Dolphins or harbour porpoises?

[Quandary]

On passage north between Insh and Kerrera a fortnight ago we were joined by two cetaceans, they spent about 15 mins. with us riding the bow wave and diving under the boat, very fast and nimble; returning this morning we encountered them again, this time there were four, though as we were motoring they did not stay with us this time. I presumed they were dolphins but they were quite small, less than 1.5m. long and brownish in colour on top when they broke the surface, much more like harbour porpoises as illustrated on our west coast cetaceans chart.
Any time this has happened in the past they have been dolphins, porpoises just go past on passage minding their own business, so does anyone know if porpoises like to play with yachts?

 

[Bodach na mara]

I have never seen porpoises playing with boats myself, they have always continued on their way without any interaction. I was once told by a marine biologist that dolfins "porpoise" (put their heads out of the water) but porpoises never do.

 

[Kelpie]

We've had a porpoise spend some time in our wake before, but I think it was more a case of both of us wanting to travel in the same direction, rather than the porpoise actively seeking to play with us.
I agree that 99% of the time porpoises are only seen as one or two glimpses of an arched black back, with the stubby fin cutting through the water like the tooth of a circular saw blade.

 

[macd]

I've only seen harbour porpoises at an aloof distance. Anything bow-riding or conspicuously playing alongside in UK waters most likely a common or bottlenose dolphin. Once had the company of a solitary bottlenose for ten hours on passage in the Celtic Sea.

 

[Contest1]

I've had many encounters with harbour porpoise around Lambay island. They normally just appear as described cutting the water with with the dorsal fin. I understand this is when
they are feeding. Occasionally they come swimming around the boat if at anchor and seem curious about what's going on. Beautiful creatures and they can be heard breathing quite loudly when all's quiet.

 

[westhinder]

Same here.
Whenever we have had cetaceans accompanying the boat, playing in the bow wave or surfacing at the quarter, as if to see what is going on in the cockpit, they were one or other species of dolphin. Numbers varying from a single animal to over a hundred, time around the boat from 2 minutes to over an hour.
Porpoise either a single of at most a couple or mother and calf, just break the surface with part of their backs and the dorsal fin an do not seem to take an interest in the boat, they just continue on their own paths.
I have noticed a marked difference in dolphin behaviour: when they are feeding they do not approach the boat, you can see them all surfacing around the same spot, often with birds overhead who grab their own meals. When they are not feeding, they approach the boat and seem genuinely interested in it until something else catches their attention and they all disappear at the same time.

 

[rotrax]

Lovely surprise just off Littlehampton a week ago-escorted for a mile or so by two large Bottlenose Dolphins.

Never been so close-a couple of metres from the hull only-and at first wondered if they were Porpoises.

Investigation proved them to be Dolphins of the larger variety.

 

[jamie N]

Stakkr at Chanonry Point.