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Depth Finder Doesn't Work- Back Again

Discussion in 'Boat Electronics' started by frank1492, Jul 18, 2006.

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  1. frank1492

    frank1492 Guest

    I apologize for this long delay in responding, but I have been without
    land-line phone service since Thursday night, hence no Internet. It
    was just restored this afternoon.
    Thanks for all the replies (which I have printed out and
    studied.) I would certainly feel capable of removing the transducer
    (which seems clearly to be the problem.) DMI Electronics (the
    reincarnation of Data Marine) has the transducers for $150, and I have
    actually seen them as low as $129.
    Because the boat will have to be pulled ($150) in order to remove
    the transducer (from the bottom), which would make total of $300, I am
    looking at other options. Most obvious is to buy a new complete unit,
    display and transducer. I'd like your opinion on a couple of points,
    however, before I go that route.
    (1) Some of these have "in-hull" transducers which are simply
    epoxyed to the inside the hull. If these are accurate, they sound
    appealing. Your thoughts?
    (2) As I occasionally fish (but am by no means "avid") I am
    wondering why I don't just buy a fishfinder. Some don't have
    fractional readouts, and I would avoid those, but for those that
    do read tenths of feet, is there any reason these would be less
    accurate than a dedicated depth sounder? To get a good
    depth sounder plus all the other features (including temp) is
    very tempting UNLESS you tell me the depth sounders on these
    are junk.
    Again thanks for your past ( and possibly future) help.
  2. GBM

    GBM Guest

    Frank - These work fine, so long as you can find a good spot to mount them -
    A "good spot", is one that is relatively flat, has no core material (i.e. is
    solid fibreglass) and is clear of external items that could give a false
    echo (keel, prop shaft etc). You can install any transducer this way, but
    the more powerful ones work better. They can be epoxied in or can be
    installed in a "water" box - usually a piece of ABS pipe epoxied to the hull
    containing a small amount of a suitable fluid (Castor Oil works well - water
    evaporates). One way to find a "good spot" is to put the transducer in a
    Zipock bag full of water and then move it around until you get a good
    reading. You could even buy the Datamarine transducer and install it this
    way until you get a chance to haul out, but a complete new unit may be a
    better bet.

    Thes links provide more detail:

    and to show you are not alone:

    Regarding a fish finder - By all means - some of them are quite reasonable
    and they provide a lot more information that a basic sounder. Perhaps going
    this way would not cost much more than the DMI transducer?
    I have used them, but never owned one, but if you buy from a reputable
    company you should be fine - check reviews on google.

    If you want to go really cheap , you can buy small dash mounted sounders for
    a reasonable price and I believe they work quite well:

    What would be interesting, is if the 200Mz transducer that comes with these
    units would work with your Datamarine head?

    Have Fun!

  3. Rather than epoxy -- hard to remove if necessary-- you can put a wad of
    petroleum jelly on the face of the transducer, and after pressing it to the
    hull, squirt something like silicon around the rim of the transducer to
    secure it.
    My boat was struck by lightning once, and one of the exit points was the
    thru mounted depth sounder. Wasn't much left to keep the water out. I
    remember wondering why this particular locker seemed to have more light in
    it than I had previously noted. Understood why at next haulout. I now rather
    favor inhull transducers.
  4. frank1492

    frank1492 Guest

    Thank you. A wealth of info. I did not realize the Datamarine would
    even work as an in-hull as the DMI guy did not mention it. Tell you
    the truth, if it did work, I would consider it as I do like the
    current display. Perhaps I will call him again.
    I have a panel-mount head and in-hull transducer combo home
    from West Marine, but I think I will return it as I really don't like
    the panel mount feature all that much ($129 though for the whole
    I would propose to place the new transducer near the site of the
    old one, which is just forward of the engine in this stern drive
    Grady White 22' Seafarer. I am told the Grady would probably be
    a good boat for an in-hull as there would likely be no bubbles,
    cavities or foam, at least at that point.
    The "continuous wave" article surely describes my transducer
    and mount to a "T." It certainly tells a cautionary tale and I now
    doubt I really would want to get into all those issues!!!
    I will look harder at fishfinders and you are right- for about
    the same price as the DMI transducer I can get a very nice fishfinder.
    (Humminbird or Garmin.) I just want to make sure I get fractional
    depth readout.
    Again many thanks for your continuning interest!
  5. frank1492

    frank1492 Guest

    Based on this and GBM's link I would certainly agree that the
    in-hulls make sense, though the thru-hull has served me well for many
  6. You are never going to believe this, but when searching for the most
    suitable place to locate an in-hull transducer, a British company found that
    of the 15 or more different materials they tried for maximum sensitivity on
    the transducer head, MARMALADE was far and away the best!

    Most boats have at least a jar of marmalade in their food lockers. Save you
    paying for exotic materials to do the same job!

    Spread it thickly!

  7. GBM

    GBM Guest

    I have heard of several instances where the depthsounder transducer was
    blown out of the bottom a boat on a lightening strike.

    One of these, was a trimaran which was fortunate because the centre hull was
    completely flooded. The mast was grounded and there were several seemingly
    better paths for a strike to reach the water - But, the lightening somehow
    caused the thin transducer wiring to fry and had sufficient power to blow
    the entire thru-hull out and char the bottom in approx a 2' radius.

    Just the other day, I saw a boat being sold for salvage that had had a
    similar strike while at dock - the boat had sunk at it's mooring - cause -
    depth transducer blow out.

    And a bit earlier, I read about a similar instance in the Great lakes - I
    forget the details.

    Not sure if an in-hull installation would be better, but I suspect so.

    Seems strange - Any theories?

  8. GBM

    GBM Guest

    Reminds me of a chorus the rugby teams used to sing:

    "Rule Britannia, Marmalade and Jam
    5 Chinese crackers up your a??-hole
    Bang, bang, bang, bang BANG."
  9. frank1492

    frank1492 Guest

    I suppose it should be that English marmalade with
    the Seville oranges for best results, no?
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