Talking about really useful and rugged inexpensive gadgets for mariners, here is a watch to watch out for, the Casio ProTrek PRW 73. And its predecessor, the PRW 70.
Do click on complete list of amazing features. :
https://www.sakurawatches.com/casio-protrek-prw-73xt-1jf .
Ordering from Japan works fine, and is quick, but shipping, import duty and VAT add to the price. My landed price here in Ireland was around € 750.00.