{"product_id":"sierra-18-6129z-zinc-anode-kit-volvo-penta-duoprop","title":"Sierra 18-6129Z Zinc Anode Kit | Volvo Penta DuoProp","description":"\u003cp class=\"nvn-hero\"\u003eThe Sierra 18-6129Z is a complete zinc anode kit for Volvo Penta DuoProp sterndrives running in salt water. You get the bar anodes, trim ring, and mounting screws in one matched set. Zinc corrodes first so your drive doesn't. It's cheap insurance against very expensive gearcase and prop corrosion, and swapping it at haul-out takes just a few minutes.\u003c\/p\u003e\n\n\u003cdiv class=\"nvn-description\"\u003e\n\u003cp\u003eIf you run a boat with a Volvo Penta DuoProp sterndrive in salt water, this Sierra 18-6129Z zinc anode kit is one of those small parts that quietly saves you from very expensive repairs. Zinc anodes are sacrificial. They corrode first so your drive housing, gearcase, and props don't. And on a DuoProp drive, where you've got two counter-rotating props and a lot of expensive machined aluminum sitting in the water, staying on top of your anodes is just smart seamanship.\u003c\/p\u003e\n\u003cp\u003eThis is a complete kit, not a single piece. You get the bar anodes, the trim ring, and the mounting screws all in one box. That matters because the DuoProp anode system works together. The trim ring protects the trim and steering area of the drive, and the bar anodes cover the lower housing. Buy them piecemeal and it's easy to end up with a gap in coverage. Here it's all matched and ready to bolt on.\u003c\/p\u003e\n\u003cp\u003eSierra builds these to meet or exceed the original equipment part they replace, so the fit and the alloy are what you'd expect from a drive anode. The zinc is cast for a consistent burn, which means it erodes evenly instead of flaking off in chunks and leaving bare spots. Even erosion is what you want. It gives you predictable protection and a clean surface to inspect each time you haul out.\u003c\/p\u003e\n\u003cp\u003eWhy zinc here? Zinc is the traditional choice for salt water, and this kit is built specifically for saltwater service. In salt, zinc gives you a reliable sacrificial metal that protects the drive across a full season. If your boat lives in fresh water, zinc isn't the right alloy, so this particular kit is one to skip for lake use. But for coastal cruisers, offshore fishermen, and anyone keeping a boat on a saltwater mooring or lift, it's exactly what the drive wants.\u003c\/p\u003e\n\u003cp\u003eFitment is the thing to nail down before you order. This kit is made for Volvo Penta DuoProp hydrodynamic drives. Those drives went through several revisions over the years, so the smart move is to check your drive model and serial number against the anode locations on your unit before you install. DuoProp systems changed the anode layout across generations, and matching the kit to your exact drive is the difference between a five-minute swap and a return trip to the parts counter. If you're not sure which drive you've got, the serial tag on the drive housing tells the story, and we're happy to help you sort it out.\u003c\/p\u003e\n\u003cp\u003eInstallation is straightforward if you've done any drive service before. Pull the old, spent anodes, wire-brush the mounting surfaces down to clean bare metal so you get good electrical contact, and bolt the new anodes and trim ring on with the supplied screws. One tip from the field: hit those mounting screws with a marine anti-seize before you torque them down. Anode screws sit in salt water all season and they love to seize. A little anti-seize now saves you drilling out a stripped fastener next spring. And never paint over an anode. Paint insulates it and kills the protection.\u003c\/p\u003e\n\u003cp\u003eHow often should you replace them? For most saltwater boats, once a year is the rhythm, timed with your annual haul-out or bottom job. But don't just go by the calendar. Pull the boat, look at the anodes, and if they're more than about half gone, replace them. Anodes that are heavily eroded aren't protecting anything anymore, and a DuoProp gearcase is far too costly to gamble on a worn-out kit. Keeping a spare on the shelf is cheap insurance.\u003c\/p\u003e\n\u003cp\u003eOne last note. Drive anodes protect the drive, but they're one part of a whole galvanic protection plan. If your boat sits in a slip with shore power or shares water with other boats, you'll want hull anodes and any shaft or trim-tab anodes in good shape too. Think of the whole underwater package, not just the drive. Get all of it right and your Volvo Penta running gear will give you seasons of trouble-free service.