Fish finders, part 2.

Hi all,
This is part 2 to getting that fish finder up and running on your kayak.
Since that last post we will assume you have bought your fish finder.
I chose the Raymarine Dragonfly 4, which is a combined unit with a plotter and fishfinder in it.
As said in the previous post it has a bonded screen so it will never fog fog up even in direct sun light.
I have heard some concerns about these units having high power consumption rate , but mine runs for 2 long days fishing on a 12v 7ah battery. Which is what most of us use. It is basically a battery from a house alarm. Can be got from most electrical retailers. Should cost less than E20.00

The actual fitting of the fish finder. 
So fitting a fish finder couldn't be easier. No drill bits need or cutting holes in your pride and joy.
At the moment I am paddling a trident 13, which has a sonar shield in front of the tackle pod.
A very handy piece of kit. Here is mine on the Ocean kayak 13.

So for this kayak all you need is 3 stainless steel screws and screw it to the front of the sonar shield.
You do this so you and mold the head unit down as much as possible for a surf landing.
Once I had done that I plugged the unit in and brought the wires and transducer out and under the hatch lid. No holes needed as the Ocean kayak hatch lid has an over lap meaning you bring wires under without much fear of water getting.
To secure the wire I unscrewed one of the hatch strap fixings and secured the wire under it.

So how easy is that, ANSWER, VERY.
Please use a a screw driver and not a cordless drill or you could over tighten the screw and ruin the fixing.
So that's done, what about the transducer.
Well on the Raymarine dragonfly it has a very long transducer.

In fact it is so long that I find it hard to get it to stay on the hull. I have fixed it on with good puraflex with the hull flexing when tying to the roof rack etc. It knocks it if again. But with this unit I found out by mistake that if you just sit it upright in the hull it works fine. Excluding the chirp the transducer really needs to be outside the hull to work at it's best.

Siting your transducer .
Ideally your transducer should be fitted to the hull with a generous blob of good adhesive/silicone.
I use puraflex as it is reasonably priced at about E8.00 and has great holding power.
So adhesive at the ready you want to place the transducer as close to the seating position as possible. Reason being it will be under the water all the time and less likely for air bubbles to interfere with the image on the screen.
Saying this it is easy done on a trident as the center hatch makes access to the hull very easy.
In a standard kayak I would just place the transducer as far back as you can reach from the forward hatch.
There is no magic in fixing the transducer. Just cut the nozzle well back on the tube of adhesive and put nozzle to spot you want your transducer to be and squeeze at least half the tube out in one big blob. Making sure there is no air bubbles int it.
Once you have you big blob done just press the transducer into the adhesive and rock it back and forward until it is pushed well into it. It normally  doesn't make any odds if the sides are covered. So don't worry to much about that.

Power supply.
This is the one that causes the most problems in the long term. If you can get a hold of stainless spade connectors they would be great, other wise you have to replace you connectors at least once a year.
I have spent mad money on connectors and they were not worth the money. So I have gone back the way and will be using this version in the future. This is a socket from an old PC. plus the plug from the power lead makes a great power plug and socket. The one below is for a different application. But the one on my battery box below is off an old kettle. The plug and socket seem resistant to corrosion for now. So all good so far. Best of all there free,

The one below is from an old kettle. As you can see the standard screws are rusting and the socket is like new. 

This box is not water tight but will do for inside the kayak. A sandwich box would be a better choice if your doing surf landings as you may get some water in the hull.

The trident 13 has battery bag up in the front of your kayak so you can just slide the box inside it.

Not the tidiest looking but it does the job.

Things to be careful with.
There are a few things you really have to watch out for with a fishfinder on a kayak.

1. Never ever leave your battery connected when the fish finder is not in use. Meaning when the kayak is lying in the garden or on the car roof. Moisture and the power from the battery will totally destroy the plug connection in a short period of time. As little as one will destroy some units plugs.
2. Always have an inline fuse. Connected up wrong once could be enough to ruin a unit.
3. When putting the unit head away be sure the plug is not lying in water when not in use. 
4. Always keep your head unit indoors when not in use. Damp garages and sheds are very hard on any electrics.

So I hope that makes your install cheap and easy. A total install cost should be no more than E15.00 including adhesive and battery box.
Good luck with your install and I hope this helped you with your install.