As the days get warmer, the kettle begins to make its journey from the sunken winter hearth back up to the summer brazier. About mid-March the Tsurigama, or hanging kettle is used. It is suspended from a chain attached to a hook in the ceiling. No gotoku or trivet is used. Extra large rings hold a bridge piece that is attached to the chain.
In placing the hook in the ceiling, it must be located exactly in the center of where the the ro is cut. It must also be attached to a beam and be strong enough to hold a cast iron kettle full of water.
Because there is no gotoku in the ro for the tsurigama, often a gotoku futaoki is used to remind us of the gotoku. This a a rather challenging pice to use, as the hishaku cup must fit within the three legs of the gotoku futaoki. Make sure that the one of the legs is designated as the front and place on the tatami mat accordingly.
As you are using the kettle and placing the hishaku back in the kettle, it swings a little and give the feeling of a spring breeze in the tea room. Be careful, though, if the kettle starts to twist on you. You may have to adjust your hishaku.
In April, the sukigama is used. It is a wide flat kettle with a large wing around the middle. The wing rests on wooden blocks that sit on the inside ledge of ro. This lifts the kettle further out of the ro and the flange keeps the fire from the guests.
As the season gets warmer, we usually do chabako temae which lifts the kettle completely out of the ro and moves it to the center of the tatami mat that the host sits on. This is good practice as about this time the cherries are blooming and we can do chabako out under the cherry trees for hanami.
Finally at Shoburo, the furo season begins. We normally close the ro and begin to use the furo in early May. Here is a post with some thoughts on the timing of Shoboro. Seasons change.