Jeff,

This is the wrench I have on my boat: https://www.suncoasttools.com/crm/I...MM+++++56317++28&VendorNumber=CHIBRA

I think this is the same thing: https://www.amazon.com/17mm-Alden-S...amp;keywords=17mm+wrench+stainless+steel

I don't tend to use the ratcheting portion, not quite enough holding power. I would prefer a standard box end wrench to reduce the chance of slipping on the nut. West Marine has a complete set for sale for $90, down from $225...
https://www.westmarine.com/buy/beta--stainless-steel-open-end-metric-wrench-set--15939309