In a letter of March 20, [14] Admiral Bloch replied, stating that the  
depth of water at Pearl Harbor was 45 feet and for this reason among  
others he did not recommend antitorpedo baffles. Admiral Kimmel was in  
agreement with this recommendation until such time as a light efficient  
net was developed. [15]  
 
However, in June of 1941, the Chief of Naval Operations directed a  
communication to the commandants of naval districts as follows: [16] 
  
"1. * * * Commandants were requested to consider the employment of, and  
to make recommendations concerning, antitorpedo baffles especially for  
the protection of large and valuable units of the fleet in their  
respective harbors and especially at the major fleet bases. In paragraph  
3 were itemized certain limitations to consider in the use of A/T  
baffles among which the following was stated:  
 
" "A minimum depth of water of 75 feet may be assumed necessary to  
successfully drop torpedoes from planes. About two hundred yards of  
torpedo run is necessary before the exploding device is armed, but this  
may be altered."  
 
"2. Recent developments have shown that United States and British  
torpedoes may be dropped from planes at heights of as much as three  
hundred feet, and in some cases make initial dives of considerably less  
than 75 feet, and make excellent runs. Hence, it may be stated that it  
cannot be assumed that any capital ship or other valuable vessel is safe  
when at anchor from this type of attack if surrounded by water at a  
sufficient run to arm the torpedo.  
 
"3. While no minimum depth of water in which naval vessels may be  
anchored can arbitrarily be assumed as providing safety from torpedo- 
plane attack, it may be assumed that depth of water will be one of the  
factors considered by any attacking force, and an attack launched in  
relatively deep water (10 fathoms [16a] or more) is much more likely.  
 
"4. As a matter of information the torpedoes launched by the British at  
Taranto were, in general, in thirteen to fifteen fathoms of water,  
although several torpedoes may have been launched in eleven or twelve  
fathoms. [17]" 
 
Page 160        PEARL HARBOR ATTACK 
 
[12] Committee exhibit No. 9. This comment was made by Admiral 
Richardson pursuant to a letter from Admiral Stark dated November 22, 
1940, in which the latter had stated, among other things: "Since the 
Taranto incident my concern for the safety of the Fleet in Pearl Harbor, 
already great, has become even greater. This concern has to do both with 
possible activities on the part of the Japanese residents of Hawaii and 
with the possibilities of attack coming from overseas. By far the most 
profitable object of sudden attack in Hawaiian waters would be the Fleet 
units based in that area. Without question the safety of the units is 
paramount and imposes on the Commander-in-Chief and the forces afloat a 
responsibility in which he must receive the complete support of 
Commandant Fourteen, and of the Army. I realize most fully that you are 
giving this problem comprehensive thought. My object in writing you is 
to find out what steps the Navy Department and the War Department should 
be taking to provide additional equipment and additional protective 
measures."