From: Commanding Officer To: Subj: Ref: Encl: Commander, Task Group 132.3 Operation Ivy: recommendation regarding future operation similar to (a) CTG 132.3 restr disp 071736Z of November 1952 (1) Data regarding recovery of Dan buoys for Project 5.4a, Operation Ivy (2) Chart indicating relative position, set, and drift of Dan buoys recovered for Project 5.4a 1. Reference (a) requested recommendations for consideration in planning and executing future operations similar to Operation Ivy. The only comments the Commanding Officer has to offer are those included herein, all of which pertain to the problem of laying and recovering Dan buoys such as those used in connection with Project 5.4a of Operation Ivy. 2. Enumerated below are certain observations based on the experience of this ship in laying, searching for, and recovering Dan buoys during Operation Ivy. It is realized that this experience is limited and that many of the observations, if accurate in general, may have been known to the planners of the operation in advance. However, even though they may be general knowledge, they are furnished for possible assistance to future planners. a. No difficulties should be experienced in the physical operationsof rigging, launching, and recovery of Dan buoys from a ship in any sea state up to heavy seas if the ship has a deck with less than 10 ft freeboard and is slowed to 5 knots for launching and stopped for recovery. b. Currents in the sea area east of Eniwetok vary considerably, both in set and drift, with regard to both space and time. Enclosures (1) and (2) illustrate this statement. c. Maximum reliable detection ranges by this ship for buoys of the type used (fitted with type MX-138A radar reflector) were as follows ina state 3 sea: (1) Radar (both SG and SPS) —5000 yd (2) Visual (eight lookouts in daylight with binoculars scanning forward 180° sector) — 500 yd. Detection is better from low positions in the ship. d. Reliable detection range is sensitive to sea conditions (8000-yd radar range and 1000-yd visual range observed with sea state 1). e. Search by P2V aircraft with AN/APS-20 radar is ineffective in state 3 sea (based on 14-hr continuous search over buoy line with no contacts). f. Using radar search, location, and recovery of buoys during darkness is as expeditious as during daylight. g. In an expanding search, missing a buoy close to its predicted position wastes as much time as having its position more uncertain than the maximum allowed for in the search plan. 3. Certain basic factors with regard to surface search should be taken into consideration in planning: a. Under given circumstances of sea state, weather, and equipment, the time spent ina successful search for any buoy is a direct function of the uncertainty of positions of the buoy and an inverse function of the search rate (area searched per unit time). b. The uncertainty of position is the product of the uncertainty in set and drift and the elapsed time since the buoy waslaid. c. The search rate is directly proportional to ship speed, if an efficient search plan is used. d. In picking up a series of buoys, the elapsed drifting time (and hence the uncertainty of position) of later buoys increases with the time required to locate earlier buoys. Thus higher speed, in addition to reducing the time required for recovery by increasing the search rate, has a cumulative effect when a series of buoys is to be recovered because it reduces drifting time of later buoys and therefore also reduces total miles steamed. Similarly, if a series of buoys mustbe laid by a time deadline, higher speed in laying reduces the drifting time of the earlier buoys and therefore also reduces total miles steamed. 4. As a result of the foregoing observations and factors, the following recommendations are submitted for consideration in future operations: 76 a