There is no definitive answer to this question as it depends on a number of factors, including the type of boat, the water conditions and the preferences of the captain and crew. However, some colors are more commonly used than others.
White is perhaps the most popular color for boats, as it is highly visible both during the day and at night. It also has a clean and fresh look that many people find appealing. Blue is another popular choice, particularly for larger vessels such as yachts. It has a calming effect and can help to blend in with the sky or water when viewed from a distance.
Red is often used as an accent color on boats, especially racing boats or those used for commercial purposes. It can help to make a vessel more visible in choppy waters or during bad weather conditions. Yellow is sometimes used for safety reasons, as it is one of the easiest colors to spot from a distance.
Ultimately, the best color light for boat will be dependent on personal preference and practical considerations. experiment with different colors to see what works best for you and your vessel.