T&T: Forward looking sonar

[George & Emilie Rankin]

 I have the Interphase twinscope and it is somewhat useful.   One problem with
it is that by default the maximum gain you can set for each range is set to
zero or very low, so it takes a lot of tinkering initially to get a useable
image.   You have to set the max gain for each range, which is somewhat odd
and time consuming.   The manual is not wonderful and the interface is less
than intuitive.



I mainly use it in horizontal mode where it does a reasonable job of showing
me shallows or where the channel is.   My most major complaint is that it is
slow.  In a very narrow passageway even at dead idle I'm likely to be on an
unexpected obstruction before it shows up on the screen.   A bow watch is
better for those circumstances.



I doubt it does much for detecting submerged logs at cruising speed.   Not
only is it too slow, but there is too much "noise".  (Note that my cruising
speed is  8 knots.)   I also have some cells that seem to be always "on" which
could be due to growth or installation issues.



It did once probably save me from putting the boat aground in a shoaling area,
so by that token it was worth the price.    It does a pretty good job of
alerting you that the bottom is coming up ahead, if it starts showing red
where you don't expect it then it is time to take some action.



George R