45 twin pulled very hard to right side

Help Support intlwaters.com:

Mathias Hof

Member
Joined
May 21, 2019
Messages
19
Hey guys maybe someone can help me. I have an 45 twin. It’s pulling very much to right. How can i solve this problem? The rudder is pulled very hard to left that it’s running straight. Some pictures attached. I also tested with shims under the turnfin but it only helped little bit.

thank you 🙏
 

Mike Hughes

Well-Known Member
Joined
Feb 23, 2003
Messages
3,052
A couple of items to try. Shim the struts about 2*. You want them to turn left like the rudder. There use to be nice airplane motor shim stock for this. But they dont make them anymore. Make sure you props are nice and sharp. Sharp blunt leading edge creates more lift than a thin leading edge. IE feather sharping further back into the blade area. You can also change the turn fin angle to create a little lift in the right sponson. You do this by pushing the bottom back end in towards the front. I would also add some tail weight to you bait box to keep the back end down in the water and less prop walk.
Mike
 
Last edited:

Mathias Hof

Member
Joined
May 21, 2019
Messages
19
Hey guys thank you very much.. i will try these things next time.. normally I think it should be an turnfin problem or not? Maybe I need to shim it more like in my first picture? Or is this the from way and need to shim at other side of turnfin? With this rudder position at the second picture it’s going straight but that’s not normal I think.. 😒
 

John Beardslee

Well-Known Member
Joined
Apr 20, 2011
Messages
1,538
Yes about 1,5 mm.. too less?
Mathias, I run 1/4” toe in on the right sponson and 1/4” toe out on left sponson of my twin 91’s. On a 45, I would start at 3/16” on each. Don’t discount the toe out on the left sponson, it’s very affective.
If you choose to change thrust using the struts, a common used constant is .017” over 1” equals 1 degree.
John
 

Don Ferrette

Administrator
Staff member
Admin
Moderator
Joined
Nov 25, 2003
Messages
15,092
All my twins run same pipe length, same prop pitch, no shimming of struts either. Most of this has been mentioned by others but my top 5 is as follows in order of importance-

1- is turn fin correctly sharpened, blended and angled?
2- is the rudder blade wide enough front to back and running deep enough?
3- props sized, thinned, sharpened correctly and be matched as a set
4- right front sponson should have more AOA than left typically .5 degree
5- zero toe in on left sponson, 3/16" toe in right sponson

Also as far as the rudder blade trim setting I hold a straight edge along the right side of the blade and adjust linkage until straight edge is parallel with the tub (leave radio trim setting to zero initially). With everything else being set as previously described I'm usually just a few clicks away from final rudder trim. A wedge rudder blade centered is not a realistic "zero" trim as I find the load on the left face of the rudder is lower due to water blowout from the props when rudder is mounted on the right side of tub. And on a side note- what is the afterplane length of the tub? I've seen twin tubs that were too short have horrible issues with tracking straight. Just a thought......
 

charles siler

Moderator
Moderator
Joined
Oct 29, 2011
Messages
1,951
I had a friend that had a guy build a single 45 Jae and it was doing the same thing come to find out the booms were off on the tub and sponsons all because it wasn’t squared and built in a jig .
 

Tim Kish

Well-Known Member
Joined
Jul 7, 2003
Messages
2,214
Definitely check the aoa on the sponsons (most likely)also make sure the rudder is in front of the prop wash.
Had a JAE 45 that pulled hard right on pipe, tucked the rudder tight to the transom and problem solved.
 

Mathias Hof

Member
Joined
May 21, 2019
Messages
19
I will check the AOA. But it’s not easy To change it because they have the messing tube where the carbon tube going thru fixed in the boat. AOA is like it comes from zipp kits I did not change anything.
thanks for so many replys will try some things and let you know what was the best way.
first also need to solve the problem that the right engine is not cooling 😒 only left one..
 

Wasted wages

Well-Known Member
Joined
Jan 2, 2006
Messages
460
I will check the AOA. But it’s not easy To change it because they have the messing tube where the carbon tube going thru fixed in the boat. AOA is like it comes from zipp kits I did not change anything.
thanks for so many replys will try some things and let you know what was the best way.
first also need to solve the problem that the right engine is not cooling 😒 only left one..
Engine cooling issue may be from having to hold so much left in it that the rudder blade holes are starving for water.
 

Wasted wages

Well-Known Member
Joined
Jan 2, 2006
Messages
460
how are you splitting the water to the motors ?

It's really a big deal, as water will take the path of least resistance and just a little bit of difference in line length, fitting diameter can cause the water to flow thru only one motor.

And once flow is established, a venturi effect can cause the water to be suctioned out of the other motor.. I always run a dual pick up blade for this reason..
 

Latest posts

Top