Re: some questions

amelliahona <no_reply@...>

--- In, "edmund_steele" <edmundsteele@...> wrote:

Mark wrote, " 2. Another way to spot coral heads is to install sonar. The transducers
seem very large for most forward looking sonars such as EchoPilot and Interphase? What
do these transducer do to sailing performance on the Amel Super Maramu? Are the sonars
practically useful for finding one's way in coral fringed islands?"

15 Feb 2006

Mark: I had Amel install an Interphase Twin Scope on my SM 2000 Hull # 335 at the time
of purchase (July 2001). Amel would only install the display and a single transducer.
They refused to install both transducers. As they explained to me, their experience was
limited to the single transducer (vertical scanning) and felt that two transducers or the
dual combined transducer, which is physically larger, would create turbulance and
interefere with the B & G sonic speed system. At my first haul out I installed the second
transducer (horizontal scanning) for the TwinScope about 18 inches in front of the Amel
installed transducer. This places it slightly higher than the vertical scanning transducer
and therefore does not shadow the signal from it. The system works well at speeds under
3 to 4 knots, even better at 1-2 knots, does not interefere with the sonic speed in any way
that I can determine and has saved out bacon several times so far. It is NOT the
ultimate answer to avoiding coral heads etc as it can be fooled by thermoclines etc., yet I
have found it a useful tool when combined with a careful watch, good lighting, and careful
navigation. I can't detect any discernable decrement in sailing performance but it only
makes sense that it increases drag and disrupts laminar water flow. I do find the
horizontal scanning mode more difficult to interpret but as with any graphical tool,
practice makes perfect. Display readability in bright sunlight is its main weak feature.
Would I do it again? Yes!

Regards, Gary S. Silver Amel SM 2000 Hull # 335

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