Silva Instruments

[Guest]

Hi, I am trying to find if people have had problems with silva instruments, in particular with echo sounders. I have put a suite of silva instruments on my fulmar and have the interesting problem, that it is great at telling you wether you are in 30 or 31 metres of water, but when it gets down to 4 or 5 metres the display suddenly goes, 4 , 3.9 , 0.2 , 0.1, 0.0 ..... very scary when going over the bar into padstow or similar, eighteen months on, still talking to silva trying to get it sorted,,, anyone else with similar probs please????

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[johnsomerhausen]

It is probably a problem with the output power of the echo sounder. if it is set at maximum power, it will read fine in greater depths, but in shallower water the returns will be false. There must be a possibility to adjust the power output mentioned in the manual; if not contact Silva for details
john

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[Guest]

Hi John, thanks for the reply, the system does not have a programmable gain, I have been sent new pcbs with different firmware to change the gain, but alas without improvement, I have now been asked to supply diagram of keel shape,, seems fulmars are fairly standard in this aspect, also been told that "in sweden keel offset is only used to go back to true depth of water, not depth under keel" seems to me a very strange way of doing it" any other thoughts welcome....

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[johnsomerhausen]

Well, that statement by Silva makes sense to me, as it is how I do it. Much easier to read the true depth of water because when you're trying to fix your position (e.g. by a bearing and depth) it's much easier to try and find the matching number on the chart than to have to continually make the addition (depth under keel plus draught). When I'm in shallow water, I know I shouldn't venture past the 6ft/1 fth/2m line (depending on the chart, US ft, UK fathom or Canadian metric).
john

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