J.T. McDaniel Wrote:
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> The only torpedoes that normally float after being
> fired are exercise types, where the warhead is
> replaced with water ballast that's automatically
> blown out to provide buoyancy at the end of the
> run so it can be recovered and used again.

Correct, but it requires a flawless operation of both the torpedo and the blowhead-mechanism. For wet-heater torpedoes it's essential that the airtank is filled just in accordance with the set distance, to ensure almost all of the air has been consumed at the end of the run. For a G7a the buoyancy was not high, and too much remaining air would lead to it sinking (the same goes if a malfunctioning would lead to a premature stop and subsequent activation of the blowing-mechanism).

Other torpedoes might need additional measures to ensure flotation after a run. For instance, germany had a telescopic blowhead to ensure more volume (and thus higher buoyancy) for their heavier torpedoes (like the ingolin models, G7u).

Modern torpedoes often use a ballon that blows up like a big "donut" around the exercisehead to achieve buoyancy.

Torpedoes that utilizes a blowhead and/ or a ballon like described above, will float vertically, with a couple of feet of it's head above water. Germany used carbide to generate a thick yellow smoke for aiding the locating of the torpedo. Modern torpedoes typically uses radiobeacons and/or strobelights.


Brian Wrote:
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> There are a number of reasons why a torpedo would
> float at the end of the run, the most common one
> being the failure of the self-destruction
> mechanism.
> German torpedoes were equipped with end-of-run
> self-destruction devices,

This claim makes me curious... I have never seen any german WW2-torpedo having such a feature (mind you: I'm not 100% familiar with all the models in various state of development though, but the standard torpedoes would definately not have this). In fact I know that not even the TIIId "Dackel" had a self-destruction device. This torpedo was subject to special concern with the germans as it's extremely long running distance and slow speed made it vulnerable to strong currents (could be washed ashore) and generel risk of detection. In stead it was ensured to have negative buyancy so it would sink when it had run it's full distance.

I can't think of any german WW2 torpedo that would have positive buyancy, with the possible exeption of the G7e's adapted for use on midget-submarines.


> to avoid one of them falling into the wrong hands.
> In case of a failure, or partial failure, the
> warhead falls off w/out detoinating & this causes
> the torp to acquire positive buoyancy, hence the
> floater. But it did not happen very often,

I can't imagine what circumstances that might cause a warhead to fall off (still focusing on german WW2 torpedoes)? There was certainly no such feature applied to the design, so "very often" would certainly be an understatement...