Rocna Anchors Sizing Guide

There’s a Rocna Original, Rocna Mk II, or Vulcan anchor to suit just about any vessel – including larger sizes not featured here. To choose the correctly sized Rocna or Vulcan anchor for your boat, follow the chart and instructions.

Anchor Sizing Guide

To choose the correctly sized Rocna or Vulcan anchor, find your vessel’s length from the column on the left, then track across that row until you find the first column with a displacement (in tonnes or pounds) the same or larger than the displacement of your vessel. The top of the column with the selected displacement indicates the recommended Rocna or Vulcan anchor.

For Multihulls: use the chart as instructed, then select the model one size larger.

Use the tabs to navigate between Metric Tonnes (t), Short Tonnes (T), and Pounds (lb).

Rocna Original/Vulcan Sizing

Rocna Mk II Sizing

(*) Classification Rules Sizing

Rocna anchors from size 110 kg (243 lb) and above may be sized based on classification society Rules for Ships for SHHP anchors. Modern rules permit a mass 33% lighter than HHP types, or 50% lighter than “standard stockless” types. Anchor sizing is based on a vessel’s separately calculated Equipment Number (EN). For more information, please consult the Rocna Knowledge Base articles on our sizing recommendations and Classification and Certification.

Our Anchor Sizing is Conservative

Unlike other manufacturers, our anchor sizing recommendations are intended to provide an anchor adequate for use in most all conditions. We base our calculations on 50 knots of wind, associated surge, and poor holding bottoms. For more on our philosophy and rationale, please consult our Knowledge Base article on our sizing recommendations.

This chart is a guideline only, so if you’d like further information please enquire with us for further advice.

The Rocna 150 (331 lb) and Larger

We do not provide standard recommendations for boats larger than those for which the Rocna 110 (243 lb) would be the recommended size. This is because of increasing complexities of the factors involved.

Furthermore, classification society rules and/or legal requirements are likely to dictate the anchor sizes mandated for these vessels.

Rocna and Vulcan Anchor Bow Compatibility

To confirm that which Rocna or Vulcan anchor will fit your vessel, there are a number of resources below to assist you.

Rocna Anchors Dimensions

Measurements important to the fitting of the anchor on a bow roller are reproduced on this sheet. Using these drawings and a tape measure, many boaters can easily determine that a Rocna or Vulcan will fit their boat.

Visit our Rocna Anchors Dimensions Page or Download as PDF here:

Rocna Knowledge Base

The Rocna Knowledge Base features a large and ever-growing collection of “boat fit cases”, with photos and other information, under Rocna bow compatibility. Popular production boats are covered, and examples of other owners of your boat type successfully fitting a Rocna or Vulcan will allow you to invest with confidence.

Also included are articles and recommendations on the topic of custom bow roller assembly design.

Which Will Fit Best, Rocna or Vulcan?

Rocna anchors are intended to fit well on most vessels. The Rocna Mk II offers improved clearance vs the Rocna Original at the shank-end and the roll-bar. The Vulcan is specifically designed to fit a wider range of vessels with the omission of a roll-bar to clear anchor platforms, bowsprits, or prods.

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