Greg Copp looks at new gear from Whale Tail…

The Whale Tail XL from Davis Instruments is a bit of an old tune on a new fiddle. However, you can’t argue with the simplicity and effectiveness of the simple bolt-on fin, which in most cases boosts planing performance for outboards and sterndrives alike. There are quite a few versions of this concept around, mainly focused on smaller engines, where lower levels of stress make a bolt-on accessory less likely to throw up any issues.

This aluminium fin set-up, like the others on the market, is claimed to boost hole shot times, increase top speed and also provide improvements in fuel efficiency. It is debatable whether it will increase efficiency at high speed, but low-speed planing and acceleration are likely to benefit from the Whale Tail.

It is claimed that it will reduce porpoising and sideways motion, while levelling out the ride in rough water in the process. The extent very much depends on the displacement and length of craft. The tail will provide extra hydrodynamic lift to the outboard/sterndrive leg, which will have the effect of tucking the bow down slightly. Extra lift means less drag with a subsequent increase in efficiency, which will also increase stability. Due to the fairly substantial width of the Whale Tail, it will provide a fair degree of lateral stability, in a similar manner to a trim tab. At high speed, careful trimming of the leg will be needed to reduce any extra drag that this fin can potentially create.

Having a plate mounted above the propeller also has the effect of funnelling more thrust aft, as less of the driven current is wasted in an upwards flow. It is claimed that this reduces the amount of confused wake, making it great for ski boats.

The Whale Tail XL is constructed from marine-grade aluminium and is easily fitted to the anti-cavitation plate on an outboard or sterndrive leg. Though manufactured and sold in the US, Davis Marine also operate from the Netherlands, where UK customers can order the Whale Tail XL. It costs from around £50 excluding delivery.




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