The Class Rule allows a whisker pole to be used on the 2.4mR in accordance with paragraph F.5 as stated below.
F.5 WHISKER POLE
(a) The spar shall be made of one or a combination of the following materials: wood, Glass
Reinforced Plastic or aluminum alloy.
Whisker pole length according to design see G.4.2 maximum 1.35 x J
Rule G4.2 states:
G.4.2 FORE-TRIANGLE AREA
(a) The rated area of the fore-triangle is:
0.5 x 0.85 x I x J
(b) I shall not exceed 3750mm.
I = Forestay height
J = Foretriangle base according to ERS (Equipment Rules of Sailing)
The pole improves the performance and makes the tactics on the downwind legs more interesting. It really improves the balance of the boat sailing downwind in heavy air. The system described here is used on almost every 2.4mR.
(A) is an aluminum tube that is 1.35 x J. It will be a little bit longer than the main boom on most boats. On a standard Norlin Mk III it is 210 cm long. The launching line (C) is a 6.5m long 4 mm line. One end is attached to the jib clew and run through the pole—front to back. Then, it runs on the outside of the pole back to a block on the mast, down through a block in the deck and to a cleat on the control bench.
The retractor is a 5m long 5mm shock cord (D). One end is attached to the back end of the pole and led into a thru-block mounted as far back on the boom as possible. Make sure to attach the retractor in a position on the pole so that the pole won't stick out in front of the mast when retracted. The shock cord is led back and forth inside the boom three times between two cheek blocks (E), to get sufficient stretch ability. Then, it goes out through an exit plate (F) close to the front end of the boom and attaches to a ring (G) that holds the pole. The shock cord can be fairly tight to hold the pole close to the boom when not the pole is not in use.
The part of the launching line that runs along the boom tends to get caught around the neck of the helmsperson. Therefore most boats have a thin shock cord with a cause (H) attached to the spreader. This shock cord holds the launching line up in the middle.
The pole has a low friction Delrin mouth affixed in each end (B).
There are variations in how the details are worked out though. For example, some boats use a bag around the pole to keep the launching line in place and some use a thicker shock cord retractor that can be shorter and still have sufficient stretch/power.