Just a quick question. What should I assign as the actual offset when setting up my ST60 depth guage on a 1984 Hunter 34 shoal draft? The trandsducer was installed and then the boat splashed however I forgot to determine the distance prior to all of this happening.And now with the boat in the water measuring becomes problematic.
Depth Offset
- Thread starter mamkt001
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To the water line
Offset to the waterline, which will remind you constantly of how much water you're in. Alternately, set it to the bottom of the keel so you don't have to do the calculation in your head. Trouble with that is that people will see a 2 or a 1 and think they're about to run aground. Where we sail in the Chesapeake Bay, the watermen have very kindly placed their crabpots in 10 feet of water, which reminds us to tack.
Offset to the waterline, which will remind you constantly of how much water you're in. Alternately, set it to the bottom of the keel so you don't have to do the calculation in your head. Trouble with that is that people will see a 2 or a 1 and think they're about to run aground. Where we sail in the Chesapeake Bay, the watermen have very kindly placed their crabpots in 10 feet of water, which reminds us to tack.
How I set mine, Mark
While at the dock, I position myself at the approximate location of the transducer. Use a tape measure, run it down until it hits the mud, make a note of the depth. Then set my depth to read that value, I believe on my boat it is a -2 offset. I tried setting to the bottom of the keel but was always re-calculating what the depth was. Gave up and just set the actual. It also freaked Joan out when she saw one foot. Jim S/V Java
While at the dock, I position myself at the approximate location of the transducer. Use a tape measure, run it down until it hits the mud, make a note of the depth. Then set my depth to read that value, I believe on my boat it is a -2 offset. I tried setting to the bottom of the keel but was always re-calculating what the depth was. Gave up and just set the actual. It also freaked Joan out when she saw one foot. Jim S/V Java
Under MY Keel
My depth gauge is setup to tell me how much water is under my keel at all times,no guess work at all. You need to check your draft from the water line down to the bottom of your keel and adjust the gauge for proper depth reading. Nick
My depth gauge is setup to tell me how much water is under my keel at all times,no guess work at all. You need to check your draft from the water line down to the bottom of your keel and adjust the gauge for proper depth reading. Nick
I Don't Set Mine.
I let it default to 0' of offset because I already know my actual "touch" depth (experience pays off, here). I don't like to sail in less that 20' (on the guage) because you never know when an exposed, but undetected, boulder may be present. So to me, 20' is usually 16.9' clearance, But 20 feet will do it. It also helps in determining how much anchor rode is needed at any time. And not interfere with calculation of scope required. As you can see from the postings, one must use their own determination!
I let it default to 0' of offset because I already know my actual "touch" depth (experience pays off, here). I don't like to sail in less that 20' (on the guage) because you never know when an exposed, but undetected, boulder may be present. So to me, 20' is usually 16.9' clearance, But 20 feet will do it. It also helps in determining how much anchor rode is needed at any time. And not interfere with calculation of scope required. As you can see from the postings, one must use their own determination!
Many answers ...
I set my offset so that the Depth sounder reads the water depth. - Other users of the boat will generally expect a depth sounder to read depth, and that's normal (in general they wont have any idea what your draft is) - If it doesn't read actual depth, then you need to do mental math (easy as it may be) or everything, including comparing your current depth to a chart location, computing the amount of anchor rode to use (though you should be adding freeboard to the depth anyway). To me, the most compelling rational is that it should be set the way in was intended, which is also the most common, and that way all users of your boat will not need to be told anything special. A "Boat Draft = X.X feet" would be a perfect sticker to attach to the depth sounder display. Chris
I set my offset so that the Depth sounder reads the water depth. - Other users of the boat will generally expect a depth sounder to read depth, and that's normal (in general they wont have any idea what your draft is) - If it doesn't read actual depth, then you need to do mental math (easy as it may be) or everything, including comparing your current depth to a chart location, computing the amount of anchor rode to use (though you should be adding freeboard to the depth anyway). To me, the most compelling rational is that it should be set the way in was intended, which is also the most common, and that way all users of your boat will not need to be told anything special. A "Boat Draft = X.X feet" would be a perfect sticker to attach to the depth sounder display. Chris
Water depth
I set mine to read actual water depth. I have a placard that indicates the depth of keel so the brother-in-law does not get into trouble. Knowing the actual depth makes using the depth sounder as a nav instrument much easier. I can calculate the state of the tide in a gunk hole much easier also. keeps me from being set aground during the falling tide.
I set mine to read actual water depth. I have a placard that indicates the depth of keel so the brother-in-law does not get into trouble. Knowing the actual depth makes using the depth sounder as a nav instrument much easier. I can calculate the state of the tide in a gunk hole much easier also. keeps me from being set aground during the falling tide.
Good old fashioned way
Mark, When I am anchored in an area wher the depth is fairly constant and the current and wind are calm, I drop a line with a lead weight off the swim ladder. I mark the depth of the water with my fingers at the waterline. I measure the length of the line and then set the offset until the sounder displays the measured depth. It is not difficult if it sounds so. If it takes ten minutes, you are taking a break in between. And there is no room for misunderstandings, math errors or wives' tales. Have fun, Mike D s/v Serenity 1998 H376 Annapolis , MD
Mark, When I am anchored in an area wher the depth is fairly constant and the current and wind are calm, I drop a line with a lead weight off the swim ladder. I mark the depth of the water with my fingers at the waterline. I measure the length of the line and then set the offset until the sounder displays the measured depth. It is not difficult if it sounds so. If it takes ten minutes, you are taking a break in between. And there is no room for misunderstandings, math errors or wives' tales. Have fun, Mike D s/v Serenity 1998 H376 Annapolis , MD
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