proping my cat
 

Now that I finally got the extension box hung, I'm trying to figure out what my boat will be needing for props. Here are statistics:

26' Firehawk cat simular to a AO
single step, 12" notched transom
The center sponson is about a inch below the outer ones.
I have a 12" adjustable extension box that is set back another 1.5". With the box all the way down, the prop is centered on the bottom. I can go up another 2-1/2". The bottom also has some major rocker built into it!
The drive is bravo 1 with a 2" imco shortie
The engine is a 600hp 540

First of all, I really need to figure out what this thing will run. Mfr says close, if not over 100. Dealer says mid 90's. I dunno. What's your guess?

Second what do cats like mine like for props? Because the drive is surfacing, am I in the cleaver range? How much rake do I need? How much pitch?

Cord;

What kind of extension box are you runnning? What is your drive ratio? Assuming you are running 1.5 gears it would be hard to go wrong starting with a 26 Bravo. My guess on speed is low - mid 80's. :) Unless you have a very light hull...not real familiar with Firehawk. let us know how it turns out.

Where are the pics:D

It's a stellings box. The drive is a 1.5

Florida, you're not the only one that's been bugging me for pics! I'd take a couple now, but it's overcast and they'd be kinda drab.

Where exactally is your prop relative to the bottom of the center pod? Even with it OK, a bravo prop will work well. A 28" turning 5500rpm and 8% slip is about 90mph. The old saying TEST, TEST, TEST. Run what you brung- what do you have? You will need between a 26 and 30". Try anything and the guessing is much easier.

I'm using a 26 Bravo with
 

1.36 gear. 5300 to 5600 depending on weather. 540 with about 625 at the prop. I would think you would need a 28 to a 30 with a 1.5 gear. 26 would give you a lot of r's. Close to 6000 :rolleyes:

Right now the prop is exactly centered on the bottom of the center pod. I can still go up 2-1/2". The only prop that I currently have is a 24" bravo 1. Naturally that will be too small. :D

I have a back issue of Hot Boat where they tested the cat with a 650 hp engine and got 98 with a 32" prop and 1.36 gear. I know that the mfr spun the snot out of the engine (700+) and put a shortie lower on for 107. This was without a extension box. Why do those numbers seem optimistic?

I have a 2600 American Offshore NSX and am currently using a 12 inch extension IMCO Box, SC drive with a 2 inch shortie, 1-34 gear ratio, and a Lab Prop. This set-up increased my speed approximately 14 mph. This may work for you too.

Iwould try a 30 bravo one,you should run 100 mph

cat-have you experimented with any other props besides the bravo? What were the results? How much hp you running? It must be quite a bit because of the drive ratio. Finally, what is your prop height in relation to the bottom?

I think you will really like the Shorty Drive and extension box. I have not tried any other props, however I turn a 32 Bravo One Lab, 5800 RPM's. I currently have 786 HP and my prop is one inch above the bottom.

How well does your application plane out?

With 6 people lots of fuel not as good as Iwould like. With 2 people it does good

Ok. Sounds like it'll be better than my old application. That one would NOT plane with two people in a heavy chop. I'll proably be reall please with this one! I may just raise it an inch before it even gets to the water. Thanks for the help!

Cord, I have been following some of your posts. I plan on doing a similar project for my next boat. Anyway I am very interested in how it all comes out. Now the first question is did your motor make 600 HP on the dyno with all accessories and the headers you are going to be running? If that is the case than you will be at around 570 HP at the prop. In the Jan 1999 hot boat they tested a 26 Firehawk with a 502 EFI 415 prop HP at 77.9 MPH on radar. Using this known (actual not estimated) prop HP as a guideline I would say mid 80's to 90 MPH is a good safe estimate. With the box you may need to play with some different drive heights and it may take some time, but that is half the fun.;)
Now if your motor made 600 HP on the dyno with dyno headers and no accessories then we have a different story. Accessories rob 25 HP and dyno headers are generally full length and are good for probably 10 HP over a set of CMI E-tops and maybe even more than that over cast aluminum types. That would put you at 535 at the prop and probably 85 to 87 MPH. If you actually do have 600 at the prop (approx 665 with no accessories and dyno headers) than you are looking low to mid 90's right in the eye. I think a 28 bravo is a great prop to start out with. I hope it does 100 MPH for ya. The old boating school of hard knocks has just taught me to look a little on the pesimistic side and be pleasantly surprised if it is faster. Great project and get some pictures for us!!!:D Oh ya the water pressure controller can be purchased for $175 if you are interested.

