I will publish more and more quite precise diving depths on my page. Mostly
thanks tp the almost scientific books by Steven Holt, Mark Romanack und Tom Irwin.
These boys have done quite a lot of experiments with the help of scuba equipment
and measuring tape and published the results. The titles are called Precision
Casting und Precision Trolling, some of the numbers I have written down with
the lures.
The following points might be of general interest:
The Longer The Line The Deeper The Lure
A lot of people seem to believe, that plugs will go shallower on a very long
line, some will say, the maximum depth is reached with about 25m line out. Both
wrong! A reasonable deep diver of medium size (like the Deep
Husky Jerk 12) has not yet reached its maximum depth with 66 meters of line out
(where it will go to 5,7). On 25m of line it will only dive to 4,6 m. Well,
that's already quite deep but the example does show, why it can make a
difference playing out more line when
trolling.
Speed Is Not Important
Except maybe for slow trolling
with a row boat the rule is: a swimming plug will practically always dive to the
same depth within the speed bracket it was designed to be used. If at all there
is an influence, it will go slightly shallower at high speeds. You will also
hear a lot of superstition on this one saying that the lure will dive deeper the
faster you pull it. But it seems that the two forces of lift by the water
resistance of the line and the downward pull by the diving lip are dependent on
the speed in the same way and always came to an equilibrium at the same depth.
The Buoyancy of the plug seems to be to weak to really play a role here.
Line Diameter Is Important
Lets take a look at our Deep Husky Jerk again. The measurement of 4,6m on 25
meters of line was with a 0,30 mm line. Now lets take a 0,25 mm (or a good braid
with 10Kg breaking strength) and the plug will go down to about 5,5m. About 20%
deeper! On a 0,20mm line or a braid with max. 6 Kg strength, it will even go 25%
deeper. Even thinner lines are not practicable and don't seem to make much
difference in the depth any more anyway.
No if we go up to a diameter of 0,35mm (20Kg braid)
the lure will lose 10% of its depth, on a 0,50mm (40Kg braid) it will lose
20%. Looks like a 6Kg braid is your first choice if you want to go deep (and the
lure is not too big).
Lead...
There seems to be a simple rule of thumb for the influence of additional
weight: 30g of lead mounted 6m in front of the lure will make it swim deeper by
a third (33%). Doesn't say what happens with 60g of lead, maybe I'll find out
some day...
Producers Lie
Can't be said otherwise if you compare the experimentally derived values of
the authors of Precision Casting/Trolling with the numbers the producers of the
lures give us.
Often it seems to be more of a wishful thinking. Especially since they rarely
ever tell us what length of line or diameter the used for there "measurements".
But still they give you a rough orientation and I do write them down with the
lures, if I find them.
