Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!think!ames!pasteur!ucbvax!decwrl!labrea!glacier!jbn
From: jbn@glacier.STANFORD.EDU (John B. Nagle)
Newsgroups: sci.electronics
Subject: Re: Depth Finder Problem
Message-ID: <17943@glacier.STANFORD.EDU>
Date: 27 Dec 88 17:35:56 GMT
References: <8812271430.AA18210@decwrl.dec.com>
Reply-To: jbn@glacier.UUCP (John B. Nagle)
Organization: Stanford University
Lines: 12

In article <8812271430.AA18210@decwrl.dec.com> starin@abe.dec.com (Mark Starin KB1KJ DTN: 264-5596 MK01-1/A10) writes:
>The depthfinder on his sailboat works fine when he's under sail. 
>However, as soon as he lights off the "iron main", the depthfinder 
>indicator starts giving messed up indications.

      Well, of course!  Depth finders are acoustic devices; they bounce 
a pulse of sound off the bottom and time the echo coming back.  Any source
of noise in the water, such as a noisy engine, will cause interference.
Try moving the depthfinder's transducer to a location as far from the engine 
and prop as possible.

					John Nagle