Have to get this sorted out as I've been arguing with Jim Courier about this for way too long. It's not totally comprehensive but it will resolve the whole "What is a twinzer?" row which soured my beer last weekend.
Generally has two larger fins at the back (middle) and two toed (set on an angle) smaller fin placed outside and further from the tail of the board. Like the Quads, Twinzer is much looser than a thruster yet maintains speed.
Are great for small waves, being fast and maneuverable, but when put into tight spots on larger waves, they become hard to control, they have two slightly larger template fins.
Four fins in the water. You may think that having four fins would sacrifice speed by creating more drag, but this is not the case. The both sets of fins are working together on the rail, which makers believe they creates less drag than a board with a center fin.
Basically a Twin fin configuration with an added small center trailer fin, this adds more stability/pivot than the standard Twin fin configuration.
Keel fins:Lower profile, longer rake version of a twinnie.
This is the original 5 fin Bonzer design though it has many new off spring these days. Big centre fin and weird and wonderful side fins.
How dja like that Jim ?