Our F45 came from Seattle where all water is deep water. No offset was entered for the depth sounder; it shows the depth from the hull to the bottom. Now that the boat is used in the Chesapeake Bay, knowing the exact depth of the water you are in becomes important for creeks and anchoring.
Our 1991 F45 has a fin keel and ~7’ draft. (Not ideal for the Chesapeake!) The transducer is located near the through-hull for the forward head. Does anyone know the measurement from the hull at that point to the bottom of the keel? I want to enter this offset in the depth finder so I know the depth of the water I am floating in.
I can measure when it’s hauled, of course, but this number would come in very handy this weekend.
I have a shoal draft 30 and has the same issue early in in my ownership. I had not yet pulled the boat out of the water and did not want to go swimming so I simply took a look at where waterline was and got a tape measure to estimate depth to transducer from inside the boat. I was conservative by adding 6 inches to my guestimate.
When I did finally come out, I think I was about 8 inches too deep on the transducer. I was pretty happy with that outcome. If I were you I would do this in combo with input from other owners just as a sort of sanity check. Different boats might be a little different.
Of course I have run aground (or scraped over the bottom) in mud many times since then and know with precision anything under 4.5 feet of water is a slow or no go for me. I have also developed excellent “get off the ground” skills.
I watch tides and, if in doubt, make sure the tide is rising before I go into shallows. I have had a few waits while the tide lifts me off
lol I seem to follow on your posts Mike- at the boat today in Emeryville and saw the post on depth offset. Loved your response. I, while at the dock, decided to check my off set— tied a line to a weighty thing and dropped it overboard. Measured from the waterline I saw 13’ 6”. Powered up my RM depth triducer and saw I had it set for waterline. Read 13’. I went to setting and changed to “keel” from waterline and set the offset. Guessing about the transducer to keel depth All good. So suggest measuring your depth at waterline, adjust for keel depth and enter those numbers to get a fairly accurate depth offset reading. BTW - been several times to Seattle and around and with all the islands and narrow passages, depths will hugely vary as well.
Ignore the the draft. The offset it from the transgucer to the bottom of the keel. So if your transducer is 2ft under the water line and your draft is 7ft the offset will be 5ft. Hope that helps.
Just remember when anchoring for example, it will be recorded depth plus 7ft (for draft) plus freeboard (water to the anchor roller) then multipy by 5 for chain and 7 for rode
