Site Visit Minutes - 380ft Towing Tank Carriage Control System.docx

N0018926QL104 – USNA 380 FT Towing Tank Carriage Control System– Site Visit 05/21/2026

Site Visit Minutes Questions and Answers Q1. Is the wavemaker controlled independently from the towing carriage?

A1. Yes, they are independent systems. The carriage can operate without the wavemaker, and vice-versa.

Q2. Do you want to be able to control the carriage from the carriage itself?

A2. No, the only control locations will be from the control room or the motor room. A physical E-stop button will be added to the carriage, but that is the only onboard control.

Q3. Is AC and DC run in the same conduit?

A3. An effort should be made to keep AC and DC separate to minimize signal noise. The current conduit runs under the red deck all the way from the Control room to the motor room at the far end of the towing tank. This conduit can be re-used. If extra conduit is needed, there are 5”x5” square cable trays that run above the red deck that can also be used.

Q4. Do you need or want E-stop buttons on the red deck?

A4. No, the existing 3 E-stop locations on the red deck can be eliminated. The 3 desired locations for E-stop buttons are the control room, motor room, and on the high-speed carriage.

Q5. Do you have system schematics?

A5. We do not have a complete as-installed schematic. See attachment for simplified line diagram, but this is not a complete representation of the system.

Q6. What is the function of the router located on the red deck?

A6. This feeds the signal between the control room touchscreen and the motor room. The WiFi is not used.

Q7. What happens if only one of the two DC motors gets power?

A7. This cannot happen, they are not wired independently.

Q8. Do you have the DC motor nameplate info?

A8. See attached for details.

Q9. Is there one motor encoder or two?

A9. There is only 1 encoder since the motors share a common driveshaft.

Q10. Are there safety requirements working on the walkways above the water?

A10. This is a question for NAVFAC. The facility will be a closed construction site during the installation and commissioning of equipment. Specific safety requirements will be up to the contractor to confirm and abide by.

Q11. Will there be water in the towing tank?

A11. The water depth is 16ft when the tank is full. The level of water in the towing tank depends on whether additional work is occurring (such as equipment replacement or concrete work) that requires a lowered water level. The tank is never fully drained, but there is a possibility that the water level will be low (3ft) which can pose a fall hazard for anyone working around the towing tank. Unless there is a compelling need for a lowered water level, the plan is to have the tank full.

Q12. Is it 180 days from award to project completion?

A12. The contractor shall propose project completion.

Q13. Does the spec require redundant systems (ie. Barcode and trimble)?

A13. No, the spec is concerned with precise positioning and accurate speed control. How these are monitored and controlled are not specified in the SOW.

Q14. The E-stop button on the towing carriage will not be hardwired into the system. Is this allowed?

A14. It will have to get back to shore somehow, but we will not drag a cable. Wireless is an option, such as the point-to-point Nano-Beam that we use for the video system on the carriage.

Q15. Is the 30 days for commissioning a hard requirement?

A15. The 30 days for commissioning is not hard. The contractor can propose commissioned completion date. U.S. Naval Academy preference is that the work occurs outside of our Academic calendar, so May through August.

Q16. Is accurate positioning the priority or constant speed?

A16. Both are important, but maintaining a constant speed is critical for getting high quality test data. Accurate positioning is important for stopping the carriage at the correct location (whether that be the beginning or end of a run). Our primary concern is safety, and the carriage shall not overrun its stop position.

Q17. Can the Bid due date be extended?

A17. The solicitation will be extended to 03 June 2026.

Q18. Can we get a copy of the existing code?

A18. No, it is proprietary to the company that installed the existing system.

General comments:

C1. The group rode the carriage at a low speed (1.5ft/sec) then the E-stop was intentionally pressed to show the abrupt deceleration. This tripped an error code that required a full power reboot to clear. The E-stop is aggressive, but maintains power (it is not a power cut). A graph is included that shows the various stop mechanisms for the carriage.