TMK

The Thompson Modern Keel (TMK) is a versatile all rounder set up to hit that sweet-spot between the pivot of an upright twin and the drive of a keel. 

The real key to this fin is all in the foil - the Apogee 13. The foil was designed by aerodynamics legend and MIT Professor, Mark Drela for his gliders. Professor Drela very kindly agreed to let us use his foil on these fins. 

Adding Professor Drela's foil means the TMK is about one-third thicker than standard fins made to fit a Futures box. Our CFD tests show thicker foils deliver more lift, with less drag through later stages of your turns because they help water-flow stay attached for longer.

The trade-off is usually more drag when you're running the board down the line. This is where using Drela's Apogee 13 foil comes into its own because it doesn't have too much camber (or curve and concave). This lets the fin glide nicely through sections. 

Through the top third of these fins the foil straightens slightly and as it does, the toe-in reduces by 0.5 degrees - pointing the flatter foil more straight up and down the board. This lets us build in a little tip-flex and also aligns the fin more nicely to the water-flow which is curving under your board. You can read more about what we are now learning about water-flow under our boards here. 

These fins are constructed out of G10 fibreglass. G10 has double the amount of glass when compared to standard hand-laid polyester panel. It is also cured under high temperatures instead of using catalyst to harden the resin. The result is the fins are heavier than standard but more solid and durable.

Under your board they feel more like glass-ons giving you a nice solid base to push off. 

The TMK is best for boards with low toe-in settings like Steve Lis style fish, or longer mid-length twins. That said, this is a versatile foil and template and will work on most designs - except narrow-tailed twins where they tend to make things feel too locked up. They are too big to add a trailer.

Be warned these fins are heavier than standard fins but it works for creating the glidey, glass-on feeling they're set up for.

I like these fins at a toe-in setting of 1/8" but they will work all the way up to 1/4" provided there's some width in the tail of your board. 

If you're not sure what toe-in your fins are set at, ask your shaper, or reach out and we will help you work it out.

Specifications

Height 5.4"

Base 5.76"

Area: 24.7"

Cant: 5 degrees

Toe-in-twist: 0.5 degrees