Transducers for DIY system

[Artey]

I've tried reading some of the many threads on here, but I'm getting a bit overwhelmed. I am refitting a lake boat and the current instruments are dead. It has old Signet marine digital instruments. The screens are completely blown out, but I believe the sensors themselves still work as I can make out slight smatterings in the busted screens when I flip the breakers on. Ultimately I want to use an Rpi and just use a tablet on the lake for gps/instrument data, and eventually link in some microcontrollers for other boat monitoring, but for now I just need to get new sensors and get some gauges going. I would like to keep my budget under $1k if thats even possible. If not, I'll bite the bullet and do it right.

What is the easiest/cheapest way for me to do that? I believe I will have to reglass and redrill for any thru hulls as the old signet stuff appears to be 2.5" holes. Most new sensors appear to be 2" or smaller.

Is it possible to reuse the old analog Signet Marine sensors and convert the data to nmea 0183, then straight to RPi and then to my android tablet? They are seperate speed, and depth/temp. Or do I need at least one screen to read the information then out from that to Rpi even with nmea 0183 capable sensors?

I know nmea 0183 sensors work more directly with stuff like OpenCPN and OpenPlotter packages, but is it the right thing to use when starting from nothing? Remember - not an ocean boat, I may race some, but mostly just gunkholing and cruising around. All advice, links, and simple explanations are appreciated.

[AndyEss]

Really old transducers were strictly analog or pulse. Unless you can get documentation (i.e. signal levels, excitation, output specs, pulse type, levels, frequencies, etc) and then design/build signal conditioning and analog to digital converters, you are out of luck. Even if you can find the design documentation (not just user/installation docs) you have a pretty high hurdle to cross to salvage that old stuff. I used to design and build custom sensors and engineering data acquisition systems for a living - I wouldn’t waste any time trying to revive that stuff.
Buy a fishfinder to get water depths, and use your phone’s gps/map function to get boat speed and location. Better yet, buy a used Ipad that has gps and use that as your “navigation” system

[Artey]

Originally Posted by AndyEss

Really old transducers were strictly analog or pulse. Unless you can get documentation (i.e. signal levels, excitation, output specs, pulse type, levels, frequencies, etc) and then design/build signal conditioning and analog to digital converters, you are out of luck. Even if you can find the design documentation (not just user/installation docs) you have a pretty high hurdle to cross to salvage that old stuff. I used to design and build custom sensors and engineering data acquisition systems for a living - I wouldn’t waste any time trying to revive that stuff.
Buy a fishfinder to get water depths, and use your phone’s gps/map function to get boat speed and location. Better yet, buy a used Ipad that has gps and use that as your “navigation” system

Figured as much. What would be your recommendation if I were to go one step up and use the existing thru hulls? I want to do more than just a fish finder so that I don't completely hurt resale. I realize resale value in boats is basically a joke, as well as DIY. Something about a fish finder feels so punky on a sailboat haha, maybe I'm just being pretentious.

[AndyEss]

Go sailing/gunkholing with a bare minimum of needed info (water depth/location). Don’t worry about resale value - and leave the old transducers in place until you actually need to change something.
I don’’t know anything about the boat market in Oklahoma, but I suspect it isn’t very sophisticated. Many sailboat sailors tend to be low technology/low glitz types. I suspect many power boaters are more enamored of the latest/greatest technology.
I bet having a clean, well maintained boat in your circumstances would have far more to do with resale value than the latest technology.
As you get experience with your boat, and see what new boater friends are doing in similar circumstances, you’ll have a much better feel on how to proceed.
I updated a lot of nav stuff on my boat because it was from the 90’s and unsupported. Then again, I hope to cross to the Marquesas from Mexico so my nav needs are different from yours. I doubt very much I will re-coup the costs of nav system upgrades when the inevitable happens and it is time to sell “Integrity”

[Pendragon35]

I use an older furuno fish finder on an Alber 35 sailboat. It's supposed to provide depth and speed but the speed has never worked reliably. The depth is usually good. I use an iPad (wifi and cell) with iSailor and iNavx for navigation, speed, COG, AIS, Position, etc. They have an Apple Watch app I just got and am excited to try out as well so the COG/Position/Speed will be on my wrist. Works great for coastal cruising on the Cheasapeake.

[AndyEss]

I like iNavx on my Ipad for another backup nav system. I actually use this as my helm nav display because my RM mfd is mounted on a swing arm in the companionway (bit of a head knocker) and is a bit hard to see for detailed navigation popping into a tight anchorage.
The Ipad mounts easy on the helm pedestal. My bimini provides pretty good shading, so the Ipad screen is pretty visible even at noon in the subtropics where I have been sailing recently.

[GordMay]

Greetings and welcome aboard the CF, Artey.

[Pete7]

Originally Posted by Artey

Something about a fish finder feels so punky on a sailboat haha, maybe I'm just being pretentious.

Au contraire, brilliant bit of kit and if included with a chart plotter would be invaluable to avoid running aground. The first thing we bought was a little 5" Garmin GPS map with sounder. 12 years on we have used it repeatedly to cross to France. The sounder display enables us to get into shallow water and the speed display a nice touch to see how small changes in sail trim affect the boat.

I think it cost £500 at a boat show and has been money well spent. Is there an electronic chart for the lake? looks quite big.

Pete

[Artey]

Originally Posted by Pete7

I think it cost £500 at a boat show and has been money well spent. Is there an electronic chart for the lake? looks quite big.
Pete

Only chart I know of are two but both are "Crowd Sourced". One is paper and is from local people who literally spent a few years compiling all the data themselves and mapped the majority of the lake with soundings, and is surprisingly accurate. The second is a Navionics map in the "lake" package and I'm pretty sure that its crowd sourced data from mostly fishermen. Its a fairly good sized lake, fed by the Arkansas River which definitely leaves some moving sand banks in some more shallow areas. There are even some islands that depending on the dam flow and water levels can be hidden and sometimes not almost like a tide, but much slower! lol

[stormalong]

Are you aware that Signet Marine is still around and has a repair service?

Signet Marine - Precision Marine Electronics | Official Website of Signet Marine Inc.

[Billnpr]

I use Navionics with Sonar Phone depth finder puck mounted in tolet boul wax inside the hull. Navonics gives navagation for lakes and rivers as well as oceans.

[Artey]

Originally Posted by stormalong

Are you aware that Signet Marine is still around and has a repair service?

Signet Marine - Precision Marine Electronics | Official Website of Signet Marine Inc.

Stormalong, thank you. I am aware, what turns me off is that to get the missing wind instrument I need alone is almost as much as a new 3 instrument sail pack from raymarine that is nmea 2k. That's what has kind of deterred me from having my instruments repaired and getting the missing masthead transducer. All I have existing are the three broken screens and the functioning speed and separate depth transducer. I still plan on giving them a call this next week to talk about repairs and prices as I've heard they give some people excellent deals to renew their instruments with them rather than switch brands. May go the fish finder route as suggested after I read more about it but currently still not a fan of that method.

[RaymondR]

Fish finders give better service than just a depth gauge, you can see the depth trend at a glance and also an indication of bottom condition and OpenCPN or Navionics on a tablet pretty well all the other information you need.