National Standards for Basic Gear: Fins

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National Standards for Basic Gear: Fins

Sun Sep 21, 2014 7:09 am

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official English translation "Diving accessories for skin divers; Flippers, dimensions, requirements and testing", is no longer in force and just 3 pages in length.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:
Dimensions.jpg

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:
Table.jpg

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:
$T2eC16h,!)cE9s4PvnR+BQ7YYOtz0Q~~60_57.JPG

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!
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Re: National Standards for Basic Gear: Fins

Sun Sep 21, 2014 1:44 pm

I appreciate how you take the Road Less Traveled approach to your topics. Thanks for the information.
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

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Re: National Standards for Basic Gear: Fins

Sun Sep 28, 2014 6:36 am

Thanks, Bryan! Right, second instalment: The Russian National Standard for fins, which dates from the Soviet era:
Image
2. Standards Publishing House (1977) Межгосударственный Стандарт ГОСТ 22469—77. Ласты резиновые для плавания. Общие технические условия. Moscow: ИПК Издательство стандартов. The full text of the Standard can be found without cost as GIF images at http://vsegost.com/Catalog/81/8131.shtml

This 1977 Soviet, and now Russian, International Standard, subtitled with the official English translation "Swimming rubber flippers. General specifications", remains in force to this day. It is 7 pages in length. Its specifications continue to be applied to rubber swimming fins made in Russia and Ukraine.

Types, basic parameters and dimensions: A rubber fin should consist of a blade and a foot pocket. Type A rubber fins have shoe-like foot pockets, while Type B fins come with straps and other fixtures. Fins should be produced to fit foot sizes from 26 to 47 in European sizing and from 165 to 305 in Metric sizing (millimetres). Each pair of rubber fins must have a size range corresponding to three adjacent shoe sizes (e.g. Metric 165-175 corresponding to EU 26-28).

Specifications: Fins must meet certain requirements for tensile strength (strap only), hardness (blade minimum 60, shoe maximum 45, strap maximum 45), elastic rebound (38%), maximum change in hardness during ageing in air (5%) and maximum change in mass after exposure to sea water (2%). Fins should have a density of 0.95 to 1.30 g/cm³. The rubber compound used to make the fins must be approved by the Ministry of Health. The fins must be made either in a single colour, two contrasting colours or in marbled colours. Single-colour and contrasting-colour fins allow mismatch without adversely affecting the appearance of the product. A maximum figure is set for defect tolerance, namely surface bubbles, cavities and indentations, sharp edges, projections and burrs after trimming.

Acceptance rules: Covers quality assurance procedures, including frequency and randomness of product sampling, for evaluating hardness, rebound elasticity, tensile strength and material density.

Test methods: Visual checks of fins for defects, which are measured with a ruler and a caliper. Visual checks of sizing, labelling and packaging. Tests conducted for hardness, rebound elasticity, change in hardness during ageing in air and change in mass after exposure to sea water. A device was proposed to test the rebound elasticity of a fin blade:
Device.jpg


Marking. Packaging. Transportation and storage: Fins are to be embossed with the manufacturer's trademark, the product name, the size and the name of this Standard, while a technical control stamp is to be applied to the rubber fins with indelible ink to mark the date of manufacture (quarter, year). The packaging is to be marked with the following information: name and trademark of the manufacturer; name of the fins; size of the fins; number of pairs of fins; manufacturing date (quarter, year); designation of this standard. Each pair of fins is to be wrapped in paper or placed in a polythene bag or in boxes and then packed in wooden crates, or cardboard boxes, gross weight not exceeding 40 kg. In city traffic, fins should be transported in cardboard boxes, with every four boxes wrapped in a strip of cardboard and tied with twine. Crates with fins are to be stacked on a flat tray. Rubber fins may be carried in any kind of covered vehicle. Rubber fins should be kept packed in a room where the temperature is between 0 and 25ºC at a minimum distance of 1 m from any heat-emitting devices and should not be exposed to sunlight, oil, gasoline, and other substances that deplete rubber.

Warranty: The manufacturer shall ensure that fins comply with this standard, including the conditions of transportation and storage. The warranty period for rubber fins shall be one year from the date of sale to the retail network, and in the case of non-market consumption, from the customer taking delivery of the product.
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Re: National Standards for Basic Gear: Fins

Sun Sep 28, 2014 7:19 am

I thought I'd add my comments and some explanatory illustrations in a new message as this is a very "wordy" Standard of 1977 from the country that gave us the lengthy classic "War and Peace". As for the content, you can see that the specifications are much broader than those found in the German Standard DIN 7876 of October 1980, including as they do criteria for testing the chemical and mechanical properties of the fin materials. I am particularly amazed, however, at the detail given for the transportation of the fins, not just the packaging of each pair in a polythene bag but the prescribed methods for boxing, crating and paletting of batches of fins and the special arrangements for transporting them through city traffic. :)

Here is an example of the marking on a pair of Soviet-era Russian-made Del'fin (Dolphin) fins:
lasty_delfin_23417896_3_F.jpg

Note how the price (7 roubles, 20 kopecks) is embossed on the sole, followed by the metric size (285-295, corresponding to EU 44-46 or US 10-12) and the GOST Standard Number 22469—77. Here is an image of several Del'fin marbled fins, which are still made by Moscow's Alphaplastic company, which also manfactures medical equipment:
20010792_2.jpg

The fins have very soft foot pockets and are sometimes used by competitive finswimmers to "cool down" after using stiffer bifins and monofins. Some people even cut out the heels to turn the fins into open-heel fins or they cut off the blade to use the remaining foot pockets on home-made monofins. Russian websites give step by step instructions for such procedures.

