25 Tantrum 28 Bravo 1
 

Are there any Tantrum guys running a 28 pitch stock Bravo 1 4 blade prop with stock HP500 motor or similar HP, if so what do you think of it? How many RPMs are ya turning?

good question..i'm looking to try a few different prop options.

I have a solid hub B1 28 that I used to run before I recently upgraded to a XR w/ big shaft. I could turn it 5300. but that is with an Extension box. i am pretty sure that this was the prop that was used back in the day when the boat was raced with the HP500. It has not been labbed but it has had something done to it... Its fast. I could turn it 100 more rpm than a stock b1 26. Explain that...

Ok following a lil test and tune day here's basically what I found. Looks like I run bout 15% slip at 5200 with more like 25% at lower rpms like 3000. I tested a standard 26 Bravo 1 and ran 72, used a BBlades 26 Bravo 1 and ran 72 except I am sure I had a some speed left but the boat was umm lets call it loose, I also had a 28 Bravo 1 that has been beat on and cup added and ran 69 but this was at bout 4700 and could not get the boat loose whatsoever. The 28 gave just about 10 mph more per given rpm vs the 26's and I really like the 50's at 3300. I'm confident the 28 was just giving too much stern lift or lack of bow lift whichever way ya wanna say it but that only seemed to develop at near max speeds at lower speeds the boat handled similar to the 26's per given mph. Anyways, so I'm thinking maybe a standard 28 or maybe a BBlades 28 with a lil bow lifting tweak might get me middle upper 70's, but that's probably a lil wishful thinkin too.

Oh water conditions were basically smooth as smooth gets on a lil inland lake. Nothing really unexpected and nothing the prop calculators wouldn't have told me, but figured I'd share. I wasn't initially expecting the high slip #'s at lower rpm's but after a bit of studying/research the propeller design stuff makes sense.

Oh I almost forgot, not that its laboratory accurate but my Garman GPS and my in dash non GPS Gaffrig were within a mph across the range so I am very pleased with the Gaffrig.

Before I rebuilt my engine, I was running a Throttle Up labbed 28 Bravo 1 at 5300 and boat usually ran around 79 to 80 GPS. Back then boat had 555hp. Labbed 30 would run around 83 at 5250.

Along with the extra 100 rpm I got 2-3 mph with this 28' that I have. And it was less efficient than the stock 26 at cruz'n speeds. But Bad a$$ up top

Yeah, but its making the engine work harder at that rpm, like going up a bigger hill in your truck. You still have to push the throttle forward just as far to run 3300rpms with the 28 as you would running the 26 at 3700rpms.

WOW you only droped 50 rpms from a labbed 28 to a labbed 30 how did you manage that. The normal drop would be 300-400- rpm drop. My old 25 was the smith bros race boat and with 500hp would run 74-76 with a 26 at 5250.

Thanks for the comments everyone, Griff's comments are making we wonder a bit bout how to get dyno curves for my HP 500 short of pullin it out. Anyone got data from maybe a rebuild or something on one as it seems factory data is a closely guarded secret ? I've also contacted BBlades searchin for their recommendations, so I'll keep ya posted with their thoughts.

There is a simple way to test.

Run the 28 at 3300rpms and mark where the throttle is with a piece of tape. Then run the 26 up to the same mark on the tape. If the throttle is in the same place, you are using the same amount of fuel. The rpms will be higher with 26 of course, but the engine is not loaded as much. The HP500 will make its best power all through the curve if you prop it to run at about 5200rpms.

Was your hull blueprinted? If so, any changes to rocker? if so, remind me what your X-dim. is at?
What was the air temp/water temp when testing? (same for each prop test?) What was your fuel load when testing each prop?
What all did you have in the cabin (weight) during each test? What was the attitude of the boat with each prop? (flat or bow-high?) When you said the boat ran "loose" do you mean chine walk? Porpoise?
We'll start with these and go from there...

You better listen to the expert! No kidding. Has anyone gone faster than Gordo in a Tantrum with a stock Hp500?

Howdie Gordo, thanks for the assistance. First off I notice I forgot to mention these tests were with the 1998 Tantrum and not the 1997 Tantrum. I am not aware of the hull being blueprinted, possible, but doubtful. The air/water temp was low 70's at about 3pm was when we started. Started with 20-25gallons of fuel, two adults, nothing extra or unusual on the boat, jackets cooler and some tools up front, anchor some tools etc under the back seat. All the tests were ran concurrent. The boat ran probably what I would call flat to bow high with all props until maybe 4500 rpms, when things seemed to change a bit. The 28 seemed to run bow low for its remaining rpms, the 26 standard ran bow high with a stable ride, the 26 BBlades ran bow high but you could clearly tell more of the boat is outta the water as it chinewalks and kinda feels skittish. I have contacted BBlades and they told me a little about the prop but I have the details elsewhere so I will have to follow up on that part, but basically it has a lil extra lift. I have a nice lil excel chart with speeds etc at the various rpms, I'll see if I can figure out tonight how to make that stuff viewable for ya. Thanks a ton for joining this topic and providing guidance.

