about sonar ?

IT-SEA-BIT-C · Guest

Does anyone have any expierience with interphase sonars or any forward looking sonar. i was wondering why these type cost in the low thousands and most other types cost in the low hundreds.,let me re-phrase my question, can any of these see say a big log floating just under the surface say at night while cruising slow say 4 to 6 knots. mabey i'm way off track but it almost seems like they can according to some ads. am i crazy to think that . ? brats please help out if you can thank - you ......john

thataway · Posted: Tue Mar 25, 2008 11:33 pm Post subject:

The Interphase or Pilot phased array sonars will probably not see a log--there is too much surface interference.

Generally these units will "see" 6 x the depth foreward. I have used one on a friend's boat--and was not impressed in our Southern waters. The sloping sand bottoms just don't show up. If places where there are rocks and ledges they do show the area. More worthwhile in the PNW or Maine than in Florida. You do have to use them at low speeds, since you can only "see" a few boat lengths.

The Hummingbird, side scan--will work up to 100 feet depth and 150 feet wide area.--but is side looking only.

The expensive units--such as the $17, 500 Furuno CH300H/225
, is like a radar. It has a rotating send/recieve transducer which is in a casing which can be lowered thru the hull and revolves, Painting the water ahead and below with the ultrasonic beam.

IT-SEA-BIT-C · Guest

Many thanks once again Bob !