What Size Anchor Do I Need?

The Jimmy Green Anchor Size Comparison Chart is compiled from individual manufacturer recommendation.

Anchor Size Comparison Chart
< 6 metres LOA6 - 8 metres LOA8 - 10 metres LOA10 - 12 metres LOA12 - 14 metres LOA14 - 16 metres LOA16 - 18 metres LOA18 - 20 metres LOA
Anchor Type< 1 tonne1 - 2.5 tonnes1 - 2.5 tonnes2.5 - 5 tonnes2.5 - 5 tonnes5 - 9 tonnes5 - 9 tonnes9 - 13 tonnes9 - 13 tonnes13 - 16 tonnes13 - 16 tonnes16 - 20 tonnes16 - 20 tonnes20 - 25 tonnes20 - 25 tonnes25 - 40 tonnes
Galvanised and Stainless SteelRocna4kg6kg6/10kg10kg10kg15kg15/20kg20/25kg25kg25/33kg33kg33kg40kg40kg55kg55kg
Vulcan9kg9kg9/12kg15kg15/20kg20/25kg25kg25/33kg33kg33kg40kg40kg55kg55kg
Mantus and Mantus MK 25.9kg5.9/7.7kg7.7kg11.4kg15.9kg15.9/20.5kg20.5kg25kg25kg29.5kg29.5/38.6kg38.6kg38.6/47.7kg47.7kg56.8kg70kg
Spade Galvanised and S/S6kg6/10kg10kg10/15kg15kg15/20kg15/20kg20kg20kg20/25kg25kg25kg30kg30/37kg37/44kg44/55kg
Ultra5kg5/8kg8kg8/12kg12kg12/16kg16kg21kg21kg27kg27/35kg35kg35/45kg45kg45/60kg60kg
Lewmar Delta4kg6kg6/10kg10kg10kg10/16kg16kg16/20kg20kg25kg32kg32kg40kg40kg50kg50/63kg
Lewmar Claw5kg5kg5/7.5kg7.5kg10kg10/15kg20kg20kg30kg30kg
Plastimo Britany6kg6/8kg8kg10kg12kg14kg16kg16/20kg20kg20kg
< 6 metres LOA6 - 8 metres LOA8 - 10 metres LOA10 - 12 metres LOA12 - 14 metres LOA14 - 16 metres LOA16 - 18 metres LOA18 - 20 metres LOA
Anchor Type< 1 tonne1 - 2.5 tonnes1 - 2.5 tonnes2.5 - 5 tonnes2.5 - 5 tonnes5 - 9 tonnes5 - 9 tonnes9 - 13 tonnes9 - 13 tonnes13 - 16 tonnes13 - 16 tonnes16 - 20 tonnes16 - 20 tonnes20 - 25 tonnes20 - 25 tonnes25 - 40 tonnes
AluminiumFortressFX7FX7FX7/FX11FX7/FX11FX11FX11FX16FX16FX23FX23FX37FX37FX55FX55FX85FX85
GuardianG7G7G11G11G16G16G23G23G37G37
Spade AluminiumA40A40A60A60A80A80A100A100A140A140A140A140A140A140A200A200
Lewmar LFXLFX4LFX4LFX4LFX4LFX7LFX7LFX10LFX10LFX15LFX15LFX21LFX21

Most anchor manufacturers publish a recommended weight of anchor by either the length overall or a combination of length, displacement and windage.

Some top manufacturers also include weather conditions and/or distinguish between monohulls and multihulls.

The top manufacturers are generally conservative and specify more criteria to help you make your selection.

The authority of each individual manufacturer recommendation may be judged by several factors: reputation, personal experience, research, the number of relevant factors that are taken into account, and the amount of detailed information that they publish on the subject.

The Jimmy Green Anchor Size Chart collates the recommended sizing for all the anchors that we offer on our website and highlights how similar the recommendations are.

Anchor Sizing Parameters by Manufacturer

Below we explain in more detail how the data for each individual anchor is presented and how it is collated into the Comparison Table above.

Galvanised and Stainless Steel Anchors

Rocna and Vulcan, Galvanised and Stainless Steel - Length and Displacement

Rocna/Vulcan recommend an anchor one size larger than indicated in their guide for multihulls

Quote from their Fitment Guide - ”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”

Mantus Mark 1 and 2 – Length, Displacement and Wind Speed

Mantus Quote - “we are generally referring to the needs of a cruising boat spending most of its time on anchor. In doing so we try to envelope high sustained winds (50 knots) and assume poor holding conditions (low viscosity bottoms)”

Mantus publish a chart in three categories – “Lunch Anchor category is recommended for lighter use, expected winds under 30 knots, working anchor for winds under 50 knots and finally, storm anchor recommendations are intended for winds above 50 knots”

N.B. The Jimmy Green Comparison Table is derived from the Mantus middle category

Spade Galvanised and Stainless Steel – Length and Displacement

Spade recommend an anchor one size larger than indicated in their guide for multihulls

Lewmar Delta and Claw – Length only

Lewmar guidelines are by length only, so you need to make a judgement regarding displacement i.e. light, average, or heavy compared with similar length yachts. If the answer is heavy, it is advisable to upgrade to the next size.

Plastimo Britany – Length only

Plastimo Quote – “Anchor weight per boat length is only given as an indication. However, your anchor selection should also recognise the specific construction of your vessel”

Aluminium Anchors

The concept of using a lightweight anchor goes against the traditional belief that weight is one of the most important factors in holding power.

Fortress Quote – “Fortress design does not depend upon weight to provide world class performance”

However, the most popular application for aluminium anchors is as a convenient, high holding power secondary or kedge anchor.

Fortress/Guardian – Length only

Fortress Quote – “Boat anchor size recommendations are for boats of average windage and proportions in 30 knots of wind, average bottom conditions, and moderate protection from open seas. Remember that the loads in 42 knots of wind are twice as much as in 30 knots”

Spade Aluminium – Length and Displacement

Spade recommend an anchor one size larger than indicated in their guide for multihulls.

Spade Quote – “Aluminium version not recommended for use as primary anchor”

Lewmar LFX – Length only