20' w/ 200 HPDI Yami

[Blue_Heron]

Hi,
Bow hop, or Porpoising, is all about too much weight in the stern (or not enough weight in the bow). As noted in previous posts, it can be fixed in a number of ways.
* Trim Tabs
* Thrust angle
* Weight shifting
I have a 18' Action Craft with a Merc 150XR4 on a hydraulic jack plate. With that big motor hanging cantilevered off the transom, it used to porpoise bad at low speeds. I have trim tabs (Bennett), but didn't like the idea of dragging them through the water to keep the bow down. I added transom wedges and now I can stop the porpoising by trimming the motor down.

Unless you're going to add trim tabs anyway, I'd start with transom wedges or set up the jackplate for more down-trim on the motor. If you add flotation to your bracket, it will help with your displacement trim (at rest or off plane), but may actually hurt your planing trim unless the addition increases the surface area of the hull bottom. Once the boat is on plane, it's just more weight hanging off the back of the hull.
Dave

P.S. Why is a guy with a flats skiff posting to ClassicSeacraft? Last week, I added a 20' CC Seacraft with a 200 Merc to the fleet. Spent part of the weekend putting trim tabs on her. All I can say is God bless the woman I married. [img]/images/graemlins/smile.gif[/img]