Hey Catnaround a little off the subject, but I,m looking for a 26 AO, and any info pro/con you could relay would be great also type of power and perforformance you get and ride. Thanks Ken

Here are a couple of pics. These were taken way back in Febuary, but things havn't changed all that much!

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This my nephew. I'm hoping that he'll let me drive a few times! Whenever I come over, he asks right away if I brought the purple boat! lol!

Very nice!!!
 

Do you think it is more economical to purchase all of the parts or just buy the boat W/O power, but ready. I know Cougar and some other companies will sell boats in various stages of completion. I don't worry about the labor because I will do most of it myself, but the parts are what I am unsure of. How much better will you come out if any if you don't mind? I priced a 22' Cougar MTR and it goes for approx 38 less engine, but wired and ready for a drop in and that includes a drive and transom assy and all gauges. They sell the same boat for 26 with seats and the necessary holes cut in the transom only. Basically all gauges, wiring, motor mounts, engine accessories, drive, and acessories will need to be purchased and installed. I doubt 12 G is enough to get that done. Now you can buy a 22 with a base BBC for around 42, which is probably the most economical. I am sure a new 7.4 MPi would sell for 3 to 4 G W/O to much trouble. When do you plan on taking the maiden voyage? Keep us posted!

Well, I've really pinched my pennies and have bought alot of used stuff off of the board. With all of the stuff that I've traded, had already on hand, or bought I'm under 47k. I think that's a good deal for a boat that runs this quick. The hull was a 2000 model with gauges, wiring, interior, and gimble that I got for 28,500 on the trailer. It's been ALOT of work, I have 6 months into the project already, and have at least 3 more to go, but I've enjoyed it. I've learned alot, and although it wasn't necessarily done right, it was done my way! :D Anyways, because of some wiring issues, I think that next time I'll just order the boat less wiring but I'm not sure about the gauges. Mind you, that this would add alot more work to the schedule.

Probably the best bet is to find a very clean used boat and pick it up for about half the cost of new, but then you can't say it is exactly the way you want it. I agree on the wiring, I could see it being very difficult to match some of the quality that comes from a factory job.

You what would have been a good deal was a 22' eliminator that was for sale up here. It was a theft recovery that had been stripped of the drive train. I'm pretty sure that it's been sold though...

blowncarrea777
 

I really like the American Offshore NSX pay the extra money for the NSX its worth it.It seems to be one of the fastest cats out there,it rides real good.

cat n around, could you tell me what the nsx model is vs. the standard thanks.

The NSX has canopies and the two front seats are move together with a consol between them. Styling wise, I prefer the standard deck model, but that's my opinion.

Thanks Cord, the one I'm looking at is the nsx set up as
you stated. I,m used to the seats apart, but being in center would sure make it easier to hear and i like the idea of canopies
re-routing all the wind. So you walk around instead of in the middle. like you say guess its what your used to.

:cool: NICE! Like Lenny says I want to fly like the wind!:cool:

Cord I bought my 26' Daytona without power wiring or gauges and purchased and installed all of this seperately. In addition to building it the way I wanted it, I eliminated the double purchase of exhaust manifolds, etc. loads of parts that are unacceptable. You sure can use many of the standard parts, but alot of them are repeat. I installed full hydraulic helm with dual ram, Hp gimbal, Mercruiser wiring harness, Gaffrig monster gauges, had motor mounts built out of stainless steel, and my custom bbc 540 with Procharger-stage 4, out back to XR drive. I am pleased with the package and have a one off custom piece with top of the line parts. Good luck with your project.

Thanks for the complements guys!

I hope this works Cord. But I did a lot of research and I think I found the perfect prop for you. You will be turning about 1000rpm's but I think it will get ya up on plane NO problem :D:D

Hey Cord maybe you and I can get a group buy on one of these bad boys. Do not laugh man. Couple Red Bulls and watch out I bet I can get the faulker on plane!!! :D:D

Notice the proper weight distribution on that family. Adults in the back Kids up front for more bow lift :D:D

Well, the engine got dynoed on Friday! Made 600 hp and 620 lb/ft.

I've heard of other people complaining of the distortion from those windscreens. I always thought that from an asthetics points that they were too narrow.

Jon, what are we going to do with you?:rolleyes: