NOAA Evaluation Report

NOAA Evaluation of the Underwater Technologies Center’s Underwater Digital Interface (UDI) for Use in Technical Diving


Background and need

In recent years, NOAA has increased its number of technically trained divers (diving to 300 fsw using mixed gas) and the number of tech dives being made. As this need has grown, so has the need to be able to communicate with the divers below. While there are wireless communications available, the use of the technology comes at a price in terms of air consumption due to the increased volume of the full face masks required to accommodate the communications electronics. The price of wireless communications is also a factor to be considered when choosing whether or not to be in communication with divers below.

While attending the 2008 Diving Equipment and Marketing Association’s (DEMA) show in Las Vegas, the author spoke with representatives of UTC about the ability of the Underwater Digital Interface (UDI) to function at technical diving depths. The representative assured the author that these units would function at depths exceeding the depth range (300 fsw) of technical diving.


The system is comprised of a boat unit and one or more wrist-mounted diver units. Some salient features of the system are it:

· allows for two way communication via pre-configured text messaging;

· provides both a diver SOS and a boat SOS that can be sent in the event of an emergency;

· has the capacity to be able to locate a “lost” diver via a homing beacon;

· incorporates a gyro-compensated digital compass for use underwater;

· included a fully functional RGBM NITROX diving computer;

· can be configured using a PC interface;

· can be configured to allow up to 14 different divers on 4 different networks to

communicate with the surface or with each other;

· increases the safety and decreases response time to deal with in-water emergencies.


The author contacted HTI Special Operations Equipment, the US distributor for UTC and asked to evaluate the system for use in technical diving operations. The distributor agreed and the author was provided with a boat unit and three diver units for a period of three months.


Evaluation Procedures

NOAA technical divers used the system on two technical diving missions; one in the Gulf of Mexico at the Flower Gardens Banks National Marine Sanctuary and the other in the

Papahanaumokuakea Marine National Monument in the Northwestern Hawai’ian Islands.

Additional tests were conducted on the units during working dive operations at Gray’s Reef National Marine Sanctuary in Savannah, Georgia.

The evaluation would consist of technical divers being briefed on the system, trained in the operation of both the boat and diver units and testing of the different functions of the system on scientific dives.


Field Evaluation Results


Text messaging – the boat unit was connected to a laptop computer and through the UTC “DiveSim” software, was configured with the following text messages:

1 - OK;

2 - NO;

3- On the bottom – meaning that the divers had reached the dive location and commenced work;

4- On ascent – indicating that the dive was over and the divers would return to the surface;

5- At Deco 1 – meaning the divers had reached their gas switch at 110 fsw

6- At Deco 2 – indicating that the divers had reached the gas switch at 20 fsw

7- Need Backgas – meant to indicate that the diver was low on the bottom mixture of gas

8- Need NITROX – which indicated that the diver had run low on their intermediate deco mix

9 - Need Oxygen – indicating that the diver required the safety diver to bring down additional O2

10 - Pick up Xtra gear – a request for one of the safety divers to come and get extra equipment

11 - Lost Buddy Look 4 Bag – an indication to the surface that dive buddies had become

separated and to look for the lost diver’s lift bag on the surface;

12 - Emergency Send Stby – indicated that there was a problem on the bottom and the divers would need the standby diver to assist;

13 - Strong Current – an indication that the divers on the bottom would be sending a bag to the surface that the chase boat could follow but the dive would continue.

14 - Remote SOS – this message slot is reserved for the diver or boat unit to send a message that will allow either to find the other or for any diver to find another diver underwater.


During the course of evaluation, all divers and topside support personnel were instructed to keep a log of all the texts that were sent, all the texts that were received and note any un-answered messages.


In general, the vast majority of text messages that were sent were also received. There were a couple of exceptions to this. On one particular dive, the divers were diving along the sheer side of an island and several messages were lost. This is presumably due to the fact that the signal was being “bounced” off the side of the cliff before reaching the divers. However, all the messages sent from the divers to the surface were received by the boat unit. If a message was sent and not received as evidenced by the lack of an acknowledgement from the recipient, then the message was resent until a response was received. In this manner, the divers on the bottom did eventually receive the intended message though repeats were necessary. It is possible that the transducer may not have been as deep as it could have been, or the lost messages could have been a result of the pitching of the support vessel and the consequential movement of the transducer. In all, 97.4 % of the messages sent by one party to the other were received.


The divers and boat unit operators had no problems with either of the units with regard to the operational steps required for sending messages. Additionally, the divers and boat unit operators agreed beforehand that if a message was sent from the boat unit to the divers, that the divers would interpret the text as a question instead of a statement. In other words the message “OK” would mean “Are you ok?” and the message “Pick up xtra gear” coming from the surface unit would be interpreted by the diver to mean “Do you need the safety diver to come and pick up extra gear?” In this manner there was a virtual doubling of the text messages and the boat unit operators could ask questions of the divers even if the divers were not forthcoming with requests. Some divers would text more often than others and it was a great comfort to the topside personnel to know that they could make inquiries of the divers even if the divers were otherwise

engaged and did not text to the surface.


