago, with the heavy crane/hoist for the rib on one side it is possible that it will cause a list. It may be that the previous owner kept more fuel in one side to compensate for that, so allowing fuel to equalise through the centre tank might allow it to "lean" a bit! This would explain the "must be kept closed" instructions. If the cross-flow valves are open now then I suspect that this would be obvious next time you visit. Thank you for the frequent and informative updates. I think we (NBN forum readers) are all looking forward to next weekend as much as you are!
  5. Jonathan

    Independence - Updates | Maintenance & Care

    Robin, I think I agree with Siddy on this but I cannot see a connector in the video. My understanding is that you have feeder pipes from port and starboard to the centre tank and that there is an isolator valve at each end of each pipe. I also get the impression that the centre tank is lower than the other two. I would expect there to be a fuel feed from that centre tank, otherwise there will always be a quantity of fuel in it that could never be used. In the video section where you are showing the depth of that tank there is a vertical pipe with a tap that is open. I’m guessing that that pipe is feeding fuel from this tank to something. I am confused as to why you have been told to isolate this tank. There is no way that fuel could siphon from a lower-level to a higher level, so a list cannot develop “by itself”. When the boat is rolling due to wave action then cross-flow would occur, but this will be limited by the pipe size and would not be significant enough to be noticeable before the boat rolls the other way. I suggest an experiment. If you have fuel level “sight tubes”, or some way of actually seeing the physical level of the fuel without relying on a remote display gauge. 1. Close the centre tank valves (as they are now). 2. Check the actual fuel level(s). One side would do, but both port and starboard would be better. Possibly mark the level with a felt-tip pen or a strip of sticky tape. 3. Induce a list! Either get lots of people to sit on one side or use the crane to displace the rib out to one side. 4. Check the actual fuel level(s) again. This might be slightly different as a result of the list. 5. Wait! 6. No levels should change, showing that the valves are closed (or the pipe blocked). 7. Open the four centre tank feed valves. 8. Wait! 9. Check to see if the fuel on the “low” side is going up and the “high” side down. 10. If it does then the valves work. But there may be a restriction (blockage) somewhere. If it does not then either the valves do not open or the blockage is total. 11. Remove the list! 12. The levels (if changed) should return to the marked positions. If there is a restriction, but not a total blockage in the pipe(s) then it is likely that the rate of fuel flow during “polishing” was much greater than the cross-flow could equalise. Unfortunately, the same would be true during refuelling. If there is some flow, then you can repeat the experiment, closing just one main valve at a time and that would tell you that those valves are working. The "worst case" occurs if no fuel flows, because then you know nothing more about the valves.
  6. Jonathan

    Who’s Dropped What In The Broads ?

    I dropped my phone into the Herbert Woods basin as I said at the time: I was VERY annoyed. I had owned that phone for many years and it was not an "expensive" one, but I had intended to contact another friend to meet-up during the week and although the other on board offered the use of their 'phones there was often no signal or no reply!
  7. Jonathan

    Big Changes Ahead

    Surely the tender has to be renamed "May 4th", being the Independence day-boat!
  8. Jonathan

    Let Off Steam In Here !!!!

    Local radio, traffic reporters saying: "...There's delays at ..." when what they mean is: ".. there are delays at ..." or "... there is a delay at...". Common mispronunciation of "Nuclear" (by BBC presenters and US presidents!) as "Noo-cue-lar" rather than "New-clear" (or perhaps "New-klee-are").
  9. Jonathan

    Big Changes Ahead

    Robin, Clearly, you have researched the subject in some depth. All I am saying is that the greater the temperature difference between the "inside" and "outside", the less work the unit has to do. Some will do so by varying pump speed, others by switching on and off. But when it is hot outside they will need to either run faster or be "on" more than "off". With a cold (water) source the pump can run slower or be "off" for more time between "on" cycles. The Peltier systems were perhaps a misdirection on my part. I was making the point that they say that they can reduce (on increase) the temperature inside the box by "X" degrees, so going flat-out they can only achive a specified temperature difference, not to an absolute value. The same is true with car "aircon", where the people who recharge the refrigerant only advertise that they can improve the cooling by a certain number of degrees below ambient outside temperature. With any refrigeration (or heat-pump) system you are putting energy "in" (usually via a pump), to move heat from one radiator to another. The job is easier, so the pump has to work less hard or less often, if the temperature difference between the radiators is greater (taking heat from the hot one and dumping it in the cold one). Anyway, don't let me drag you down into these details. It's your boat (or will be?) so just enjoy it and do what you prefer, as I said last time, I'm sure either option will work satisfactorily. Good luck with the purchase (and research of the other thousand and one other things that I know you are looking at for it).
  10. Jonathan

