How bout 2 navy seals with night vision goggles come underneath the both and end the pirates lives in the first .5 seconds of engagement. This is getting idiotic.
Given that it is a fully enclosed boat, that might not be an easy thing to do.
Even so- I can see no reason whatsoever why the lifeboat couldn’t have been immobilized by a swimmer fouling the screw (propeller) with a few yards of netting, or just detaching the screw and letting it fall away into the depths. Fouling the screw could have been done absolutely silently, without alerting the pirates and risking the captain’s life. Navy tactical combat swimmers use closed circuit SCUBA gear, so no telltale bubbles. No risk in and out.