Changes and comments

Nettstedet for Norske dykke- og behandlingstabeller

Changes and comments

About this website

This website is edited by Jan Risberg (principal author of NDTT 4th edition). It is constructed to be a link between the authors and readers of these tables. Corrections and comments to the tables will be formalized through publication of new revisions. In the time period preceding a revision, there will be discussion between the editors as well as professionals. This website will present suggestions for table changes. We sincerely appreciate comments to the tables: supportive, improvement proposals, inaccuracies a.s.o. Please send us an  e-mail to allow us to follow up!

Topics discussed on this particular page of the website has not been approved/formalized and is not intended to replace recommendations of the last official edition of the table.The revision proposals available for download at the right hand panel, should not be used operationally.

Areas subject to revision or correction in the sixth edition of the NDTT


The next edition will hold a bottom text on each page identifying the edition/Revision. (Rev A)


A short description of  adjustments introduced in the NDTT relative to the original US Navy Diving Manual Rev 7 has been provided. (Rev A)

Flying after diving

Serial 9, second sentence shold read: "The rules for flying after diving should be respected for all exposures to heights exceeding 1750 m asl.

Serial 12, the text in Ed 5 last paragraph should read (changes marked in bold types: "The diver has a Repetitive Group Designator of “B” from the preceding dive giving a penalty of 15 min to the 18m table. The repetitive group designator should be calculated for a bottom time of 35 min (15 min penalty + 20 min actual bottom time). A 35 min bottom time at 18 m will cause a Repetitive Group Designator of “F”."  (Rev B)

Standard air decompression tables

We have received a suggestion of inclusion of a formula/equation or alternatively a seaparate table that will allow preparation of no-decompression dives for smaller depth increments than 3msw. A practical example:  Maximum allowed bottom time for a no-decompression dive according to the 15 msw table depth is 90 min. The similar no decompression time for 18 msw table depth is 60 min. If the diver plans for a dive to 16 msw he/she will be restricted to a bottom time of 60 min for such a dive. However, if the bottom time is calculated as a linear interpolation, a bottom time of 80 min would be acceptable. The authors have not taken a position to this request, but we would appreciate any comment as to the operational use for a separate table for no-decompression dives rated in 1 msw steps in table depth.

Procedures in the case of omitted decompression or uncontrolled ascent (+last page)

We discovered 1.11.19 that a printing error has caused page 109 and 110 to be incorrect. Page 109 holds the procedures in the case of omitted decompression or uncontrolled ascent, while the very last page only holds the ISBN number. Corrected pages can be downloaded here. We have not taken a decision as to how to handle this error yet. The PDF version is correct.


The authors were approached aug 2019 by the Norwegian Oil and Gas Association, Forum for diving and subsea intervention. We were asked whether we could provide standardized tables for TUP-diving (transfer under pressure). The authors have confirmed our interest to provide a framework for TUP-decompression tables. It is our intention  to give a presentation on this subject on the Bergen International Diving Seminar autumn 2019.


In this panel you may download the latest internal draft/working document for the forthcoming table revision.  This document is not approved for operational use. It is published to stimulate comments. The document has not been properly reviewed and layout is not finalized. This will typically affect Table of contents, location of figures and page shifts. Such errors will not be corrected until the final official revision has been published.