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Boat Projects Forum

Digital Depth Display

by argonaut » 18 Aug 2020, 20:26

Another project for my new boat.

I do water sports and having a configurable depth alarm means I can concentrate on driving and when I start getting shallow (<5’) it beeps away, I can then start a controlled turn into deeper water.
Makes it easier for the driver – and safer.
Previous boats have had standalone depth gauges ….. with configurable alarm.
My new Four Winns has a digital ‘smart’ Medallion GDig system…. In the analogue speedo are 2 digital LCD displays that you can configure to show, time, Hrs, rpm, heading, air temp, water temp ……. etc.

This includes a depth display but for me was of limited use …… no configurable depth alarm, and the LCD display is small and low down …. The driver has to constantly look down to see it.

Now the ‘nuts’ thing is that I had during pre-sales discussion a picture of the dash sent to me ….. and it had a 2” depth alarm display, I took this up with the Manufacturer – they advised I was shown and old picture, not of current production boat !
I asked why no configurable depth alarm ….. to be told ‘no call from users for this

Then I had a lot of frustration, while I could get a standalone alarm, it was not capable of hooking into the CanBus of the instruments, and nobody makes a standalone display that will work with the installed thru-hull transponder (CanBus signalling)

I looked at UK dealers they wanted a lot of money and that was for a transom mount transponder – not what I wanted.
FourWinns advised that easiest thing is to swap out the transponder and fit an AirMar P319 as hole though the hull is the same size … i.e. 2” diam.
A major issue, as all initial depth display manufacturers I found, use a 1 5/8” transponder. Eventually, I tracked down a company ‘HawkEye Electronics’ who specialise in-depth measuring instruments.
They did offer their unit with a 2” transponder and a 2” display …… don’t you love it when a plan comes together.

Hawkeye display unit :
depthtrax.png (216.15 KiB) Viewed 3512 times

I decided to go for the DepthTrax 2BX, this has integrated air & water temp displays - useful as I will lose water temp display on the integrated Medallion display when I remove their transponder.

Ordered and arrived in a week – the whole thing including shipping & tax was cheaper than transom mount units in UK.

So first remove the existing transponder – FourWinns advise they use 3M 4000 adhesive that does not set hard, run a sharp blade around it and it will come out …… will it hell as like
2 of us spent 6 Hrs cutting around the existing fitting, it had about 5mm spare all round and that was filled with the adhesive, and around 40mm thick hull, and the mushroom dome on the underside was also fitted with 3M 4000.
We snapped a lot of scalpel blades, Stanley blades were not flexible enough.

The unit finally removed looked like this:

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Putting it in new transducer was easy enough, but VERY messy, my mate who was on the inside of the boat seemed to cover himself in the adhesive, and the only way we could remove it was with acetone.

Now the original Transducer cable ran under boat floor with main electric cables, simply no access to go that route.
Had to remove a lot of internal trim panels but managed to get Transponder cable behind the dash following the route of steering Teleflex.
The 2” hole in the dash was already there – just had to remove blanking ‘dummy’ dial, and new display fitted easy enough. Wiring was pretty simple … +12V ‘ignition’ and -12V, the new transducer cable screwed in via watertight connections. There was a short lead with air temp sensor on it …. Just cable tied in a central location behind the dash.

I ordered the chrome bezel ….. they do multiple colours, they simply clip onto the front, they also supply a clip over cover to keep it clean.
It looks like this is place, pretty neat :

L resize21.jpg
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It gives depth in 0.1 foot increments or metric, and air & water temp in C or F, the important bit is the configurable depth alarm …. and a nice addition a Keel offset … here you set the draft of the boat, and it subtracts that from actual depth ……. So if your draft is 3’, you set offset to 3’ ….. then if for example, you are operating in a depth of 5’ the display will show 2’ which is your safe water under the keel
So my dash now has 2 new digital displays …… the GPS Cruise Control and now the depth display.

The black item on the dash is the GPS antennae for the Cruise control

L resize31.jpg
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Aug 2020
FourWinns H210, Volvo 280-C-N duoprop, Monster MTK tower, SBS 2600 twin axle trailer
Tow Vehicle - Landrover Discovery Sport
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