I like an anchor light that hangs just above head height, either in the fore-triangle or over the cockpit. A light lower down like this illuminates some of the boats superstructure and is more likely to be seen by boats moving into the anchorage than is a masthead light. I don’t really care if my anchor light can be seen two nautical miles away, as required by the rules, I’m more concerned with being seen by boats operating in my immediate vicinity.
When we first went full time cruising we used a hurricane lamp as an anchor light. It did the job, it never blew out even in strong winds and we could easily recognize its warm glow amongst other boats in the anchorage. Later, we succumbed to the convenience of an LED anchor light.
The development of LEDs has been hugely beneficial to boats – we get the light without the big power penalty or fragility of incandescent lights – and this applies to anchor lights as much as it does to other navigation lights and interior lighting.
Some will be happy to stick with the masthead all round white light provided by the boat builder, but if you want an independent ‘hang-in-the-rigging’ anchor light there are several LED lights to choose from today, some good, some not quite so good – choose carefully.
The light can have its own battery or be powered from the ships electrical system, it may have a photocell to provide automatic dusk to dawn operation and it can incorporate downlighting to provide illumination in the cockpit.
The two main qualities I’d be looking for are watertight integrity and adequate visible range. To provide the first, when the manufacturers own efforts have proved inadequate, you can use silicone compression tape and sealant – the life of LEDs is such that you won’t need frequent access to change the bulb so seal the lens joint as well as the cable gland. For best visibility to other vessels I prefer a light focused through a Fresnel lens and, of course, an adequate light source – typically an 8 or 9 LED cluster.
A final word of warning that applies to all on-board LEDs – make sure they don’t use a voltage control system that interferes with VHF frequencies. This is particularly important if you fit a masthead LED light next to your vhf antenna. Losing your AIS targets or radio communication every time you switch on the navigation lights is a definite no-no.