Sea Fighter Analysis, U.S. Coast Guard Research and Development Center, 2007

“Sea Fighter” in Coast Guard colors

Thought perhaps this study might be of interest, and did not want to loose the link to the study. Some of the conclusions seem to bear on any discussion of the important characteristics of Coast Guard cutters, particularly as our Maritime Domain Awareness improves.

Characteristics such as speed, crew size, deployable surface and air assets, and requirements for a reconfigurable mission bay would influence the design of any possible future Cutter X. In terms of deployable air assets, it is likely a helicopter/UAS combination would be preferable to the two helicopters considered here, and would make it easier to provide hangar space.

Any requirement for extremely high speed requires careful consideration of the attendant consequences, as we have seen in the LCS program, but we have known how to reliably get speeds up to 33 knots for decades.

I have provided the Executive Summary below.

(Thanks to Lee for bringing this to my attention.)


EXECUTIVE SUMMARY

Introduction/Objective

The U.S. Coast Guard (CG) Research and Development Center (R&DC) evaluated the U.S. Navy’s Sea Fighter vessel for potential applicability to CG missions. When compared to other CG cutters, Sea Fighter has four unique capabilities/characteristics that could significantly impact CG mission effectiveness:

  • High-speed (50 kts)
  • Multiple deployable surface and air assets (three 11m Rigid Hull Inflatable Boats (RHIBs) (Cutter Boats Over-The-Horizon (CB-OTH)) or five 7m RHIBs (Short Range Prosecutors (SRP)), two HH-60s or two HH-65s, and multiple Vertical Unmanned Aerial Vehicles (VUAVs))
  • Small crew size (26 persons)
  • Reconfigurable Mission bay (accommodates 12 mission modules)

Methodology

This project evaluated Sea Fighter’s unique capabilities through a combination of engagement modeling and simulation, human systems integration modeling, and Sea Fighter crew and shiprider insights (following multiple R&DC operational test and evaluation exercises).

Results

High-speed and multiple deployable assets were evaluated using engagement modeling. Scenarios were developed to simulate fishing-like vessels (lower speed with higher density) and drug smuggling-like vessels (higher speed with lower density). The results of the analysis showed that by themselves high-speed and multiple deployable assets made little improvement in mission effectiveness. However, as Sea Fighter’s sensor detection range and/or its off-board detection capability (a vital contributor to maritime domain awareness (MDA)) improved, highspeed and multiple deployable assets did lead to significant improvements in mission effectiveness. In the simulated scenarios, improving components of MDA (off-board detection capability) was the critical performance driver, followed closely by increasing intercept speed (from 30 to 50 kts) and increasing the number of deployable assets from two to four (particularly increasing the number of deployable helicopters). These improvements result in an almost 30 percent increase in the number of high-speed targets that can be boarded.

Crew size, required functions, and fatigue associated with a typical CG patrol were evaluated through human system integration (HSI) modeling. With Sea Fighter’s highly automated bridge and engine room, a 26-person crew can sustain many of the required functions. For a typical 14-day patrol, Sea Fighter’s crew could sustain normal Condition-3 watches, multiple boardings (some simultaneously), and multiple VUAV launches. However, HSI modeling showed that Sea Fighter’s crew could not sustain regularly scheduled helicopter flight operations.

To account for these deficiencies, the crew was optimized by adding two boatswain mates and a six-person detachment—Law Enforcement Detachment (LEDET), Maritime Safety and Security Team (MSST), or Maritime Security Response Team (MSRT). This 28+6 optimal crew was able to sustain all required functions. In a typical 14-day patrol scenario, the 28+6 optimal crew averaged three boardings, two helicopter sorties, and three VUAV sorties each day without exceeding acceptable fatigue levels.

Finally, crew and shipriders provided firsthand observations and insights relative to Sea Fighter’s unique capabilities. Some key insights are:

  • High-speed capability is a distinct advantage in a vessel accomplishing any law enforcement mission and is especially effective at intercepting fast, evasive, and uncooperative targets.
  • Sea Fighter’s ride quality at low speed (less than 15 kts) is very poor and can adversely affect operations or activities; however, ride quality significantly improves at higher speeds (20+kts). The trade off is largely due to hull design consideration made during Sea Fighter’s planning phase.
  • RHIB launch and recovery is limited to 5 kts due to the poorly designed stern ramp and vessel movements at low (less than 15 kts) speeds.
  • A crew of 26 is too small for typical CG operations.
  • Overall, ship layout and configuration are excellent. Bridge layout affords excellent visibility, internal communications, and improved situational awareness with all underway watchstanders located on the bridge. Flight deck lighting, configuration, and manning are exceptional from both a crew and pilot perspective.
  • Sea Fighter’s mission bay can provide remarkable mission flexibility, especially for deployable teams such as MSRTs or MSSTs. However, spaces for 12 mission modules seem a bit excessive for CG needs. In addition, the design of the X-Y crane prohibits moving payloads (including extra 11m or 7m RHIBs) while underway.

