Four-Day Planet by H. Beam Piper

We had been away from the boat for about two hours; when we got back, I saw that Abdullah and his helpers had gotten the deck plates off the engine well and used them to build a more substantial barricade at the ruptured stern. The heater was going and the boat was warm inside, not just relatively to the outside, but actually comfortable. It was even more crowded, however, because there was a ton of collapsium shielding, in four sections, and the generator and power unit, piled in the middle. Abdullah and Tom and Hans Cronje were looking at the converters, which to my not very knowing eye seemed to be in a hopeless mess.

There was some more work going on up at the front. Cesario Vieira had found a small portable radio that wasn't in too bad condition, and had it apart. I thought he was doing about the most effective work of anybody, and waded over the pile of engine parts to see what he was doing. It wasn't much of a radio. A hundred miles was the absolute limit of its range, at least for sending.