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Custom Marine Tanks for Boats Worldwide

Custom-made fuel, water and waste tanks designed to fit boats of all shapes and sizes. Built in New Zealand from strong, lightweight materials, with complete design, construction, fitting and plumbing available.

View our CE Certificate
Call 0800 788 265

CE 1521 – Our Diesel & Petrol Fuel Tanks are CE Certified and built to ISO 21-487.

Hercules Tanks designs water, waste and fuel tanks for boats of all shapes and sizes worldwide.

  • Fresh water tanks are made from polypropylene
  • Waste/Sewage Tanks are made from polypropylene
  • Fuel Tanks are made from polyethylene
  • Tanks baffled
  • Tanks thickness guaranteed
  • Tanks welded inside and outside
  • Tanks made in New Zealand
Marine diesel tank
Marine diesel tank
Marine waste tank
Marine waste tank
Marine fresh water tank
Marine fresh water tank
Marine diesel tank
Marine diesel tank
Marine water tank
Marine water tank

We can customise your boat tanks

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Marine Tanks

Frequently Asked Questions

Find answers about our custom marine fuel, fresh water and waste tanks.

Custom-Made to Fit

Every tank is designed around your space, capacity and application.

Proudly NZ Made

Locally manufactured using strong, lightweight plastics chosen for lasting performance.

Complete In-House Service

Design, construction, fitting and plumbing are handled by one team.

Get a price for your tank
Can you custom-make a marine fuel tank to fit the available space in my boat?

Yes. That’s the core of what Hercules Tanks does. Every tank we make is custom-designed and manufactured to fit the exact void in your vessel, whatever the shape or size. No shape is off limits with us. If you can draw it, we can build it.

We’ve built fuel tanks for boats of all types and have not found a shape or design we cannot make. We also ship worldwide, so location isn’t a barrier to getting a tank built to fit.

Yes. Hercules Tanks offer the full service from design through to manufacture and can assist with fitting and plumbing solutions as well. Everything is done in-house at our Katikati workshop in the Bay of Plenty, using our own custom-matched welding rods and locally sourced materials, so the same team that measures and designs your tank is the one that builds and can help install it.

We also proudly supply boat builders all around New Zealand that handle installations as well. We can recommend local installers in your area.

For fuel tanks, we build in HMWPE Polyethylene rather than metal. It’s lightweight, doesn’t corrode or rust, and is a proven, widely used material for fuel storage – it is also fully recyclable.

We manufacture our own matching welding rods in-house from the same plastic material.

Every joint is welded both inside and outside the tank for strength, and every tank is baffled to control fuel movement and manage weight distribution as it drains. Wall thickness is guaranteed to spec, and materials are sourced locally in New Zealand, making our tanks proudly New Zealand made.

Yes. Because we build to your measurements rather than off a standard mould, awkward spaces — underfloor, below-deck, in a bilge, or tucked around structural members — are exactly the kind of job we’re set up for. We work from a dimensioned order form (length, width, and height in millimetres, plus measurements to any inlet, outlet, or breather fitting) so the tank we build matches the actual cavity in your boat, not just a generic size.

HMWPE Polyethylene tanks have a strong track record in marine use precisely because they don’t suffer the corrosion and rust that eventually take out metal tanks in a saltwater environment. Our tanks are welded inside and out with guaranteed wall thickness and CE-certified pressure testing, which is aimed at giving you a tank that’s built to last the life of the boat rather than something you’ll be replacing again in a few years. If you want a view on expected service life for your specific application, it’s worth asking us directly — we can speak to that in the context of your boat and how it’s used.

Because every tank is custom-built, cost depends on size, shape complexity, fittings, and material. The best way to get an accurate figure is a free quote: fill out our tank order form (or send us your dimensions and fitting requirements) and we’ll come back with pricing for your specific job.

To get started, we need:

  • Tank type (boat, motorhome, caravan, or other) and its application (petrol, diesel, fresh water, grey or wastewater)
  • Overall dimensions in millimetres — length, width, and height, including measurements from the top, bottom, front, back, left and right of the space it needs to fit
  • The location and size of every inlet, outlet, and breather fitting

We use one order form per tank, and our team are happy to talk you through it by phone if you’re not sure how to measure your space — call 0800 788 265.

Boat owners in New Zealand can choose from petrol tanks, diesel tanks, and integral or portable tanks, made from either metal (aluminium, steel) or plastic. At Hercules Tanks, we manufacture custom petrol and diesel fuel tanks from high-density polyethylene (HMWPE) – a corrosion-proof alternative to metal that won’t rust, pit, get diesel bug or degrade in a marine environment.
Every tank is CE 1521 certified and built to ISO 21-487 standards, and we’re a Recognised Member of NZ Marine Industry Association.

See our recent work

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Hercules Tanks supplied diesel tanks to three of the race yachts.

Camper, Team Telefonica and Abu Dhabi, from a fleet of six vessels. The 2014-15 Volvo Ocean Race, Hercules supplied diesel tanks to all seven yachts of the fleet.

Hercules Tanks are the proud suppliers of all water tanks and battery boxes to Profab Central Engineering Ltd of Palmerston North.

"We have your fuel and water tanks in our Rapido 60 Trimaran, built by Triac Composites in Vietnam. The tanks are fantastic, especially as they are custom made to fit the available space. It’s great to have such NZ made quality."

Dougall Love Tweet

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0800 788 265
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