OK, here is the missing stuff from my earlier post, lol. BBlades says the prop has "extra trim reaction" and the only other detail I could get is there is room for having less "extra trim reaction" but still being more than stock. I tried to get a reference like on a scale of 1 to 10 but that didn't seem like it was gonna happen, apparently an understandable secret. Basically I'm thinking I want a 28 with more "extra trim reaction" but less than my 26, seems doable so far.

And here are my playin around charts and graphs, all the same data, same day, etc.
[IMG]http://i671.photobucket.com/albums/v...opSpeeds-1.jpg[/IMG]

[IMG]http://i671.photobucket.com/albums/v...ropSpeeds2.jpg[/IMG]

http://i671.photobucket.com/albums/v...ropSpeeds3.jpg

Hey it worked, lol.

You forgot Prop depth. Drive in neutral trim, measure from keel to centerline of prop shaft.

Well the young gal is stacked and packed in a rack until spring so ..... unfortunately additional measurements aint gonna happen any time soon. Dangit lol !

Ok, I'm an old guy with bad hearing, limited vision, a brain injury and I'm fat. So you have to help me out here.
I assume "Extra trim reaction" means the amount of bow lift the prop creates?

I am old and a little fat too and I was not sure what he meant by that either. It probably has some rake added.

LOL, you guys are too much. I was actually hoping someone else know what it meant as the tech wouldn't be any more specific. Maybe I presented the info poorly so let me try again, and I apologize in advance as I am not a word smith. BBlades tech Brad advised me the 26 P prop I have has had "Extra Trim Reaction" added and would not specify anything further. I can tell ya the boat runs more outta the water with the BBlades 26 than my standard 26 as the boat runs noticeably lighter and kinda chine walks a bit and had to be throttled back to avoid exceeding my personally set benchmark of 5200 rpms. I also realize that throttling back is counter productive to max speed, but all out max speed isn't really my goal. My goal is to prop the boat to run 5200 max and have the best cruising speed at 3000 - 3500. In reality I am probably just gonna purchase a stock 28 and see what I get and if it falls short on top probably send it off to BBlades for whatever "Extra Trim Reaction" is and hope I am satisfied with the results. I guess initially I was hopeful someone with a similar setup would be able to confirm a 28 was the best choice but kinda getting the idea that aint gonna happen. I also enjoy playing with excel and turning collected data into a justifiable excuse to buy something, and at this moment it's a prop that I don't need in the first place cuz I have like 5 or 6 already. I probably should post a pic of the boat we are referring since I have 2 now to avoid some possible confusion. Also, thanks so much for helping me with my journey !

Minor puter issue earlier, here's the pics, lol.
[IMG]http://i671.photobucket.com/albums/v...0905021223.jpg[/IMG]
[IMG]http://i671.photobucket.com/albums/v...0929020837.jpg[/IMG]
[IMG]http://i671.photobucket.com/albums/v...0929020838.jpg[/IMG]
[IMG]http://i671.photobucket.com/albums/v...asinoDock1.jpg[/IMG]

Nice looking 25!
Did you have a garage/shop where you can easily get to it throughout the winter? or is it tucked away for good till the snow melts?

Unfortunately the older gal got the building I built last year apparently too small lol. The new gal is tucked away aloft in a rack basically unreachable. If I woulda been thinkin I shoulda took the prop off then I could compare the BBlades to the stock one, but thats gonna have to wait until Aprilish along with measuring the "X". Gordo what do you run if it aint too secret ? I guess my logic or lack of logic is if I can turn whatever size it ends up being to 5200 wide open then I'm probably in good shape not overly stressing anything at the lower cruising speeds. This point like everything else on this subject for me is kinda subjective I know since I'm lacking dyno data and a few other key pieces of info. It is interesting to note that the 1997 sits in the water noticeably higher in the stern (6 or more inches) and a lil lower in the bow than the 1998. I'm gonna guess this is due to the 2 extra trim pump assemblies, the batteries being further back in the 98 and maybe the motors are a lil different in weight. The BBlades 26 seems bout perfect on the 97 which has a 454 mag, the 98 with the hp500 in my mind at least should/could spin a bigger wheel in similar conditions.

Well we gonna test the BBlades 28 I purchased during the umm white stuff season so keeping my fingers crossed to see some extra mph over last year !

Then your gonna have to ship it, lab it, ship it, test it.... should of just bought mine. Ha Ha Good luck.


I hate this new format

Well your probably right as first round is over and I aint real pleased, but I feel confident BBlades will get me where I wanna be. I will say the thing looks awesome as they did really nice work on the prop, but rpm was about the same and slow speed handling seemed to suffer. The process continues lol !!

how much power are you running to see those speeds ?

Nice!