Driftbars prevent deep drawdown Flouts from colliding. This arrangement is made of 3/4" or 1" SCH40 plastic pipe and elbows. The ends are attached to the vents above the waterline with stainless steel screws.  The bar should extend close to the Flouts. A drainhole must be drilled into pipe at the floor to prevent floating.  If the Flout is on a shim, the driftbar may pass under the swingpipe, cradling just one Flout.

Alternator units have a built-on driftbar suitable for up to 36" drawdown. The type shown above is added for drawdowns over 36"