Precision Sensing for AS(X) Submarine Tenders

Navy SBIR 24.1 - Topic N241-022
NAVSEA - Naval Sea Systems Command
Pre-release 11/29/23   Opens to accept proposals 1/03/24   Now Closes 2/21/24 12:00pm ET    [ View Q&A ]

N241-022 TITLE: Precision Sensing for AS(X) Submarine Tenders


OBJECTIVE: Develop a precision sensing system capable of providing real time relative positioning and orientation between a submarine and its tender in open water during resupply operations.

DESCRIPTION: Submarines are typically resupplied in port, or under benign sea state 2 conditions typically found in sheltered waters that may be far from the submarine’s operational area.

In higher sea states, the differing movement of the tender ship and the smaller submarine becomes a major obstacle to high-precision transfer of supplies. The tender, submarines, and the resupply materiel will move in their own frame of reference. Precise sensing of relative pose is critical when applying automation of motion mitigation to support the tender’s operations during transfers. The sensing system must operate in real-time, and accurately provide the distance to the transfer destination on the submarine, as well as the relative velocities between the two vessels in six degrees of freedom (DOF) in Sea State 3 (Objective) and 4 (Threshold). No satisfactory commercial sensing system exists currently.

The system must be operable and accurate in a marine environment, day and night, including in conditions of fog, salt spray, icing, etc. The sensors and computers performing analysis of the sensor data will be based on the tender, without excluding possibilities of establishing other temporary vantage points for transfer operations. The system must be operable at a distance to the submarine of up to 50 feet over the side of the tender, and 30 feet vertical from the location of transfer equipment on the tender. The position sensing system should also be usable for vertical lift transfers. No permanent targets or sensors may be installed on the submarine.

The system must provide an indication of when sea conditions permit safe operations for the capabilities of a given transfer method. The actual transfer method is outside the scope of this SBIR topic. A design for the sensing system is expected to enable this technology to operate on other platforms as needed.

PHASE I: Develop a design to address precision sensing for AS(X) submarine tenders during underway replenishment of submarines. Identify sensor choices, locations and methodology for sensor data analysis, yielding real-time 6-DOF motion identification outputs. Validate the feasibility of the approach in a marine environment by providing computer simulations or other evidence. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype system in Phase II.

PHASE II: Develop a prototype system for evaluation based on the results of Phase I. Develop a test methodology to show how the technology will be evaluated to determine if the system has the potential to meet Navy performance goals described in the Phase II SOW. The goals will be defined by the Navy in Phase II. Testing in a two-body wave tank or an equivalent marine environment is expected. Develop plans for full-scale testing in an open water environment in Phase III.

PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology to Navy use. Perform full-scale testing in an open water environment and further refine the technology for Navy use.

The same technology needed to transfer supplies from tenders to submarines can also be used for other Navy ship-to-ship transfers, as well as offshore oil and wind industry applications.


  1. Ziezulewicz, Geoff. "Navy planning to bring back at-sea missile reload capability." Navy Times, 1 August 2017.
  2. "U.S. Navy Tries Reloading VLS Missile Cells With a Commercial OSV." The Maritime Executive, 7 October 2022.

KEYWORDS: Relative Position Measurement; Underway; Inertial Measurement Unit; Precision Real Time Sensing; Sensing in Marine Environment; Cargo Transfer at Sea


The Navy Topic above is an "unofficial" copy from the Navy Topics in the DoD 24.1 SBIR BAA. Please see the official DoD Topic website at for any updates.

The DoD issued its Navy 24.1 SBIR Topics pre-release on November 28, 2023 which opens to receive proposals on January 3, 2024, and now closes February 21, (12:00pm ET).

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Topic Q & A

1/9/24  Q. What is the objective weight and time on station for typical transfer of supplies?
   A. The weight capacity for the crane is not yet defined. A conservative assumption for minimum crane weight capacity is 7000 lbs. Time on station may range from 6 to 24 hours
1/4/24  Q. Does the Navy feel the problem is solvable with current high TRL sensors making this more of an integrated system concern; or is the Navy seeking novel sensing capabilities to overcome the unique challenges to precision sensing caused by the (high) sea state environment?
   A. The problem proposed in this SBIR may be addressed with current high TRL sensors. The precision sensing solution should incorporate the sensors (existing or novel) into a novel integrated system.

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