Thread: Center of Gravity
01-15-2007, 01:28 PM #1
Center of Gravity
Some where on this board there had been a discussion about where the COG is on the new Ultra hull. I can't seem to find it so I'm starting a new thread.
It had been mentioned that when on a PWC stand the Ultra appears to sit with the stand toward the rear of the craft, possible suggesting a rearward COG. It is usually accepted that the more weight carried in the rear of a boat, the less hp needed to keep the boat on plane and the faster the boat will run. The current company brochure shows an Ultra viewed from the top, with the engine position shown. It seems that the front of the engine begins at the half way (center) of the hull and extends rearward from there. I thought that this was pretty good, until I took some measurements from other PWC. The front of the SD GTX/RXT 4-tec engine is positioned about 14 inches toward the rear of the watercraft which should equal a more rearward COG. The older style GTX hulls have the engine about 10" rearward of center. The Ultra 150 has the engine several inches ahead of the boats center. (maybe why the Ultra 150 is nose heavy when operated at idle speed, but it rides clean when on a plane) Actually all of this is speculative because the engine weight and size is different on all these boats, but interesting non the less. Having the Ultras battery mounted in the bow not only puts the COG further forward but it subjects the battery to more stress in rough water than if it were mounted in the rear or midship.
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