My land yacht ain't got no handle bars . . . . . ?
Do you mean the two bars either side of the front wheel?
They are for my feet, I steer with my feet while my hands are busy with the sail sheet,
On a windless day I'll rig up the mast and sail and find a suitable guinea pig (daughter) to sit in so you can see the setup.
The diagonal brace bars to the top and bottom of the mast support tube brace the mast to the back axle triangulating everything in making it a strong frame.
Your bum is in the seat and your legs pass through the triangular frame to the foot pegs either side of the mast tube.
The tabs at the ends of the foot bars prevent your feet slipping off the ends.
When sat in the thing your knees are bent and your feet are braced against the foot bars all the time pushing your bum into the back of the seat.
This arrangement pins the pilot into the landyacht, though a lap belt is optional if additional pilot security is required

When you climb in, because of the low ride height and the mast brace bars to hang on to, it feels quite cozy.
Equal pressure on both feet keeps the front wheel straight and unequal foot pressure causes the front wheel to pivot on its bearing allowing turns

Here is a photo of the land yacht executing a left turn, at a low speed this gives me a turning circle of about 10 feet.

You can see in this photo just how much the back wheels cant in toward the centre line, this serves to increase axle width thus stability and save wrecking the wheel bearings with the huge side loads generated by the sail.
At speed, the slightest movement of the front wheel either side of centre will put you in a sliding turn which is great fun!

The front wheel pivot is slanted 30 degrees up from horizontal (you can see the bolt head just behind the tyre), the centre line of the pivot bolt passes through the ground 1" in front of where the tyre touches the ground, this gives me Castor allowing me to keep the thing straight easily at speed much how a shopping trolley wheel works.
If you are unfamiliar with land yachts, it takes a while to get the idea as most people learned to steer a bike with handle bars

(imagine a cross between flying a plane steering the rudder with your feet . . . . . and a sailing dinghy where you control the sail sheet (rope) with your hands).
Its totally alien at first but after half an hour buzzing up and down the beach it becomes quite natural
