Photo: TPSB with ballistic protection, Anmyeon Beach, Republic of Korea, June 30. Exercise CJLOTS 2015 (U.S. Navy photo by Mass Communication Specialist 1st Class Kori Melvin/Released)
Got an interesting link from Luke S. “Evaluation of Composite Armor for Coast Guard Vessels” (pdf) is a study from 1989, looking at how selected portions of the 110 foot WPBs might be protected from small arms fire. Here is the summary of their findings.
Up to a firing range of 100 yards, which was the limit of this study, personnel inside Island Class cutters are vulnerable to lethal rifle fire coming from drug smugglers. Test results showed that unconditional protection for personnel inside can be obtained by adding KRP (KEVLAR reinforced plastic–Chuck) armor panels to the cutter. This is also a more weight effective solution than increasing the thickness of the hull and superstructure. Although it was found that placing the KRP either in front of or behind the 1/8″ aluminum was equally effective, it should be noted that the aluminum by itself was overmatched by the threats. In general, it is more efficieut to place the KRP behind metal.
The USCG R&D Center defined three areas of the Island Class cuttfer that required protection in order to allow it to continue its mission if it came ander fire. These were the bridge and the communications room, both behind 1/8″ aluminum, and the magazine behind 5# steel. A visit was made to the USCGC Matinicus to take measurements and assess the feasibility of retrofitting KRP armor in those areas. Retrofitting them inside the bridge and communications room could be done by placing them in the space between the exterior aluminum skin and the interior trim panels. This might require some fit and trim but KRP panels can be cut and drilled so there should be no particular difficulty. Another option is to place the panels on the exterior of the bridge and communications room. This would appear to be an easier task but would present a different set of considerations. Since the KRP panels would have to be spaced 3″ in front of the aluminum, the panel supports would have to be designed to withstand green water loading. Environmental effects on these panels caused by exposure to seawater and UV radiation is not a problem for adequately sealed KRP. For the remaining area requiring armor, the magazine, mounting the panels against the steel hull inside the vessel did not appear to be difficult.
The amount of material and weight added in each of the critical areas is summarized in TABLE 6 for the worst case threat, the 7.62mm, M80 at point blank range.
TABLE 6 included the location to be protected, the total area to be armored, the weight per square foot for the armor, and the total weight for protection to that level. I have summarize the data below, but did not include the weight per sq.
- Bridge 33′ x 4′ – 132 sq ft, 1056 lbs.
- Communication rm. 14′ x 6′ • 84 sq ft, 672 lbs.
- Magazine 6. x 6′ 36 sq ft, 180 lbs.
- Total area covered: 252 sq. ft. weight: 1908 lbs.
These numbers are guidelines because the minimum armor density required was not determined in this study. Nevertheless, realizing these numbers are on the high side, the material cost from a commercial panel manufacturer for a KRP panel weighing 8 psf (lbs/sq ft–Chuck) with 20% resin would be about $40,000. This is basd upon a panel cost in the $20 to $24 per pound range.
Makes me wonder if anything was done about this, particularly for the WPBs based in Bahrain. Also, was anything included in the Webber class WPCs?
Even this relatively light armor would also provide a degree of protection against heavier .50 cal. and 14.5mm machine guns if fired from a greater range and/or if the round strikes at an oblique angle.
In addition to the bridge, comm space, and magazine, the gunners on open mounts could also use some protection as I’ve suggested before.
I have heard that ballistic protection for the Offshore Patrol Cutter has been deleted. This may be a mistake, particularly if it is as inexpensive as it appears.
Late addition:
Just found this. The photo below is Prince Charles boarding the HMS Middleton (a 32 year old, 750 ton mine countermeasures vessel) in Bahrain. The post is interesting regarding the situation in Bahrain, but I wanted to mention the gun crew protection visible between the stack and mast. The gun is an M134 “mini-gun,” a six barrel 7.62mm “gatling” gun. The additional pretection is apparent. Apparently the Brits recognize the need to protect their gun crews. It is not just about protecting the gunner, it is also about keeping the gun that is defending the ship operational.
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This sounds like a reasonable effort that provides protection, especially for our cutters in the Middle East.
My first thought was inspired by the picture: I wonder if a Humvee style gun turret could be fitted on a RHIB of that size? Or would the weight penalty that far forward negatively affect seaworthiness?
My second thought was to recall the continued debate over the effectiveness of sloped panel Radar Cross-section Reduction measures, such as we see in most modern Euro frigate designs, the Royal Navy’s Type 45 and, at it’s most extreme, the Zumwalt DDGs. While at the higher end of this scale one doesn’t doubt there is some useful effect, sloped panels have become a fashionable addition to all classes of vessel, cropping up on far less complex platforms like OPVs. Basically, don’t show up at an arms show with a ship that doesn’t have space age sloped panels!
So they’re fashionable, but even if they don’t reduce the chances of being spotted on radar, they’re also quite practical. Extending the superstructure out to the sides of the hull encloses a lot of useful volume that is accessible in all weathers, reduces the crew fatigue of those personnel working in those areas, and helps protect equipment stored there which would otherwise be exposed to the elements even when not in use. Thus, I was interested to note that the Offshore Patrol Cutter doesn’t have this feature – in fact, in design terms it looks like a throw-back to before the millennium. This now has ramifications for added KRP protection panels, because if they could be fitted to the interior surface of a sloped superstructure, not only could they usefully cover a larger area, not only could they not necessitate a refit of internal compartments (removing consoles, etc.) but they would also offer the best possible protection because they would be sloped! As any tank driver will tell you, sloped armour increases the apparent thickness of armour presented to an incoming projectile for no additional weight or volume penalty.
So, definitely missed a trick, there.
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