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul class=\"nvn-features\"\u003e\n  \u003cli\u003eZinc alloy sacrificial anodes cast for a consistent, even burn in salt water\u003c\/li\u003e\n  \u003cli\u003eComplete kit includes bar anodes, trim ring, and mounting screws in one matched set\u003c\/li\u003e\n  \u003cli\u003eEngineered for Volvo Penta DuoProp hydrodynamic sterndrives\u003c\/li\u003e\n  \u003cli\u003eBuilt for saltwater service, protects the drive housing, gearcase, and props from galvanic corrosion\u003c\/li\u003e\n  \u003cli\u003eBolt-on installation using the supplied mounting screws\u003c\/li\u003e\n  \u003cli\u003eSierra parts meet or exceed the original equipment anode they replace\u003c\/li\u003e\n  \u003cli\u003eTrim ring protects the upper trim and steering area while the bar anodes cover the lower housing\u003c\/li\u003e\n  \u003cli\u003eSacrificial design corrodes first so the expensive drive components don't\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cdiv class=\"nvn-trust\"\u003e\n  \u003ch2\u003eWhy Buy from NVN Marine\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eAuthorized Sierra Marine reseller, full manufacturer warranty\u003c\/li\u003e\n    \u003cli\u003eNMEA member and ABYC certified, advice from real boat techs\u003c\/li\u003e\n    \u003cli\u003eSame-day shipping before 3 PM ET on in-stock items\u003c\/li\u003e\n    \u003cli\u003eNY headquarters and Fort Lauderdale flagship retail store\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"nvn-faq\"\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat does the Sierra 18-6129Z anode kit fit?\u003c\/summary\u003e\n    \u003cp\u003eIt's built for Volvo Penta DuoProp hydrodynamic sterndrives. Those drives changed the anode layout across generations, so check your drive model and serial number against your unit before ordering to be sure it matches.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhy zinc instead of another alloy?\u003c\/summary\u003e\n    \u003cp\u003eZinc is the traditional sacrificial metal for salt water, and this kit is made specifically for saltwater use. If your boat lives in fresh water, zinc isn't the right alloy for that job.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat's included in the kit?\u003c\/summary\u003e\n    \u003cp\u003eYou get the bar anodes, the trim ring, and the mounting screws. It's a complete set, so you're not hunting for the pieces separately.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should I replace the anodes?\u003c\/summary\u003e\n    \u003cp\u003eFor most saltwater boats, once a year at haul-out is the rhythm. Don't go strictly by the calendar though. If the anodes are more than about half eroded, replace them.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eIs this only for salt water?\u003c\/summary\u003e\n    \u003cp\u003eYes. This kit is a zinc alloy built for saltwater service. Fresh water calls for a different anode metal.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow do I install it?\u003c\/summary\u003e\n    \u003cp\u003eRemove the old anodes, wire-brush the mounting surfaces down to clean bare metal for good electrical contact, then bolt on the new anodes and trim ring with the supplied screws. Never paint over an anode.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eShould I use anti-seize on the mounting screws?\u003c\/summary\u003e\n    \u003cp\u003eIt's a good idea. Anode screws sit in salt water all season and can seize. A little marine anti-seize on the threads makes next year's swap painless.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eDo drive anodes protect my whole boat?\u003c\/summary\u003e\n    \u003cp\u003eNo. Drive anodes protect the drive. If your boat sits in a slip or on shore power, you'll also want hull anodes and any shaft or trim-tab anodes in good shape.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow do I know the anodes are working?\u003c\/summary\u003e\n    \u003cp\u003eHealthy anodes erode evenly over the season. If they look untouched after months in salt water, that can point to a bad ground or bonding issue worth checking. If they're nearly gone, they need replacing.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eAre Sierra anodes as good as the original equipment part?\u003c\/summary\u003e\n    \u003cp\u003eSierra builds these to meet or exceed the OEM anode they replace, using cast zinc for a consistent, even burn.