Yes, that’s correct, the minute hand has the arrow instead, probably a good idea since it’s easier to spot that way and I’d imagine you’d deal more in terms of minutes vs. hours when sport diving. Also, the second hand is white (some had a luminous tipped second hand like the 1960s Speedy), and the bezel counts elapsed time instead of countdown. All these were changes made to the SM300 after 1960.
Here is an interesting article about the various changes made to the SM300, you can definitely see where the Planet Ocean got it’s looks from (1969)...
http://chronomaddox.com/seamaster_3oo_a_history.htmlClick to expand...