Tue, 12 Dec 1995 18:04:40 +0100
 P-O Gustafsson <[log in to unmask]> wrote:
 
> There are very few beekeepers here (Sweden) that use top entrance during winter.
> Personally I belive it's better to have a bottom board that provides sufficient
> ventilation. There are different constructions on bottomboards that will do the
> job, more or less complicated in construction. One of the best is probably
> the "barras" bottom that I think originate from Norway. Tony would be more
> suited to explain about it.
 
The barras baseboard was designed by Barras here in Norway and
introduced commercially as part of the Norwegian standard hive
system. Many individuals and local producers have built baseboards based upon
the same principle and this type of baseboard is now known generally
as the <netting base>.
 
NOTE:
(1) my comments only apply to practice in mid-Norway ie. the
counties of North and South Trondelag which are situated respectively
to the North and the South of Trondheim Fjord. Latitude 63 deg 30 N.
(2) almost without exception the bee race here is A.m. carnica
(3) almost without exception hives here sit on some sort of support
which raises them up from the ground approx 0.5m. When we transport
them to the coastal heather heaths in Aug/Sept we usually have ready
placed out transport pallets cut in half (2 hives per half pallet)
which gives a good air space underneath.
(4) The norwegian standard hive (universally used) has a bottom bee
space.
 
There are essentially two type of base used here:
----- the older shallow, direct entry, non-ventilated type
----- the deep, indirect entry, ventilated netting base.
 
Netting Base:
The base entrance admits bees to a chamber whose floor is metal
netting and whose ceiling is a loose plywood baffle plate. This ply plate has
a slot cut down each side which gives bees acess to the bottom of the
hive. The base normally has enough depth over the plate for a debris
collection tray (used over winter for varroa detection).
The plate is easily removed for cleaning -- some of the more fancy
variants make it possible to slide the plate and debris tray out from
the back of the base without the need to lift the hive body.
The plate can be removed for enhanced ventilation during transport -  in
extremely hot weather augmented with a ventilated top board.
 
Overwintering techniques vary for the two types of base board. In
both cases top insulation is provided usually by a soft <cushion> of rockwool
4 to 6 in thick constrained by an outer wood frame
placed directly over the the frame tops. Usually  2 or 3 strips of
wood are placed under the insulation to provide a certain amount of
top bee space for movement of the cluster.
Traditional wisdom locally has it that <if the base is not ventilated the top
insulation should be porous but if the base is ventilated the
insulation should be air tight>.
 
 Non-ventilated base: the insulation is contained in sackcloth
(burlap?) and the hive roof is held raised slightly to provide the required
ventilation.
Netting base: the insulation is wrapped in plastic (mine are wrapped
in black refuse bag plastic).
 
In my experience of use of the netting base and air tight top packing
moisture is not a problem and survival rate so far has been 100%.
 
I hope this rather verbose description is of interest to someone out
there! Anyone confused by the description or interested in more
details should take contact and I can try to produce a drawing of the
base.
 
Cheers, Tony.
 
 
---------------------------------------------------------------
Anthony N. Morgan (Tony)                 Fax: +47 73 89 62 86
"Stavshagen"                          E-mail: [log in to unmask]
Midtsandan                               Sor-Trondelag College
7563 MALVIK                              Elec. Eng. Department
Norway                                   7005 TRONDHEIM, Norway
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