This is an example of a project that tends to find its own way during its execution. The boat was originally outfitted with courtesy lighting in the companionways, but we decided it was too bright at night, and we preferred a more subdued effect. The original impovement idea was to attach a dimmer circuit to the lighting so that we could change the brightness to match the mood of the moment. This called for the installation of a Blue Sea 12V@2A dimmer module.
As you enter the cabin, immediately to the starboard is the lighting switch unit. The left-most switch controls the cabin lights while the right-most switch controls the courtesy lights.
During the initial thought process of this project, I ran across a company that made LED replacements for the incandescant GE-563 light bulbs used in the courtesy lights. As long as I am making a concerted effort to improve things, I thought that I would carry the project to a new level and install LED lighting as well.
One issue with LED lighting is that compared to incandescant lighting, it is highly directional. Therefore, if you purchase replacement LEDs, you may be able to order the lights with a differnt orientation, depending on your desires. This was the case in my situation, and I purchased an orientation that would focus the light down. The cost of the replacement LEDs was about $12 each.
The LED replacement modules require about 100 milliamperes (0.1 Amps) each, and I am using three of them, so the load is less than the requirement of the incandescant lights, and well within the capacity of the dimmer module. The dimmer module requires the addition of a momentary switch to brighten the lighting, one momemtary switch to dim the lighting, and an on-off switch to turn the dimmer on and off. The two momentary switches can be consolidated into a single rocker switch - and in fact, one is available from Blue Sea.
As long as I am going to all this trouble..... I decided to make one additional improvement. The boat has exterior lighting for the outside deck above the Aft Cabin. Unfortunately, the switch for these lights is at the flybridge helm. Had this boat been equipped with a lower helm, then that would not have been a problem, since it is likely that a second switch would have been located there. However, lacking the lower helm, the only way to turn the lights on and off is to climb up to the flybridge helm and operate the switch. The obvious improvement would be to locate a second switch in the cabin.
Typically when you use two swiches to control lighting, you would rely on 3-way switches. This has an advantage of allowing either switch to turn the light on or off. A typical wiring diagram for a 3-way switch is shown below, and if you follow it, you will see that either switch can turn the lights on or off:
While this is a common method of lighting control, I will not be using this method for the project. Instead, I will be using what I am calling a "dual-sourced" circuit. The primary reason for this circuit is that the helm has its own breaker, which I usually leave off when the boat is not in operation. I just don't like the idea of having power applied when not necessary. Unfortunately, using a 3-way circuit would require the helm breaker to be on.
The dual sourced circuit will allow either switch to turn the lights on, but not necessarily off. For instance, if I did leave the helm switch on, the switch in the cabin could not turn the lights off - however, if I turn the helm breaker off, control of the lights reverts to the cabin switch. Essentially, the method here is that either switch can turn the lights on, but both switches must be off to turn the lights off.
I am using a double-pole switch for the lower switch for isolation. If I had wired both switches in parallel with SPST (Single Pole/Single Throw - or simple On/Off) switches, there could be a condition where I would re-power the helm by turning the lower switch on, if the helm switch was left on.
I have finalized the design I wish to use in the schematic below. You should be able to see three distinct circuits; one for the cabin lighting, a dimmer-controlled switch for the courtesy lighting, and one circuit for the deck lighting. The deck lights are powered by either the helm breaker or courtesy breaker, depending on the position of the switches. It always helps to draw a schematic before attempting to begin wiring. I always do, whether it be a simple or complex project.
The first challenge is to determine how to convert the courtesy light switch to a dimmer, and where to locate the switch for the deck lighting. The existing cabin and courtesy light switches are located adjacent to the entryway, so this is a logical place to put the deck light switch as well. The easy solution (assuming there is enough clearance space), is to rework the switch box for three switches. Although standard 120VAC resident wiring fixtures and switches were used in the original construction, the project is exclusively 12 VDC.
The sketch below shows how I plan on building a new switch box. I will use a standard plastic electrical box, cut the back off, and install a piece of Starboard, which will provide a base to mount the dimmer and wiring.
I could not find a suitable "Decora" type switch for the dimmer, so I will use a blank Decora panel and custom make one. The upper and lower pushbuttons will be momentary (i.e. they stay pushed in only as long as you push on them), while the center pushbutton will be push-on/push-off.
To keep the same box size, I also had to replace the left switch with a combo unit having a SPST and SPDT contacts. The top switch will be for the interior lights, and the bottom switch will be the new switch to the deck lights.
Construction begins with cutting the back from the electrical box. Be very sure you have removed all hardware and other metal objects from the box prior to cutting. The box should be one inch deeper than the depth of the switches. In addition, be sure the box you selected has a suitable mounting method after cutting, in other words, be sure you do not cut the mounts off the box. As an alternative, you may be able to find a pre-cut "low voltage" box typically used in home construction for stereo, home theater, and video purposes. Either box will work.
After cutting, the box gets fit with a piece of 1/2 in Starboard at the back, secured with sheet-metal screws from the box sides. You should have at least 1/2 in of clearance from the back of the switches after installing the Starboard.
The switches are installed on the front of the box, a terminal strip to the back, and the dimmer module adjacent to the box. Be sure that you check clearances so that everything will fit into the intended areas. The result is that everything is wired together in a neat/compact module.
The switch module is mounted to the sidewall panel board in the cabin - replacing the original box. The final wiring, including splicing into the deck lights is also completed at this point. I also added a molex connector so that I could easily remove the sidewall panel board in the cabin. Behind this board is the main wiring cableway to the bridge, so the panel does get removed occasionally.
Before the project can be called completed, we must replace the incadescant lights in the courtesy light housing with the LEDs. Note that the LEDs are polarized, so they only work in one direction. The particular LEDs I purchased have a diode that prevents damage should they be reversed. With these LEDs, if they do not work - simply reverse them. However, not all replacement LEDs may have this feature, so be sure you observe the correct polarity (positive and negative) when installing them.
After the LEDs are installed, the courtesy lighting fixtures are re-assembled. Now all that is left to do is to wait for the evening for a night-light test.
The final result is a very nice glow from the lights. One unintended advantage is that with incandescant lighting, as you dim the lights, the color of the light turns yellow. But with the LEDs, a more constant white light color is maintained throughout the dimmer's brightness range.
With the cabin sidewall panel board re-installed, the resulting modifications to the switch looks just about the same as the original, but with the advantage of both a dimmer for the courtesy lighting, and a switch for the deck lighting.
As I commented at the start of this article, this project just seemed to take on a life of its own. This continued until the last step. The manufacturer of the lighting fixtures just made available a chrome housing version. I used these on the exterior of the boat on deck to replace the yellowed light fixtures that had set out in the sun for 10 years.
While most of this project utilizes standard off the shelf electrical parts that can be found at any home improvement mega-store, the following components are harder to find, so I have provided a source for them: