I'd highly recommend you read this POST to help you get the most out of sailnet. Your current OP is a bit on the vague side and not likely to be getting any good answers. It would really help if you said what dielectric silicone you were specifically referring to. IIRC, most silicone is dielectric, since it is a lousy conductor... are you talking about a dielectric silicone-based grease, a sealant, self-fusing tape???
Also, why do you need to splice your VHF wire. Most of the time, splicing it, unless there is a specific need for doing so, is a bad idea, as it introduces a fair bit of signal loss. A dielectric grease won't help with signal loss, but may help in preventing the connectors from corroding.
I will try to be more specific. I was refering to the dielectric silicone-based grease. I was wondering what kind of application you would use it on. On the VHF cable, there was a slice put in at the bottom of the mast instead of a connector that could be unscrewed. We had the mast taken down last weekend and the cable had to be cut. I plan on putting on a connector that I can disconnect in the future.
The silicone dielectric grease is good if it is a high-pressure contact fitting. If it isn't the dielectric grease can prevent good contact between the two pieces.
What you should probably use to terminate the cable coming out of the mast is a male PL-259 connector. To reduce the number of connections, I would get an extended PL-259 female-to-female barrel connector and install that as a pass-through connector through the cabin top. The cable inside the cabin should also have a male PL-259 connector, and should be attached to the barrel connector inside the cabin. This will result in a solid but removable connection for the VHF cable. It also reduces the losses to a minimum.