Hive weighing

Hefting hive formula

David Friend, one of our members, has devised an economic method of accurately weighing beehives to check the weight of stores remaining. It certainly beats spending a large amount of money on high-tech weighing solutions.

When manually hefting a hive to either assess the weight of stores for winter or monitor seasonal changes in weight the lifting position is generally very awkward, the hive is heavy and the estimate is inaccurate. It is often better to use some form of balance attached to a convenient and ergonomic point away from the hive.

I have a hive on wooden rails sitting on concrete blocks. Between the inner pair of blocks and the rails are two tubes or round bars secured to the rails at A and B and spaced L1 apart (see diagram above). The outer blocks have loose packing between them and the rails to prevent any unwanted tipping. The rails are joined by a spacer near each end. The hive sits between the pivots at A and B. Hooks are screwed into the spacers L2 apart.

With the packing pieces removed I hook my electronic ‘baggage’ scales onto the left hook and pull vertically until the rails just tip. This is can easily be done with a straight back. The balance automatically records the force, F1, after it is steady for a few seconds so it can be read at leisure when convenient. The same procedure is repeated for F2.

The total weight of hive and rails is W where:

W = (F1( L1 + X2 ) + F2( L2 – X2 )) / L1

This may seem complicated but if the various lengths L1, L2 and X2 are chosen correctly the computation becomes very easy.

Case 1 If L2 = 2L1 = 4X2 then W = 1.5 ( F1 + F2 )
Case 2 If L2 = 3X2 = 3L1 then W = 2 ( F1 + F2 )

Example of case 2. If the rails are each a standard length of 2.1m then the spacers can be set to accommodate hooks at 1.8m apart. The pivot tubes or bars would be 0.6m in from each spacer and 0.6m apart. If the first reading was 15 kgs and the second was 20 kgs then the total weight is 2 ( 15 + 20 ) = 2 x 35 = 70 kgs. If you record the initial weight of each hive part such as floor, box with frames, crown board and roof as well as the rails then you will have a very good idea of the combined weight of bees and food.

This method can be achieved in almost any weather without disturbance to the bees and can clearly show changes in forage conditions and colony development.

Written by David Friend,
Member of Exeter branch