I must respectfully disagree with Bob, or note that it is more complicated that that. Abstracted from e-mails from Karl Andersson years ago:
A vessel at anchor must show an all-around white light (visible from 360-degrees like the light Bob lists), but NO red or green. If you see a white light, and a red or a green (or both), that vessel is underway. Kayaks move so slowly, it is hard for any other boater to tell that we are *not* at anchor.
What about red and green sidelights? These are tightly regulated, and each must show an arc of light at exactly 112.5 degrees, from straight ahead to just past abeam. The white stern light must be 135degrees. Hmmmmm- 112.5+112.5+135= 360! Unfortunately, the red and green lights that are available for kayaks are often of very poor, if not illegal, intensity, more often they are illegal in their arc. And on top of that, it is written in the law, and should be obvious, that any light that compromises your ability to have a proper lookout (night vision!) is also illegal.
So you need a bright light (visible over 1 mile at minimum). You cannot shine the light at the other vessel in such a way that it is in the eyes of the other boater (see last paragraph - illegal).
"I have found that one of the best ways to use your Bright Light, is to first show it in such a manner to indicate to the other boater that something is up (don't just turn it on, move it a bit. In ripply water, with city lights, a single light is very hard to distinguish). Next, show it over your foredeck. Any other boater with some height greater than ours can see your size, and most important, your heading. If you need to signal intent with a course change, showing your initial heading by illuminating your foredeck, then changing course and immediately illuminating your new heading, is remarkably helpful."
Most important advice - be aware, anticipate the other boaters, and avoid areas where they are common.
Here is the general rule for manually powered boats less than 23 feet in length for night lighting.
"These vessels should exhibit a white light visible for 360° around the horizon and visible from a distance of at least one mile away if operating on natural lakes, Corps of Engineers impoundments, border rivers, or impoundments on inland rivers. If this light is partially obscured due to the nature of the vessel, an additional white light must be on hand to be shown in sufficient time to prevent a collision."
Here is a link to the one I purchased from REI, there are other similar lights available on the market. https://www.rei.com/product/722830/paddlers-supply-company-led-kayak-deck-light-with-suction-cup-base
Hope that helps,
I have a headlight.
I don't know anything about kayak lights for night paddling. Please suggest,
inform, guide, help.
with constant appreciation,
Oregon Ocean Paddling SocietyPortland, Oregon