Rocna Anchor Information and Sizing

By Olivier Onorato, Last updated: 6/9/2026

Key Takeaways: Rocna Anchors for Reliable Boat Anchoring

• Proven modern anchor design: Rocna anchors were developed by New Zealand sailor Peter Smith and are designed to improve setting reliability and holding performance compared with many older-generation anchor styles.
• Fast, controlled setting: The Rocna Original uses a roll-bar, setting skids, and a chisel-like fluke tip to help the anchor orient correctly and penetrate the seabed. Actual setting performance still depends on bottom type, scope, rode angle, boat handling, and whether the anchor is properly sized.
• Concave fluke for holding resistance: The Rocna Original uses a concave fluke intended to develop strong holding power once buried.
• Wind and tide shifts: Rocna anchors are designed to reset or remain engaged through changes in load direction, but boaters should still monitor the boat after a major wind or current shift, especially in crowded anchorages, soft mud, grass, rock, or reversing tidal areas.
• Vulcan option for modern bow configurations: The Rocna Vulcan removes the roll-bar and uses Rocna’s design. It is intended to fit a wider range of bow rollers, pulpits, bowsprits, and powerboat bow arrangements, but fit should always be checked against the boat’s roller, stem, pulpit, and windlass geometry before purchase.
• Shank strength and seabed penetration: The Vulcan uses high-tensile steel and Rocna’s patented I+V profile™ shank design to improve resistance to bending and help the lower V-edge cut into the seabed.
• Conservative sizing matters: Anchor sizing should follow Rocna’s current sizing chart and should account for boat length, displacement, windage, anchoring conditions, rode type, and intended use.
• Warranty limitations: Rocna offers a lifetime warranty, but warranty coverage is subject to Rocna’s terms and proper anchor sizing. Do not imply that the warranty covers misuse, incorrect sizing, poor installation, or every form of damage.
• Safe anchoring practice: A high-quality anchor does not replace good seamanship. Set the anchor under controlled reverse power, use adequate scope, confirm holding with bearings or electronics, allow for swing room, and re-check the set when weather, tide, or bottom conditions change.

Complete Peace of Mind

How many times have we been at anchor when the wind turns or blows harder than expected, and we find ourselves praying that our anchor will hold fast? Every boater wants the peace of mind that their anchor is going to keep them safe while they sleep, even if the weather changes dramatically.

After cruising for over 100,000 nautical miles, a New Zealand cruiser named Peter Smith felt sure he could build a better anchor than the options available – and he set out to prove it. Released in 2004, after years of testing and tweaking, the result was the Rocna anchor – the best multi-purpose anchor on the market.

What makes it work?

The biggest change Peter made from old-style anchors was the addition of a roll-bar, which helps the anchor turn over – positioning itself into the proper setting angle as soon as it hits the seabed. The Rocna also has setting skids (which keep it in the proper position while it's setting) and a sharp, chisel-like tip that cuts into the seabed, burying the anchor quickly and efficiently. In addition, a concave fluke gives the greatest holding power to secure your boat, even with a 360-degree wind shift, no matter what the seabed consists of. Lastly, the steel shank is designed so that the anchor self-launches and self-stows on the majority of bow-rollers.

Independent tests by publications such as Cruising World, Practical Sailor, and SAIL have all shown that this new-generation Rocna anchor consistently outperforms more traditional anchor designs in a variety of seabeds.

Striving for perfection – the Vulcan

While Rocna anchors have developed a near cult following with their users, there were still some boats that had difficulties accommodating the roll-bar design on their bow – particularly powerboats with a bow pulpit. So Peter got back to work on a new design, released in the beginning of 2015 – the Vulcan anchor - available in both stainless or galvanized. This new anchor capitalizes on already finely tuned design elements, infusing many of its elder sibling's proven performance advantages, while featuring a unique new combination of shank and fluke geometry. The biggest difference is what they call the roll-palm™ at the rear of the fluke. This feature allows the Vulcan anchor to self-right on the seabed without the use of a roll-bar. This is assisted by the V-bulb™ which extends the fluke ballast downward to gain maximum leverage and efficiency – that directly equates to more holding power and security.

