Tuesday, May 7, 2013

Keel Repairs

 May 2013                      Keel Repairs

It looks like that the winter slowly is going over into spring, at least the temperatures at night are getting above 5° Celsius which means that I’m able to get some parts glued in.
One of the underwater ship projects left is the replacement of a part of the keel.
The most forward part of the keel where it meets the bow is split and looks rotten.
Although I have checked the inside and the wood of the inside part of the keel is sound and good.
First it was decided till how far the wood would be removed. Than the bolts which hold the inner keel against the outer keel were removed and it showed directly that water ingress had been around the threads of the bolts resulting in some rot in the wood.
When all hardware was removed the wood needed to be removed.
First attempt was with a plainer which did work but was not wide enough for removing all wood in one run at the time. The good news was that the wood was not as rotten as expected but just cracked.
Next attempt was with a tiger saw, reciprocating saw with a long saws blade.
Did worked well but as expected the cut line was not 100% straight.
After several hours working I was satisfied with the form of the removed wood by sanding and shaping the form to a more square form where the new wood would be fitted in.

The next step was that a template was made from a piece of scrap wood and fitted against the hull.

This form was than checked on both sides of the keel at the position of the removed wood and then drawn onto a piece of wood for the new to be shaped keel.

The new piece was shaped out a square beam of 150 X 150 mm.

During the fitting the new piece was regular fitted against the hull and in steps shaped to the best possible fitting.

One should take care during the fitting that the new keel will fit flat against the hull otherwise one will find large gaps on one side and a perfect fitting on the other which creates extra work or the chance that too much wood is removed from one side.
Therefore I used a support with kegs to fit the new piece as straight as possible against the actual bottom of the boat.

When I was satisfied with the fitting of the new piece especially where it meets the old keel under an angle the new piece was fitted with kegs against the hull in such a way that it was in the right position and as tight as possible against the hull.
It was than possible to drill the holes from inside out through the new keel for the threaded rods which fix the inside keel against the outside keel.
Nuts were tightened and another check was performed if the fit between new and old was satisfactory.

New keel was then removed and shaped for a better fit on the sides and bottom, it is easier to perform this task when the new keel is not mounted yet, but I made sure that at least 1mm on both sides would stick out for final sanding.

The new keel was removed, threaded rods as well.

Now the new keel was fitted with seal and glue from Sikaflex pretty large amount was used to make sure that no holes would be between the old and new wood, so at least 200 ml was forced out between the old and new keel but I was sure now that a 100% coverage of the kit was between old and new wood.
At the same time it was made sure that the threaded rods were covered with kit before they were pushed into the holes for the rod, this to make sure that a water tight seals would be created.

After drying of the kit, which took several days, the new keel was sanded in shape to fit the old keel, bow beam and hull.

To make sure that the shaping would be similar port side and starboard side the stainless steel rubbing stroke was fitted temporarily against the new keel. This way shaping was done by following the rubbing stroke.

Picture 10

After the final sanding was finished the wood was protected with linseed oil like the rest of the hull.

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