Conquest again

[GRAEME LOUW]

Hi GuysI help again
My last threads re the conquest has really helped me but I was out earlier and only managed98 km/h as I could not open throttle up as boat is too unstable. THE BOAT wags its tail left back down then right down as well as porposing.I think this is called chiming. I listened to Race Mechanix and Fluid and bought the speedmaster skegged strut and the boat is beter and does not turn to the right nearly as bad as it did but still the boat is very unstable at higher speeds
.Current setup
Conquest
2028 motor
300 amp esc
4 x 5000 mah 45-90 c batts 5 cell x 2 38 volt x 10000 mah
speedmaster strut with skeg 6 mm to right of boat centre.
Propshaft -between 10mm and 16 mm from bottom of sponson to middle of propshaft. 0 degree offset
CG Between 28 and 33 %

[srislash]

You could try the weight forward a bit more.I have had to go to 40% on my cats.

[Fluid]

What prop are you using? The symptoms appear not to correspond to an improper CG (since you tried 28-33%) but rather to the prop controlling the boat. Depending on the prop you may need to change the strut height, but the wrong prop can exhibit the same problem. A photo from the side showing your transom might help.



.

[GRAEME LOUW]

Hi Fluid Srislash
Prop Tried Oct 462 and 465 sharpend and balanced
Will post pic soonest
Cheers
Graeme

[GRAEME LOUW]

IMG_0070.jpg[ATTACH]91851[/ATTACH]]91850[/ATTACH]IMG_0069.jpg
IMG_0069.jpgIMG_0069.jpg

Hi Fluid
As promised. Pics of transom
Cheers Graeme

[RaceMechaniX]

Normally the X series Octura props run very good with these hulls. The prop does not look sharpened from the pics?

[GRAEME LOUW]

Hi Tyler
I appreciate all your time.
The prop is very dull no shine as it was run in a dam full of industrial fallout so it dulls in about a week but I did sharpen with various files and then fine sand paper. The edges are about the sharpness of a blunt non serated steak knife. Is this enough ?
The more I think about the boat its as if the boat wants to climb out of the water dancing from left to right on its ass and I have set the strut angle from positive to negative
From the pics what do you think of the strut /prop angles etc
Cheers
Graeme

[Fluid]

The prop needs to be sharper than that, but I doubt that is causing you problem. What you describe is similar to what happens when the prop is run too deep, lifting the transom out of the water. But your prop does not look to be set too deep. Still, I'd try raising it another 3mm and see what that does.




.

[grsboats]

The strut is too much high for a cat and will produce a lot of propwalk in your boat.thumb of rule for this class is have the botton of the strut parallel with the botton of sponsons to start testing.I would also try a smaller detongued X serie prop like a X460 or a X457/3 to counteract the torque.The Cg around 30/33% is perfect for a cat and 0 degree on strut is also good.Finally your prop definetely is not sharpened at least on pics and will produce lot of bites instead of cutting water so take your time with your props.Let we know the progress. Gill

[oscarel]

Not always true. I run mine high and don't have issues. I've seen some say 30% of prop in water?? On gas boats we normally run 1/2 to 3/4" up but also we use bigger props. Try raising it as high as possible and see if it stops. Then slowly move down.

Sent from my SAMSUNG-SGH-I997 using Tapatalk 2

[Fluid]

Gill has a point - running the prop too high can cause a side-to-side wiggle which the OP describes in his first post. But he also describes chine walking and porpoising. I suspect that a video will be needed to further diagnose the issue.



.

[grsboats]

Looking to the pics I see a misplacement in height of the strut...too much high! At that height those big wheels will act like paddles and overveer the boat leading to rudder correction that means loss of speed.Again props MUST be razor sharpenned & balanced otherwise they will cause problems to the boat.

[oscarel]

I think you have some other issue besides strut level. Does your boat sit level on a table and not rock? Rudder straight and tight? Search on jrcbd, lots of Conquests there. http://www.jrcbd.com/showthread.php?...light=conquest is one. Strut levels range again with most around 1/2" up.

[GRAEME LOUW]

Hi Guys
Thanks for all the input.This is really frustrating me. What I dont understand its the same hull that ran great with the leopard that ran at 60 mph with non of the problems now so the hull is straight and not warped,. (It does lie flat on a flat surface. ) and the only real difference is the new 2028 motor and I dont think that can be the cause.It is more powerfull than the Leo but I dont think my problem lies there. The prop I used with the Leo was a X452 so my prop size is a lot bigger now. Rudder straight and no play.
I will resharpen the prop tonite and set the strut again and adjust 2-3 mm each run and see what happens.
The setup once correct will I think get me about 70 mph as right now I cant fully open throttle for too long without the boat taking off, and even as it is now I am hitting average 58mph with the highest being 62 mph,so there is lots of potential

I need to ask another perhaps stupid question. Once I have sorted my handing problems out would it make any difference to my Conquest if I add a overhang on the transom. Basically a continuation of the front sponsons. They would be higher than the bottom of the hull so they will not effect the performance.I want to do this for looks only, and weight will be minimal !
Once again thanks for all the great advise.I will get it right.
Cheers
Graeme

[grsboats]

First You can't compare the Leo to the 2028.Second the bigger is the prop more torque is applied to the hull causing this taking off.Why don't you try to work with smaller props an see what happens as with the Leo your boat was great.Forget the top speed and concentrate in a good prop for the new motor.I'm pretty sure you will figure out that big props aren't really compatible with Fe boats.My sprintcat 90 equipped with a Proteus 524 runs really fast with X457/3.There's no need at all to add overhang to a cat.....check again the Cg of your boat...maybe forward batts .Hope this help Gill