Update - my husband says that the engines are below the funnel slightly midships AND at the stern are the propellers. These cause the most vibration particularly when going into reverse. We have sat in both restaurants (deck 7 and deck 12) and felt hardly any vibration when we were at sea. We have a suite A157 booked so should be 11 decks above the engines. Not worried though as we felt nothing in all parts of the ship and previous cabins were on decks 6 and 8 midships.

I was on OV1 in it's former life as P&O Arcadia. The lower deck which is now the Gym at the rear, was the Main Dining Room. The vibration was bad to the point you held on to your wine glass before it hopped off the table & all around you could hear the jingle of cutlery on the tables. Bear in mind this ship is 'Old Technology' compared to what else is now on the water so no point in comparing it to Voyager Class ships & the like.

it was my 3rd time on ov1 having been on a b and c decks although aware of vibe nothing to keep you awake or annoy you in my opinion.... after all it is a sailing vessel not a building just go enjoy and make your own review

The engines must be at the rear of the ship and always produce some vibration but this is usually less the higher the deck you are on. Having looked at the cabin position, the only structure nearby is the funnel which presumably is the exhaust from the engines below. Could there be something in that causing vibration? or does it transmit vibration from below. I too would be interested to know. The only thing I saw was a complaint of noise from crew scraping sun loungers along the deck above in the early morning and evening.