On a couple of occasions, my depth finder has registered as little as 5.3 feet of depth. Since my boat draws almost 6', and since I didn't run aground, I don't think this was right. I have it set for depth from the surface of the water to the ground. At depths of about 7 feet and over, it seems to be accurate, but below this, this problem recurs. I was tied up at a marina over the weekend and checked with the boat tied next to me. His depthfinder registered the same as mine (about 7.3') so I don't think it needs to be reset. Is it possible that at less depths it simply is inaccurate?
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SF Bay
1998 C36
What type/brand/model is your depthfinder?
Do you have a keel adjustment option?
If so, what is it set at?
Can you manually adjust or does your depth finder automatically adjust between strengths of signal (50 hz/200hz)?
James J, C36 MK I, Hull 537
Weeds? Ours reads shallow if there's weeds below the boat.
Could also be fish. You don't say where you sail, but as the waters heat up, especially on the east coast we quite often get temperature gradients, warmer water sitting over the colder deep water. This change in temperature can register as a "false" bottom.
Ken and Vicki Juul
SV Luna Loca
C34 #1090
Chesapeake Bay
Weeds are always a problem in out harbor, especially in late summer. The depth often shows I am sailing out of the harbor in 3 feet of water.
Richard
1994 C36 Tall Rig M1.5
Waukegan Harbor
Lake Michigan
Thanks for the suggestions. I sail in the SF Bay and tributaries. I think it could very well be weeds and/or temp differences. The problem is that it's exacctly at the shallow depths that you want your most accurate readings. I guess there's not much can be done except watch the charts closely.
SF Bay
1998 C36