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Depth Sounders?

Posted: Sun Oct 20, 2019 10:33 pm
by RNoe
I am considering installing a depth sounder on my 17 ft. steam launch hull.
It is 1/4" to 3/8" thick mahogany, cold molded, and fiberglass covered inside and out.
I would prefer an internal mount for the transducer, rather than through hull.
Because this is a Thistle sailboat hull with no keel and a planing configuration, the shaft, prop and rudder are exposed to damage.
The prop does have a stainless steel protection structure ahead of it, but that's all.
A forward-mounted depth transducer seems like a good instrument to have.
ST prop installed 1 sml.jpg
ST prop installed 1 sml.jpg (152.79 KiB) Viewed 3798 times
I have searched this Board unsuccessfully for any discussions on death sounders.
Anyone have info and advice for my quest?

Re: Depth Sounders?

Posted: Mon Oct 21, 2019 2:12 am
by TahoeSteam
Lowrance makes some very nice units with forward-looking sonar, but the transducer is through-hull (actually easy to pull while in the water to wipe slime off). We have one on Persistance as when one draws almost 6 feet of water and plys the waters of a tidal delta it is wise to be looking out ahead. Wouldn't want to run aground at high tide...

I'm not sure if they make any forward looking units that can be mounted inside the hull.

Re: Depth Sounders?

Posted: Mon Oct 21, 2019 2:56 am
by Lopez Mike
Any possibility of adding a bottom support from your rudder to the strut? For prop protection.

Re: Depth Sounders?

Posted: Mon Oct 21, 2019 4:35 am
by RNoe
Thanks for your suggestions I will research forward looking devices. That is my preferred solution.
Transducer mounting? I'll just have to see what works. The bow section is near vertical making it difficult to mount thru-hull transducers.

The rudder on my launch is hinged on the transom only. No lower supports.
So it is unable to support struts on the bottom, without major design changes.

Lots of things to consider.
Thanks all. To be continued

Re: Depth Sounders?

Posted: Tue Oct 22, 2019 1:53 am
by barts
I wouldn't get too worried.

Otter's prop has been 'hanging low' w/o even a preceding skeg for the almost 30 years she's been steaming. Yes, I've grounded the prop on a rock a time or two, but nothing really bad that a bit of light filing didn't clean up. I do stand and slow down when steaming in shallow, rocky water for better visibility; those struts really only help on gently sloping bottoms. It's quite possible to 'sideswipe' a rock as well. If unsure of the bottom due to murky water, a boat hook or paddle will serve to investigate. These small boats draw less than 2', which is easily reachable.

Depth sounders can be useful for navigation w/ a chart, watch and tide table, but on a small boat a tablet and/or phone w/ Navionics software and gps is pretty unbeatable.

- Bart

Re: Depth Sounders?

Posted: Tue Oct 22, 2019 3:51 pm
by RNoe
Thanks for your Real Life input. I'm leaning toward your approach and it's good to hear of your experience.

Menlo Park? I grew up in Los Altos (1950 - 1968) and my Father worked at Stanford Research Institute in Menlo Park.
We often visited Friends there.
Nice huge oak trees all over the place then. Hopefully still there. I moved north in 1969.

Re: Depth Sounders?

Posted: Sun Oct 27, 2019 9:05 pm
by cyberbadger
Nyitra has a pretty shallow draft, at Point Chautauqua I have pushed that envelope with the her birth (There were already 5 boats on our dock that we share with two other familes). It's also rocky on the bottom on our side of our lake.. So with Nyitra I go into her shallow birth waters expecting a prop hit, I use as little steam on the engine throttle as necessary and get ready to turn off steam. After I close the throttle valve I will sometimes throw the stephenson lever to reverse till the motion stops and then put it in the center. In this way I have "tinked" the bronze 18"x24"propeller Wes sold me several times, but I wouldn't even call them dents, they are just a little marring IMHO. :-P

When I sailed on the Great Lakes on my buddies 22' Catalina it had a swing keel, and we had and used a deep sounder. However, I think we would have been fine without it for the whole trip because we had a really nice tablet charting app with all the charts we would need preloaded on two tablets.

I find that having an accurate chart and using it is a very important strategy for a long trip regarding strikes from hazards.

There is nothing like the confidence from looking at a navigation buoy symbol on a chart and looking up and seeing that buoy on the horizon at the correct bearing.

You still have to confirm it visually. If things go abandoned channel markers can be dangerous if conditions have deteriated, I've experienced that in Chautauqua with shifting sands on the bottom myself...


Re: Depth Sounders?

Posted: Wed Oct 30, 2019 11:05 pm
by malcolmd
We bought an ageing Seafarer depth sounder for Befur on eBay (about 20 pounds) and installed a through-hull sensor, and it does provide a certain peace of mind :-)