Question About Antenna Length Before I CUT

[JIMJAM]

I am in the process of installing a FM radio on ground freq in a submarine. The way the water tight container is setup is for you to attach your reciever wire to a bolt which goes through the container. On the outside, there is a antenna wire already hooked up to the outside of the bolt. Question is, do I measure the outside wire lenght and then cut the difference off my reciever in order to keep my original antenna total length? The guy who owned it before kept his antenna the same and just sodered it. I understand the wire is tuned and must be a certain lenght in order to work properly. Any help appreciated

[DaveW]

Hi,

I used to build RC submarines. For the distances you will experience running the boat, antenna length is not critical. I used to run a music wire whip, insulated with shrink tubing, out one of the periscope housings. The wire inside was the length needed to reach ! No problem.

In fresh water the radio will work below the surface, in salt water, contact is lost the instant the last of the antenna goes below the surface. A safety device or some residual positive bouyancy is mandatory in salt water.

I always used a small amount of positive bouyancy and a speed control that stops the motors when signal is lost. Works fine. Never lost one.

Leaks are a much greater problem. Put a small muffler pressure tap ( model airplane part ) in the pressure chamber, connect a few feet of tubing to it then submerge the boat by hand and and blow in the tubing and look for air bubbles! The smallest leak will show up with this test. Cap the fitting of course when done. Good idea to check on a routine basis.

Dave Wick

[JIMJAM]

This is my 5th sub and fastest. Its a AKULA with all the bells and whistles. Its got the D&E 3.5 WTC which compared to my others is a real work of art. I posted some pics in the sub section to try to get something going there cause its dead. My other boat is a Lafayette class boomer. Some earlier pics of it ther also. Compared to aircraft or helis, subs are truly a real challenge. Combining water and expensive electrics, sinking it and hoping it comes up is a real challenge. My Akula has a auto leveler, Subsafe to blow the ballast in case of signal loss and a water detector which also blows the tank. Thanks for the info, I always get nervous anytime I go to cut the reciever wire.