starin@abe.dec.com (Mark Starin KB1KJ DTN: 264-5596 MK01-1/A10) (12/27/88)
I am posting this for a friend at DEC. 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. The depthfinder is located 3-4 feet from the engine and is apparently well grounded. According to him, it is connected directly to the battery - not to the alternator system. Any assistance would be appreciated. Regards, Mark ***************STANDARD DISCLAIMER APPLIES******************** ______________________________________________________________ Mark Starin KB1KJ US NAVY RADIOMEN DO IT Digital Equipment Corp. WITH MORE FREQUENCY Merrimack, NH (603)-884-5596 DECWRL::"abe.dec.com!starin" ______________________________________________________________
jbn@glacier.STANFORD.EDU (John B. Nagle) (12/28/88)
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
king@kestrel.ARPA (Dick King) (12/30/88)
In article <8812271430.AA18210@decwrl.dec.com> starin@abe.dec.com (Mark Starin KB1KJ DTN: 264-5596 MK01-1/A10) writes: >I am posting this for a friend at DEC. > >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. > >The depthfinder is located 3-4 feet from the engine and is >apparently well grounded. According to him, it is connected directly >to the battery - not to the alternator system. > >Any assistance would be appreciated. The problem is probably the engine's noise rather than any electrical problem. A depth finder is, i believe, a sonar device. Is it possible to lower the transducer into the water on a string to test whether this is the case? If so, the transducer should probably be moved to somewhere far from the engine. -dk
larry@pdn.UUCP (Larry Swift) (01/03/89)
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. Mine is sensitive to engine noise from passing power boats. I have decided that it's mostly the cavitation causing it, since the depthfinder persists in resetting itself for several seconds after the power boat and its noise is gone. I might add that my transducer is several feet away from my engine (more like 20 or so). Larry Swift UUCP: {peora,uunet}!pdn!larry Paradyne Corp., LG-129 Phone: (813) 530-8605 P. O. Box 2826 Largo, FL, 34649-9981 She's old and she's creaky, but she holds!