Triducer/transducer?

[Graham W]

Slightly different questions to the ones posed in the depth/fishfinder thread.

My Garmin and its associated transom-mounted transducer (in front of the centreboard slot) is getting old.  Being Garmin, the chart updates are criminally expensive compared to tablet-based versions like Navionics, which ironically is owned by Garmin.  So I’m looking at alternatives, building on what I already have (a tablet and various Tacktick wireless instruments).  I don’t want to get another GPS/fishfinder as it would be helping to perpetuate the oligopoly, and at my own expense.  And I really don’t need the very expensive sophistication that modern fishfinders seem intent on providing.

Has anyone tried to install a triducer on their boat?  I’ve done a forum search for ‘triducer’ but results came there none.  The triducers available are mostly quite small and not too expensive 2” diameter vertical cylinders that measure water speed (paddle wheel), depth and sea temperature.  They are intended to be poked through a hole drilled in the bottom of the hull.  I don’t want to do that and instead have the idea of fairing in the gap ahead of the centreboard slot with robust plastic of some kind, where the existing transducer currently sits, and poking it through a hole drilled in that.  Photo of a typical triducer below.

Any past experience or observations?  I fear that the water speed paddle wheel will get jammed quite quickly but the depth sounder should continue to work properly.  I could just cut out paddle wheel misery and go for a simple through-hull depth transducer, installed through the new plastic fairing in the same place.  It would be cheaper and probably more sensible and it looks very similar to the triducer.  Incidentally, as far as I know it’s not possible to install a transom-mounted style triducer ahead of the centreboard slot as they’re too big to fit.

[Sea Simon]

GW, you are right in that paddle wheel speed transducers will require very regular removal for cleaning.
Debris and marine growth are both issues.
Easy enough to do, especially  in a smaller open boat. Make sure you have the blanking bung handy tho, as a surprising amount of water comes in! However, mounting this thru hull perhaps not so easy in a BR?

My new to me Raymarine uses Transmar brand transducers (model about 5 years old?) as do many others. These have a hull hole with a small non return flap valve to limit the inrush. However, due to past experiences  (fouling/debris unsurprisingly also affects the valve!) I  don't  trust this (or indeed, my crew to assist me..some get quite spooked), and have just ordered a blanking  plug. £40! You then do a speedy swap over, and can clean the paddle wheel at your leisure, undistracted by an open 30mm hole in the bottom of your boat!
This unit has a dual function speed thru water paddle wheel, and water temperature (of no interest to me, a fish finder function?).
It has a separate depth head, in another thru hull mounting tube.
I'm  investigating  using this hole for a NASA electromagnetic  log...

NASA Clipper do an electromagnetic speed log, with no moving parts (£350ish?) However, note that they still say that this needs cleaning.
Others do ultrasonics etc, to eliminate the pesky paddle wheel which WILL CLOG UP.

Speed thru water is, imo, important especially  for racing...I seem to recall that many classes didn't allow GPS years ago (on a race boat, we "invested" in an early TackTick network, which i think was appx £2200, about 20 years ago! That was paddle wheel only. I seem to recall top flight boats had very fancy ultrasonics?) so STW was vital. STW also reacts faster than GPS speed (SOG) so is better for trimming to max boat speed I  think?

Of course, both my navtab and phone have GPS "speedo" displays,  so I can retire my trusty Garmin GPS72...if only I was smart enough to figure out how to transfer all my historical waypoints/routes...

[Graham W]

I doubt that my boat will be in the water for more than a week at a time next season.  So the obvious solution to jammed waterwheel misery is to get under the trailer with an old toothbrush when I get home.