This is a strange one and causes a little scratching of the old grey matter.
Importantly,it’s annoying for your friend and no doubt yourself.
I don’t thing anyone is being abrasive in the true sense.
We all express ourselves differently and sometimes like text messages on phones things can be taken out of context.
Is he sailing on the Exeter flood relief system or salt water.
Look at the possibility of a dry joint as I suggested before,and Yes the motors should be suppressed.