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Fitting a Fish Finder or GPS combo unit to a fibreglass Kayak

Lowrance Hook 4 South Africa Kayak Jetski

This article is designed to assist a Kayak Angler fit a Fishfinder to a fibreglass Kayak. Models include Stealth Supalite, Supalite X, BFS, ProFisha, 465, 495, 525, Evolution 465, 495, Pinnacle, Pinnacle Elite, and Erics Gt and Tunny range of Fishingskis. I am situated in South Africa however the same applies to any fibreglass Fishing Kayak around the world. Firstly I would like to say that if you intend fitting a Fish Finder to a Kayak yourself it is quite a simple process if you are a keen DIY’er. The most difficult part is deciding where to install the transducer and the battery. This process often means cutting your Kayak and also removing a small section of the buoyancy material. As I said earlier though it is quite straight forward and if you don’t want to attempt it just contact us

Ok before we begin let’s have a look at what we are trying to achieve

  1. We want to decide to use a fishfinder or a fishfinder / GPS combination unit
  2. We want to find and see fish!
  3. We want to know where we are and where we are going
  4. We want the battery secure and as dry as possible
  5. We want the head unit protected
  6. We want the unit removable to store when going through the surf
  7. We want to decide either to mount the transducer internally or externally
  8. We want to keep the unit dry out at sea in rough conditions
  9. We want to keep the unit dry and protected when in the surf zone
  10. We want to keep the wiring tidy or hidden
  1. The first question for me is a no brainer unless you already own a Sonar, Fishfinder, or GPS unit. If you already own of the aforementioned and are on a budget just purchase the other unit and use them independently. If you are purchasing your first unit or upgrading to the new HDI or CHIRP units I would definitely suggest a combination unit. The reason I would suggest a combination unit is you have the head unit right in front of you and it is simply a matter of a few button presses to obtain the information you require.
  2. Yes we definately want to see fish and the bigger the better. A 4″ unit is ok for a Kayak, especially the new high definiton range, however if you can afford a 5″ go for it.
  3. Yes we definately want to know where we are and where we are going. That is the purpose of a GPS. The new units have the added benefit of a SD or Micro SD card to upload and download Waypoints often referred to as GPS marks. There is also a range of  MAPCARDS available for the East Coast of Africa nd Mozambique as well as other regions if you are elsewhere in the world.
  4. We keep the battery dry and secure by adding a battery box into the side of the Kayak internal fish box. You could also use a food lock box, however this is not as effective.
  5. To protect the head unit you can use a food lock box or a PADDED FISHFINDER BAG or a DRY BOX or DRY BAG
  6. The ideal way to mount the head unit is to use a quick and easy velcro solution which works very effectively or a complete STEALTH HATCH LID. These are only for Stealth Kayaks however contact us for other manufacturers.
  7. When deciding to mount the transducer internally or externally here are your options. Internally you will be “wire or cable free” ok not free but well hidden. This is a really neat setup. The downside is that you will have a slightly weaker fish signal (80/200khz) and the high defination (455khz) will not work, or will be very weak. The positive side of mounting externally either with velcro or a SUCTION CUP is that you will receive a full strength signal. You will just have to hide as best you can the transducer wires.
  8. To keep the unit dry while out at sea quite simply use a FISH BAG
  9. When in the surf zone which is where you could potentially damage your unit it is best to keep the unit stored away in a FOOD LOCK BOX, PADDED FISH FINDER / GPS BAG, or a DRY TUBE BAG
  10. The best way to hide the wire is behind the battery box or along the ridge of the hatch (see below photograph)

List of tools required


Drill bits

Rivet gun

Hole cutter


Electrical crimping tool

Soldering iron

Screw driver

List of materials required

Epoxy (2 pack)

Rivets or screws

Marine silicone



Shrink tube

Rivets or screws

Transducer Installation

Ok so its time now to start the installation. If you are mounting the transducer internally you must allow time for the epoxy to dry. I would recommend overnight. So you could start by cutting out the hole in the side of your Kayak Gulp! Yes you must make sure you are cutting in the correct place. Dont call me and say I told you to do it. If in doubt contact me or the manufacturer of your Kayak. The hole you cut out will be made with a template provided with our BATTERY BOX HOLDER. This size hole allows you space to fit the transducer comfortably. The hole is then covered with the battery box holder. You can cut the rectangular shaped hole with a drill by drilling a hole in each corner and then making more holes, or use a hacksaw blade broken into a manageable piece. You could also use a Dremel type tool. Keep trying your battery box periodically to make sure it is quite a tight fit which will help with the sealing later.

Once the hole is cut to size you may need to remove a small piece of the buoyancy material where the transducer will fit. This is usually a polystyrene looking material, but may be foam. When the space is cleared you can sand the hull area with a rough 80 grit sand paper. Choose an area which is as flat as possible so that the transducer points straight down. Once you have found your chosen spot sand the bottom of the transducer again with 80 grit sand paper to remove the shiney gloss surface so that the 2 pack epoxy adheres better to the transducer. You are now ready to mix the 2 pack epoxy and apply to the transducer. I like to use a wooden spatula and latex gloves as you don’t want this stuff on your hands! After a liberal coat of 2 pack epoxy has been applied carefully site the transducer with the widest part facing the back of your Kayak and as I said earlier as straight to pointing down as you can. This ensures that what you see on the screen is what is directly under your Kayak. it is very important that no air is trapped so very slowly rotate the transducer slightly backwards and forwards to “bed in” the epoxy. If the transducer starts to lean to one side or twist you may have to use some duct tape to support the transducer until it dries. It is very important the transducer dries in the correct position.

