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Ratios and Props Need Input!

S

silver bullet

Member
Hi
I'm new to the site and just wanted input on some prop info with a 2.68 box? what r u guys running , what rpms at cruise, whats snappy but doesn't have to rev at 3600 to cruise down the river?

I have talked to Dave and he had alot of good input but everyone I talked to has a different setup and I'm getting really confused :x

Im building and decent 383 500hp on a 13'X7'6" hammant( .125 bottom .090 sides). I want it to be a strong Marsh boat not all out race and just wanted to know what other similar boats were turning for good all around snap :?:
 
There has been so much posted on this subject. In my opinion it depends on where your engine makes its power and if quiet is important to you. So figure out those things and look back in here on some of the other posts, you can use the search feature up above to help find them.

I run a 3.12 stinger and swing a 84" four blade sens super wide. My boat is 15' x 8' with a double size front deck, and 12" walk boards along the sides. I run a small block stroker 396. I assume it has at least 475 hp and 500 tq. I don't know for sure wher eit comes in at so I have been working towards sound. It was designed to come in below 5000 rpms however some times things don't work out right. I know engine builders who build hundreds of the same engine and for what ever reason sometimes they turn out different. I will be getting mine on the dyno now that race season is over and then I will know.

I cruise at anywheres from 2000 to 3000 rpms but I go by the way the boat is riding at the time as to the cruise speed. I am usually just a little faste rthan a coot flies, ask stan he can vouch for that. LOL I usually slow down and let them out of the way but everyonce in a while doo doo occurs.
 
with a 383 and a 2.68 box, if you get the right diameter prop, it will be snappy, no doubt

Like CNTRY said, really depends if quiet is important to you. I don't see why it wouldn't be

I'd look at a 3 blade super wide Sensenich S Series, they are working great so far
 
I WOULD GO WITH DAVES INPUT ! HE HAS BEEN PRETTY STEADY ON HIS INPUT ON HERE ! HES NOT HAPPY UNLESS HE IS IMPROVING ON HIS STUFF ! HE ALWAYS GOT A SANDSPUR UP HIS BUTT TO GET BETTER !
 
Quiet isn't as important as performance to me. I just want a good all around prop, put some pitch in to cruise at a low rpm, take it out to race!

Again everyone has a different idea:
Whirlwind said 3 blade master blaster 2.3 84" and anything narrower will not work with the 2.68 on 500hp

Dave's input is what I'm leaning toward:
3 blade wide 78"(not super)

I just was hoping to find someone running something similar to see what the cruise rpm's are, how much pitch he or she has in it and how much out of the hole snap it has
 
I will state put an 84 inch prop on it (like suggested) and I will out run you with a foot paddled floating bike, you know the ones you see at the beach. I believe your performance guide lines are a lot like mine I always wanted a fast or I should say the fastest ride boat still wanting to go faster. You also want something fast, with snap, that is fun to drive that runs free on the water but you also want a low cruise RPM and push. You will screw up your whole boat if you put an 84 inch prop on it. Also Whirlwinds are great for static thrust but on an airboat in a drag race they are generally 3 to 4 boats slower in 400ft. So are the larger diameter props they show more thrust especially static but put them on a boat and is just like dragging an anchor. I have tested them a ton. Take a boat and time it and measure your speed with a power shift or Sensenich then run a Whirlwind you will see how much slower your boat is. This thread can go on forever. To make your boat as fast as you want and keep it a good ride boat your going to need a 78" three blade. You would be surprised the 400ft ET difference between a 78'' to an 80'' it's over a boat. Now on paper all the engineers will say that's BS because the 80 makes more thrust well we don't run on paper and there are many more things involved then just thrust.
 
Hey thats why I asked the question.
The manufacturers all tell me different, I wanted to know what has actually been tested on the water and what works. The people on this site seemded very educated in the different combos you can run and helpfull. I'm going with the 78 3 blade wide Sensenich per Daves advise.

Thanks again Dave!!!
I am putting the bug in the ears of some friend about the 9th

Oh yeh who's got the best prices on the Senesnich :?:
 
Cool thanks. I KNOW you will be the happiest with your choice. The Q series Super Wide is a bit quieter but you will loose a little in the 400ft area and if you ran a two blade your cruise RPM will not be what you wanted. You choose the best all around prop for YOUR needs. P.S. get some of them aircraft boy's out there I'm loaded for bear and will run what ever they bring! We can go ridding afterwards that night . Please make sure the people you talked about show up. I will have a few of the supercharged boys show up also.
 
I have also listened to dave with the prop and gear box combo and I'm happy with the out come My boat runs a whole lot better now that I got rid of the warp drive and went with the q super wide
 
AIRBOATCAPT TALK TO FARON ! DONT THINK YOU CAN BEAT HIS DEAL ! HE WILL GET YOU WHAT YOU WANT CHEAPER THAN ANYONE ESLE ! :shock:
 
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