Overview

The Hella Marine 178560281 is a 24V 10W incandescent festoon replacement bulb with an SV8.5-8 base in an 11 x 41 mm size. It’s the style used in many traditional navigation light and interior lamp fixtures that take spring-loaded festoon end caps.

This is a straightforward drop-in bulb for 24V DC onboard systems. Match the base style and overall length to your existing lamp, then you’re back to full function without changing the fixture or wiring.

Key features

• 24V, 10W incandescent festoon bulb (6429 type) for 24V DC electrical systems
• SV8.5-8 end-cap base with 11 x 41 mm overall size for common festoon holders
• Clear bulb that outputs white light through your existing lens
• No polarity concerns and no external driver or electronics
• Useful spare to keep onboard for quick restoration of navigation or interior lighting

Compatibility and fit

Confirm three things before ordering: system voltage (24V), festoon base style (SV8.5-8), and the physical size (11 x 41 mm). If your fixture is 12V, a 24V bulb will be noticeably dim, so voltage match matters just as much as length.

Festoon holders vary by a few millimeters and by how the spring contacts grab the end caps. If your current lamp sits tightly between the contacts and clears the lens, this bulb is the right format.

Installation and setup

Switch off power at the panel, let the existing bulb cool, then remove it by compressing one spring contact and lifting the bulb out. Seat the new bulb evenly between both end contacts so it can’t rattle loose in chop or vibration.

On exterior fixtures, check that the lens and gasket are clean and seated after replacement so spray and washdowns stay out of the housing.

Use on board

This bulb makes sense for boats running classic festoon-based navigation lights or interior lamps on 24V systems, where you want a direct replacement that keeps the original look and beam pattern through the fixture’s lens.

What’s included

• 1 x replacement bulb