Help Error with more than 11 Obi Solvers in a Scene

[Gartenschere]

I get an input velocity of NaN (see Detailed Error) when I have more than 11 Obi Solvers assigned to an Obi Fixed Updater in one scene.

I want to have several boats in one scene and these boats can tow other objects with ropes. That's why I have an Obi Solver for every boat. It all works up to that point, but nothing works anymore when I have more than 11 boats.

Is there a maximum of  Obi Solvers you can have in one scene and I so, what is an alternative way to implement my towing boats? 
Thanks in advance!


Detailed Error:

rigidbody.velocity assign attempt for 'BoatSimple' is not valid. Input velocity is { NaN, NaN, -735136576.000000 }.
UnityEngine.Rigidbody:set_velocity (UnityEngine.Vector3)
Obi.ObiRigidbody:UpdateVelocities (UnityEngine.Vector3,UnityEngine.Vector3) (at Assets/Obi/Scripts/Common/Collisions/ObiRigidbody.cs:62)
Obi.ObiColliderWorld:UpdateRigidbodyVelocities (System.Collections.Generic.List`1<Obi.ObiSolver>) (at Assets/Obi/Scripts/Common/Collisions/ObiColliderWorld.cs:428)
Obi.ObiUpdater:EndStep (single) (at Assets/Obi/Scripts/Common/Updaters/ObiUpdater.cs:96)
Obi.ObiFixedUpdater:FixedUpdate () (at Assets/Obi/Scripts/Common/Updaters/ObiFixedUpdater.cs:52)

How to reproduce:

• A Cube with BoxCollider, Rigidbody, Obi Rigidbody, and Obi solver (all components with default values)
  
• Duplicate this cube 11 times to a total of 12 of these cubes in the scene
  
• An Empty Gameobject with Obi Fixed Updater
  
• Apply all Obi Solvers from the cubes to the Obi fixed updater