My new 410 is just about completed with its commissioning. I asked the rigger if the transducer read from its position forward of the keel, or at the surface. He told me that I would have to figure that out for myself. Implying that they, or someone experienced a past legal issue. So, using logic, I assume that it is not read at the water's surface. Am I right? John Richard s/v Jack's Place
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depth finders
I would like to think that the rigger just did not explain it correctly rather then say you would have to figure it out your self! What he was most likely trying to say is that you can set the gauge to read with an offset for the bottom of the keel,bottom of boat or the water line or whatever you want to use as a mark. Some like to use the keel as a mark that way the know how much water is under the boat with out having to do the math to subtract the draft for the current reading. Still others want the water line depth for matching against water depth of the chart. It is realy your option as to what you want. I like to use the water under the keel method. Read the owner's manual and it will explain how to adjust the offset. You will most likely have to recalibrated your knot meter also so read that manual also. Lots of reading to do on calm days! Good Luck with your new boat!
I would like to think that the rigger just did not explain it correctly rather then say you would have to figure it out your self! What he was most likely trying to say is that you can set the gauge to read with an offset for the bottom of the keel,bottom of boat or the water line or whatever you want to use as a mark. Some like to use the keel as a mark that way the know how much water is under the boat with out having to do the math to subtract the draft for the current reading. Still others want the water line depth for matching against water depth of the chart. It is realy your option as to what you want. I like to use the water under the keel method. Read the owner's manual and it will explain how to adjust the offset. You will most likely have to recalibrated your knot meter also so read that manual also. Lots of reading to do on calm days! Good Luck with your new boat!
My guess
John: My guess by default is that the transducer is reading from the transducer to the bottom. Unless someone set it there is no way that the mfg would know the offset. When you read the directions for the instrument it should explain how to set the offset. It will probably also show you what the offset is set to. My preference is just the opposite of Petes', I want to know what the water depth is so I can compare it to the charts. Now you have two differing opinions so what are you going to do?
John: My guess by default is that the transducer is reading from the transducer to the bottom. Unless someone set it there is no way that the mfg would know the offset. When you read the directions for the instrument it should explain how to set the offset. It will probably also show you what the offset is set to. My preference is just the opposite of Petes', I want to know what the water depth is so I can compare it to the charts. Now you have two differing opinions so what are you going to do?
in olden days
John- another thought came to me about the depth gauge. You can alway check it the old fashion way with a lead weight and line to check for accuracy and what if any offset. I agree with Steve that it most likely has a zero default offset and is reading from the bottom of the boat.
John- another thought came to me about the depth gauge. You can alway check it the old fashion way with a lead weight and line to check for accuracy and what if any offset. I agree with Steve that it most likely has a zero default offset and is reading from the bottom of the boat.
I checked this out when my H410 was on the hard. I'm setting the offset to below the keel this year. So the offset to the bottom of the keel is approx. -4 ft (fin keel) the offset to the water line is approximately +2 feet. And definitely find a nice calm day to calibrate the knot meter. Bryce H410 S/V Spellbinder
confirmation
As confirmation of Bruce's offset measurements, I got the same results, also on a deep keel, grounding my 410 in a shallow slip at low tide. I program my sounder to show clearance rather than depth, and have been able to confirm on (ahem)numerous occasions that Buoyant touches the mud precisely when 0 clearance is showing. This with an offset of -4 feet. The problem with using offset rather than depth is you have to remember to add 10 feet to the clearance when calculating anchor scope. (Remember, scope should be calculated from the roller, not from the waterline.) BTW, Bruce, I consider my keel a "bulb keel" rather than a "fin keel." Buoyant feels a lot stiffer that way, and I get something to brag on when hanging out with a bunch of finners.
As confirmation of Bruce's offset measurements, I got the same results, also on a deep keel, grounding my 410 in a shallow slip at low tide. I program my sounder to show clearance rather than depth, and have been able to confirm on (ahem)numerous occasions that Buoyant touches the mud precisely when 0 clearance is showing. This with an offset of -4 feet. The problem with using offset rather than depth is you have to remember to add 10 feet to the clearance when calculating anchor scope. (Remember, scope should be calculated from the roller, not from the waterline.) BTW, Bruce, I consider my keel a "bulb keel" rather than a "fin keel." Buoyant feels a lot stiffer that way, and I get something to brag on when hanging out with a bunch of finners.
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