This time round I thought I'd change tack a little to build on forum members' interest in technical literature relating to diving equipment. I am going to dedicate this thread to three National Standards (German, Russian and Malaysian) prescribing specifications for swimming fins, exploring the similarities and differences between each of them.
1. Deutsche Institut für Normung(October 1980) DIN 7876. Tauch-Zubehör: Schwimmflossen. Maße, Anforderungen, Prüfung. Berlin/Cologne: Beuth Verlag. Available for purchase from http://www.beuth.de/en/standard/din-7876/865285
This German Standard, subtitled with the official English translation "Diving accessories for skin divers; Flippers, dimensions, requirements and testing", is no longer in force and just 3 pages in length.
Scope: The Standard excludes long-bladed "competition fins" but includes both full-foot fins (Form A) and open-heel fins (Form B).
Dimensions: The bulk of the Standard is devoted to the dimensions of full-foot and open-heel fins. The two key measurements are the maximum length and width of the footspace provided by the fin:
In the above diagram, they are designated as "Fußlänge" (foot length) and "Fußbreite" (foot width) and measured in millimetres. In the case of an open-heel fin (Form B) with a foot length of 250 mm, the fin would be labelled "DIN 7876 - B 250".
The Standard provides a table, based on the Mondopoint shoe-sizing system, with a recommended foot-pocket width for each foot-pocket length. The first three rows of the table are reproduced below:
So, for a foot length of 160 mm, Form A fins are recommended to allow 55 to 65 mm of foot width, while Form B fins with the same dimension are recommended to have a minimum of 30 mm foot-length adjustability in the heel strap and between 93 and 120 mm in the length of the foot pocket.
Material: The Standard covers fins made from either rubber or plastic.
Safety and Testing: The Standard stipulates that wherever the fins comes into contact with the feet no protruding edges should be in evidence. In the case of heel straps, they should be adjustable and retain their settings when wet; a 10-minute pull test was prescribed to confirm this specification.
Marking: The Standard required any fins complying with its specifications to be marked with the name or symbol of the manufacturer, distributor or importer, alongside the Foot length (FL) and Foot width (FB) in millimetres. Here is a real-life example of this practice:
The marking indicates that these Italian-made Marina Delfino Pro rubber full-foot fins have a foot length of 275 mm and a foot width of 105 mm. Although they claim to comply with the requirements of DIN 7876, the corresponding foot width range for foot length 275 mm in the German Standard's table is 110-115 mm, so the foot pocket is a little on the narrow side!