The latest ORCA attack was made last week on my colleagues in the VO65 racing yacht in the Ocean Race 2023 approaching the Straits of Gibraltar - the same area as many others. The encounter involved the now typical nibble of the rudder with the aim of doing substantial damage. The Orca involved appeared to give up quite quickly. Whether Carbon Fibre rudders are less tasty, perhaps harder to get your teeth into, or because the Carbon hull and structure of a VO65 acts like a drum with sound and the banging on deck by the crew was sufficiently unpleasant that it gave up is not clear. Most of us do not have carbon fibre rudders and hulls so that is not a quick fix.
Thinking on solutions - we are not going to know for sure why they are doing this, so the goal in the meantime must be deterrence.
Perhaps a simple solution worth trying could be: on sighting the Orcas in these areas or feeling first contact to stop or slow the boat right down, then deploy a wide mesh net as a curtain around the hull from amidships either side around the transom. With the top of the net secured to your four mooring cleats by loops (easy to release in emergency), and the bottom edge with weighted line just enough to sink it and hold vertical. Prior to use during transit of the risk zone the net is in place but bundled up with ties on the guard rail / lifelines ready for swift deployment. The depth of the net being from toe rail to bottom of rudder (3 - 4m ?).
Would this discourage / confuse them? Are they already sufficiently wary of nets to know to stay away?
If this were to be developed clearly this is not a piece of kit we all want to be lugging around once through the risk zone - so as was done with Armed Guards on ships going through the Piracy Risk Area in the Arabian Sea - with sufficient interest one organises pick up and drop off points at either end of the transit area. Maybe La Coruna, Cascais, Algeciras, or such like? With the equipment being hired by yachts for the duration.
If it were to prove effective, and again with sufficient yacht owner interest, insurers might engage and provide some seed funding to the collective efforts to reduce the number of claims they are experiencing and by all accounts may continue to.