Gauging Weir is immediately after Ibis Point.
IMPORTANT NOTE: The dynamics of Gauging Weir change depending on the the state of a temporary causeway 250m downstream of the weir. If the causeway is removed or lowered, water no longer backs up to below the weir. This effectively exposes the anti-erosion concrete-base and lip. (2018-12 Update: The causeway downstream has been rebuilt recently, so there is more water covering the lip below the weir, but not to the extent that it used to be, so be cautious).
The challenge, is to avoid damaging your boat on the concrete lip below the drop.
In low to medium levels you will have to shoot the weir at an angle to avoid the lip. Stick to the centre where it is slightly deeper. Fortunately there is very little suck back when the river is low. If you get the angle right your boat should avoid damage. You should aim to have your rudder/tail off the slope before your nose crosses the lip.
The portages (left or right) here are easy and quick, so if in doubt get out. On the Dusi Marathon there is usually a watering table on the left bank at the weir which is very conveniently placed along the portage.
If the river is very full you can shoot it on the extreme left high side, which is a very easy and much safer option.
Low Water Level (Lip exposed)
Medium-Low Water Level (Lip covered)
After Guaging Weir it is a short paddle to Marianne-Foley