Q-Sport 40 Rudder Length & General Setup Info.

[BJD_FE]

I have a Q-Sport 40 Hydro that I just finished building and am trying to set up. I finally got the boat in the water last week and notice that the boat had a tendency to rock/hop back and forth a lot on the straight a ways. I am currently running a full Speedmaster 21 Rudder (The full length of the rudder is 6.25" top to bottom) and am wondering if the longer rudder blade maybe the source of my problem.

Can anyone tell me what the recommended rudder length and strut depth is for a sport 40 hydro?

Thank you!!

[JimClark]

where is the CG on this hull?

[Fluid]

We simply can't help without knowing more about your boat:

- exact hull
- motor and ESC
- 1P or 2P
- prop
- turn fin
- strut depth and angle
- CG location
- pics would be great

Once we understand your setup we can make meaningful recommendations. Realize that there are so many variables and we aren't mind readers.....

BTW, why are you using a .21-size rudder on a .40-size hull??


.

[BJD_FE]

Thanks guys

Additional Info.
- Blazer Sport 40
- TP-4070 (1650Kv) / Turnigy 240
- 2P (Revolectrix 4400mAh 6S LiPO - 60C)
- props tried M445, M545, 1450 and X646/3-blade (ran the best with the X646/3)
- Virginia craftsmen
- strut depth 3/4" & 1"/ angle flat
- 2-1/2" behind sponson

Pics to follow

Using the .21 rudder b/c that is what the Blazer instructions recommend

[ray schrauwen]

Haven't got mine here to measure length. Sharpen rudder carefully to knife edge and after cutting it down file the bottom round.

Others may articulate better than I.

[JimClark]

not really firmillar with the hull but 2.5 inches behind the sponson seems like it is a long way back

[Shooter]

You picked a great boat for that class. A lot of us are running it with success (me, Terry, Ken, Ray, Pags, Howard, etc...). My strut is 5/8" from the bottom of the boat to the center of the prop shaft (no angle).

Things that could possibly cause it to porpoise:

1. Turn fin angled, pulling nose down or up. Try running some passes without.
2. Too much weight up front.
3. Too much angle on strut.

[ezhitz]

Here are a couple pictures and I will try and post a short video later. I will take a better picture showing rudder length.

IMG_2555.jpgIMG_2554.jpgIMG_2556.jpg

[ezhitz]

Here is a video running the X646/3.

https://youtu.be/UrrEdfI10wo

[BJD_FE]

Thanks Ray / Shooter!!

Can you let me know where the CG is on your Q-Hydro?

[Shooter]

CG is 1-1/2" behind back of sponson. Rudder length is 4" below bottom of boat. Here's a vid from a race in 2014:

https://www.youtube.com/watch?v=fTKVhVPsJtI

[ray schrauwen]

My least favorite heat sorry Bob.