There are days when a big stick float with strung out shots works much better than a float with a bulk shot arrangement. I realised this many years ago on deep River Severn swims and also on other rivers like the Trent and Wye. Use a No4 shot per foot of depth so for a 10ft deep swim a 10No4 float is the one to go for.

RECOMMENDED SILICONE RUBBER
TOP 3mm to 8mm mixed
BASE 1mm