Conclusion

A 50-kt Sea Fighter-like vessel with four deployable assets (two 11m OTH RHIBs and two HH60 helicopters) can provide significant performance improvement compared to a traditional 30-kt CG vessel (CG High-Endurance Cutter (WHEC) or CG Patrol Boat (WPB)).

A highly automated Sea Fighter-like vessel, with the crew size of a patrol boat, provides more mission capability than a WHEC. The ModCAT hullform and large mission bay provide excellent flexibility for emerging CG missions and demands. Sea Fighter’s speed and multiple deployable asset capability offer outstanding performance improvement potential for the CG; however, a critical enabler is improving detection capabilities – an element of maritime domain awareness. As MDA improves, a 50-kt patrol vessel capable of deploying four assets could provide a tremendous improvement over current and future 30-kt vessels.

Recommendations

The CG needs to continue to evaluate non-standard hull forms such as ModCAT-type vessels for both speed and modularity purposes. High-speed vessels normally have endurance problems based on their fuel consumption rates. This has been one of the perceived shortcomings of this hullform type. However, the ModCAT hullform (i.e. Sea Fighter) provides very good fuel economy and, given the typical patrol profile (12 kt patrol speed, 20 kt transit speed, and 50 kt intercept speed), the vessel is capable of remaining within the patrol area for an entire patrol period. Opportunities exist for the CG to further evaluate other Navy/DOD high-speed vessels (HSV) such as the M88 Stiletto for MSRT type missions and the HSV platforms, HSV Swift and HSV Joint Venture, for extended duration missions.

Additionally, the CG should look at ways to optimize the number and type of deployable and off-board assets through a more detailed M&S analysis. A 50 kt Sea Fighter-like cutter with four deployable assets (e.g., two 11 m OTH RHIBs and two HH-60 helicopters) can provide significant mission performance improvement compared to a standard 30 kt cutter. To maximize the benefit from embarking four deployable assets (two 11 m OTH RHIBs and two HH-60s), a revised approach to boardings would need to be established. Currently, boardings are to be conducted within two hours from the WHEC (at the WHEC’s maximum speed). Under the MSRT CONOPs, the boarding teams would need to be trained similar to MSRTs which are able to defend themselves while conducting a boarding at greater distances from the patrol vessel.

The CG needs to continue to incorporate more automated systems on-board cutters, but have contingency plans (both personnel and equipment) in place for changes in operational requirements or causalities. In order to derive optimal mission effectiveness, the patrol cutter must be able to safely navigate and operate deployable assets in varying sea states and at a reasonable speed. Sea Fighter’s automated systems allow for these evolutions to be conducted with fewer crew members and with an acceptable margin for safety.

16 thoughts on “Sea Fighter Analysis, U.S. Coast Guard Research and Development Center, 2007

  1. Some concern has been raised with regard to the use of aluminium alloys almost exclusively in the construction of Sea Fighter’s hull, as well as future vessels based on the design. While aluminum alloys have a high specific strength, they melt at a lower temperature than steel. Some lay concern has been expressed about aluminum hulls actually burning, but only aluminum dust or powder is considered flammable. Additionally galvanic corrosion may result between the aluminum hull and steel fittings, as happened to the littoral combat ship USS Independence.

  2. I love it for a role where there is no need to possibly play bumper boats. Less Coast Guard, more navy. Platforms that should be avoiding hits to begin with. Similar thoughts with composites/fiberglass. Has a place, plus American expertise and capacity. Assuming we get on the stick before the industry dies out.

  3. This ship is reportedly a very rough wide at slow speeds. That is mentioned or eluded to in the report.

    For a vessel that spends most of it’s time patrolling and only occasionally chasing, this is a big drawback of the hullform.

    • Yes poor sea keeping at low speed is a non-starter for the Coast Guard, but the the study defined several important characteristics for future cutters. It contains some significant traits that might be applied to Cutter X, that might make a dual service ship of 1,500 to 2,000 tons cutter for the Coast Guard and corvette for the Navy:

      Automation similar to that of the Sea Fighter.
      Crew of 34 for the cutter so accommodations for about 45.
      Room for at least a pair of 20 foot container or alternately ASCM launchers (probably between bridge and hangar)
      At the stern, at least two 11 meter boats or USVs or alternately additional containerized capabilities, e.g. more ASMs or ASW mission module sonar (plus maybe one or two 8 meter boats amidships)
      Flight deck and hangar to support atleast one MH-60 plus a UAV, presume Navy would want MQ-8C
      Speed higher than typical CG cutter–35 knots is a good target–two diesels to provide reliable 20 knot cruise, plus an LM2500 for sprint. Perhaps two shafts with red gear with CP screws for the diesels and a central water jet for the turbine like the German built MEKO A-200 South African Valcour and Algerian El Radii class (MEKO A-200AN) class frigates. (CODAG-WARP system (COmbined Diesel And Gas turbine-WAter jet and Refined Propellers) which consists in a water-jet drive, in addition to two propellers) https://www.navalanalyses.com/2019/12/erradii-class-frigates-of-algerian.html That way you get both redundancy and simplicity.

      • Maybe torpedo tubes out the side like the old Knox frigates? Anti-ship capability without “missile tubes” shrieking when people see one.

  4. Interesting design…strikes me as a sort of a scaled-down helicarrier. I imagine it would make for a versatile interdiction/SAR platform, with its ability to field 5-10 cutter boats and an assortment of helos/UAS. Where do you think these would most likely be stationed Chuck? I think the Bering Sea would be a no-no, based on fellow commenters’ observations 🙂

  5. I think that the US Navy learned with the Arleigh Burke Flight Ones the need for a helicopter hangar and thus haven’t repeated that design omission since.

    The Sea Fighter concept seems better as a FEMA CONUS Disaster Relief or Wildfire Helicopter transport ship (for the US government or USCG) than for overseas due to its poor ride quality at slow speeds and the lack of a helicopter hangar. No mechanic would want to repair helos on an open deck in the sea spray and wind without overhead cover. If the sole purpose of Sea Fighter is to transport two helicopters and two RHIBs, then as a ship, the purpose seems minimal.

    I’m not saying that the Sea Hunter doesn’t have any uses…it does. It could be an Arsenal Ship (Medium) by removing the RHIB deck and installing VLSs on the Flight Deck to drill down into the lower decks (no RHIBs or helicopters at all) and then adding CIWS, NUKLA, ECM, and (Sea)RAM around the Bridge for self-protection—or a mast for fire control. Sea Hunter makes sense as an Arsenal Ship, able to speed to the area of Operations, fire, and then retreat back to CONUS or a Tender for resupply. It should not really be part of a CSG or ARG, but should have enough armament to protect itself in solo or Wolfpack transit (the CIWS and VLS will give it that) for Dash-and-Fire tactics as it doesn’t have the facilities for 6-8 months on tour.

    The use of Aluminum can be changed to include steel and the elimination of the RHIB deck should allow for more fuel to increase the range beyond 4,400nm

    • Apparently there is an elevator that would allow the helicopters to be hangared on the vehicle deck.

      The Coast Guard Yard built one of the very first SWATH.

      I don’t really see a future for this platform in the Coast Guard. But the analysis is interesting for the features that they found important for a minimal offshore patrol vessel.

      • Thanks, Chuck.

        I didn’t see/know that the Sea Fighter had an elevator to the vehicle deck for the helicopters, and knowing that now, in hindsight, totally improves my outlook on the prototype ship.

        I still believe that Sea Fighter can have a purpose, such as a USSOCOM SEAL boat transporting TF-160 or MH-60R helicopters and SEALs in RHIBs as QRF. Add some self-protective weaponry, and Sea Fighter can be used in conjunction with the ESBs.

      • The elevator does not allow helicopter to be hangered on the vehicle deck:
        Page 24: Air Deployable Assets
        “… There is currently no hangar on Sea Fighter; however, there is an elevator from the flight deck to the Mission bay. The elevator can accommodate helicopter parts or VUAVs similar to the Eagle Eye (or smaller). …”
        (39th page of the pdf)

  6. Thanks for the HMS Sheffield link – interesting -I was certain that at the time much of the blame was put on an Aluminum superstructure – but it looks like they had some major issues being prepared as well as other things that burned – just seems to not have been prepared

    • @Captmike. One of Sheffield’s two fire main circuits was inoperative when the hits occurred. Much of the fuel in the missiles was unburned when the hits were made and that added to the fire.

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