Finally, I mentioned that GOST 22469—77 is an international standard applicable to manufacturers in Ukraine as well as the Russian Federation. Here is an example of the marking on a pair of Soviet-era Akvanavt (Aquanaut) fins made by Kievguma in the Ukrainian capital:
443851358.jpg

Notice how these fins too are marked with their price (8 roubles 50 kopecks) as well as the metric size 265-275 (EU 41-43, by the way) and the Standard number GOST 22469—77. For anybody who is curious, here's a picture of a pair of Akvanavt fins:
aquanavt01.jpg

As you can see, Russian and Ukrainian full-foot fins come with closed toes. So did the GDR (East German) full-foot fins "Naiade":
$(KGrHqF,!oEFIs1zt3VNBSMLWoZbVg~~60_58.JPG


Hope the above is some interest!
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Re: National Standards for Basic Gear: Fins

Sun Sep 28, 2014 9:24 am

I wonder what the medal looks like for being on the Fin Committee :)
Those marbled fins are ugly...I guess if I ever decide to make fins the plans for the testing jig is available. Great post as usual David! This is the type of information that keeps folks coming back to the forum. Thank you
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

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Re: National Standards for Basic Gear: Fins

Mon Sep 29, 2014 12:52 am

Awesome post David, thank you! As a guy who loves casual fin swimming, I appreciate it. I am always on the hunt for that perfect pair of fins.
The impossible missions are the only ones which succeed. -JYC

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Re: National Standards for Basic Gear: Fins

Sun Oct 05, 2014 12:14 pm

Thanks, Bryan and Ron! OK, for the third and final instalment, we’re moving to South East Asia: the Malaysian National Standard for fins, whose first version dates from 1985 and whose first revision was published in 2002:
MS974a.jpg
MS974b.jpg

3. SIRIM (1985) Malaysian Standard MS 974:1985: Specification for rubber swimming fins. Selangor, Malaysia: Standards & Industrial Research Institute of Malaysia. Malaysian Standards can be purchased at http://www.msonline.gov.my/

The first, 1985, edition of MS 974 is 12 pages in length, while the second, 2002, edition of the Standard is 10 pages long. Both are entitled “Specification for rubber swimming fins.”

Scope: The Standard applies to rubber swimming fins used in underwater swimming by “free divers, body surfers and swimmers.” They are further categorised as full-foot and open-heel types. “Heavy duty” scuba diving fins are excluded.

Classification: This establishes that two different natural rubber compounds are to be used, a stiff one for the blade and a soft one for the foot pocket. The difference between full-foot and open-heel fins is elaborated.

Dimension and tolerance: Foot size, blade length and thickness are by agreement between the manufacturer and buyer.

Quality: This section covers appearance (the smoothness of the outside and inside surfaces and colour matching); material (use of natural rubber compounds, softer for the foot pocket, stiffer for the blades, need for comfort and easy movement); physical requirements (tests for bending, strap strength, permanent set of heel portion, corrosion resistance).

Sampling: Examination of random samples.

Test methods: Describes tests for appearance, ozone, bending (range of movement in water to be 50º), strap strength test (for open-heel fins), permanent set (soft part of fin pocket or strap stretched to 200% of original size), corrosion resistance test (applies to metal buckle) and hardness (use of an indenting ball).

Marking: Fins to be marked with foot size, code to show year of manufacture, name or trade mark of producer.

Compliance: If samples prove satisfactory, the lot, batch or consignment is deemed to comply with the Standard.

Appendices: Appendix A duplicates the foot length to foot width ratio found in the German Standard DIN 7876, while Appendix B relates to “crack variation and classification” in fins.
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Re: National Standards for Basic Gear: Fins

Sun Oct 05, 2014 12:53 pm

As usual, I'm appending a message about examples of the Malaysian Standard in practice, but first I should mention the significance of Malaysia in the history of fin production. From the 1980s, the production of rubber fins was largely outsourced to Asia and South America. Mares sent their rubber fin moulds to Turkey, while Cressi sent theirs to South America. In the Far East, first Taiwan and then Malaysia moved in to meet demand for rubber fins in the snorkelling and swim training market. Malaysia focused on full-foot fins with shorter blades, advantaged by its position in the natural rubber production industry. Here are two examples of an early Voit fin made by their Malaysian manufacturer in their DF100 and DF300 styles respectively:
Voit-DF100.JPG

Pro_Black.JPG

I recall purchasing a pair of Voit DF300-style Malaysian made fins at a "The Finals" store on a visit to New York. They fitted me perfectly and gave me good service when I snorkelled.

