Cat props
#1
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Cat props
Ok, I want to do some research on what is working for other people. My application is a 26' Firehawk catamaran. It's a center sponson, single step, notched transom cat that is simular to the Talon and American Offshore cats. I have a 600hp big motor, Imco 2" shortie drive and a 12" setback Stellings adjustable box. The center of the propshaft is currently set about 3/4" above the center sponson. With a Bravo prop the boat planes out with absolutly no slippage. Because of this, I'm thinking that I can go higher with the X. I finished the boat late last year, and really don't have much seat time. Our calcs show that if I can turn a 30" prop that the boat will go 100. If I have to step down to a 28", I'll be in the mid 90's.
My question to the board is what prop works for you? I know that the Bravo 1 is a easy winner. I currently have a 30" stock B1. But what about cleavers? Hydros? (I'm leary of Hydromotives having broken one) Be sure to include info on your combo, slippage, pitch/type, handling characteristics, and of course speed. Thanks!
My question to the board is what prop works for you? I know that the Bravo 1 is a easy winner. I currently have a 30" stock B1. But what about cleavers? Hydros? (I'm leary of Hydromotives having broken one) Be sure to include info on your combo, slippage, pitch/type, handling characteristics, and of course speed. Thanks!
#2
Spinelli's seem to be fast on cats with low "X" dimersions, the only issue is finding one now. I have a 26 Carrera cat that had a very high "X" (only prop that would plane was a bravo and it broke loose) I put an Imco box on very late last year with no real time to experiment before winter. Before the box my slip was around 12.5%, after the box my cruise speeds were essentially the same but planning was much easier. Motor is NA 632", 900HP.
Before box results;
30 bravo @6100 101 GPS
28 bravo @6500 98 GPS
30 Bravo @6700 108 GPS (175HP NOS)
To see 100 with a 30" Bravo thorugh 1.50 gears you'll need to turn ~6000 rpm. @12-13% slip. A 26" Bravo would need to turn 7000+ in the same scenerio.
Before box results;
30 bravo @6100 101 GPS
28 bravo @6500 98 GPS
30 Bravo @6700 108 GPS (175HP NOS)
To see 100 with a 30" Bravo thorugh 1.50 gears you'll need to turn ~6000 rpm. @12-13% slip. A 26" Bravo would need to turn 7000+ in the same scenerio.
#3
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HTM Sr-24 boat likes 4 blade Hydro 27 pitch props best. With a 540ci motor, Bravo 1 1.36 gears, nose cone, IMCO drive extension it ran 93. With a 500 hp motor it ran 87 with a 26 pitch prop.
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You didnt say what gear set you have I put my little motor in a profile cat this winter just to see how fast it would run it has a Imco sc drive std.lenght on a 3' imco box with 1.5 gears with a bravo 32 turning 5500 the boat run 94.6 mph on gps this was full of gas (120 gallons) and two people I dont think my motor makes as much power as yours so if you have 1.5 gears I would think your 30 would be to small. but I run the boat for less than 2 miles I just had to see the differance between my v-hull and the cat.
Eric
Eric
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jd-do you know what you x-dim is? The box should help with planing. Are you thinking of a Spinelli cleaver? Man, think of the speed of you could just get those slip numbers to come down! Assuming a 1.5 drive, it calcs out at 116mph.
KC-what kind of power do you have? Does the hydro surface? I feel that my old hydro broke because it was surfacing-so I'm really reluctant to try another.
EWB-I have a 1.5 gear. When I calculate your slippage, I come up with 17%. Is this correct? I don't know what your hp or boat is, but if was a small single engine cat, a 32" @ 5500 should get you over 100.
KC-what kind of power do you have? Does the hydro surface? I feel that my old hydro broke because it was surfacing-so I'm really reluctant to try another.
EWB-I have a 1.5 gear. When I calculate your slippage, I come up with 17%. Is this correct? I don't know what your hp or boat is, but if was a small single engine cat, a 32" @ 5500 should get you over 100.
#6
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On the 540 I would guess in the area of 550hp never had it on a dyno and it was abit mild. I have had zero problems with the hydomotive prop. I had more of a problem with prop shafts.
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I take it that you're breaking them? I've heard that on a surfacing application that the Bravo will chuck it's shaft with as little as 500hp. Something that I'm a bit nervous of.
#8
Put hard shafts in...I've never broke a prop shaft in 3 yrs. Now gear floors are another issue. I've seen many Bravo's sling blades that were "surfaced", labbed and non labbed.
#9
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That is what solved my problem with prop shafts. Sucks was breaking the shaft off in the water with a brand new prop on it.
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Its a Profile 28 with a stock Bravo 32 the motor is a 502 with a 250 powercharger and Nickerson carb I have know idea how much horsepower it makes the prop shaft is even with the bottom of the boat the motor run my H2X 24' v bottom 82 on gps with a labbed bravo 30 at 5000 I dont know how heavy the cat is but I would think it would be more than H2X ether way the cat is faster with the same power even though its 4' bigger.