Strategic Underwater Lighting: Best Placement For Boats

Underwater lights are a great way to add some flair to your boat. They can be used to light up the water behind the hull, increasing visibility and safety, as well as creating a stunning visual effect. While they are not necessary, they can enhance your boating experience, especially if you enjoy boating at night or spending evenings docked at the marina. These lights are usually installed in the boat's transom below the waterline, ensuring they don't cause drag or turbulence when the boat is in motion.

There are two main types of underwater lights: thru-hull and surface-mount. Thru-hull lights are typically used on larger boats and require drilling a circular hole in the transom. They are brighter and offer a wider range of lighting options but may be more expensive and complicated to install. On the other hand, surface-mount lights are ideal for smaller boats and only require drilling small holes for the power cord and mounting screws. They are generally more affordable and easier to install but may have limited brightness due to their smaller size.

When choosing underwater lights, consider factors such as colour, brightness (measured in lumens), beamwidth, and additional features like fading, strobing, or emitting multiple colours. It's also essential to select lights designed for prolonged use in marine environments and to ensure they comply with safety regulations.

Surface-mount lights

Location:

It is recommended to mount the lights about one-third of the way in from each side of the boat. This provides a good balance and ensures the lights are not too close to the edges. However, make sure to select a location that is flat and avoid any seams in the gel coat.

Interference:

Be sure to choose a location where the lights will not interfere with the boat's equipment. Check for any surf tabs, and ensure the lights are positioned high enough so that they won't be blocked or cast shadows when the tabs are actuated.

Access:

Select a location that provides easy access to the bilge. You may need to remove any necessary items or panels to gain access to this area. This will make the installation process easier.

Drilling:

Before drilling any holes, thoroughly inspect the interior and exterior of the boat. Choose a reference point, such as the exhaust port, to verify where the drill will break into the bilge. Use a drill template to mark the holes, and always protect the drilling point with masking tape to avoid chipping.

Wiring:

Plan the wiring route in advance. Typically, the wires are run up the starboard side of the boat, as most helms are located there. Ensure the wires are secured with cable ties and protected with sealant to prevent water seepage.

Surface-mount underwater lights offer a convenient way to enhance the aesthetics and functionality of your boat. By following these guidelines, you can ensure a smooth installation process and enjoy the benefits of underwater lighting on your vessel.

Drain plug-mounted lights

There are a variety of drain plug-mounted lights available on the market, offering different features and benefits. Some products offer remote control functionality, allowing users to control the lighting from a distance. Others boast smart cooling systems and anti-corrosion properties, ensuring the lights remain durable and effective even in challenging environments.

The brightness and colour of drain plug-mounted lights are also worth considering. Blue lights are ideal for saltwater as they travel the farthest distance, while green lights are better suited for freshwater environments. White lights are perfect for attracting fish, and red lights make the water appear more vibrant.

When choosing drain plug-mounted lights, it is essential to consider the size of the drain plug on your boat. Most lights are designed to fit standard 1/2" or 1" drain plugs, but it is always important to check the measurements before purchasing. Additionally, some lights may require additional adapters or splitters to accommodate different types of drains, such as plastic drains.

Overall, drain plug-mounted lights offer a convenient and effective way to add underwater lighting to your boat without the hassle of drilling holes. With a range of colours, brightness levels, and additional features available, you can find the perfect set of lights to suit your specific needs and preferences.

Thru-hull lights

To install thru-hull lights, you will need to haul the boat to remove and replace the lights. First, carefully measure and mark the light's centre position on the outside of the boat with a pencil. Check inside the boat to ensure there are no structural members, wiring, or anything else that could impact the placement. Double-check your measurements, then drill through the hull. Use a hole saw to cut the hole, using the smaller hole as a guide for the drill bit. Clean up any rough spots around the hole with sandpaper, then wipe the hole and the inside of the transom with acetone to remove any residual dirt and grease. Brush on some epoxy resin to seal the edge. Once the epoxy has dried, feed the cables into the hole and test fit the light. Remove the light, then use a scraper to remove any antifouling inside the line back to the original gel coat. Wipe the scraped area with acetone to remove surface contaminants, then feed the cables back through the hole. Apply a bead of adhesive sealant around the flange of the light and press it into position. On the inside of the boat, screw on the retaining nut, then route the wires and connect them to a suitable switch or breaker.

