i also note - that it is commonly called stainless - and not stainfree
Yep like all steels different grades
Yep your stainless knives will rust, and so will a lot of bolts washers etc if not rinsed, and you will find it is still magnetic. ..lower chromium content (bit simplified for those who want to split hairs later)
Then we get into food grade 316 grade and above.. not magnetic, will not rust, very very hard.. lends itself to heat hardening, so if going to drill it.. never stop for a rest even once or the drill will burn out.
And it is very brittle, doesnt carry stress sideways so never use it ot lower grades for suspension , holding up wobbles etc.
Never use a stainless U bolt on the trailer (any WoF inspect worth their salt will fail it unless it has been certified.
And if thinking .. "what about the stainless bolts holding the outboard on?" No they are not stainless.. cant rem off hand the alloy name.. but they are specialist alloy bolts that look like SS.
Anythings are made of steel brass/ chrome plated , or brass/ chrome plated...like bollards etc because SS is not suitable for the loading.
Even outfitting a boat/ trailer takes expertise, training and knowledge.. just like a tradie builder has over a hammer man.. or a plumber has over a person on the shovel.