stage6
The FEA produces a model that gives displacement and stress distributions through all the modelled elements. Once the FEA model was created and validated it was then used to evaluate possible modification programs to address the hogging deformation shown in the vessel. Primarily the focus was on the reduction or elimination of this deformation.

The primary areas of investigation were the modification of main weights to remove loading from the ends of the vessel, the addition of additional supporting structure and the refastening/recaulking of the entire vessel.

Modification of main weights

The results of the FEA showed a modest reduction in the overall keel vertical displacement when compared to the unmodified vessel. The level of reduction was too small to consider the weight reduction and redistribution approach a solution in its own right.

mod weight

Keel vertical deformation – Modified weight distribution

Additional Supporting Structure

The results of the FEA showed a modest reduction in the overall keel vertical displacement when compared to the unmodified vessel. The level of reduction was too small to consider the installation of additional structure as a solution in its own right.

add structure

Keel vertical deformation – additional structure in place

Refastening & Recaulking entire vessel planking

The results of the FEA showed a significant reduction in the overall keel vertical displacement when compared to the unmodified vessel. Net z-direction displacements were reduced from a maximum of 71mm overall displacement to a maximum of 24mm, a reduction of 66%.

This reduction is significant and shows clearly the importance of the planking stiffness.

recaulk

Keel vertical deformation – Recaulking & Refastening

From the analysis of proposed solutions to the vessel deformation problem, it is clear to see which option provides the most directly beneficial solution. The solution to counter and correct the tendency for this vessel to experience hogging deformation is to refasten, re-caulk and re-plank (where required) the hull. This will have the most direct benefit to the structural integrity of the vessel as well as creating a robust and watertight shell that is also critical for seaworthiness.