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Floating Male

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  • Occupation
    Retired Technical Dir
  • Boat Name
    Sans Souci

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  1. Floating Male

    RPM measurements

    I tempted to mention this seems like almost a U turn, although a J turn would fit better. ☺
  2. Floating Male

    RPM measurements

    If all else fails you could try this;- I was advised when I joined my last employment that they used to calibrate instruments by injecting known values and marking the values on a blank scale. They employed a man whose sole role was doing this! He was an artist rather than an engineer I guess. 😂 So all you need is a sticky label and a biro.
  3. Floating Male

    RPM measurements

    No need to be amazed! As I mentioned earlier these devices have no adjustment as such. The 0.05% will be the temperature coefficient of the crystal clock (over the stated operation ambient temperature) and the 1 digit is the resolution of the display. (Actually its nice to see accuracy quoted correctly!) They are similar in accuracy to your digital watch. I dont see people geting them calibrated regularly. A digital tacho is one of the few measuring devices that normally has no analogue components that affect the reading. They pretty much work or dont! (Slight simplification?) Instruments that can get out of calibration generally have an analogue aspect to the measuring system. eg multimeters, temperature guages, anything with a moving pointer. As a retired head of a calibration laboratory I did sit down and contemplate all the possible sources of error in the standard alternator driven rev counter. I got to eight and decided that a drink was needed and the project was abandoned!!! Consider +/- a few % a good deal! Back to OP post. I would suggest you set the rev counter to match your digital tacho. Best to do this at as high a speed as possible and ideally try to get an engine speed that matches one of the scale points on your rev counter. This will help get the best fit. Then check now and again and see if it varies much. If it does investigate. If it doesnt pour a glass of wine and relax. John
  4. Floating Male

    RPM measurements

    Precisely! Actually all measurements are 'wrong' to an extent. In the calibration world we talk about uncertainties. As a number have pointed out reading the pointer of the engine rev counter can lead to significant possible errors. The snag is these errors may (will) not be consistent. The same probably applies to belt slip, being dependant on alternator load! Unfortunately you don't know the extent of these uncertainties in your case. Reading the pointer, rev counter calibration and possible belt slip are possible issues. However it is still likely that the tacho is the most dependable indication. Really what you want is to have a rev counter that actually measures revs and not a system that relies on pulleys and adjustments. :-)
  5. Floating Male

    RPM measurements

    Whilst I have no first hand knowledge of the tacho you have bought these are usually spot on. They use a timing system that is derived from a crystal clock, so there is normally no 'adjustment' as such. One review on the amazon site seems to corroborate this as he tested with a digital scope. The engine tacho however will be analogue and need to be calibrated. This is essential because as noted the pully ratio needs to be acounted for. If this has not been done correctly then there will be your problem.
  6. Floating Male

    Battery wiring at fault? 12v socket reading jumping.

    Not necessarily. It depends where you are measuring and also the extent of the poor connection. With high currents a poor connection could simply be a terminal not tight.
  7. Floating Male

    Battery wiring at fault? 12v socket reading jumping.

    It seems as if there may be more than one issue here. The two most likely causes of a fluctuating reading are either volt drop due to loads varying (as per chewbacka) or a poor connection. The 6 hour charge time may be sensible depending upon the state of your batteries. Without being able to monitor the charge current you are not able to tell how far you have got with charging. If you dont get a eeasonable charge daily then the whole situation will rapidly deteriorate. You need that monitor!!! Also it may be that we need more info. Is the "charger box" some sort of split charge from a single alternator, or something else?
  8. Floating Male

    Rule shower waste box

    Afraid not. And since it worked so well I have fitted shelves in the cupboard that make it tricky to get to! However it is just an open top box of the right height. I will look to see if I can find the float switch I used. But it was 24 years ago.☺
  9. Floating Male

    Rule shower waste box

    Whilst agreeing with the above views, you might like to consider what I have;- I made a fibreglass box which is the hight of the gap below the shower plus the depth of the tray. This sits along side the tray in an adjacent cupboard. It has a float switch (An industrial one) that runs a whale gulper. Features; - It runs automatically but unlike the above. It's solid and isn't going to leak. It has no filter to clog up. If the float switch fails, ( happened twice in 24 years) it's obvious because of the water in the shower tray, but no water goes into bilges. I have never seen anything like this for sale however. HTH John
  10. Floating Male

    App "Wish" nuisance

    In response to anti - android I like to recount the recent brag of an iPhone user;- "How much do you think I paid? he smiled." "Too much I said" -"Go on he chided" "A four figure number I said" - "No a three figure he responded in triumph" "what?" "1200" - "But that's four figures" - "No - There only three, I don't count the zeros" Apple user brain size????
  11. Floating Male

    Mifi device with twin antennas

    Just to clarify. A splitter will most definitely not help. As the name implies they send half the signal to each output. (At best) Dual aerials should help, but as per the info in the link it depends upon the configuration of the aerials. On a boat there may even be some virtue in having separate aerials mounted well apart because if you are cruising each mooring location will potentially have dead spots. You may be only picking up on one (hence slower) but better than nowt. :-)
  12. Floating Male

    Drive Plates, how long do they last?

    Hmmm Well another variant... My drive plate (which is a Centa CF) has no pegs like the one Pete has shown above. The Centa plate is just two concentric rings with rubbers in between. If the rubbers disapeared then there would be no noise (or drive!) My engine had one similar to the above but when the gearbox played up about 10 years ago TW Marine recomended changing drive plate for the Centa. As I always do as I am told (And had an income then) it got changed!!! Hope this doesn't start a drive plate comparison war. John
  13. Floating Male

    Drive Plates, how long do they last?

    Phew! Of course I had had two coffees, which trumps one tea any time. :-) Could add that in my case the rubber had disintegrated and jammed the whole thing, so simply no movement. John
  14. Floating Male

    Drive Plates, how long do they last?

    Well I am not an expert, but have had first hand experience! First I don't understand the F/R thump comments. The engine drive plate is between engine and gearbox, so the thrust is in the same direction for forward and reverse. If you (or they) are talking about coupling between gear box and prop shaft then Ok. Second, as I understand it, the engine drive plate is there to smooth out the engine rotation before the gearbox. My gearbox recently started to slip. On taking all apart it transpired that drive plate rubbers had collapsed possibly leading to premature failure of gearbox. There was no obvious evidence of this. I might add that I am somewhat paranoid about odd noises being something of a sound engineer. :-) Having stripped down gearbox and plate myself I would be in the 'wait till it goes wrong' class. Cost more, but avoided grafting for as long as possible!!! Hope this helps John
  15. Floating Male

    Propeller gap

    It was about 4 feet deep at bank, so decided against paddling. (I can't swim!) Was hoping when bizzard posted he had invented a brass magnet. Life is full of disappointments.

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