Due to common sense any very long and slender boat is a skerry cruiser. In fact, it is a boat type that originated from the Skerry Cruiser Rules agreed upon in Stockholm in 1908. These rules were fundamentally revised in 1916, 1920, and finally in 1925, and have remained in effect ever since. A look back at the invention of the skerry cruiser, a look at the key steps leading up to the relaunch in 1925.
Different names, one boat type
This globally unique boat type has many names. First, there’s the Swedish Skärgårdskryssare, Finnish Saaristoristeilijä, Dutch Scherencruiser, and in English Skerry Cruiser, Square Metre Boat, Square Metre Yacht, or Square Metre Class. In German, it’s called Schärenkreuzer. This is confusing because a cruiser is generally understood to be a comfortable boat for relaxed sailing. As the above photo of the 55 m2 boat Sonja from 1920 with a length-to-beam ratio of 15 to 2 meters shows, it is less so.
When the Skerry Cruiser was chosen for racing in the Stockholm skerries after several years of research, the goal was to find a boat type that could easily navigate the countless islands of the archipelago. This is best achieved by sailing close-hauled zigzagging through narrow passages between the skerries like a sewing machine.
Many Square Metre Boat types
Then there are all sorts of abbreviations for the numerous archipelago cruiser classes, such as A 22, A 30, B 15, B 22, M 15, M 22, M 25, Sk 15, Sk 22, Sk 30, S30, 15er, 22er, 30er, 40er, 55er, 75er, 95er, 120er, and 150er. In Germany during the 1920s, the 40 m² archipelago cruiser was called a racing cruiser. Forty-eight were built in the German Reich between 1920 and 1925. The English refer to the 30 m² class as a Thirty Square. Adding to the confusion are all the cruising versions. These are merely compromises based on the original, designed for family-friendly and comfortable cruising, and therefore, strictly speaking, not true archipelago cruisers. Now, after this initial clarification of terms, let’s take a look at the history and development of the classic archipelago cruiser, from its invention in 1908 to the final version of the archipelago cruiser regulations in 1925, which remains valid today.
The 1908 Skerry Cruiser Rules
After several years of exploratory talks, a committee of the Swedish Sailing Federation proposed two boat types with 30 and 50 square meters of sail area for regatta sailing in the Stockholm archipelago in the autumn of 1907. Unlike previous regional building regulations, these proposed boats would disregard length and limit only sail area. The proposal was discussed—and debated—at several meetings with Finnish and Gothenburg sailors the following winter. The idea was controversial, and the creation of the Skerry Cruiser was not straightforward. Thus, Karl Ljungberg, Professor of Strength of Materials at the Royal Institute of Technology in Stockholm and a member of the influential sailing club KSSS, took the reins. The fathers of the Skerry Cruiser were: C.A. Hellstrand, engineer and board member of the KSSS; Albert Andersson, boat designer and engineer; Axel Nygren, boat designer and engineer; Hugo Schubert, boat designer and engineer; August Plym, boat designer and engineer; John Carlsson, master glazier and well-known sailor in the KSSS; Knut Bovin, bank director and board member in the KSSS; Max Wibom, landowner; Arvid Rosengren, engineer and canoe designer; Karl-Einar Sjögren, postman, boat designer and one of Sweden’s best sailors.
On January 21, 1908, the Skerry Cruiser Rule was proposed for an initial seven sail area sizes of 30, 45, 55, 75, 95, 120, and 150 square meters, supplemented by some construction regulations, a minimum displacement, and minimum cabin sizes. On February 22, 1908, the 22-square-meter class was added, and the Swedish Sailing Federation initially approved classes up to 55 square meters. In the spring, the first Skerry Cruiser, Älfvan, was rigged.
In 1913, two more types followed: the 15 and 38. The larger 75, 95, 120, and 150 models were now officially recognized. The hulls became longer and more elegant, acquiring the elongated, V-shaped bow typical of archipelago cruisers. The sterns initially remained short and wide.
First rule change in 1916
On November 1, 1916, the minimum displacement and hull thicknesses were slightly increased, and the 38 and 45 sq m classes were replaced by the 40 sq m archipelago cruiser. Finnish designers such as Zake Westin, Gösta Kyntzell, and Gustaf Estlander focused on length, while in Sweden, Erik Salander and the brothers Tore and Yngve Holm were prominent in this trend. The First World War had brought fortunes to some fortunate individuals in Sweden, and they sailed the popular archipelago cruiser class. Ambition led to extreme designs. At the end of the 1910s, the significantly more efficient Bermuda rig, with its long, continuous mast, prevailed over the gaff rig. The mainsail acquired its elongated, bird-wing-like shape. This made it excellent for sailing in the archipelago.
