Sailboat depth transducer - useful?

[Spot]

Do people mark their sounding lines specific to their boat?
My hull sits about a foot deep, the fixed keel and point of no return for the rudder at two feet, and the centerboard down is 5 feet, all give or take a few inches.
So would it be worthwhile to have smaller increments until a fathom, then do to fathoms for the rest?
I am slowly making progress towards a casting. 3D printed model to visualize and a CNC wooden mold with some improvements like more lead around the eye.

[JoeRobertJr]

Originally Posted by Spot

So would it be worthwhile to have smaller increments until a fathom, then do to fathoms for the rest?

My first mark is at one fathom. While taking soundings, I find it is pretty easy to estimate that the sounding is one or two feet more or less than that mark. So, I would not find it useful to have finer resolution on the marks.

That casting looks like a fun project!

[csonquist]

Where I sail in the north end of Lake Huron, the North Channel, the glaciers have scrubbed the soil away to the south. It now resides in Ohio and Indiana or some other glacial moraines. With hard rock under the surface, knowing to parts of a foot is important. BANG, with your whole boat and your soul feeling it makes very exact depth measurement very important. I need six feet to float so eye ball estimates like one can gather from perceived water color is too fuzzy and while the water is very clear, not clear enough for my giving it an eye ball glance and have that be good enough

[Benz]

Originally Posted by Spot

Do people mark their sounding lines specific to their boat?
My hull sits about a foot deep, the fixed keel and point of no return for the rudder at two feet, and the centerboard down is 5 feet, all give or take a few inches.
So would it be worthwhile to have smaller increments until a fathom, then do to fathoms for the rest?
I am slowly making progress towards a casting. 3D printed model to visualize and a CNC wooden mold with some improvements like more lead around the eye.

For your boat I might make a mark at a yard, since you'll still float there, and then fathoms from then on. I need five feet to float, so if it gets under a fathom, I'm pretty close to bumping anyway.

[Spot]

Originally Posted by Benz

For your boat I might make a mark at a yard, since you'll still float there, and then fathoms from then on. I need five feet to float, so if it gets under a fathom, I'm pretty close to bumping anyway.

Originally Posted by csonquist

Where I sail in the north end of Lake Huron, the North Channel, the glaciers have scrubbed the soil away to the south. It now resides in Ohio and Indiana or some other glacial moraines. With hard rock under the surface, knowing to parts of a foot is important. BANG, with your whole boat and your soul feeling it makes very exact depth measurement very important. I need six feet to float so eye ball estimates like one can gather from perceived water color is too fuzzy and while the water is very clear, not clear enough for my giving it an eye ball glance and have that be good enough

Originally Posted by JoeRobertJr

My first mark is at one fathom. While taking soundings, I find it is pretty easy to estimate that the sounding is one or two feet more or less than that mark. So, I would not find it useful to have finer resolution on the marks. That casting looks like a fun project!

Thanks Everyone!

[fcallard]

Originally Posted by realem

I have a Kelt 8.5 with a swing keel when I looked at boats another owner with a kelt did not have a depth sounder he just let the keel swing up. The mechanism is more like a rocker. In South Fl there are a lot of shallows so even with the swing keel which I had to raise just last week from shallow water I have depth sounders. It is nice to know when you are approaching shallow water and I just do not like running aground. In fact I have several depth sounders including one in the GPS. The GPS and the depth sounders are very useful at anchor if you start to drag into shallow water which did happen in the keys

Depth sounders are worth the investment to minimize wear and tear on a swing keel in shallow waters. We've marked the Dacron pennant for our 3000# swing keel in 1 foot increments so we have an idea of how close our keel is to the bottom as we try to avoid "sailing by braille". You can best calibrate your depth markings when your boat is in a travelift and you can progressively set the swing keel at 1 ft increments.

[Spot]

Report on the sounder casting over here, looks like we're back on topic here so I will try not to derail (again, sorry):

https://www.cruisersforum.com/forums...ml#post3358051

I am hoping to complete a mounting of a Garmin transducer on my hull to give me depth and fish finding and temps. The Garmin head unit also has basic GPS and maps too.

[Benz]

Originally Posted by Spot

Report on the sounder casting over here, looks like we're back on topic here so I will try not to derail (again, sorry):

https://www.cruisersforum.com/forums...ml#post3358051

I am hoping to complete a mounting of a Garmin transducer on my hull to give me depth and fish finding and temps. The Garmin head unit also has basic GPS and maps too.

Nice casting. What does it weigh?

[Spot]

Originally Posted by Benz

Nice casting. What does it weigh?

Thanks. It is 4.84 pounds or 2.2kg now, it will probably be 4.6 pounds or a hair over 2.1 kg once I fix the bottom and drill the top. CAD reports the weight as being 5.14 pounds or 2.3 kg so I am not sure what is going on there.

[Spot]

Second attempt at molding. I added some metal bits to form the cup on the bottom. It turned out better but still not smooth enough on the bottom to use without trimming. The gasket + more clmaps worked. The mold is deteriorating, softer parts of the wood are charring into undercuts and the 'pimples' that form the 'dimples' where the hole is to be drilled for the rope split off again after being re-glued to the mold after they failed the first time. I might try replacing them with carriage bolt heads to make a third and final attempt, I might just stop as the second one is not too bad now that it is trimmed. Once I decide on the plummet, next thing is to attempt an eye splice and then measure and fix the markings.