Oval Plastic Drain Plug with Base 25 mm – Short & Long Versions + Spare Insert

This oval drain plug kit with base provides a complete solution for a fixed drainage point on your boat. It consists of an oval plastic flange base that screws onto the hull and a threaded inner plug (male piece) that seals the opening in the base. The drain opening sealed by this assembly is 25 mm in diameter – a common standard for many boat drainage systems.

Two body length versions are available to adapt to different transom or hull thicknesses:

• Short version (code 00923) – with an overall tube length of about 27 mm. It’s suitable for boats with a thin transom or single-skin hull where a long penetration is not needed. For example, some inflatable RIBs or small fiberglass boats have relatively thin transom boards, and this length is sufficient for those
• Long version (code 00923-1) – with an overall length of about 67 mm. This is intended for thicker structures – a solid wooden transom, a double-skinned hull wall, or insulated panels where the drain needs to go through a significant thickness. This version is often used on larger boats and yachts where the transom thickness can be several centimeters

Both versions have the same diameter and use the same inner plug, meaning the included spare plug (code 00923-2) fits either base. This spare insert is very handy – if during draining the main plug gets dropped overboard or damaged, you have a backup ready to use without needing to replace the entire assembly.

The base is made of white ABS plastic, which is weatherproof and UV-resistant, so it won’t yellow or become brittle easily from sun exposure. The flange has pre-drilled holes for screws – installation is straightforward, requiring only suitable stainless steel screws and sealant. Once installed, the oval shape of the base provides a smooth, low-profile finish over the opening, with no sharp edges to snag lines or toes. The inner plug features a rubber gasket (O-ring) that ensures a watertight seal when you screw it into the base.

Application and recommendations:

• Use this oval drain plug for standard transom drain holes – for example, draining a self-bailing cockpit, or emptying livewells/lockers in the stern. It can also be used on deck or hull drains where you want the ability to open and close periodically
• Short version (27 mm) is suitable for boats with thin transoms or single-layer hulls – ensure the total thickness at the installation point is less than the length of this plug so it can tighten properly
• Long version (67 mm) should be chosen if you need to span a thicker material. When installing in a deep transom, insert the base until the flange sits flush and check that the inner plug can thread in fully; if the wall is too thin for the long plug (meaning it sticks out too far inside), it’s better to use the short version to avoid excessive protrusion
• During installation, apply a marine-grade silicone or sealant under the flange and around the screw holes. This will ensure no water seeps in around the base when the boat is in rough water or rain. Use stainless steel screws to prevent corrosion
• Keep the spare plug in a secure place (for example, in a locker or tethered near the drain with a cord). If you ever remove the main plug to drain water and forget to put it back (or it falls out and is lost), the spare will save the day and prevent issues
• Check the plug’s gasket periodically – if the rubber O-ring becomes worn or stiff, replace it to ensure you always have a positive seal. The all-plastic construction requires minimal maintenance; just avoid striking or over-tightening the plug to prevent damage to the threads