How Waterproof are Accutrons?

Even though the gaskets may have been replaced, it is common for the crown gasket not to be replaced on the 214 and 218, as the crowns are riveted closed and the O ring inside is inaccessible. For both the 214 and 218 watches that have a locking-ring type back (ie most of them), they were never really waterproof even back in the day when new - even though many are marked as waterproof. From around 1970 onward, the term "waterproof" was no longer stamped on the case backs. Some had "water resistant", others said nothing at all about it.

Having said that, if everything is perfect, they are capable of being waterproof to some extent, to say about 30 feet. This today is what we would refer to as "splash resistant". For this to be so, the case back has to be perfectly flat, all gaskets new, the crystal of the correct size in excellent condition and fitted correctly and lastly, the case must not have any corrosion spots on any of the sealing surfaces or any chips or dings where the crystal seals to the case. Most proper waterproof watches have "tension ring" type crystals, which some Accutrons do, but the majority have "snap in" crystals. The design of the Accutron back is not conducive to waterproofness to any depth due to their having been made of thin pressed metal. The only 218's that were truly waterproof were the diver type watches that have "compressor" type cases. These cases have a solid machined screw back and "O" ring back gasket, such as the Deep Sea and Snorkel types. Even so, the crown is usually the weak point in these watches as the "O" rings can't be replaced in them. No Accutrons had screw down crowns which we commonly see now in modern dive watches.

For both the 214 and 218, having back gaskets replaced during service is important not only for waterproofing against wet hands, but in the case of the 214, the gasket thickness is critical to the setting mechanism, and the gasket tabs act as shock absorbers. For the 218, the gasket locates the movement vertically in the case and allows some shock absorbing.

Bottom line: I recommend to treat vintage Accutrons (and I would suggest all vintage watches as well) as being only splash-proof and not suitable for any immersion in water. Do that, and you can relax in your jacuzzi and not have to worry if you are doing any damage to your watch.