I was working on a boat recently, and I found that someone had installed the anchor windlass control relay inside the anchor locker. Now, I really have to wonder why anyone would do something this stupid. It leaves the anchor windlass system completely vulnerable to corrosion, and the chances that the relay will fail is almost 100%, given the exposure the relay has to salt water spray on an ocean-bound sailboat.
A better idea would have been to install the relay on the inside of the forward cabin, and run just the power wires for the windlass out to the locker. The connector for the windlass switch could have also been mounted through the bulkhead with minimal additional work, and it would leave the wiring safely inside the boat’s forward cabin. This would have increased the reliability of the anchor windlass with very little effort.
Unfortunately, the small amount of effort it would take to avoid such lousy installations decisions seems to be beyond most of the people doing work on boats. Some generally good ideas are:
Electrical equipment should not be in exposed locations unless absolutely necessary.
For instance, the windlass needs to be in the locker, but there’s absolutely no good reason to have the control relay there. Terminal blocks and such should be covered to prevent accidental electrical shorts.
Equipment should be as accessible as possible.
The more often the piece needs to be used, the more accessible it should be. Burying the seacock for the engine cooling intake under the engine, where you have to have three joints in your arm to reach it isn’t a great idea, especially if you want to close the seacock every time you leave the boat. Now, there are some constraints imposed by the design of the boat, the need to have hoses run reasonably short and straight, and things like that, but in most cases, access can usually be improved.
Label equipment, wires, hoses, and switches as clearly as possible.
You’d be amazed at how many boats have almost no labeling of any sort on anything. So troubleshooting the systems become a real task. A few minutes with a roll of white electrical tape and an ultra-fine tip Sharpie marker goes a long way to making troubleshooting and maintenance much simpler.
Using color-coded cable ties can also make tracing wiring a lot simpler. They’re now available in a wide variety of colors, and getting a bulk pack of a few different colors can make things a lot easier for you in an emergency.
Use as few connections as possible in wiring runs and installations.
On one boat I saw a few months ago, I don’t think a single circuit had fewer than five or six connections in it. If you can minimize the number of connections used in wiring a boat, the wiring will be both more reliable and simpler to troubleshoot. This is also true of plumbing connections.
Eliminate color changes in wiring if at all possible as well.
On the boat I previously mentioned, in some cases, the wiring changed colors at the connections and there was no real rhyme or reason to the changes in color. If you keep the wiring the same color throughout the circuit, it makes troubleshooting it far simpler. I would also recommend using YELLOW for the 12 VDC ground wires rather than BLACK. BLACK is also used for 110 VAC hot wiring, and it is far safer to work on a boat if the 12 VDC ground wires can not be mistaken for 110 VAC hot wires.
Leave yourself some slack in hoses/wires/lines for future changes.
If you cut everything exactly to length, you can often run into problems if you have to make a small change in the future. Leaving a foot or so of extra wire on each end can make small modifications or repairing broken connections much simpler in the future. This goes for plumbing as well. It can also apply to lines used on a sailboat, but not as often.
Try to group things logically.
For instance, don’t run 110 AC wiring with the 12 VDC wiring (this is also against ABYC code IIRC).
Run hoses and wires as directly as possible, given the constraints of the boat’s build and interior.
This can save money and reduce weight, since shorter runs of wire can result is weight savings, since the shorter a wire is, the smaller diameter it generally can be.
Use the right equipment for the job.
For example, don’t install ball valves onto through-hulls, where there will be a thread mismatch. Use a proper flanged seacock and backing plate instead. It will be more reliable, easier to repair, and safer generally speaking. This is true of most things. It is also generally less expensive in the long run to do it properly and once, rather than having to go back and repeat efforts and waste time to repair something that wasn’t done properly to begin with.
I hope this helps you avoid some problems when doing work on your own boats.