This has been running around the sailing blogs. The best theory is that if they are fin keel boats with a fin rudder, a sailboat looks like a turtle swimming. I have not seen what type of boats have been approached, so, hard to say.
All I know is that our boat is a full cutoff keel with a supported rudder. All I know is the other day when we were crossing the Savannah River and hit a submerged tree in 50ft of channel, we just kept on going with no damage.
I hate to say it, but I vividly remember a video of a poor seal on a massive block of ice, clinging for dear life as a pod of Orcas did the exact same thing to the little iceberg, trying to get an easy meal.
Don’t know how it turned out, but I wonder if the Orcas were hungry, and wanted to check out how the funny looking animals on the iceberg with big cloth sails would taste.
I am happy to go my own way peacefully, but if that happened to me, I’d be looking at trying to smoke every Orca in range before the boat sank and I was in the water with them.