Sea-Breeze Boogie

As I was setting up my paramotor the sea breeze began to arrive coming against the prevailing south-westerly. It came in fits and starts as it was establishing itself as my friend Pete said was typical for the area. About 20min after it's initial arrival I was in the air and climbing. At about 1000ft I climbed up into convergence. I thought, this is interesting in that it implies that you can fall out the bottom of a convergence when free flying. I flew around watching my ground speed on the GPS. The sea-breeze is a north-easter so I was surprised to find an area where the wind was northerly. Especially so since the wind had swung thrugh the south as the sea breeze came in. The inflow into the convergence wasn't as simple as the classical model would suggest.

I headed off with the breeze towards my destination of the Woodford Folk Festival about 10km downwind. On the way I flew thru what seemed to be four separate convergences. The first two didn't change my ground speed much but the third dropped my ground speed by about 10km/hr. The fourth convergence was in the south-westerly itself. I had overtaken the sea-breeze. The third convergence had the strongest lift.
It seems these separate convergences were why the arrival of the sea-breeze came in fits and starts, with changes in wind strength and direction.

We have known from our local free-flying sites that often the sea-breeze arrives in a couple of waves, but four convergences implies four waves. Probably the different area could produce different sea-breeze effects.

I flew around and over the festival, only flying low where there were safe landing options if the motor should cut out. I wouldn't want to have to land in the middle of a sea of bodies. There was a grassy, largely unpopulated ridge with a helipad on it almost in the middle of the whole place where I could do low passes (30ft). The sea breeze arrived as I was playing around. Maybe next year I'll ask permission to land on the ridge to attend the festival. I would think that the organisers would be happy for the spectacle and not ask me to pay admission.

The festival site is at the base of an east-west range, tucked in amongst spurs that run down off the range. On the other side of the range is a little valley that is open only to the west. As I flew over the end of the range towards this little valley heading cross down wind, my ground speed suddenly went from 50km/hr to 30km/hr. I was back in the south-wester! The sea-breeze was flowing like water thru the five kilometer gap in the mountains and the south-wester was flowing along beside it in the opposite direction. There were eddies in the interface between the two winds that kept trying to turn me around. It was rough enough to be unpleasant but not dangerous. I had a couple of small tip collapses so I headed off back into the sea-breeze into the gap in the mountains and promptly got pinned in the venturi.

My ground speed was down below 10km/hr so I dropped down to about 50ft where I had a ground speed of about 15km/hr. I slowly crept forward until I had a bit more ground speed. Then I climbed back up thru the stronger breeze until at about 1500ft it eased up. At about 2000ft I started hitting the turbulent shear layer at the top of the sea-breeze. So I just stayed below the shear layer, put on speed bar and flew the 10km back against the wind to my launch point, dropping back down thru the stronger breeze as I neared my destination. It was after sunset by this time and the ground inversion was setting in. I landed in nill wind next to my car, and looked over to some trees on top of a little hill nearby to see the tree tops still moving just 50ft higher up.

This is my first real sea-breeze convergence exploration. I'll have to do significantly more before I come to definite conclusions. It's one of the real bonuses of paramotoring in that it offers the ability to explore all sorts of meteorological conditions. So it can even improve my cros-country free flying. I think I would be more comfortable though on a wing that is more roll stable than my APCO Santana. I have tried an Ozone Electron and it was much more comfortable in turbulence. The new APCO Fiesta comes in a paramotor version and also looks promising.

PS I ended up with an Arcus