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable class=\"nvn-specs\"\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003eTitle\u003c\/th\u003e\n\u003ctd\u003eSierra 18-6129Z Zinc Anode Kit for Volvo Penta DuoProp Drives\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003ctd\u003eSierra Marine\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eManufacturer Part Number\u003c\/th\u003e\n\u003ctd\u003e18-6129Z\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eUPC\u003c\/th\u003e\n\u003ctd\u003e808282315641\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eAnode Material\u003c\/th\u003e\n\u003ctd\u003eZinc\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eRecommended Water Type\u003c\/th\u003e\n\u003ctd\u003eSalt Water\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eApplication\u003c\/th\u003e\n\u003ctd\u003eVolvo Penta DuoProp Hydrodynamic Drives\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003ePart Type\u003c\/th\u003e\n\u003ctd\u003eSterndrive Anode Kit\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eKit Includes\u003c\/th\u003e\n\u003ctd\u003eTrim Ring, Bar Anodes, Mounting Screws\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eMounting Hardware\u003c\/th\u003e\n\u003ctd\u003eIncluded\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eProtection Type\u003c\/th\u003e\n\u003ctd\u003eSacrificial Anode\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eSold As\u003c\/th\u003e\n\u003ctd\u003eComplete Kit\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n    \"@context\": \"https:\/\/schema.org\",\n    \"@type\": \"FAQPage\",\n    \"mainEntity\": [\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What does the Sierra 18-6129Z anode kit fit?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"It's built for Volvo Penta DuoProp hydrodynamic sterndrives. Those drives changed the anode layout across generations, so check your drive model and serial number against your unit before ordering to be sure it matches.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Why zinc instead of another alloy?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Zinc is the traditional sacrificial metal for salt water, and this kit is made specifically for saltwater use. If your boat lives in fresh water, zinc isn't the right alloy for that job.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What's included in the kit?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"You get the bar anodes, the trim ring, and the mounting screws. It's a complete set, so you're not hunting for the pieces separately.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How often should I replace the anodes?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"For most saltwater boats, once a year at haul-out is the rhythm. Don't go strictly by the calendar though. If the anodes are more than about half eroded, replace them.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Is this only for salt water?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Yes. This kit is a zinc alloy built for saltwater service. Fresh water calls for a different anode metal.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How do I install it?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Remove the old anodes, wire-brush the mounting surfaces down to clean bare metal for good electrical contact, then bolt on the new anodes and trim ring with the supplied screws. Never paint over an anode.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Should I use anti-seize on the mounting screws?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"It's a good idea. Anode screws sit in salt water all season and can seize. A little marine anti-seize on the threads makes next year's swap painless.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Do drive anodes protect my whole boat?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"No. Drive anodes protect the drive. If your boat sits in a slip or on shore power, you'll also want hull anodes and any shaft or trim-tab anodes in good shape.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"How do I know the anodes are working?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Healthy anodes erode evenly over the season. If they look untouched after months in salt water, that can point to a bad ground or bonding issue worth checking. If they're nearly gone, they need replacing.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Are Sierra anodes as good as the original equipment part?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Sierra builds these to meet or exceed the OEM anode they replace, using cast zinc for a consistent, even burn.\"\n            }\n        }\n    ]\n}\n\u003c\/script\u003e\n","brand":"Sierra Marine","offers":[{"title":"Default Title","offer_id":45071889236061,"sku":"2009153","price":49.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0299\/7266\/0317\/files\/ImageServerAPI_a6508547-b510-4c70-85ae-07b8e07a8c43.jpg?v=1789726095","url":"https:\/\/nvnmarine.com\/products\/sierra-18-6129z-zinc-anode-kit-volvo-penta-duoprop","provider":"NVN Marine","version":"1.0","type":"link"}