Higher diameter higher load...more blade surface in contact with the water. Usually a larger diameter prop will drop rpm's with the same pitch number. Think of your drives having to spin a larger wheel through a fluid/frictional envoronment. If you have the power to spin a larger diameter, higher pitch prop...more propulsive force, and greater performance.

2 identical pitch props...1 with larger diameter will require more power to spin it at the same rpm as the smaller diameter prop. In your case if you had a 19P prop with a larger diameter than the rev 4 19P your rpm would drop, but since you have more blade in contact with the water your thrust would be incresed. Thats why I figure the 21p Rev would work well. Diameter the same as your 19P but a greater pitch...the bravo's have a larger diameter and a larger pitch which would drop your rpm's more than I think you want... but like you said...give em a try and you won't know till you see what they do on your setup. All I know is 22P Bravo's were too much prop for my Stinger with 400-450 hp each. Had the diameter been cut down slightly they may have been perfect. I personally don't know whats better...same pitch with more diameter, or larger pitch with same diameter...may not make a big difference between the two...

I don't know if props alone will get you the 5 mph needed to match speed with your friends Scarab. Maybe props / nosecones / very light fuel load, no tabs, perfect trim, and a perfect 3' swell...unfortunately it takes so much to get another 5mph on our old heavy hulls.....5mph I think equals about another 120hp in improvements.

Just noticed these in the ad's here for ya Joe if you are going to try some......

http://www.offshoreonly.com/classifi...p?product=3076

Tried some props the past couple weeks. Ran Hydromotive 22P quad IV's, port tach 4800, starboard 4600, 57mph on gps. One of the props has a couple slight nicks, which was on the port side.

Ran 23P quicksilver mirage's yesterday. Port tach 5000, starboard 4900. Had five people on board, and 3/4 fuel, water was rough and planing was real tough. I did like the was it handled, and rpm seems where i should be. Forgot the GPS, so not sure how fast I was going. But my buddies Scarab III could no longer pass me!!!!!!

Im wondering if a little cup added to the mirages would be good, to help plane and bow lift? Also thinking of having the hydros checked out to make sure they are balanced just right together. I wonder if it would be worth anything to try a pair of 22P bravos?

I brought the GPS with today. Still had the 3 blade quicksilvers on. Water was 1-2ft chop, was at 5100 rpm, and only 56mph on gps. So basically I saw no increase in top speed with the 3 blades, and the cruise speed sucks, at 4000 rpm I was only going 43. With the hydro's I was at 47mph @4000 rpm. Im thinking either a 21p REV 4, or 22p bravo . I think this hull is much too big for 3 blades.

Weak Thunder, I had 40 Hawk, TRS drives, we used
3 blade Kiekhaefer Cleaver Sport Props 17 x 24, cruise speed was 58-60 MPH @ 4,000 RPM At 5,700 RPM 80 MPH Tried Hydromotive 4 blades, boat was 2 MPH faster top speed but cruise was down around 54-55 MPH. With Kiekhaefers had bow lift with Hydromotive's had stern lift. You just need more power. Good luck.

jons, what kind of power were you running in your hawk to see 80? That must have been a nice ride. How did it handle at speed?

Boat was very good in all water, little lazy in flat water. 60 MPH cruise was good for most trips, if water got to 4 to 6 foot would have to run 40 -50 MPH. Ran boat in Lake Michigan most of the time. Ran out of North Fort Myers to the keys every winter. Boat was ordered new in March 1984, glass not Kevlar, TRS with raised X 2 inchs, no step or notch in bottom. Boat had 330 Merc's with Gil Headers for one week ran 56-57 MPH. Then 511 inch Tall deck Chevys for one year 72 MPH. Then 540 inch Tall Deck with CMI Big Tube Headers 655 HP @ 5,700 RPM ran those untill sold boat. Boat would break TRS drives at will. Big prop, Big power for the time, small gears and shafts. Good luck with yours.

Im thinking of going to at least 550-600hp this winter. I would really like to see 70 in this hull. Love the ride quality. Tried to sell it several times lately, and cant seem to get any interest and had offers of 15k. Id rather light it on fire and roast marshmellows on it than let it go for 15k. Mine is glass, not kevlar, does have some stress cracks around the corners of the windshield area. Im thinking of going with bigger power, and raising the x dimension a bit, Im sure the transom isnt what it used to be anyway, and then maybe konrads sooner than later. Love the Black Hawk you had,

Mild, I ran 23p Mirage Plus on mine when it had the 400's in it. I have another 40 here that has the clevers on it and it does not want to cruise very well at all. I am actually working on 2 Hawk 40's right now. One of them is getting 540ci 625HP engines. I am looking for 70mph out of it and a 50mph cruise at 3500rpm.

Wow, I have not seen another 40 hawk in person ever, and you have two in your shop! How about some pics? The one with the 540's, is it gonna run the trs setup??