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Suunto Fused™ RGBM Copyright © 2012 by Suunto Oy. All rights reserved. Oy. Suunto © 2012 by Copyright THE PATH TO FUSED™ RGBM At the heart of every Suunto dive com- Over the next decade, the algo- With the launch of the Suunto HelO2 puter is an algorithm that calculates rithm was further improved to in- in 2009, Suunto introduced a new decompression for a dive, called the re- crease diver safety. These include, for decompression model, the Suunto duced gradient bubble model (RGBM). example, voluntary safety stops, asym- Technical RGBM, also developed with Relentlessly pursuing ever safer models metric on and off -gassing, as well as Dr. Wienke. This algorithm included all for divers of all types, Suunto continues modifi cations based on the work of previous implementations and added to push for RGBM perfection. A storied Dr. Merrill P. Spencer. new features for handling helium gas. history full of science, development, and underwater experience lies within During this time, the dive community Since the late 1980s, Dr. Wienke had every Suunto dive computer. was still seeing too many accidents. been working at the Los Alamos To address these problems, Suunto Nuclear Laboratory on the so-called This document explains detailes of our launched the Suunto Vyper in 1999 ‘full’ RGBM. This development was tar- algorithm, and how the new Suunto which featured the new Suunto Re- geting the needs of deep divers and FusedTM RGBM has been developed. duced Gradient Bubble Model (RGBM). military personnel carrying out diffi - cult dives. Suunto's work on decompression The Suunto RGBM was developed in models for dive computers spans over co-operation with Dr. Bruce Wienke. The new Suunto Fused™ RGBM com- three decades. A pioneer in the fi eld, The new algorithm could account for bines the benefi ts of Suunto’s Techni- Suunto’s modelling has adopted the diver behaviors which increase health cal RGBM and the ‘full’ RGBM, bringing latest scientifi c know-how and theo- risks. These behaviors include multiday the benefi ts of both to recreational ries from leading experts. diving, reverse dive profi les and short divers and technical divers. surface intervals. Suunto’s fi rst dive computer was the None of this development would have Suunto SME ML (1987). Given the When deep stops (Pyle stops) became been possible without the pioneering technology available at the time, it a proven benefi cial method for de- work of Dr. Wienke. Despite the range was essentially an electronic dive tab- compression, they were added to the of dive computers off ered by Suunto le. This was obviously not adequate, Suunto D9 and Vytec DS (2004) as a for most any type of diver, he has and soon Suunto’s Ari Nikkola im- voluntary notifi cation. played a vital role in the practical im- plemented the Buhlman model for plementation of his theories. Suunto dive computers. 1987 1999 2009 Suunto’s rst dive computer Suunto Vyper Suunto HelO2 Suunto SME ML Suunto Redudec Gradient Technical RGBM Bubble Model (RGBM) Implementation of Developed with Buhlman model Developed with Dr. Bruce Wienke Dr. Bruce Wienke 1990’s 2004 2012 Algorithm improvement: Voluntary Suunto D9 Suunto Fused™ RGBM safety stops, asymmetric on and Vytec DS o-gassing Developed with Dr. Bruce Wienke Dr. Merrill P. Spencer Suunto has been working together with Dr. Bruce Wienke for well over a decade. Dr. Wienke is a Program Manager in the Nuclear Weapons Technology Simulation And Computing Offi ce at the Los Alamos National Laboratory (LANL), with interests in computational decompression and models, gas transport, and phase mechanics. He is the developer of the Reduced Gradient Bubble Model (RGBM), a dual phase approach to staging diver ascents over an extended range of diving applications (altitude, nonstop, decompression, multiday, repetitive, multilevel, mixed gas, and saturation). "RGBM is the most realistic model in science. The parameters are correlated with real data of thousands of dives which makes it good physics, and the data is validated and correlated. I have been working with Suunto since the 90’s and Suunto’s progression from Suunto RGBM to Technical RGBM and now to Suunto Fused™ RGBM is a very natural one. The new algorithm is a supermodel that covers all types of diving." - Dr. Bruce Wienke Suunto Fused™ RGBM www.suunto.com 2 Copyright © 2012 by Suunto Oy. All rights reserved. Oy. Suunto © 2012 by Copyright DIVING AND YOUR BODY Diving is a great activity with the The pressure change under water can potential for one-of-a-kind experi- aff ect sensitive areas such as your ears ences you can only get in an aquatic and sinuses. Discomfort in the ears environment. Our land-loving bo- when taking off in an airplane is also dies, however, can