K6
Koster boats are unique designs adapted to the windy and notoriously demanding Skagerrak waters off the Swedish west coast. Their hulls are wide above a sleek waterline to generate initial stability but given their narrow waterline wetted surface is low so they allow for good speed in light airs.
The design of the K6 originally stems from a design competition held by the Göteborg sailing club SS FRAMto promote sailing as a family activity. The request was for 6m in length and 18 sqm sail area. The design should form a standard and it was referred to later as well as the 18 sqm regelbåt. Three design offices accepted the challenge. The criteria were to design, build and sail the three boats before choosing the winner. When each of the designs were built and tested in races against each other, in the summer of 1944, the Ohlson boat built by Carl-Eric Ohlson himself as an apprenticeship test proved to be the fastest. It became the Koster Association’s protype. The Malmsten brothers were interested and wanted to build a K6 each, with the requirement that their boats would be number 1 and 2. The Association agreed to this. Therefore, Carl-Eric Ohlson’s K6 became number 3. In the time following until th e1960s, 55 boats were built by yards across Sweden but serial numbers are not entirely correct as built # 4, 6, and 7 were wrongly assigned to K25s.
Boats differ somewhat as the initial ones up to #15 were planked in pine whereas later boats were planked in oak, always on oak frames. The interior was made from oak but was later changed to mahagony. Rigs were built in local spruce, though for the later boats, US-imports of knot-free spruce was used. The initial galvanized steel keel bolts were later exchanged to those from stainless steel.
During 2024 the keel was laid for a new boat by Anders Annell in his recently moved shop at Henån on the island of Orust, right in the epicenter of Swedish boat building since centuries. She is constructed over molds, lapstrake planked in oak from southern Germany, bronze fastened with sawn frames from grown crooks of oak and with deck of Douglas fir. The mast will be made from Sitka spruce. Keel will be cast-iron, with stainless steel bolts.
The K6 owners are organized within SKBF, the Swedish Koster Boat Association, who is organizing annual cup races on the Swedish West Coast. Areas where small fleets of K6s are based were Strömstad and now is Främnäs. Drawings belong to SS Fram and requests should be placed there.
Plans see veteranbatsarkivet: http://register.veteranbatsarkivet.se/IMG/MSF_3_62_12/25kvm_modifierad%20koster_1945_linje_spant.jp
