colinhilton: Panelplane Prototype
The 2.40 metre prototype panelplane.
Modified version of type used six months ago for static test without motor. Also based on a 2-inch PU foam of 92kg/m/cu density displacing 150 litres, but with deck foreshortened to 32” square and thickened to 6” to put tiller of 15HP 2-stroke Mariner in reach. Hydro-skis made from 3/8” (9mm) strips of marine ply.
Motor fixed with tilt-and-steer removed weighs 27 kg and boat the same. Test 23rd April 18 established CG ideally centred around grab-handles for winching and deck stable enough for boarding with waterline as expected. Lateral balance on par with a kayak and thus less than ideal.
Application of moderate power pitched the nose beyond acceptable limits at too great a rate, due moment of thrust and absence of countervailing weight and surface area. Test also proved weight-shift alone is ineffective for steering at low speed.
The craft required towing toward open water and with a tow-line in hand at the mid-point (itself possible due lightweight construction), this capsized the craft, ending test that may have been prolonged by conventional tow (but its initial aims largely met).
Going forward following recommendations to be applied to new-build:
(a) increase of length to counter thrust moment
(b) use of GRP pultruded keel-ski instead of ply
(c) a keel-ski ideally extended beyond propeller
(d) fitment of out-rigged foam stabilisers at rear
(e) addition of control trimmer behind propeller