Adding A Keel

I Own A 22ft Cris Craft Dory Performs Great In The Rough As Long As Your Moving The Bottom Is Rounded Design .i Would Like To Add A Full Keel (shamrock Design).the Boat Rolls In A Ripple When Stopped It's Rock-a-bye-baby I've Been Searching For Info On This Project Nothing Is Avalable
How Do I Calculate The Sizing? .what Are The Pro's & Con's On Adding A Keel?
.is It Worth Doing?
I Already Have Money & Time Invested Into The Boat I Converted The Gas Inboard To Diesel About 2 Yrs Ago And Love The Performance I Really Like The Boat It's A Center Console But Would Like To Add A Pilot House Someday
I Need Some Input On Adding The Keel
Thanks For Any Help

 

The nature of that design is what we call "tender" meaning she's a bit tippy. Under power she squats down and is quite a bit firmer, but at rest or low speeds a roller.

The keel you talked about is called a skeg (I think this is what you want) and it will help a marginal amount in the rolling action, but will not do too much as it's real role is to help the "tracking" or ability to move in a straight line, without wandering around, requiring continuous course adjustments.

Anything attached under the water of a boat will affect it's performance. In power craft, skegs can disturb the water flow to the prop, causing a loss of efficiency, extra drag, etc. though it can protect the prop if you go bumping into things.

Frankly, the rolling thing is the nature of this design and though a bunch of money and effort could be tossed at the issue, few of the reasonable efforts will do much to dampen the motion. A "keel" large enough to really add form stability will be quite large and severely detract from performance, draft, weight and other elements that are key to the design's success.