Stanchions
Bavaria yachts are generally strongly built, but like so many other boats, they have a few weak points that need attention. One of them is the way the stanchion bases are bolted to the deck. When I took possession of my second hand 2001 Bavaria 40, the stanchions were all loose and the bolt holes were leaking. Bavaria apparently used clear silicon as a sealant, where polyurethane sealant such as Sikaflex would have made a much better job. Upon inspection under deck, all nuts appeared to be loose and there were signs of moisture and rust. The type of sealant was not the only cause of the problems. The washers were too small and had been deformed and/or partly pulled into the deck/hull joint due to the great forces placed on them. Imagine the force placed on the bolts when someone uses a stanchion to pull him/herself up when boarding the boat or to hold the boat off when docking. The stanchion acts like a lever and the force placed on the bolts is many times the pulling force.
The stanchion bases used on my Bav40 were of the stainless steel type as on the left in the picture. Shortly after my boat was built, Bavaria switched to the cast aluminum model on the right. Not without reason! The stainless type could be bent when enough force was placed on them. Also they did not have much strength in longitudinal direction. As can be seen only two bolts were used. The aluminum bases are much stronger and look better. Plastic inserts are used to prevent galvanic corrosion. I played with the idea of replacing all the stanchion bases by the later aluminum model.
However, the aluminum model,
which is the model still used on the current Bavarias, also
has a disadvantage. They are fixed to the deck with 2 bolts
and for further strength rely on the lip which fits under
the top edge of the toe rail extrusion. Other production
boats use a similar construction method. This places
considerable force on the aluminum rail when the stanchion
is pushed inward. When this happens, the lip tends to pull
the toerail up and away from where it meets the hull. Test
this on your own boat while you keep a finger on where the
rail meets the hull at the position of the stanchion base
and you can feel it. I tried the same on other production
boats with similar construction and the result was the
same. Fortunately the toe rail extrusion is strong enough
not to be permanently deformed, but still...
I still liked the newer
aluminum model much better than the stainless steel ones
and decided to replace them all. But the stainless steel
ones have a nice big bolt in the centre of the stanchion
and I would need to fill the holes in the deck as they
would become unused. The bolts go through the hull-deck
joint and give it extra strength, so I did not like the
idea at all of making them redundant. After some thought, I
decided to modify the aluminum bases to be able to bolt
them on deck with a third bolt in the original position as
where the stainless model had the main bolt. This way good
use would be made of the existing hole and the construction
would be improved by making it less reliant on the
toe-rail.
I spoke to an engineer and we
decided to tap thread inside the bottom part of the
aluminum and make 5mm thick threaded disks out of marine
grade aluminum that would form a base for an extra
bolt-hole. 2 holes were drilled in each disk, one for the
bolt and one for water drainage.
The 2 holes made it easy to
turn the disks in the thread with the help of plyers. Epoxy
glue was put in the thread before the disks were turned in
to prevent moisture from entering and to improve the
integrity of the construction. Of course the 2nd original
hole in the deck used for the inward bolt of the stainless
base, had to be filled (with epoxy) and 2 new holes had to
be drilled.
Under deck, 3 mm thick
stainless steel back plates with 3 holes were used instead
of individual washers. The edges of the back plates were
rounded off to prevent them cutting into the fiberglass of
the hull-deck joint and damaging it.
The end result is a very strong construction, and no more
leaks. I still don’t like it if guests use the
stanchions to pull themselves aboard from the dock, but I
know they can take it. The whole exercise was worthwhile
and in my view one of the best of the many improvements I
have made to my Bavaria. I can recommend it.