I noticed elsewhere that you are building the Dumas Bluefish. I myself built the Dumas Akula, but I suspect that there is a similar procedure required to assemble the dive planes. The instructions call for you to first solder one plane to the shaft (OK, so far so good), then insert the shaft into position through the hull and carefully solder the remaining plane to the shaft. This last step requires EXTREME caution. A little too much heat and you can turn that vacuum formed styrene hull around the shaft area to molten goo in a hurry. Even as a professional with years of delicate soldering under my belt, I cringed at the prospect. I decided instead to solder on the first plane, then CA glue the second in place, reinforced with a small screw through the shaft. Be careful here.
George "Crazy Ivan" Protchenko
“There are the assassins, the dealers in death; I am the Avenger!”-Nemo
"I'm disinclined to acquiesce to your request; means No!"-Capt.Barbossa