(UNDERWATER RADIO RECEPTION)
FOR FRESH WATER OPERATIONS
A correctly sized and positioned antenna will give plenty of range in fresh water.
However, operating your model in heavily Chlorinated pools or in brackish water severely reduces radio range. For example: At a local heavily chlorinated pool one of my subs experienced complete lose of r/c control at a cross range of only 15 feet! Yet, the same model is consistently operated submerged as far as 200 feet away in a local fresh water lake. Dissolved minerals, particulate matter, or chemicals mixed or dissolved in fresh water can greatly affect radio range.
When operating the model in a new location determine submerged radio range by sailing the submerged model away from you, keeping it near shore... well within wading distance. Once you've convinced yourself that you have ample range, you can conduct 'deep water' patrols with confidence. Yes, you have a fail-safe on board to blow the model to the surface if the r/c link is broken, but knowing the limit of your r/c link will prevent unnecessary discharge of Propel gas through fail-safe actuation.
FOR SALT WATER OPERATIONS
Though we don't recommend running a model submarine in salt water we do understand that some of you don't have the luxury of a sizable body of fresh water available to you - either you operate in salt water or take up knitting!
Running the model in salt water involves rigging a vertical antenna out from the top of the sail to permit reception of the r/c signal from periscope depth. When operating in salt water, a portion of the antenna must remain above the surface!
(insert sketch of vertical antenna option)
At least 6 inches of vertical antenna should project from the top of the sail. Plastistruc produces a 1/16 inch diameter plastic coated rigid wire which serves this task well. About 6 inches of this rigid vertical antenna piece will run from the top to the bottom of the sail, terminating just above the WTC.
Reduce the length of the flexible antenna by the length of the rigid antenna piece and solder the two together. Drill a hole through the hull and sail to accept the rigid vertical antenna piece and secure it in place with RTV adhesive.
Install a single pin connector between the flexible antenna wire near the motor bulkhead to facilitate removal of the upper hull half. All solder connections should be reinforced with heat-shrink tubing and made water tight with RTV sealant. Each time the single pin connector is taken apart and rejoined, it will have to be made water tight by a thick coating of RTV sealant.
Cross range on the surface will be OK, but you will be reduced to about 100 feet at periscope depth, and you'll lose signal completely when the antenna wire goes under. Trim the boat a bit positive when in submerged trim - when the r/c signal is lost, the speed controller stops the motor, and after a moment the slowing boat bobs back to the surface, and the r/c signal is regained.
It is vital that after running your model in salt or brackish water to immediately rinse the hull and WTC with plenty of fresh water.