The Diesel motors that run the propulsion system would not be affected by EMP, even if the sub were on the surface. But the sub, at depth, is powered by battery-driven electric propulsion, which if on the surface, WOULD be vulnerable to EMP, as there are all kinds of load-switching electronics, to shift between the charging of the batteries, and the draw-down of energy stored. Also, virtually all the guidance wiring and control surfaces would be knocked askew.
Could they cripple back to port? Maybe, but as a combat vessel, they would be virtually useless. And there might not be a serviceable port for them to repair to.
But the sub, at depth, is powered by battery-driven electric propulsion, which if on the surface, WOULD be vulnerable to EMP, as there are all kinds of load-switching electronics, to shift between the charging of the batteries, and the draw-down of energy stored. Also, virtually all the guidance wiring and control surfaces would be knocked askew.
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Not Hardly! I lived on a boat for several years.
First, even when running on the Diesel the sub is really running on the battery. The Diesel simply turns a generator that charges the battery, the battery then supplies DC to a variety of motor generators and inverters to supply the needs of ships systems and of course an electric motor attached to the shaft of the screw that propels the ship. Generally the speed is GREATLY reduced to a few knots or so.
Nearly every electronic system on a submarine even though not exposed to any effect from an EMP has over voltage drains that carry away any voltage close to harmful. The only systems remotely exposed are those that have antennas and those too have over-voltage drains.
As far as the switch gear being hurt by the high voltages of induced EMP, not even close. This is massive equipment that is designed for huge amperages. The amperages from EMP’s are tiny by comparison. Without high amps to go with the high voltage larger equipment won’t be affected by an EMP.
The shell of a submarine (hull and superstructure) will effectively act as a Faraday cage.
EMP’s are generally overrated. Yes they can be very harmful to equipment, especially equipment nearby and equipment tied to the grid without overvoltage protection. In the US now most electrical service providers that are tied to the National Grids are adding equipment to drain away harmful high voltage spikes of the type that will be caused by an EMP. That does not help much to consumers whose local power lines will pick up the spike and carry it to your home equipment. Most equipment in your home if turned off or unplugged will not be affected. Most cars even though they have vulnerable computers and other accessories will not be affected because of where the equipment is located, that is behind a steel sheet that will keep the EMP from penetrating.
The effect of an EMP detonation is similar to what would happen if you had a lightening strike close to your home. You may lose equipment like a cable modem or even a telephone but likely little else. Lightening creates an EMP very similar to what this thread is discussing. Cable companies have had to replace so many modems that they have now started installing high voltage drains in their equipment to keep costs down. This is especially true in areas that are subject to frequent thunderstorms.
IF you put an EMP detonation close enough it will do damage but not like the movies would have you believe.