Wing Spoiler ????????

[Xtrasharp]

I've just redone the seating in the rear of my boat to try to eliminate purposing. At speeds above 48 my boat is purposing I was considering putting a wing or spoiler to attempt to lift the transom and level the boat out more but I have not been able to find any lit. or specs on wings/spoilers for boats. Do they even work?

[Eric Sponberg]

The problem is not that your stern is sitting too far into the water, it is that your center of gravity is too far aft. Move weights forward--that will be more effective than trying to rig up a spoiler with enough planform area to lift the stern of the boat. I imagine that such a spoiler would have to be pretty big, therefore heavy, therefore contributing to the weight-aft problem.

Eric

[safewalrus]

and if that don't work learn to slow down and enjoy life a little more!

[Petros]

porpoising is a complex interaction between waves, hull shape and stiffness, aerodynamics, and cg. Doing the wrong thing could make it worse.

Moving the CG may help, try that first. Thrust angle can also affect it, and so would adding a trim tab along the trailing edge of the hull. A trim tab allows you to adjust for various conditions. Depending on what the deck on the bow of your boat looks like I would consider alterations to kill any aerodynamic lift the fore deck might generate.

Good luck

[Guest-3-12-09-9-21]

suggest moving some female form with adequate weight above her centerline to the front of your vessel...at least it makes the act of porpoising much more enjoyable to watch.

[dsuursoo]

trim up.