One of the consequences of the "Marking" section of the Malaysian Standard is the dating of fin manufacture to a particular month, e.g.
Df500.jpg

The number at the centre and the dots in the "petals" of the "daisy wheel" above on the sole of a DF500 Malaysian-made fin indicate that the fin was manufactured in September 2011.
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Re: National Standards for Basic Gear: Fins

Sun Oct 05, 2014 6:39 pm

David,

An unusual and informative topic. :shock:
Kim,
Ocean Trekker, Dangerous When Wet.
"Rules are for the obedience of fools and the guidance of wise men" Douglas Barder.

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Re: National Standards for Basic Gear: Fins

Sun Oct 12, 2014 6:14 am

Thanks for the acknowledgement, Kim.

If we compare the three national Standards for fins, we can see that although there is some overlap in the ground they all cover (e.g. the importance of eliminating sharp edges in the foot space), there are many differences too. While the German Standard focuses mainly on the dimensioning of foot pockets, the other two have much more to say about the properties of the material used to make fins. The Russian Standard is perhaps the most attentive to detail of the three, providing copious information about packaging and transportation. I guess the differences between the three Standards goes to show that such "normative documents" don't just embody the current state of science and technology but also incorporate aspects of life and culture in the country where they were written. By the way, a new European Standard for fins is in preparation with the English title EN 16804: Diving equipment. Diving open heel fins. Requirements and test methods. It is flagged as "approved", meaning that the "idea has been approved to proceed in the relevant committee and work is under way." See: http://standardsdevelopment.bsigroup.com/Home/Project/201402226

So watch that space! If you haven't had your fill yet of documentation relating to fins, there is a wonderful report of 1 March 1957 by W. G. Fischer of the Navy Experimental Diving Unit with the title Comparative Evaluation of Swim Fins. To my mind, it has never been bettered in the way it identifies and implements both physical and more subjective test criteria when measuring and comparing different swim fin models. See for yourself by downloading the report (it's free! :D ) at
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD0780665
and tell me what you think.

Finally, and I mean "finally" as far as this topic is concerned, there are three, more recent, French-language files providing functional analyses of fins from an educational perspective:
1. Ministère de l’Education Nationale (1994) Matériels pour activités aquatiques. Palmes destinées à un usage collectif. Enfants de 4 à 12 ans. Focuses on fin use by 4- to 12-year-old children. See pages 178-181 of the PDF file freely downloadable from http://www.economie.gouv.fr/files/directions_services/daj/marches_publics/oeap/gem/5718/5718.pdf
2. Ministère de l’Education Nationale (2004) Matériels et équipements pour la pratique des activités physiques et sportives des adolescents et des jeunes. Collèges et lycées. Matériel aquatique. Palmes. Focuses on fin use by teenagers. Free download of PDF file from http://www.economie.gouv.fr/files/directions_services/daj/marches_publics/oeap/gem/equipements_sportifs/55.pdf
3. Dinel, L. and Adele, F. (2007) Analyse fonctionnelle palme randonnée aquatique. Focuses on fin use with no particular target population in mind. Free download of Excel file from http://www.optimisations.fr/stats/OP_P&P/temp/Analyse%20fonctionnelle%20palmes.xls
For those who read the language, these files are an interesting illustration of the way French schools teach the subject of product design.

For my next project, I am minded to review the literary history of national and international Standards for dive masks. The thread would follow similar lines to the present one. I hope this would be of interest to Bibliophile Forum visitors :D. I have all the documents ready!

In the meantime, please feel free to voice your opinion, or even better, to start a thread of your own here with a review of your favourite item of vintage diving literature.

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Re: National Standards for Basic Gear: Fins

Sun Oct 12, 2014 11:15 am

You are a hard act to follow David....I look forward to reading you post on mask standards. Your contrabutions help keep VDH as the number one source for accurate historical information.

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Re: National Standards for Basic Gear: Fins

Tue Dec 09, 2014 2:03 pm

In my recent online research I chanced upon an addendum to this list of normative documents for swimming fins. It's a military specification that originated on 15-Feb-1965, with an amendment notice of 03-Jul-1968 and a cancellation notice of 12-Oct-1988. The blurb says: "This specification covers the requirements for swim fins made of gum rubber for wear by military personnel for swimming purposes and for general utility." Here's the bibliographical reference:

US Department of Defense (15-Feb-1965) Military Specification MIL-S-82258. Swim Fins, Rubber. Free download from http://www.assistdocs.com/search/document_details.cfm?ident_number=33098&StartRow=52751&PaginatorPageNumber=1056&status_all=ON&search_method=BASIC

It's a very detailed Standard and I highly recommend it to anybody who is interested in, or has dived with, Duck Feet fins, because they are the "rubber swim fins" whose specifications are reviewed in this document:
Image
If so, enjoy, and more importantly tell us your thoughts about this US Navy document.

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