    Big Changes Ahead

    Robin, I'm not a heating/cooling engineer so someone else may be able to explain this much more eloquently than I can, but there are two disadvantages to using the "office" system you suggest (both points below assume you are cooling the cabin, but the same is true when heating with a heat-pump). Firstly: The specific heat capacity of air is much less than water. This means that you have to shift a much greater volume of air through your "hot" radiator to cool it than you would with water. That in turn means that the radiator and fan need to be bigger, noisier and power-hungry. Secondly: The air temperature outside the cabin (in Summer) is likely to be quite warm, whereas the water will be a lot cooler. The air-conditioning unit has to work much harder when there is not much temperature difference between the "inside" and "outside" radiators. It is far more efficient (and therefore less power-hungry) to transfer "cold" from a cold radiator to a hot cabin and many "air-conditioning" systems only guarantee to reduce the temperature by a specified number of degrees for this reason (think of those 12V electric cool boxes). As you said, this is why the ground-based heat pumps are preferred to the "air source" ones. I don't want to sound too negative. I'm sure your ideas will work; I'm just adding a few more things for you to worry about (as if you don't already have enough with this project). Keep us up-to-date!
  11. I will echo Springsong's recommendation. David is a very friendly and helpful person, but I would guess that you already know that!
  12. Jonathan

    Big Changes Ahead

    Robin, Firstly let me say that I have no idea what I’m talking about when it comes to boats and you have obviously put a lot of time and effort into your research, but the report details would worry me! Some (uninformed) thoughts follow: If the sea cocks have not been tested or exercised because of poor access, then replacing them might be an “interesting” job. If the anodes have needed replacing then that might have caused the rudder bearing (and possibly other) problems. The owners seem to have spent a lot of money on gadgets. You have mentioned navigation equipment, interior accommodation items and the rib, but it sounds like they have neglected the routine maintenance. To my mind, they have had their priorities wrong, and that rings alarm bells for me too. The stern photograph shows the name “Lily Jean”. Unfortunately, none of the photographs seem to show anything that the report talks about so there are no clues about remedial work having been carried out, although if the photographs were taken recently (as you say) then it would have been foolish to lift the boat out and NOT attend to several of those points. I think you need to go and look in person, and if possible take a marine surveyor with you, or at the very least a volunteer who “knows a thing or two about boats”, at least then you will know what the current state is, and how many of these jobs have been done. I don’t want to sound too negative! I’m enjoying this exciting “journey” with you, and I hope you achieve another of your ambitions! …. Thoughts for a name: “Another Ambition”.
  13. Jonathan

    Forum Display On Pc

    DM, It might be worth trying another browser. It works in Chrome, Edge and an old version if Internet Explorer (on Windows 10) I do not use Firefox though. Also, you might try a wider window (if you are not already full-screen) because some browsers assume that you need a different layout if the window is narrow.
  14. Jonathan

    Broad Ambition - The Model

    Thank you for the picture. That makes the problems you describe much clearer! I can now see the difficulty you would have extending the prop' shaft, it would mean either using a smaller propeller or moving the bearing up a bit, and changing the angle of the drive shaft and motor, which would be a major modification at this stage! I hope your faster motor solves the problems for you.
  15. Jonathan

    Broad Ambition - The Model

    Grendel, I realise that you want more speed too, but with regard to turning circle: I don't recall a picture of your model prop' and rudder, but would it not be possible to extend the rudder a small amount ahead of the pivot? That way you gain rudder area and get nearer to the propeller too. I know nothing about model boats so apologise if it's a stupid suggestion! I recall that the handling of the full sized version was improved by adding a bigger rudder, but presumably that addition was all behind the pivot.
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