Naval Historywith Dr. Alex

Q&A · 3:06:26-3:12:11

The right OPV gun depends on the fleet

Thailand can justify a 76 mm OPV gun because it is common across its fleet, while Britain gains a cheaper and more proportionate upgrade by standardizing on 40 mm.

3-inch Guns30 mm Guns40 mm GunsAmazonas Class Patrol VesselsForce StructureKrabi Class Patrol VesselsNaval CommonalityNaval GunneryNaval ProcurementOffshore Patrol VesselsOTO Melara 76 mmRoyal Thai NavyThailandWeapon Standardisation
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Question

What gun caliber is too large for an offshore patrol vessel?

Short answer

It depends on the navy: a 76 mm gun fits Thailand's fleet commonality and force structure, while 40 mm is the more proportionate British upgrade from 30 mm.

Notes

The question of when an OPV gun becomes too large has no fleet-independent answer. Thailand uses the OTO Melara 76 mm widely on Western-designed ships, so fitting the same weapon to its patrol vessels supports national standardization and compensates for a different force structure. For the Royal Navy, moving from 30 mm to 40 mm offers more ammunition growth and reach with similar crew demands and less risk of confusing an OPV with a frigate. The relevant tests are mission, commonality, support cost, and the capabilities of the ships above the patrol vessel in that particular navy.