react negatively to felt just diving down to the bottom of diving if we are not careful. Whenever a pool that is three meters deep. you enter the water, be aware how your behavior before, during and But the most signifi cant impact is on after the dive can aff ect your health. your circulatory and respiratory sys- tems. These need to be taken seri- Under water your body is being pus- ously as they can lead to major health hed in from all sides. This added pres- risks. To understand and avoid these sure changes how your body func- risks, we need to fi rst have a look at tions. Some of the changes you notice, the world of gases. like with breathing. Other changes 10 meters you may not immediately feel, but the eff ects can cause serious damage to your body, and even lead to death. Ambient pressure Ambient pressure increases much faster underwater because water is denser than air. Ten meters down is already twice the 20 meters pressure at the surface. A WORLD OF GASES In the physical world, we are most gas. The oxygen dissolved in water, It is these gases that can cause so familiar with three phases of matter for example, is what allows fi sh and much trouble for divers. Even oxygen – gas, liquid and solid. Certain ele- other aquatic life to breathe. which our bodies thrive on at surface ments and compounds are naturally pressures can become toxic under in one state or the other at a given Our bodies are also full of dissolved certain conditions. temperature. gases. Some of them, like oxygen, our bodies actively use. Other so- Nitrogen and helium are the main Typically we think of water being called inert gases like nitrogen and culprits when we look at the number merely a liquid, but that is only true helium, are not used by our bodies, one risk divers are concerned about: for pure H2O (between 0-100 C). Both but are carried in blood and tissues decompression sickness (DCS). liquids and solids naturally contain nonetheless. Gas exchange in alveoli When air enters the lungs, it goes through a maze of smaller and smaller tubes until it reaches tiny sacs called alveoli. Woven into the walls of these sacks are very fi ne, almost transparent, capillaries. Suunto Fused™ RGBM www.suunto.com 3 Copyright © 2012 by Suunto Oy. All rights reserved. Oy. Suunto © 2012 by Copyright DECOMPRESSION SICKNESS The amount of gases dissolved in When we go down to sea-level and There are different stages and forms our bodies depends on the ambi- then under water, we increase the of DCS. Symptoms can range from ent pressure around us. Each gas has pressure on our bodies, allowing minor joint pain and skin irritation to a specific partial pressure, and the more gas to be carried by blood and severe nerve damage and death. For combined pressures of the gases in tissues. Again, to equalize the pres- a diver with DCS, the symptoms may our bodies stays in equilibrium with sures, our bodies take on more dis- commence while still underwater, or our environment. solved gas from the air we breathe. it may take several hours after sur- This is called on-gassing. facing. In some cases the symptoms Your body is fully saturated with may not show for several days. Most gases at the elevation where you If we come up from a dive too quickly cases are treatable with, for example, typically reside. If you hike up a (dropping ambient pressure), the recompression chamber treatment mountain, air pressure drops, so your natural off-gassing mechanisms are (hyperbaric oxygen treatment). body can hold less gas. Your tissues overloaded. Like the bubbles you see are at this point supersaturated rela- when you pop open that soda, the tive to the new ambient pressure. To dissolved gas in our bodies comes get back to equilibrium, our bodies out of solution too fast, forming bub- release gas through diffusion and bles which can ultimately cause DCS. breathing. This is called off-gassing. DECOMPRESSION MODELLING A century ago, our understanding of DCS was fairly rudimentary and there 100 were no good ways to ensure divers avoid it. In the early 20th century, 90 work by John Scott Haldane helped lay the foundations for future decom- 80 pression models which divers could 70 follow to minimize risks of DCS. Halftime 60 During a dive, tissues saturate at dif- ferent rates. This is determined by the 50 blood flow to the tissue in question. 40 The brain, for example, has a very good blood supply, and is classified 30 as a “fast” tissue, whilst joints have 20 poor blood supply and are rated as “slow” tissue. There are several 10 others in between. % 0 The length of time that it takes for a 0 5 10 15 20 25 30 tissue to reach a 50% saturation level at a given depth is called the tissue Time halftime and is usually measured in minutes.

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