IMHO, it's not a good idea to use UHF barrel connectors for this purpose. They, and the PL-259's which screw into them, are far too prone to corrosion and water intrusion to be used on deck.
Much better to use a thru-deck fitting which will allow you to carry the coax, with it's PL-259 connector, belowdecks, where it can be screwed into a short barrel connector/PL-259 on coax leading to the radio. Blue Sea Systems makes one which will work fine.
Here you go: CableClam Sealed Thru-Deck Connectors
NB> These are available in 3 sizes. The PL-259 connector needs an 18mm clearance, so the BS-1002 (with a 21.18mm hole size) is the one you need.