Once the transducer is dry and you have checked that it is seated in the correct position you can neatly tie the excess transducer cable with a tie wrap and feed it through the Battery Box hole so that it will be out of site once the installation is completed.

Kayak, Transducer installation,

Kayak Transducer installation

Battery Box

Its now time to fit the Battery Box which can be done by either simply drilling a few holes and fastening with stainless steel self tapping screws, or drilling holes and then riveting for or a more permanent fixture. It is down to you if you want to completely seal the Battery Box. I do and I use a clear marine silicone sealer. The reason I seal it is to keep the fish hatch and the hull two separate sealed compartments which act as buoyancy should your Kayak be compromised and leak water.

Battery, Box, components, fish finder, fishfinder, installation,

Battery Box components

Battery, box, trya, Kayak, Fishfinder, Fish finder,

Battery box for Kayak Fishfinder

Fishing Kayak, Battery Box, Battery, Batteries

Fishing Kayak Battery Box

Fibreglass, Stealth, Kayk, Battery, Tray, box,

Fibreglass Battery Box to house battery

Stealth, Kayak ,Battery Box, Tray,

Battery tray finished

Power Cable

Once the transducer and battery box are fitted its time to drill a hole for your power cable plug and transducer cable plug to fit through. These plugs maybe combined into one. During this process you must decide if you want to push both plugs through one hole or have a separate plug for each wire. Also you will have to decide if you want to leave the plugs hanging externally when you remove the head unit or do you want to push them back through the bung hole and insert a bung plug to water seal the Kayak. It is a very very minimal amount of water which can enter through this hole even if your Kayak turns upside down so I wouldn’t worry too much about it.  NOTE Some of the new units 2014 have large plugs. You must either cut the plastic female part of the plug and slide the wire through it which may mean you have to leave the plug outside your Kayak. I am trying to source larger bungs and plugs.

Kayak, Power, cable, Bung Plug,

Power cable Bung Plug

Kayak, Wiring, Fishfinder, Fish Finder, GPS,

Kayak Wiring…. Tie the plug up high when not plugged in to prevent shorts & corrosion. Note the rubber plug covering the plastic plug. This keeps the plug dry.


Rubber plug

Rubber plug…..you can store the rubber plug by pushing it into the plastic bung plug when not using.

Kayak, Fish Finder, Wiring,

Kayak Fish Finder Wiring. The wiring can be easily hidden under the ridge of the fish hatch. Just use Velcro strips to kep the wiring out of the way.

Sonar / GPS Head Unit

Now to fix the head unit. There are basically three methods. Method 1…. You can permanently fix the Fishfinder base bracket to your Kayak hatch lid by screwing it to the hatch lid with stainless steel screws. Method 2….You can attach the base plate to a piece of fibreglass and attach Velcro to the bottom of the plate and the hatch lid which makes the unit easy to store when in the surf zone. Method 3…. Fit a hatch lid which has the Fishfinder head built in. See them here STEALTH FISH FINDER HATCH LID

Dont forget if you would like to order a Fishfinder or GPS you can do so here FISH FINDERS Please feel free to contact us for any advice. If you are going to fit any Marine Electronics yourself please also contact us if you need any help.

Care of your unit

Once you have done all the hard work. Or we have done it for you, it is now time to take care of your unit. Salt water is a conductor of electricity so you must not drop the battery, head unit, power plugs in salt water or your unit will short, burn out or corrode quickly! Periodic spraying of your unit with Salt Away (to remove salt) and Dolphin Spray (electrical spray) will ensure many years of trouble free service. Forget to do this and your unit will fry! be warned!

Lowrance, Fish Finder, head unit, bracket,

Fish Finder head unit bracket

Lowrance, Elite4, Elite 4, HDI Kayak, Fish Finder, Sonar, South Africa,

Lowrance Elite4 HDI Kayak Fish Finder

Lowrance, Elite 4, HDI, Rear View,

Lowrance Elite 4 HDI Rear View

Kayak, Fishfinder, Velcro, Deck, Removeable, fitting,

Kayak Fishfinder Velcro Deck

Lowrance, Elite4, HD,I bracket,

Lowrance Elite4 HDI bracket

Lowrance, X4, X4 pro, Durban, South Africa, Kayak,

Lowrance X4 Pro Fish Finder South Africa

Lowrance, Fishfinder, Fish Finder, Durban, South Africa,

Lowrance Fish Finder

Map cards

A great benefit to a GPS unit or a combination unit is a map card from Navionics. You can buy them here MAP CARDS. There are various cards available right up to the platinum. See information and screen shots here MAP CARDS

I would also advise fitting a Fishfinder / GPS protective cover called a FISH FINDER COVER

In summary if you install your electronics correctly you will have hassle free Kayak Fishing. Get to know your unit so you are not messing about with it out at sea. Its much better to learn at home. Once you have made the decision to use a Fishfinder and GPS there will be no going back. Only upgrades as it will fast become your best fishing friend.

Tight lines


**** Please note this website is supported by products purchased from this website. Quite simply the more I sell the more I write and support the site. Codfather****



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