In the imagination of many carp anglers, carp follow phantom scent trails created by various flavours and attractants until they reach our rigs.
But from what distance are they able to perceive the chemical stimuli that we put into the boilie?
Assuming that the boilie is well made, that it does not have a superficial crust of gelled starch which blocks the entry and exit of the various substances, a lot depends on the nature of the products we use.
Everything we put in liquid form is technically dedicated to creating attraction by exiting from the bait and this process is all the more driven the more 'liquid' the substance.
So dense, sticky liquid foods move more slowly than flavours, and oils resist more than sweetners.
This is a question of solubility, which is why in a technical bait there must be several ingredients with different characteristics in order to achieve a certain stability that allows attraction for 10-15 hours continuously (ideal technical time for 20 mm baits).
Another important factor is the amount of stimuli inserted into the boilie itself, as a higher internal concentration leads to a greater outflow of substances.
Dosing a dense liquid food up to 50 ml. per kg. of mix can make some difference in terms of taste, but represents a mild attractive action compared to inserting 100-200 ml.
From this point of view it is logical to assume that a big influence is also given by how much boilies I throw in the water, because the single bait rigged + another 4-5 on stringer, obviously create an area less attractive than the single bait surrounded by a few kilograms of crumbled boilies!
Clearly there are many factors that add up to determine the strength and duration of the signals that reach the fish.
For the sake of simplicity in this pill, let's try to understand how far an adult carp smell a GOOD single hunting boilie (such as those proposed in book Boilies).
Let's say that empirically calculating the amount of substances that come out of the bait itself in the first 5 hours of immersion, we can say that after at least half an hour from the launch, the size we measure ourselves against is at most the cubic metre, then a linear distance from the bait, in the various directions of about 50 cm. upwards and a little more near the bottom since most organic substances tend to have a neutral weight or higher than that of the water.
Taking the concept to the extreme, it is important to understand that if we are fishing with only one bait on the hook and nothing around, we must place it a few dozen centimetres from where we think the fish will pass.
In my book Boilies you can find all chemical and non-chemical attractors explained in detail.