I’m really enjoying kayak fishing and after considering a bunch of non-permanent, portable finders like the FishHunter or Deeper I decided to pick up a Lowrance Mark-4 CHIRP fishfinder/chart plotter on clearance.  There are a lot of expensive options for mounting the thing however I wanted to minimize the holes drilled into my precious boat while maximizing the convenience and professionalism of the installation.  After scouring the internet and a few hours in 123D Design I came up with this…

 

Update: It was pointed out that I did not seek RailBlaza’s permission to use their star design.  I’ve redesigned the Lowrance mount to connect directly to the rail.

Here are the custom 3D Printed parts:

The left two items are the scupper transducer mount.   You’ll need a galvanized 5/16 hex bolt roughly 1″ shorter than your scupper depth, nut, and washer.  I’m using a 3.5″ bolt which is slightly longer than it needs to be but plenty of room to spare; the design is forgiving.  The nut is captured in the bottom part and the bolt is inserted through the middle with the wire running through the notches:

The scupper is then attached at the bottom.  The hardware that came with the Mark-4 was slightly short for the design but it holds just fine:

The third 3D-printed part mounts the Mark-4 on any RailBlaza mount any rail.  The Moken has the Unitrack system so I can adjust the location as needed:

 

I plan on keeping the battery in the hull and using through-hull fittings for the scupper mounted transducer and fish finder.  I picked up some PG-9 cable connectors for the battery box and went with the Hobie Through-Hull Wiring Kit for the through-hull fittings.  I considered using PG-9s all-around.  They’re a great little design.  However, I want the ability to pull off the fish finder and the Hobie kit has ‘blank’ inserts so it will be 100% water-proof with the fish finder removed.  They also have a 2-wire insert so it’s only one hole for both power and transducer up front:

For the box itself I picked up a large Outdoor Products Dry Box.  I had originally drilled two holes with the intention of keeping the NEMA cable in-tact however after tangling around with that extra, useless cable I changed my mine.  The hole was plugged with a 1/4″ bolt, a couple fender washers and a neoprene washer… still water-tight.  I clipped the NEMA cable and heat-shrinked the open end:

On the inside I wired up the fuse that came with the fish finder and stuck some packaging foam to the walls:

So now for the more agonizing part.  I had a tough time deciding where to place the Hobie Through-Hull plugs.  Most installations that I see tend to place the through-hull holes at the bottom of the foot wells.   That makes sense as they are vertical walls that are less prone to leakage and protected against knocks on 3 sides; all sides if you count the foot pedals.

Both holes were drilled with a 1″ Forstner.

Most people will then place the transducer in the scupper directly below the holes.  Unfortunately that is a pretty shallow scupper on the Moken and the transducer is more likely to scrape there.  I instead routed the cable along the foot well and in the drainage channel to the under-seat scupper.

 

The seat is flush over the cable and stays out of the foot well pretty good.  If I later decide this is a pain I can always switch to the foot well scupper with little effort.

The transducer cable is installed:

As well as the cabling for the fish finder:

 

 

The leads need to be fed into the box and the battery hooked up:

All that’s left now is to place the mount in the right position and hook everything up:

 

Hopefully I can per her to the test this weekend!

 

You can download the Lowrance mount STL from here and the transducer mount STL from here.