In a typical sounder installation there are at least 3 wire-to-wire connections made in the wiring; one on the black wire and two on the red to facilitate the inclusion of a fuse. It is critical that these are kept high and dry. However the first step in insuring these connections are protected is to seal them securely. In the past we've used electrical tape sheathed in standard heat-shrink tubing. More recently we've started using heat shrink tubing that releases resin that seals around the wiring securely. Either way will work - whats important is to make sure the connections are securely sealed with not a single strand of wire exposed. Here's an example:
We generally aim to have the fuse holder secured underneath the top deck of hull somewhere close to the centre hatch. This makes it easy for the user to inspect the fuse in the event of power failure. The position of the fuse varies from model to model but in many cases we will use a 'P clip' secured under the rim of the hatch making use of on the holes created by the self-tapper screws that hold the hatch rim in place. We almost always use the screw point in the 3 o'clock position (the bow being 12 o'clock) on the starboard side. We start by removing the self-tapping screw and then drill out the hole so we can insert a thru-bolt screw.
The image below shows the P clip, thru-bolt screw and nut that we use (note - you'll want 2 of each of these, as we'll be performing a similar trick on the rear hatch):
Before securing the fuse holder underneath the hatch using this hardware we loop the wiring around the top end of the fuse holder twice and secure the loop with two cable ties. This helps to eliminate any tension from being applied to the wiring connections (for reasons that is about to become apparent).
The image below is an example of how we might go about securing the fuse holder underneath the hatch area.
In this position the wiring fuse holder is easy enough to access for inspection if required.
There are no wiring connections in the section of wire leading from where we've secured the fuse area to the sounder unit, so it's not as critical to keep this wiring clear of the bilge, though we still aim to keep that high and dry as well. We've managed to achieve the height and tension for the wire leading to the bow by cable-tying the wire up high to a scupper tube on route to the hatch area where we've coiled the excess power cord, as demonstrated in the three images below:
Now we get to the interesting part and where the phrase 'spring loaded wiring install' begins to make sense. It involves the length of wire leading from the fuse area to the stern where we are going to place the battery. We're going to create a suspension (or 'spring-loaded') segment in this section of the wiring, roughly in the central point between the center and rear hatch. It's not overly critical where the suspension section goes, providing it's not too close to the center or rear hatch. To create the suspension section we first need to tie two basic knots with the wire itself, roughly two feet apart. The knots don't need to be pulled terribly tight.
Then we're going to add a short length of bungee cord (3mm thick is ideal) of around a foot in length. Feed one end of the bungee cord through the eye of one knot and then secure it in place with a uni knot that acts as a stopper knot against the outer side of the knot the cord was passed through. Do the same with the opposite end to the other knot. If you've followed so far, you should end up with something that looks like this:
Before going any further it is best to prepare the rear hatch by removing a self-tapping screw, drilling out the hole and putting a thru-bolt screw in it's place using the same method we described before. Only this time instead of replacing the screw in the 3 o'clock position, you're going to replace the screw in the 12 o'clock position.
Now you'll want to run the wiring up to the rear hatch from the center hatch where its going to plug into the battery. We use flexible battens to do that but an old flexible fishing rod will also do the trick. Once we've got the plug at the end of the wiring up at the rear hatch we're going to secure it into place by passing the wire through the P clip and then attaching the P clip to the screw, securing that in place with the nut. But before you take this step take a moment to make sure the length is right, and here's where it gets a little tricky (and every kayak model is different). The aim of the game is to have the length set so that the the plug can be pulled out through the rear hatch easily, but still retract in neatly to the rim of the hatch.
Part of getting this right is in estimating roughly how much wiring you need to run from the fuse holder to the rear hatch and cutting it down to length (be careful not to cut it down too short - you need enough length to go from the centre to the rear hatch and allow for an extra 8 - 10 inches to allow for the retractable plug end). You can also adjust for length by making adjustments to the suspension section by increasing or shortening the distance between the knots. This is where it can get a little fiddly, but it's worth persisting by making adjustments as required to get the length about right.
Once you're happy with the length you can secure the wiring into place underneath the rear hatch like so:
You'll need to secure the P clip in place so that the eyelet allows the wire to pass through freely. Here's what it should look like from the top side:
If you've got the length and tension right, you should be able to pull it out at least 5 - 6 inches without there being too much tension, like so:
If the tension is too tight it will pull the battery holder out of whack when the battery is installed. It needs to be just taught enough so that the plug retracts to the rim of the hatch, and the wiring underneath runs up against the topside of inside the hull, like this:
With the battery installed the cradle should sit perfectly flat, as intended:
And you'll have the ability to remove the entire battery and holder for simple insertion and removal of the battery.
It is very good practice to lubricate the (female) plug with a good corrosive resistant lubricant regularly. Lanox, Inox and Inox+ are all good choices. Spray both ends of it: where the wires feed into the back of the plug, as well as the pins in the other end. You are well advised to do the same on the battery (male) plug. It is also a really good idea to do this to the plug and pins at the sounder itself as well. This regime of maintenance will go a long way to protecting wiring plugs and pins on the sounder unit from corrosion, as well as keep them lubricated to prevent them from getting gritty.