Transom vs. Thru-Hull Underwater Lights: Mounting Options Explained

Underwater lights come in two main mounting styles, and the right choice depends on your hull and how invasive you want the install to be.

Surface-mount (transom) lights

Surface-mount lights bolt to the outside of the transom below the waterline and require only a small hole — typically 1/2" — for the wire to pass through. The SeaBlaze X2 is a surface-mount light. Advantages: far simpler installation, no large hull penetration, and easier to add or relocate. For the vast majority of recreational boats, surface-mount is the practical, lower-risk choice.

Thru-hull lights

Thru-hull lights mount through a larger hole in the hull, sitting flush or near-flush. They can offer a very clean look and broad light spread, but require a significant hull penetration, more involved installation, and careful sealing. They're more common on larger vessels or new builds.

Which should you choose?

For most boats from 20–45 ft, surface-mount transom lights are the sensible pick: dramatic results, a tiny hole, and an installation many owners can do in an afternoon. That's the approach behind our SeaBlaze X2 Spectrum Transom + Control Kit — premium output with a simple 1/2" pass-through rather than a major hull cut.

Related reading: Underwater Boat Light Installation: What to Expect.