The trailer is quite narrow and fits between the Pontoons. The Trailer actually lifts the deck of the Boat and does not support the Pontoons and the wheel base is quite small. This style of pontoon boat trailer can be retrieved and launched in the shallowest of water, since the Pontoons are very low to the ground.
Tanking is, as its name suggest a method of sealing a wall to prevent water ingress (think 'water tank). often mis-specified as a cure for damp problems it is basically a waterproof cementious slurry (wet mix) that is applied to a surface to prevent water penetrating the internal surface of a building..
Curtain grouting is the construction of a curtain or barrier of grout by drilling and grouting a linear sequence of holes. Its purpose is to reduce permeability. It may cross a valley as a vertical or an inclined seepage cut-off under a dam; it may be circular around a shaft or other deep excavation; or it may be nearly horizontal to form an umbrella of grout over an underground installation.