The omission of a roll-bar along with a carefully designed shank profile allows for a snug fit on the bowsprits and bows of a widely expanded range of vessels. In addition to the use of high-tensile steel, shank strength is optimized by a unique I+V profile™ shank design, granting improved resistance to bending courtesy of a computer-optimized I-beam geometry. This not only makes the shank stronger, it also improves setting performance with a lower V edge, which cuts into the seabed and minimizes resistance to a deep and secure burial. To top it off, the new design still encourages self-launching and self-stowing upon retrieval on the majority of bow rollers – making life easier for boaters everywhere.

The theory is great – but does it really work?

We have quite a few employees that love to rave about their Rocna – one of them has definitely put it to the test. She and her husband are currently out cruising, having left in the fall of 2012 to circumnavigate. While home recently for a visit – she raved about how happy they were with their Rocna and told us the following story…

"While we have more stories than I'd like of when the Rocna has saved our bacon, the most recent one happened last October. We anchored in a great little bay in Fiji, but unfortunately, the winds turned overnight, which meant the anchorage was completely exposed to both the wind and the open seas. As the night progressed, the wind began to build and it was soon blowing 20-25 knots – directly into the anchorage. The chop also began to build, and by about 4:30 AM we were experiencing 4-6 foot waves in the anchorage. The boat was hobby-horsing like mad – we knew we had to get out of there – but we had to wait until there was enough light to navigate as Fiji (while beautiful) is poorly charted and has reefs everywhere.

To make matters worse, we were anchored just off a reef – so if we dragged, we would be in big trouble. For the next two hours the bow of the boat was crashing up and down in the waves – 4 feet out of the water one second and 2 feet below the water the next – it was complete madness. Finally, it was light enough out to raise the best anchor and move. Not only did our trusty Rocna hold us through an incredibly rough night – it also released easily just when we needed it to. We've been cruising now for three years, and I will not trust my boat to any other anchor. I highly recommend a Rocna anchor to anyone that plans to spend time on the hook in their boat."

Okay – I’m convinced – but will it fit my boat?

If you need help figuring out which model will best fit your boat, check out the full anchor dimensions for each size or the multitude of “boat fit cases” with photos and other information at the “Rocna Knowledge Base” – a great place to look for similar situations to your own, and also refer to our helpful sizing guide.

Sizing Your Rocna Anchor

There's a Rocna or Vulcan anchor to suit just about any vessel, including larger sizes. To choose the correctly sized anchor, find your vessel's length in the column on the left, then track across that row until you find the first column with a displacement (in tonnes) the same or larger than the displacement of your vessel. Once selected, follow the column to the top where the recommended Rocna or Vulcan anchor is indicated. For reference: 1 t (metric tonne) = 1,000 kg = 2205 lbs and 1 meter = 3.28 feet. The rows at the bottom of the chart give equivalent anchor weights in pounds and kilograms, recommended chain sizes, and fluke areas.

If your boat's weight falls in between two columns, it's best to give preference to the larger anchor model. In addition, a relatively high displacement or high windage vessel should consider choosing a larger anchor, while a smaller anchor may be more appropriate for especially light-displacement boats.

While this sizing may seem a bit conservative, Rocna's recommendations are designed to provide an anchor that can accommodate a wider range of vessels and is adequate for use in even the most challenging conditions.Calculations are based on 50 knots of wind, associated surge, and soft, moderate holding bottom conditions into which the anchor has set. For multi-hulls: use the chart as instructed, then select the model one size larger.

So if you want to sleep like a baby, even when it's blowing like stink outside, an appropriately sized Rocna will provide holding power in excess of what most manufacturers recommend in a wide variety of conditions. Still not convinced? Just walk down the dock until you find a boat with a Rocna on the bow and ask the owner if they're happy with their purchase. You'll be sure to get an earful of how the Rocna has helped them sleep peacefully at anchor.

Real-World Performance and Endorsements

The performance of Rocna anchors is not just theoretical; it has earned accolades from seasoned sailors across various conditions. Its high tensile steel construction provides exceptional holding power, allowing for reliable anchoring even in challenging seabeds, such as soft mud, kelp, and hard sand. Additionally, the anchor comes with a lifetime warranty, a testament to its exceptional quality. User endorsements highlight the anchor's ease of use and efficient retrieval mechanisms, making it a favored choice. The meticulously designed shank and roller ensure a snug fit on a broader range of boats, solidifying its reputation as the best anchor choice.

Related Products & Accessories

• Anchor rodes and chains
• Anchor shackles and swivels
• Anchor windlasses
• Anchor rollers

Frequently Asked Questions