Rocker is a curvature in the hull bottom like that on a rocking chair. It can induce poor handling traits such as porpoising but I honestly don't know how it will affect your boat. It's something to look into with those who have the experience.

Sounds like I should ask the question Thirdchildhood, there is also some very good new and that is I GOT THE BOAT THIS MORNING!!!! Paid my money down on it and it now mine the owner accepted my offer! THAT makes my day!!
karl

There's nothing at all wrong with having a hull with rocker built into it , as long as it works for the intended application. When the BH drive was introduced many a manufacturer installed them only to find that they didn't do what they expected. The BH drive isn't really a bow lifting set up by its nature . Donzi , and a few others did some homework and decided that the chosen hull they wanted to use it on needed rocker in the bottom to get the bow up and aired out . Their existing boats with B1s and other single prop 'deep units' didn't need it as they provided bow lift naturally. People who wanted to air the bow out even more could also opt to experiment with the newly engineered selection of props coming on line but BH drives on those hulls without rocker just didn't seem to cut it .
There's a good few people who have changed out the BH to a B1 on their Donzi 22Cs mainly because they got tired of trying to find replacement parts as time went on. There is discussion on it in various places and it makes for interesting reading . My guess is that the bottom line would be that a B1 driven Blackhawk hull would be more sensitive to trim input than a straight C22 hull with a B1 setup .
If the rocking chair analogy provided above isn't clear enough try to picture placing the boat , on its keel , on a dead flat surface. On a boat without rocker the keel of the boat will fall flat and run straight on the surface. On a boat with rocker in the hull you'll see that the keel has curvature in it from the bow running to the transom .

madbouyz thanks much for the analogy I was thinking on that line by the description, it sounds less stable but gives you the ability to get more hull out of the water hence increase speed? or so it seems, as usual there is never anything for free is there. What relationship will the prop have on this setup if any? In my old outboard world I never had any prop adversely effect handling, all I ever looked at was throttle setting/RPM and MPH, which ever prop got me the best MPH with a time to plane that was livable was the best prop there was, it sure sounds like that is going to change. Madbouyz my boat is coming with a 27" P 5 bladed prop, again in my old outboard life it was said that the more blades you have the more drag your dealing with, is that adage still true with the boats we are using?
Thanks much for you time on this madbouyz its very much appreciated
Karl

If your looking for propping advice on a C22 I'm not the person . I've driven only one and to be perfectly honest I didn't find anything strange about its handling that caused me to 'forget everything I knew about driving a boat.' Mind you , it wasn't one with a huge power package either . Remember , these boats utilize 1960's design technology and back then the largest marine V8 available was the 330 Merc (which was more like 290 HP by today's standards) . If what you describe about your engine is true then you're in a different ballpark altogether. But many have done it already and are there !
There's been a lot written about the BH hull when it's been re-rigged with the B1 drive and I think that without too much searching you can find a lot of what you need to know over on the Donzi.net

Thank your for the advice madbouyz, its appreciated
Karl