Captain John R. Y. Blakely to Admiral William S. Benson, Chief of Naval Operations
M e m o r a n d u m
For: Chief of Naval Operations
Subject: Preparation for mine planting on Atlantic Coast.
1. There are four general spheres of mining to be considered:
First, mine fields under the guns of coast fortifications. This is done by the Coast Artillery.
Second, on the coast beyond the reach of fixed fortifications under the Army. This is the province of the Naval Districts.
Third, mining in the vicinity of non-continental bases, and in coastal areas off-shore beyond the scope of localized mining forces. This is the province of the Mine Force of the Fleet as recommended by the General Board and approved by the Secretary.
Fourth, offensive mining in the face of the enemy. This requires fast vessels or ample supporting forces and is to be done by cruisers and destroyers, as recommended by the General Board and approved by the Secretary.
2. The withdrawal of the Mine Force from our coast, therefore, would not remove the Force responsible for mining our coastal waters, because the Coast Artillery and the Naval Districts are responsible for all defense of this kind on our coast. The Mine Force could materially assist where present, but the responsibility rests with the local district forces.
3. As yet the Naval Districts have done little mining. They have no vessels or at best very few in service that could be used for any extensive mine planting. The mines now furnished, however, require little technical experience for successful planting unless observation mine fields are required. So far, these are arranged for by the Coast Artillery.
4. For mining vessels in the Districts, ferry-boats could be readily equipped, and if not desired to take them away from their ordinary employment, the equipment could be prepared, ready to place at short notice. These vessels have sufficiently good maneuvering powers, light draft, carrying capacity, and clear deck space. They would be suitable for outside work in smooth water, and a breakwater built forward on the main deck would probably enable them to go outside in a moderate breeze, if their structural strength were sufficient. The weight of the mines carried is not great. Twenty-nine mines to 100 feet of track and five feet athwartships for each track is the closest spacing allowable. This would give a weight of about twenty-five tons to 500 square feet of deck area.
5. Training with mines is given at the torpedo station and Mark IV mines are available in a considerable number both for training now and planting later if wanted. The equipment for mine planting vessels consists mainly of tracks to carry the mines, a curved section of track for launching, and means for embarking the mines on board from shore or other vessels. Where ferry-boats are not available, or it is undesirable to withdraw them from present employment, training in planting may be had by using flat lighters, of the Navy standard coal barge type, either wooden or steel. A tug alongside can handle the mine planting barge with sufficient precision.
6. Since all Naval Districts should be prepared to plant mines on short notice, immediate steps are necessary to provide the equipment and to train the personnel. The material may be provided in the usual way upon plans and requisitions from the several Naval Districts. The training may be had by the detail for a short time of a few petty officers or officers from the Naval Districts to the torpedo station. The ordnance pamphlet on the Mark III and IV mines is so full in detail, it is probable that there may be no necessity for some or any of the Districts to send personnel for training.
7. It is recommended, therefore, that the Commandants of Naval Districts be directed to prepare to undertake mining, as outlined in paragraph 6, above.
J. R. Y. Blakely