All divers agreed that the limit of 13 preconfigured messages was not enough and would like to see this capacity built out to at least 25 messages. At some point the scrolling necessary to go through all the messages would be onerous but having more options would be a nice addition to the functionality of the units.


Another noted disadvantage is that even though there are four different “nets” or networks that can be configured, only the common texts between users on the same net could be shared. In other words, even if a diver on the same net wanted to send a text to another diver on the net and the texts were not the same, the recipient would receive the same “number” or slot of the text that was sent from the originator of the text. This example was brought to bear in one case where one of the diver units did not synchronize with the others after there had been a change to the messages. When the diver sent a message from slot 12 which formerly had indicated “Strong current look for bag” what was received by the other units was the new message which read “Emergency Send Stby” which was the current message in slot 12 on the units which had successfully been synchronized. This was chocked up to “operator error” and underscores the need to ensure that the texts in all the units are checked for consistency prior to commencement of the dive.


There was also a bit of a learning curve to getting the units to synchronize together. The user manual indicates that the unit’s antennae should be in close proximity to each other and to the transducer in order for synchronization to be successful. Several attempts had to be made to get the units to successfully synchronize. This did not result in any real problem other than the patience required to ensure successful communication of the devices. An attempt was made to synchronize the units while immersed in a bucket of water and even this did not work every time.


Diver and remote SOS – due to the limited dive time and complexity of the technical dives, the SOS function of the units was not tested during deep diving missions. The SOS function was instead tested on shallower dives conducted in Gray’s Reef National Marine Sanctuary offshore of Savannah, Georgia.


The diver units are equipped with a button on the lower left that will initiate (with two button pushes) an SOS signal to all other users on the net. Once this button is pushed and

acknowledged, the other users on the same net receive a signal which allows them to use two different methods to find the “lost” buddy.


While both methods were evaluated, the “one step method” seemed the easiest to use but both yielded the same results. Once the SOS was initiated, the recipient units would beep and flash and come up with a screen which asked which of the two methods would be used to locate the diver initiating the distress signal. When the recipient of the SOS received the message and selected either method, the screen would switch to a “compass” mode which would give a range and relative bearing to the lost buddy. The functionality of this feature was tested a total of 20 times with the result of every test being the location of the lost buddy. The accuracy of the unit was so precise that even when conducted “blindly” by looking only at the unit and swimming the indicated course (e.g. not looking around for the diver) the result was that the divers would eventually bump into one another.


This function can also be initiated from the boat unit and a message will be sent to the divers so that they can locate the vessel. This function was tested on every shallow dive once the divers were ready to return to the boat and in every instance it was as accurate as the tests conducted to locate a lost diver.


RGBM NITROX Dive Computer – the RGBM function of the dive computer was used on

shallower dives and was found to be very easy to interpret and use. Since the RGBM function is an adaptation of the algorithm designed by Dr. Bruce Wienke, it followed closely with the RGBM models used by many of the NOAA test divers. Having a functional NITROX computer in the diver unit reduces redundancy and the necessity to have another wrist-mounted item on the dive. Incorporating the dive computer into the diver unit makes it a much more valuable tool for underwater use.


Comments from users and ideas for future upgrades – following are some comments from the users that might be considered to make the unit even more functional for NOAA’s scientific diving needs:

· Size – most users initially commented on the physical size of the unit being too large;

given the functionality and the many features incorporated in the design, the size quickly

became a non-issue;

· Decompression algorithm – for use in technical diving, it would be nice if the software

could allow the use of a decompression algorithm such as VPM or VPM-B. As was

stated earlier, the peace of mind of knowing that the divers 300 feet below are ok and that

the dive is progressing as planned is priceless. Being able to wear a diver unit that

incorporates a decompression algorithm would make the unit a “must have” for all

NOAA technical diving operations and would reduce the redundancy of having to wear

two additional diving computers;

· Locator functionality – the location mechanism and functionality in the diver unit works so well that several testers commented on the fact that it would be great to be able to have a lower-cost (relative to the diver unit) “pinger” that could be placed on underwater equipment and could be located using the diver unit. Ideally, the diver unit would be able to “query” the pinger and wake it up to begin transmitting a location signal. With the pinger turned on, the diver wearing the wrist unit would be able to locate the equipment using the location functionality. NOAA has a lot of expensive scientific equipment on the ocean floor and having a unit with this kind of capability would greatly increase the efficiency and effectiveness of our diving operations and reduce the incidence of lost equipment;

· Text messages – as was noted earlier, in complex mission where there are many needs for communication, it would be nice if the units could be configured with approximately 11 more text fields to allow for more messages to be conveyed. There were several times

during the tech mission where we would liked to have had more messages but had to

decide which were more important and remove the ones that could not be included;


Conclusion – The UTC UDI is a remarkable unit which should be considered to be a “must have” item for all diving operations of a complex or technical nature in situations where a voice communications system is not available or appropriate. It will be the recommendation of the author to approach the NOAA Diving Control and Safety Board and suggest that the UTC UDI be approved for use in NOAA diving.


The author wishes to acknowledge Roy “Bud” Fultz of HTI Special Operations Equipment for his guidance and for allowing NOAA to evaluate the system at no cost to the U.S. Government.


Greg McFall


National Ocean Service

Line Office Diving Officer

October 2009