Friday, August 19, 2011

Bow Replacement August 19 2011

A new part has been added as well to the original blog firts inspection to make it a complete story explaining how the bow was replaced

                                                              The Bow Replacement

Although I was aware that some of the hull planks under the deck connected to the bow needed replacement I was not really prepared to replace the complete bow, a so called nose job.
Earlier repairs had been done by removing planks of the hull which are connected to the deck and replace them with plywoodn due to rot.
The result was that, in my opinion a part of the strength of the construction was lost. Not only the hull planks were rotten away , but also the longitudinal deck beams running under decks were rotten and gone in several places. Especially where this beam is connected to the actual bow beam. Although new wood was added and rotten wood removed,  I have the impression  that the actual problem, water leakage from the deck down, was never addressed.
After removing all the rotten and bad wood from the hull as well as under decks of the actual bow the situation did not improve, more repairs were found, which in my opinion were not done professionally. The result of these further inspections resulted in that it was decided to remove the complete bow from deck to the keel.  Although this is not a difficult job it has to be well thought through. Luckily I have my neighbor who helps me more than regular and who often thinks outside the box. His solution was simple: cut the complete bow out and just built a new one. So we did .
The actual bow beam consist of 3 pieces one center piece from top to bottom and two side pieces, these three  pieces are hold together with long screws and threaded bolts. The next step was to find oak beams from which the new bow had to be built and shaped. To prevent a lot of cracking and distortion of the new bow I have bought old used oak which normally will not move or crack anymore. The next step is simple just copy paste the old on the new.  To do this a lot of measurements were taken as well as shapes on different positions of the old beam which were transferred to the new beam.
When all measurement were transferred from the old bow beam to the new to be built bow the actual work started with cutting out the wood of a square beam and shaping this piece of wood into a new beam.
When the new beam was shaped and several times checked against the old one it was time to install the new beam, we must have done it right since the moment we placed the new beam against the ship it fitted exactly in the correct place no changes had to be made. The height was correct and even it ended up in the center of the deck. The beam was now placed in position with threaded bolts , connection between the inner bow beam and the new bow beam, and positioned at the top in the center of the deck and temporarily hold in this position  with some screws.
With the bow in place the next step was to install new hull planks, although this sounds simple it is far more difficult than replacing the hull planks from the aft side as was done in an earlier stage. The challenge is that the planks from the bow do have a different form than from the stern. They do not only bend from aft to forward but also bend from the keel to the deck as well as they are tapered from the  stern to the bow. The first plank at the keel was not to difficult but the next one had to much torsion that after three attempts it was decided to make this piece out of a laminated piece of wood. From there on it was just placing plank after plank one left one right to keep the bow beam in place.
Than the point is reached where the last plank reaches the top of the bow, at this point the new longitudinal deck beams have to be installed before more bow planks can be inserted.

The Planks were screwed against the beam and glued/sealed with Sikaflex Glue and Seal, this to create a flexibla seal between two different materials mahogony and oak. The planks were not glued with an epoxy glue or any other type of glue. This is the is done in the same way as original built.
The fabrication and installation of the replacement of the longitudinal deck beams will be another subject at the same time the finishing of the hull planks against the bow beam will be further explained.

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