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Top speed questions for 283 Convincor

Keytime

Keytime

Active member
Last weekend I got out solo in my 1999 283 Convincor (twin 454 EFI Mags, Bravo 1's, 27P 3-blade Mirage Plus props) for some top speed runs with about 1/4 tank of fuel.

I'm full-throttle with no tab and trimming up to get the boat out of the water. As I trim it up further and further, instead of just porpoising, I start getting a back-and-forth rocking motion that I assume is chine-walking.

Is this to be expected from this boat or is it a possible indication that something else is off? IE, is it possible my drives aren't trimmed exactly the same?

I'd love to hear suggestions.

Thanks! :D
John
 
Twin I/O's don't seem to be the common-place around here.

I am interested to see the responses!

In a single o/b, steering impulses will typically cure the chine walk (side to side rocking) issue.

What speed were you getting before letting off?
 
Your going to get chine walk its the nature of the beast. I have not seen any real good results on here with people running any 3 blade on a convincor. Bravo 1 4 blades seem to be the props of choice on the Convincor. I would borrow some 26p bravo 1 4 blade and give that a shot I think it will com your chine walk down but it will not go away at max trim. Also try dropping the left trim tab down 2 inches and leave the right side up.:thumb:
 
My boat is a single engine, but it never chine walks. I think you should borrow some 24 pitch Bravo 1 props and see if that goes away. Also verify that your trim indicators are matched by measuring the rams on the drives. Max trim should be 21 3/4, So put them at min and max and make sure they are the same. Also wiggle the drives and make sure the bushings are tight.
 
Not trying to start anything with you OLDNAVY but today in the fun run I was running a 24p bravo 1 4 blade and was turnning it 6000. But threw the day depending on water conditions I have Chine walk. It comes and goes with me between 5000-6000 rpms it depends on the water and trim. I have my trim at 22.5 center to center on the pins at max trim. But from half trim to full trim depending on the water and chop I get chine walk. I am not saying its the prop just the nature of the boat.

He does need to check his trim settings to make sure they are right. 24 bravo 's would be a better choice like Oldnavy said I was thinking your engine's where hopped up. I would hve never thought the twin engine boat would have chine walked

" do not go by my specs of 22.5 this is where I have mine set it may not be right for other people
 
Last edited:
hotdaddy27 said:
Twin I/O's don't seem to be the common-place around here.

I am interested to see the responses!

In a single o/b, steering impulses will typically cure the chine walk (side to side rocking) issue.

What speed were you getting before letting off?
Click to expand...

I hit 73.1mph. Was shooting for at least 75mph before season's end with those props.
 
Big Red said:
Not trying to start anything with you OLDNAVY but today in the fun run I was running a 24p bravo 1 4 blade and was turnning it 6000. But threw the day depending on water conditions I have Chine walk. It comes and goes with me between 5000-6000 rpms it depends on the water and trim. I have my trim at 22.5 center to center on the pins at max trim. But from half trim to full trim depending on the water and chop I get chine walk. I am not saying its the prop just the nature of the boat.

He does need to check his trim settings to make sure they are right. 24 bravo 's would be a better choice like Oldnavy said I was thinking your engine's where hopped up. I would hve never thought the twin engine boat would have chine walked

" do not go by my specs of 22.5 this is where I have mine set it may not be right for other people
Click to expand...
No problem here. Maybe mine does't chine walk is because its so heavy in the middle and its not really fast enough to see that problem at speed.
 
I drove a friend of mines 29 fountain w/twin 454 EFI' last weekend at our annual radar run, it's running 26 bravo 1 props, and after much testing at fountain they say that they are the best prop package for the boat. this year with a passanger and a fuel tank of fuel could only run 72, but the water condtions were not good, had a pretty bad chop coming right from the side and kept upsetting the boat, pretty bad chine walk at times, last year I got 74 out of it with no chine walk....props and water conditons make a big differnce in the chine walk in all the boats...my 251 is the same, one pass may be strait and true, the next was a handfull....Rob
 
On my 300 convincor I am running a 23 pitch 3 blade that runs about 71 mph (not GPS) at about 4900 rpms. My motor is a single 496 HO. I have no chine walking or issues.

Jason
 
Old Navy said:
No problem here. Maybe mine does't chine walk is because its so heavy in the middle and its not really fast enough to see that problem at speed.
Click to expand...

Top max speed is where I get it but their is nothing in the water but the very back of the pad. My cabin only has the bed and couches in it so my front is on the light side.
 
Big Red said:
Your going to get chine walk its the nature of the beast. I have not seen any real good results on here with people running any 3 blade on a convincor. Bravo 1 4 blades seem to be the props of choice on the Convincor. I would borrow some 26p bravo 1 4 blade and give that a shot I think it will com your chine walk down but it will not go away at max trim. Also try dropping the left trim tab down 2 inches and leave the right side up.:thumb:
Click to expand...

Considering these: http://www.offshoreonlyclassifieds.com/mercury_bravo_1_props_for_sale-o26257-en.html
 
Keytime said:
Does that apply more to a single engine boat? What's the theory on that?
Click to expand...

I don't need 2 props and would never buy anything used from somebody that lived so far away that I did not know, Their or to many liars that sell parts. Not trying to be rude just learned the hard way a long time ago.

I was showed that by a highly qualified Checkmate gooroo and that was on a single. I did not ask him if that applied to twins also. That keeps the boat straighter in the water at high speeds. Its just something to try with higher speeds
 
I looked at the link to OSO, "balanced and blueprinted" probably means Labbed. Most props are worked (labbed) for a specific application or charicteristic that is needed to tune the boat. Merc Racing lab finished props are the exception out of the box, but are sometimes tweaked by shops like BBlades to further fine tune performance. I would not pay $750 for unknown props. Some vendors sell new B1's for under $500 each new. Ebay is a good source during the winter for props and the best part is Left hand props go for peanuts. You could get some used, unworked, props and try them, and if they are close, tweak from there. If not close, then sell them and try again.
 
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