Anodes and saildrive wear: measure, then cross-reference

How marine diesel and saildrive anodes interchange (Tecnoseal, Martyr, Sierra). Use live clusters. Measure pencil zincs versus collars. Match thread pitch before you guess a model.

Anodes are marine wear items

A heat-exchanger pencil or a saildrive collar is marine hardware. It has broad aftermarket interchange. Tecnoseal, Martyr, Sierra, and others recast the same plug and zinc under their own SKUs. They also recast aluminium and magnesium versions. This page shows how to use those clusters.

Don't mix a 1/4 NPT pencil with an M8 stud. I only list numbers I've sourced. If your anode is missing here, measure it. Don't pick the nearest OEM from a photo.

Identify by geometry, then by OEM

Identify where it lives. Heat-exchanger end cover, engine block freeze plug, saildrive leg collar, or hull. Shapes differ.

Identify the thread or stud. Options include 1/8 NPT, 1/4 NPT, 3/8 NPT, 1/2 NPT, M8, split ring, or solid collar. NPT uses a taper pipe thread. A metric bolt uses a different thread.

Measure length and diameter of the wasting metal.

Identify the alloy. Use zinc for most salt water. Aluminium or magnesium use different SKUs (Martyr …A / …M, Tecnoseal …AL / …MG). Mixing alloys in one bonding group is a separate corrosion topic. Buy what the cluster specifies.

Pencil zincs: Universal / Westerbeke example (live)

Universal/Westerbeke 1/4 NPT pencil:

OEM Westerbeke 11885 / Universal 011885 (zero-padded BOM form)
Sierra 23-6400
Tecnoseal TEC-E0
Martyr CME0 (also listed against 11885)

Related: Universal 301069 (1/8 NPT, M12/M18/M25 family HX) → Sierra 18-6141. Universal UNI301068 is a 3/8 NPT × 1 in zinc on several M-series. That cluster is separate from the 1/4 NPT cluster.

I've graded these aftermarket rows confirmed. Still match thread with the hole in your exchanger.

Yanmar pencils and saildrive collars (live)

Engine pencil 119574-18790 → Tecnoseal 01317 (confirmed). Martyr CM119574-18790Z (likely).
Smaller HX pencil 119574-44150 → Tecnoseal 01318, BoatZincs E-1F (confirmed).
Intercooler-style 177301-54900 → Tecnoseal 01306 (confirmed).
Saildrive collar 196420-02652 → Tecnoseal 01305, Martyr CM19642002652Z (confirmed). Split-ring 196420-02651 is a different part (01305/1).

Don't order a solid ring because the diameter matched.

SP60 saildrive: cross-brand collar (live)

Technodrive / Twin Disc SeaProp 60 anode:

Twin Disc 209-00509 → Tecnoseal 02516, Martyr CMAR672Z
Vetus KGF60-95 → Tecnoseal 02516

Same aftermarket SKU, several marine badges. One physical anode, many OEM boxes. Beta/Nanni/Solé SP60 installations join this cluster when their OEM numbers are in equivalents. If I haven't got a row for your marque, I haven't sourced that OEM yet. Tecnoseal 02516 still fits the SP60 collar when the geometry matches.

How to use this page

Inspect the wasting metal. Waste rate depends on the marina. Buy the alloy the cluster specifies. These anodes are marine hardware. See marine-only parts.

FAQ

Can I use a hardware-store zinc bolt? Only if thread, length, and alloy match. Most hardware-store bolts miss at least one of those.

Why is my engine missing? No sourced row. Measure and contact with OEM PN if you have a catalogue.

Kits. Some Martyr/Yanmar kits bundle plug + anode. A bare Tecnoseal may assume you reuse the brass plug. Read the listing. I store part numbers. Kit contents live on the listing.

These numbers come from public and third-party sources. They can be wrong. Check against an official source before you order. Methodology · All guides.