Work on the Hull begins

The entire rebuilding project of the "Tamarack" is based on the hull and how deterated the steel is and if we have the knowledge and equipment to repair it. It would be a shame if we did a quick patch job on the hull and put the hours and dollars into the boat to find out later probably in not favorable conditions that the hull is not holding up to the strain and stress of a sail boat. Both masts are connected to the hull so when your under sail all the force is being pushed onto the hull.

Glen Rowe (father of Cadet Rowe) hired Testing Engineers & Consultants (TEC) to conduct in-depth testing on the thickness of the hull.



The picture above shows Marvin from TEC performing his steel integrity test and writing the different thickness on the hull.

In the picture below is circled in red the area's which needs new steel. On either side of the keel going up the hull about 3 feet and probably about 6 feet long.

Tony Morris from TEC is willing to weld in the new steel if we can have the bad steel cut out and bring in new steel cut to size. Another thought Tony had is to just run new steel over the old and bondo the edges so it is flush with the rest of the hull.  I e-mailed Thomas Colvin (the designer of the Tamarack) to get his input on what the correct fix should be.

Below is his response:
        
          "Adrian,

The original thickness of the plating was supposed to be 10 ga. steel which is .1345" thick. However mill tolerance range is .1425" to .1265". In practice it is seldom to these extremes. As a builder when I ordered steel I required that the steel be of the nominal thickness or + and would never accept a -. There can be a slight variation from mill to mill and also in a particular run of plate from the same mill. Since wwll the variation from .1345" by different large mills has been negligible. About 10 years ago I did get a shipment of 5 tons of under thickness and rejected it. I never did get my money back as in the fine print it stated that all orders are shipped by weight.


Your questions.


In my yard a plate that had worn either by erosion or rusting that had lost more than 6% of it's thickness would be replaced especially if it were along the keel. If it were a small spot or pit surrounded by sound metal we would add sufficient weld metal and grind it smooth.


Running a strip of metal over the old metal is at best only a temporary repair as it will be destroyed by the plate you are covering up. That is like placing good wood over rotten wood and thinking that it is as good as new.


Rebuilding is a tedious and time consuming task of removing the bad material and prepping the structure for the new material. The time required is several times more than the actual repair. As for bondo it has been used in marine applications some times with success but it was not developed for this purpose. The feather edges seem to present the greatest problems.


Regards,


Tom Colvin"

We started to remove the old steel with a metal cutting saw to prepare for new steel.

Clink on link below to view video.

http://www.youtube.com/watch?v=TDhvHOEYBwQ