Thank you everyone, you're all very kind.
Amnon - the hints I gave for Anne were only the beginning. After that you have to ride round and round on the rafts many times, so my way was probably no more elegant than yours.
LCD, I notice from your screenshot you have a sphere in the central water. You need 2 spheres in the far left water beside the breaktile.
Here's a walkthrough for the first bit of the blue sphere room.
Push the sphere inside the boulder L. Go down and push the prism U onto the timer. Push the blue sphere D and L. Push the boulder U to blow the barrel and step up. When the boulder stops push it down and leave it there for now. Push the prism up the ice onto the conveyor button and leave it there for now.
Here's a walkthrough for the raft bit.
Get on the raft and ride L, D, U, L, D. Change to the other raft and collect the 2 remaining coins on the water, ending up just above the first raft.
Ride the rafts round and round the top section until they are in a horizontal line at the bottom of the ice, then ride the raft D and R.
The prism/breaktile bit:
Using the ice curve push the prism down and onto the lower raft so it goes to the other side. Ride the top raft L, U, R, D, L and push the prism all the way L above the blue boulders in the water. Use the breaktile to collect the 3 coins and push the prism up onto the conveyor and into the water. Ride the raft round and push the other prism off the ice and into the water. Change to the lower raft and ride up to the top section.
And finally the timer bit:
Ride round and round until you have one raft at the bottom of the ice and other other beside the blue timer. Push the blue sphere round the conveyors to start the timer and ride the top raft L to leave the area.
See ... nothing complicated about it
I guess I got a bit carried away
