Vanguard Magazine

E N D U R A N C E conventional submarine life completely revolves around power generation and storage – the battery. A diesel-electric sub- marine (including those fitted with AIP) run diesel generators, while snorting, to recharge the battery, which is then used for both propulsion and domestic services – known as the 'hotel load'. While modern AIP systems allow for the ability to gen- erate power without snorting, they are all limited by the amount of liquid oxygen carried onboard, which typically reflects less than three weeks of operation. This is fine for nations that operate their subma- rines close to home with access to resup- ply, but for Canada a lengthy transit to a distant patrol area is a fact of life. A lengthy "snort transit" to an assigned patrol area is the reality of Canadian sub- marine operations and how often the bat- tery needs charging is dependent upon the mission specifics, transit speed and other electrical power demands of the subma- rine. Because lengthy transit distances nec- essarily require a higher speed of advance than when patrolling in a defined area, the battery must be frequently recharged. Moreover, when snorting, the submarine must operate at periscope depth with a number of masts raised, thus risking de- tection. Consequently, all efforts must be made to reduce the amount of time need- ed to snort, which is dependent on the ability to rapidly generate electricity and efficiently store it. 7 Finally, Canada has indicated that it wants a submarine with sufficient endur- ance to patrol covertly for three weeks before the return transit home. Current AIP technology offers the ability to meet this requirement without snorting, but it is limited by the amount of fuel required by the fitted AIP system that can be car- ried. Again, the bigger the submarine the greater amount of fuel that can be carried, but conversely it also means the greater amount of power that is required to pro- pel a larger submarine which impacts the subsequent power draw on the battery. That said, once in its assigned patrol area, a conventional submarine normally oper- ates at very slow speeds to maximize bat- tery life as well as reducing radiated noise for acoustic advantage when conducting passive sonar searches. In summary, to meet anticipated future 21st century geo-political threats, Cana- da's future submarine, must be designed with the endurance critical to meeting na- tional requirements, which necessarily in- cludes range and the ability to persistently patrol "up-threat" for extended periods. This is significantly different from most navies operating conventional submarines today. References: 1. Department of National Defence, CADSI OUTLOOK 2023 Canadian Patrol Submarine Project brief, April 2023. 2. A 'snort transit' is when the subma- rine operates its diesel generators by snorting (snorkeling), at periscope depth, to charge the battery while transiting to its patrol area. 3. GIUK Gap – Greenland, Iceland and the United Kingdom the gap that separates the Norwegian Sea and the North Sea from the open Atlantic Ocean. https://en.wikipedia.org/ wiki/GIUK_gap accessed 20 Septem- ber 2023. 4. Typically referred to as the "hotel load" a submarine must have suf- ficient power for atmosphere main- tenance (breathable air), weapons and sensors, cooling and food storage and preparation. 5. IMO Polar Code at https://www. imo.org/en/ourwork/safety/pages/ polar-code.aspx#:~:text=The%20 Polar%20Code%20covers%20 the,waters%20surrounding%20the%20 two%20poles and https://wwwcdn. imo.org/localresources/en/Our- Work/Safety/Documents/How%20 the%20Polar%20Code%20protects%20 the%20environment%20(English%20 infographic).pdf accessed 20 Septem- ber 2023. 6. For example, if the maintenance philosophy is 'repair by replacement' then it assumes adequate spares being available and not having to cannibalize other submarines in maintenance for replacement parts. 7. The percentage of time that a sub- marine must snort, when measured against the total time at sea, is termed the "indiscretion rate". The lower the indiscretion rate, the less time the submarine must snort and therefore risk detection. Capt(N) Norman Jolin (Ret'd) is an Associate Consultant with CFN Consultants specializing in naval and maritime issues. Prior to joining CFN, he provided advice on Canadian defence procurement in the private sector, following a 37-year career in the Royal Canadian Navy. HMCS Windsor. Photo DND.

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