There appears to be a strong correlation between the standard Japanese verbs 助ける tasukeru, 助かる tasukaru, 助く tasuku and 救う sukuu, as well as the Kyushu shimo nidan verb すくる sukuru. In standard Japanese, 救う implies more strongly the idea of rescuing from a danger or a crisis than 助ける. In Southern Kyushu, すくる is used in much the same way as standard Japanese uses 助ける.
The question here is, given the parallel between sukuru (*sukeru) and tasukeru (*tasukuru), and noting the verb sukuu:
- What does the prefix ta- do? Are there similar verbs for comparison?
- What difference exists between sukuu and sukuru?
Side note: the verb 透ける sukeru exists in Japanese, but means "see-through" or "transparent", and is connected to the verb 透く suku "to be transparent", and not the above verbs.