Andrew Langdon HydroSport 646 Sport

Langdon has been racing monohulls from a very early age. Drew Langdon has achieved National Offshore Endurance Champion, Two National Water Speed Records, One World Water Speed Record and Four times runner up in the Powerboat P1 World Championship and is the current water speed record holder, along with Miles Jennings, for World Marathon Class A at 109.18mph.



The 646 is a sturdy looking RIB with nice clean lines and comfortable seating for four with storage in the rear locker and within the helm and navigators seat. The deck level is above the water line making a very practical dry deck with self draining and worry free berthing during the rainy months if you are away from port. The transom allows complete trimming of outboard engine clear of the water at rest. With the tubes providing good stability to the boat at rest.

The 646 was very easy to manoeuvre within the confines of the marina, at 3-5mph she produced almost no wake and the engine idling at this speed is almost silent.


From zero to the transition onto the plane the 646 maintains good manoeuvrability with little change in the level attitude. Visibility all round is excellent and the screen provides good clear protection requiring no sunglasses at speed to maintain a forward watch.


The attitude of the 646 is very level throughout the transition on to the plane and it is effortless. There is no traditional climb over the hump and acceleration is swift. Planing is around 15mph with full negative trim and is almost unnoticeable.

Andrew Langdon HydroSport 646 Sport


The acceleration is very responsive taking only 10 seconds to travel from planning at around 15mph to 45mph which can be achieved with full negative trim. The bow wave breaks at the entry point of the first step which is just about where your feet are while helming. With positive trim applied the speed increases a little and the breaking wave moves aft to about the bottom of the first step and the attitude of the 646 increases accordingly which makes a very useful reference point and easy to find. Over trimming the engine produces no porpoise or chine walking and merely over revs the engine with no negative handling attributes. The ride is stable with level or full negative trim and gives no indication of bad handling characteristics on the horizon. In a small chop the stable ride is maintained and there was no tendency to hook or bow steer. At 6,000 rpm approximately 50mph was achieved on a small chop. Iin these conditions at full speed the 646 required a small amount of correction to maintain a stable level ride but felt safe and comfortable in doing so.


Cornering in the mid speed range was good. Although the hull is stepped there was ample grip and no sliding occurred with both negative and level trim. Cornering to port was favoured due to the propeller rotation and provided a better lean in angle to the turn than to starboard which had a lesser angle although remaining comfortable. At the higher end of the speed range cornering was the same well mannered response.

Andrew Langdon HydroSport 646 Sport


The 646 represents a very clean, robust and well mannered boat and at no time did it feel like there were negative surprises waiting to surface. It has quiet effortless planning, safe handling and very responsive acceleration. The instrument package with keyless starting was clear and easy to read at speed providing all the information required for an enjoyable coastal passage.

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