Could someone help me out and tell me what the "X Dimension" is exactly? I've read a lot of posts referring to it and haven't quite figured it out.

Thanks

Simply put, it's the vertical height of the engine and drive. The higher it is, the faster the boat is (generally) and the harder it is to get on plane. The vice-versa is also true.

X-dimension is the vertical distance from the bottom of the boat or the keel, up to the crankshaft centerline, measured on the transom. The larger the X-dimension number, the closer the propeller shaft is to the water surface. It is widely accepted that raising the X-dimension one inch, will increase the speed approximately 2 mph.

X dimension is the measurement everyone talks about because when the manufacturer drills the hole for the drive, that's the number he uses. But the important number from the functional point of view is the distance of the propshaft below (or sometimes above) the bottom of the hull. The object of the game is to reduce gearcase drag as much as possible, without losing thrust because your props are no longer in the water. This game involves almost as much time and money as the "increase HP without blowing up" game. Right, Bruce?

Gotcha.....I get it now. Thanks everybody.

So I would guess it is natural for twin engine applications to have a higher x dimension due to them being off to each side of the keel centerline? What affect does the X dimension have between twins and singles?

BT