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270 prop question

C

Craig

Active member
I’m looking for thoughts on propping my 270 (259) Convincor. I have owned mostly outboard models in the past and am not up to speed on I/O’s. Should I go with a Hydromotive or Bravo 1? My understanding is that Bravo 1 props are good for bow lift, and Hydromotive 4-blades are good for boats that already have natural bow lift. Does the 270 have natural bow lift? When I drove it last fall, it sure seemed that it likes a lot of trim, again just like the Checkmate OB’s I’ve had. The more trim I gave it, the faster it went. I bought a 28 Bravo 1 for it last year and it really ran well with it (72 gps on flat water). When I ran a Hydromotive 4-blade on it, it didn’t carry the bow very well. It was only a 24, so I was wondering what a 28 Hydromotive would do?

-Craig
 
I’m looking for thoughts on propping my 270 (259) Convincor. I have owned mostly outboard models in the past and am not up to speed on I/O’s. Should I go with a Hydromotive or Bravo 1? My understanding is that Bravo 1 props are good for bow lift, and Hydromotive 4-blades are good for boats that already have natural bow lift. Does the 270 have natural bow lift? When I drove it last fall, it sure seemed that it likes a lot of trim, again just like the Checkmate OB’s I’ve had. The more trim I gave it, the faster it went. I bought a 28 Bravo 1 for it last year and it really ran well with it (72 gps on flat water). When I ran a Hydromotive 4-blade on it, it didn’t carry the bow very well. It was only a 24, so I was wondering what a 28 Hydromotive would do?

-Craig
 
Craig, unless you put a procharger or more HP in that thing i don't think personally the the Hydro will be any faster.A 3 blade Mirage will most likely be your best top end prop for smooth water but it won't handle and have the mid range of the Bravo especially in ruff water.Depends alot on what water conditions you run in on a regular basis.
icon_biggrin.gif
 
craig; something isn't right. i run a 270 with a 500hp efi motor and i run a 25 pitch hydromotive 4 blade. i turn 5300 rpms at 74-76 mph. i also run a 26 pitch bravo 4 blade at 5300rpms at 74 mph. there is no way you should be running a 28 pitch prop with a stock 496 motor. the hydro works a little better on my boat. hope this helps you a little. bill
 
hey craig,sorry to clutter your thread, but do you ever get down to the bellevue or sabula area? There is a beach upstream from the locks in bellevue we hang a once in a while. we have a cabin along the back water in bellevue. Ever been to homeport in sabula?
Dan
 
Craig,
What rpm were you turning that 28" Bravo 1 to? Is it labbed or stock? Here is some information you should know before deciding on another prop. The pitch of a Bravo 1 4 blade prop is measured at its' maximum pitch, whereas Hydromotives, Mirage etc are measured at their average pitch. This means that a Bravo 1 actually has 1 1/2" less pitch than it is rated at. So, to compare your Bravo to a Hydromotive, you would have to consider your 28" to actually be a 26 1/2" . This also holds true when you are running a Bravo prop thru the speed formulas. You should always subtrate 1 1/2" from the pitch to be accurate.
 
craig;what rpms are you turning with the 28 bravo? you need to prop your boat at as close to the maxium rpm that the manufacture says.Kip is right about the 3 blade getting you the best speed, however the handling will be a whole lot better with the 4 blade.
 
Thanks Kip, Vinny, Bill for the replies

Vinny and Bill,
I did not know that the Bravo 1 props were actually 1 1/2" less pitch.... Last Sept & Oct after I bought the boat, I ran it a lot. It came with a 24 hydro. My gear ratio is 1.65. I hit the rev limit at 3/4" throttle. I talked to some other I/O guys that I know, and they said to try a 28 bravo, so I bought one new. I can turn it 5000-5100 rpms and I got 70-73 mph consistantly on GPS. I know that doesn't quite work with the speed calc if you put in 26.5" instead of 28" and subtract slip, but that's what I get, no bullshit. 70 up river 73 down river.

Anyway, Just want to be sure I'm running the best suited prop, sounds like you need to be running a little faster in order to make a Hydro work? I'm not real interested in the Mirage. Tried a 25, and came out of the hole real hard. Hit the rev limit with the 25 mirage with lots of throttle left as well....Being that I'm up at 5000+ rpms, if I blueprint that 28, will It take me up past the rev limit? A prop guy can make that work, right?

Dtaube, yes I get down to Bellevue from time to time. Nice beach down there. Maybe I'll see ya this year. My 270 is white with purple and black flag graphics. My old boat was the white/red Pulsare with 300.

-Craig
 
craig; i know a lot of us check owners that run hydros.my boat runs at a better attitude running the hydro. i would lab that 28 bravo first,looks like it will put you right in the rpm range you need to be in.if you are running 70-73 i wouldn't expect any more speed from a 496 ho. actually that is good for that motor hull combo. have agood summer; bill
 
Craig.. Toward the end of the year last fall, we were coming back from dubuque and passed a checkmate that sounds like yours floating of the beach a ways we lowed down and putted by and took off. I have a 19' brown eluder w/ merc 175.. as we continued on down the back way through bellevue, we may have seen the red ceckmate w/ the 300 heading upstream towards you... Was that you by the beach?
 
Craig,
You are right. Your speed numbers do not figure out correctly with a calculator. At 5100 rpm spinning a 26.5" prop with only 10% slip puts you at 70 m.p.h. But who knows for sure. There are just too many inconsistencies to get an accurate speed on the water. The only thing that really matters is if you are faster than the guy next to you.
If you wanted to talk to a good prop place try http://www.throttle-up.com/ Julie will answer the phone, tell her I sent you.
 
DTaube,

My 21’ with the 300 was white with red and black stripes. It was gone by August 14 and I didn’t pick up my 270 until the end of September. So probably wasn’t me…

-Craig
 
Craig,
First let me say that I think you should talk to a trustworthy and proven prop shop. However, I can give my opinion based on my experiences. For starters I have never attempted dialing in a boat with a 1.65 gear. That throws me off bit. Based on your numbers with your stock 28 Bravo, I feel that your best choice may be a labbed 30 Bravo. The reasoning behind my thoughts are :

1 You couldn't have your 28 labbed unless it was heavily modified because you will get too much rpm.

2 A 30 Bravo that is labbed will kill some rpm due to the extra pitch but at the same time add rpm due to the labbing. So, hopefully, the prop shop can get you right back at max rpm spinning a 30" prop vs a 28". Thereby increasing top speed.

3 I just like Bravo 4 blade props on Checkmates with your power. Both myself and a friend have had good luck with them in the past.

For myself, I will be trying a labbed P5X Hydromotive 27" this season due to my new power. I can post results when they become available in the Spring.
 
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