Interchangeable thru-hull lights can be serviced (removed and replaced) from inside the hull with the boat in the water. The hole for these fixtures' stems is larger, so this type is installed on larger powerboats. Most thru-hull fixtures include an external driver box to operate the LEDs efficiently on DC and AC voltages. When mounted on a metal hull, they require an isolation sleeve to protect the hull from galvanic corrosion. These fixtures need to be attached to the bonding system of the vessel. Interchangeable thru-hull lights are designed for transom, side, and bottom mounting.

The brightness of underwater LED lights is measured in Lumens. The beam angle of the light determines how the beam appears around the hull. Lights are available in Narrow Spot (less than 90°) or Wide Flood (greater than 90°), which produce an even glow of light and allow lights to be spaced further apart on the hull.

Light placement

• Mounting Options: There are two main mounting options for underwater lights: surface mounting and thru-hull mounting. Surface mounting is often used for smaller powerboats and sailboats, requiring only small holes for power cables and mounting screws. Thru-hull mounting, on the other hand, is typically used for larger powerboats and requires drilling larger holes in the hull.
• Transom or Hull: Underwater lights can be mounted on the transom (the vertical section at the rear of the boat) or along the sides of the hull below the waterline. Surface-mounted lights are commonly placed on the transom, while thru-hull lights are usually transom-mounted.
• Beam Angle: The beam angle of the underwater light determines the spread of light around the hull. Narrow Spot beam angles are less than 90 degrees, while Wide Flood beam angles are greater than 90 degrees. Wide Flood beam angles allow for more even lighting and enable spacing lights further apart on the hull.
• Lighting Purpose: Consider whether the lights are primarily for fishing or aesthetic purposes. For fishing, lights mounted on outrigger spreaders or under the hull can attract bait and fish. For aesthetics, focus on lighting up the water behind the hull or creating a visually pleasing effect.
• Boat Size: The size of your boat will influence light placement. Smaller boats may opt for surface-mounted lights to avoid drilling larger holes, while larger boats can accommodate thru-hull lights for increased brightness.
• Water Conditions: Different colours of lights perform better in different water conditions. Blue is popular for its peaceful ambiance and works well in a wide range of water conditions, especially saltwater. Green is suitable for freshwater, especially in silt-laden water or inland waterways. White is ideal for shallow, sandy bottoms and attracting fish.
• Safety and Regulations: Ensure that your underwater lights comply with safety regulations and do not interfere with navigation. The U.S. Coast Guard COLREGS state that decorative lights should not be mistaken for navigation lights, impair the visibility of navigation lights, or interfere with the operator's ability to maintain a proper lookout.
• Maintenance and Access: Place lights in areas where you can easily access them for installation, servicing, and maintenance. Consider the proximity to exhaust outlets and existing penetrations. Also, ensure that the lights are not positioned too close to the bottom or submerged objects to avoid accidental impacts.
• Lighting Effects: If you plan to use lighting effects, such as fading, brightening, or strobing, consider placing lights in locations that enhance these effects. For example, spacing lights further apart can create a unique lighting display.
• Wiring Considerations: Be mindful of wiring when placing lights. Avoid running wires over the transom, and ensure you have access to the power cable and fittings inside the boat. Consult a certified marine technician if you're unsure about wiring.

Light colours

The light colour you choose for your underwater boat lights will depend on the water conditions and the purpose of the lighting. Blue light travels farthest in saltwater, making it the most enjoyable colour in a wide range of water conditions. Blue underwater lights are illegal in some places, however, so be sure to check local ordinances before installing them. Green light works well in silt-laden water or on inland waterways, while white light is best for attracting fish and is well-suited over shallow, sandy bottoms. Red light makes the water come alive.

If you want to be able to switch up the colour of your underwater lights, multi or colour-change lights with limitless colour options are available. These lights can be adjusted to match the water conditions, fishing patterns, or simply your mood.

Frequently asked questions