Länge läuft: Die Entwicklung der Schärenkreuzer – Aus: The World of Square Metres, S. 17
Second Amendment 1919/20
As the table for four 55 m² archipelago cruisers shows, the boats became quite long within five years, while their beam decreased. The Sonja shown above is a full two meters wide at 15 m in length. Such a hull offers little resistance in light winds and heels considerably in 3-4 Beaufort winds.
Boat
Year of construction
Length
Beam
Length/Beam ratio
Eva
1915
12,60 m
2,35 m
5,4 : 1
Nerida
1916
13,33 m
2,30 m
5,8 : 1
Lila
1919
13,65 m
2,13 m
6,4 : 1
Sonja
1920
15 m
2 m
7,5 : 1
Following the rapid development, in November 1919, greater hull thicknesses and slightly increased displacement were agreed upon. The so-called “suitcase measure,” an imaginary rectangle within the boats with its lower edge at the waterline, was intended to enforce greater beam. Finnish designers, in particular, complied with the rule change by using folded hulls. The boats remained long and extremely wide.
The repeatedly amended construction regulations made life difficult for the sailors. The classes even started separately based on the rule changes. What had been a convincingly simple idea had become a battle of materials and a complicated affair. This could not continue. Professor Karl Ljungberg considered the matter. As the following drawing shows, the hull was now measured at different heights, so-called horizontal planes. The crucial length measurement is determined a few centimeters above the waterline (horizontal plane 0), horizontal plane 1. Its height above the waterline is specified for each of the nine archipelago cruiser classes, from the 15 (13 cm) to the 150 (39 cm). See row 8 of the table below. In horizontal plane 1, one of the three width measurements (b1) is also determined.
So wird jeder Schärenkreuzer-Rumpf seit 1925 vom weltweit zuständigen Schwedischen Dachverband (SSKF) vermessen – Svenska Skärgårdskryssare Förbundet (SSKF), Übersetzung: Internationale Vereinigung der 30 m2 Schärenkreuzer Klasse
The Third Amendment, in Effect since 1925
The third amendment to the Skerry Cruiser rule is so significant that it represents a complete reboot of the class. Put simply, the length was cleverly linked to other dimensions. This curbed the rapid development of the class. The length is measured slightly above the waterline of the standing boat. Since 1925, longer Skerry Cruisers, and therefore faster boats, have been permitted. This advantage comes at a price:
a longer keel with a larger wetted surface area
increased displacement
greater beam, now determined by a sophisticated system based on the so-called mean beam
greater freeboard, resulting in correspondingly more wind resistance and weight
Die mittlere Breite wird in den Höhen b0, b1 und b2 am Hauptspant gemessen – Svenska Skärgårdskryssare Förbundet (SSKF)
A wider and heavier boat with a larger wetted surface area, propelled by the same sail area, is only advantageous in strong winds. Otherwise, it is a disadvantage. This rule change brought an end to the rapid development of the 40-square-meter Skerry Cruiser in the German Reich. After 48 boats of this type had been built in Germany alone within just a few years, no new 40-square-meter boats were built after 1926. A new boat would have been slower than the old ones. The 22- and 30-square-meter Skerry Cruisers, on the other hand, still benefit today from real regattas with comparable boats, where sailing skill is more important than the boat itself. Professor Karl Ljungberg’s revision of the Skerry Cruiser rules was a major achievement.
It is available as a 47-page PDF in English on the website of the Svenska Skärgårdskryssare Förbundet (SSKF) with a single click. It delights us with a beautiful and impressively durable class of boat. For decades, archipelago cruisers have been passed down from generation to generation and sailed with endless enjoyment. In 1930, the sail height was limited, and in 1935, the minimum freeboard was raised by a few centimeters.
Tabelle mit Grenzmaßen der neun Schärenkreuzer-Klassen vom 15er bis 150er des Schwedischen Schärenkreuzer Verbands (SSKF)
Further reading/sources
The world of Square Metres. The Square Metre Rule – 100 years. Facts, History, and Reports from all over the Globe. Svenska Skärgårdskryssareförbundet (SSKF), Stockholm 2008, ISBN 978-91-633-3069-8 (English): Craig Dalgarno ↑ page. 6ff., Bo Bethge ↑ page. 8ff., Olle Madebrink ↑ page. 18ff.
Per Thelander: Alla våra Skärgårdskryssare, Svenska Skärgårdskryssareförbundet (SSKF), Stockholm 1991, 160 Seiten (Swedish), secondhand, ISBN 91-970902-1-2. ↑ Chapter Regeln och des utveckling, page 11ff.
The information for this article is largely based to the aforementioned chapters in the excellent books Alla våra Skärgårdskryssare and The World of Square Metres. The above photo by Wolf Hansen shows the 55 Square Metre Boat Sonja at the Schlank & Rank Regatta. Published October 29, 2025, updated October 29, 2025.→ Subscribe to the newsletter here, and you won’t miss future articles.
