40ft Excalibur Prop
 

I have a 40ft Excalibur Hawk with twin 425HP 454's. I currently spin a 19P Revolution 4 blade to 5300 rpm. Its a heavy TRS boat, and I am looking to gain speed up top. Boat seems stern heavy. Out of these props, what is recomended

3 blade cleaver
3 blade mirage
3 blade mirage plus
4 blade Hydromotive QIV
4 blade Bravo

Im thinking a 21P should put me at 5000 rpm

Well since you have the TRS Drives on a 1982 boat I would assume that your prop shafts are pretty deep. I would suspect 3B are best for your set-up but a 4B cleaver may give you some stern lift and help carry the transom better. If you can try several of the sets you listed I would do so. You might be surprised and find a great prop for your boat.

Julie

Im thinking the Hydro quad IV may be the best prop. I think the cleaver design may work best, since I need stern lift. How about the old 3 blade cleavers? Powerboat magazine did a test on my boat with twin 400HP mercs with 3" log manifolds and 21P 3 blade cleavers and got 57mph on the gun. I have twin 425's, and a perf exhaust, I would like to see 62-62, but that may be a long shot.

Hey Joe, still tinkering with the Hawk?

After trying the Mirage 21P on my boat a few years back after getting on plane, I immediately wanted to take them off after less than a mile. Lots of slip. The 4 blades are much much better for our boats.

The tests back in the 80's with the cleavers were based on the technology at the time. I think with our deep x on the TRS drives on these hulls that cleavers are not the best choice. I think they are best for a shallow x drive where they can pierce the surface to reduce drag. On fully submerged drives I think cleavers are pretty inefficient, and there is lots of info about that around here.

I would say a set of Rev 21P's would work great for you. I run the 19P Revolutions with the 454 mags and can get 5000-5100rpm. I would think with your power on the same boat that 21p 4 blade revolutions would be perfect, and you might get a few MPH.

Remember too those tests were conducted with very low fuel, on a new boat with no gear on board, brand new engines/drives/transmissions, and every single advantage taken. The test on my Stinger in the same time period with 370's showed a radar top speed of an even 60. (most likeley with a midget driver, on fumes, with a gutted interoir)

I actually have the powerboat magazine issue from 1982. They tested a Excalibur Hawk 40 with Twin 400's 21P props, 57mph on radar. Chris Craft Stinger 39 with 370's and 21P props and 370's did 60 on radar. According to them, the stinger was faster by 3 mph with 60HP less. Same bottom, same props, same rpm, but 3mph difference. The excalibur weighed in a bit more, so maybe thats the difference? Who knows. Im gonna try a 4 blade hydromotive 22p, thats what was on my boat when I first got it, but the engines were not right when I had them, and never got to really test them, plus i had 3" logs manifolds then too. Maybe I could spin them now with the better exhaust and better intakes to about 4900-5000 and gain a few mph. Ill keep my eye open for a 22p RH prop, mine is damaged beyond repair :(

I have a 39 1983 Chris Scorpion. It ran 56-57 with 370's and 19 3 blade cleavers, 60-62 with 420's and 19 3 blade Mirage and now runs 72-74 with 630HP 540's and TRS's. I think the 22 is too much prop. You may get exactly what you want by labbing your 19's. I run labbed Mirage 3-Blade 23's with the 630's and spin them around 5600 at that speed. I can bump them up to 6000 RPM when I run labbed 21 3 blade Mirage's but I don't need to abuse them that much for the extra couple of MPH. I would ask ThrottleUp or Bblades to assist. They both have excellent rep's on this site. One goofy thing, talked with everyone and they all said a waste of time, but when I put on the Hydromotive nose-cones, picked up just over 1 MPH. Cheap 1 MPH!

The only reason i say the 22p props might work, is that I spin 19p four blades to 5300. Id like to keep my max rpm around 4900-5000, and i heard for every 1 inch in pitch increase, you lose 150 rpm. 150 x 3" equals 450 rpm, which should in theory get me to my goal.

I guess my main concern is whether a 3 blade is a good prop for my boat. I know the drives are deep, and with the rev 4 blades, it seems to carry the bow well, but the stern feels heavy. There was another guy on here with a 40 hawk, running 21p mirage 3 blades with twin 400HP's and he got 62 i think. Cruise speed is important, but top speed is my goal. Some guys dont care about last couple MPH, but my buddies scarab III runs about 60-62, and he pulls away from me ever so slowly, so I need to prop it for top end, so I can run along side him or maybe even pass him!

So it looks like I will try the 22p hydro's, and 21p three blades first to see how the hull likes it. Then adjust my pitch needs from there i guess. It seems the 21-22 is where i need to be. Thanks!!

I had an old twin engine Cig with TRS drives and 3 blade cleavers were the fastest on top, but sucked out of the hole and in the middle.
We also ran Merc Mirages and Turbo Vectors with the Turbos being about 1mph faster.
4 blade props did not work on that old Cig but the Rev 4 did not exist as of yet.
My guess is that a 3 blade with lots of blade area would be fastest.
Call BBlades and test a set of 21pM+, 21pRev4, and 22pB1.
Throttle up would be the place for Hydro Q4s but I'm not sure if they make a 21p.

Hey Joe...I would also keep in mind overloading the engines with too much prop. Detonation and all if your running 89 pump gas....just food for thought.

Also, where are you getting the 5300 rpm...fully loaded with pax and fuel, or light? That could make a difference on how much bigger you go. Gas is what...6.7 lbs / gallon or so, and that really adds up.

I had Bravo 22P on the boat with the old engines that had all the problems a few years ago. The best I was able to get to was 4600 rpm with 1/4 to 1/2 fuel and they were supposedly 450hp each but who knows really...they sure did not last long....(what a mess but thank god it's over with) Also, look at the diameters of the Bravo's vs. the Revs...I think the Bravo has a slightly larger diameter which will drop your rpm's as well, and the smallest size they make in Bravo's is 22p. I always thought reworking Bravo 22's to a 20-21p with the larger diameter might work well, but now you are spending some bucks on experimentation.

Anyway, Pat has a good plan for you there. Those Ocean Performance guys know their stuff. Lots of places rent test props also, and I have even seen guys on the board here offering props out for test from time to time.

Good luck,
Todd

I always heard the Bravo 4 blades were "light" on pitch. For example, a 22P bravo 4 blade is equal to a 21P hydromotive or rev. I guess i really wont know until I try a couple different props. I think I would be okay spinning the engines at 4800-4900 rpm, I believe merc recomended 4800-5200 on the 425's. I got 5300 with a light load, but I usually run light, just me and wifey and 1/2 tank of fuel.

Whats the deal with the prop diameter? bigger vs smaller? How does that work? Thanks guys!