2626
2626
26
VERSION 1.0VERSION 1.0
VERSION 1.0VERSION 1.0
VERSION 1.0
NOAA Trimix Diving Tables, and the Andrea Doria Off-
Shore Diving Tables. These tables have thousands of dives
experience with very good results.. This is the model
included in NAUTILUS.
‘Thus to wrap up, DCAP is a practical result of many years
of collective experience in preparing and evaluating many
types of decompression tables. The DCAP concept does
not limit it to calculations with any specific model there is
currently a choice of several models, and others are under
development. DCAP’s main feature is that it facilitates the
computational and table production process. It can allow
different models, approaches, ascent constraints, and table
configurations to be used. A good set of criteria provides a
practical approach to trimix decompression in the self-
contained, open circuit range with a good track record.
While it would be wonderful for DCAP to be an inexpensive
desktop decompression program it just can’t. The powerful
features of DCAP make it far too complicated and involves
far too many variables that need to be handled by a
researcher to make it practical for recreational use. This is
where NAUTILUS comes in. NAUTILUS allows the free
swimming diver the ability to create dive excursion profiles
with reasonable assurance that the numbers work well.
NAUITLUS incorporates the Hamilton-Kenyon Algorithm
derived from Tonawanda Iia.
3.5 Hamilton Kenyon Bubble Model (HKBM
The Hamilton-Kenyon Bubble Model (HKBM) is a
melding of Haldane’s method of calculating inert gas
uptake into theoretical compartments. Keller’s method of
summing the partial pressures of multiple inert gas uptake
is employed as well. In the Hamilton-Kenyon Bubble
Model, the half-times for each compartment are taken
from the Hamilton-Kenyon decompression model that has
years of reliable decompression schedule production.
1. Rather than using Workman’s M-value
methodology for determining allowable supersaturation
for the theoretical compartments, Yount’s “tiny-bubble”
method of calculating allowable compartment
supersaturation is employed.
Application of Yount’s method to Hamilton-Kenyon’s gas
uptake model produces decompression schedules that
have initial decompression stops up to twice as deep as
conventional dissolved gas models and shallow decom-
pression stop times that are significantly shorter than
dissolved gas models call for. The use of Hamilton and
Kenyon’s compartment half times avoids the extremely
aggressive shallow decompression stop times that VPM
and RGBM models yield.
This combination of Hamilton, Kenyon, and Yount
produce decompression schedules that algorithmically call
for deep stops, rather than arbitrarily adding them into a
dissolved gas model and having to “pay for it” at the
shallow end of the schedule. The shallow stops are not
arbitrarily shortened based upon the intuition of diver’s in
the field.
The schedules produced by the Hamilton-Kenyon Bubble
Model square with the past 15 years of technical diving
experience that has yielded the following observations:
• Dissolved gas models do not produce initial stops
at great enough depth
• Shallow stops called for by dissolved gas models
are much longer than necessary
• Deep stops arbitrarily added to dissolved gas
model add an unwarranted shallow decompression
penalty, as do adjustments to the M-values
• Buhlman’s halftimes used with dual-phase bubble
models (VPM) may be slightly too aggressive for field use
(skin-bends are commonly encountered )
Hamilton-Kenyon Bubble Model produces schedules that
include stops and times that describe a more linear, rather
than exponential arc across the depth time matrix, yet still
take into account the empirically derived compartment
halftimes.
