(This may be a bit of a mental exercise, just thinking out loud. But I'm not perfectly happy with the answer I have so far...)
So... you have yourself a magical boat. Greater Device, lots of room to invest effects.
And (being a refined sort) you want to make the boat "comfortable" - storms, wind, water - how unpleasant. So you want to add an effect to the boat that will shield the passengers on deck against the elements - say, to start, against strong wind*. And it would be nice to be able to ward both the passengers and the boat, and items lying about on deck - we don't want stuff blowing away.
(Or water hitting the deck, or lightning striking it - several diff parallel effects could be desirable here.)
ReAu Base 5* - Ward someone against a type of severe weather*. Good against "gale force winds" - that's ample.
(* I'll choose "5" to make math easier for everyone to follow - the exact effect is less important than the format.)
Q1 - How does one go about "warding" the passengers and anything/everything on deck against such?
Q2 - Second question - how does one do that for magi, with Parma up?
Because it's a boat, "rings/circles" are really not going to work. Either a ring is going to leave out the front/back of the boat, or it would have to be much, much wider than the boat itself - both unsatisfactory, from what I can see.
The Ward rules (p 114) state "the Target is the thing protected...", and the Range is the range to the Target, to the thing protected from that Form.
So, the enchanted item (the ship) must cast a "Touch" range ward, and maintain it...
(Base 5, +1 Touch, +1 Group, +1(?) Size, +2 Sun, +3 Lvls Env Trigger, +1 Lvl x2/day)
ReAu 34 [i](& maybe more with more size)[/i]
(* Again, not at issue here. And if you want to include a level of Complexity to include "the boat, the passengers, and loose items" in "Group", whatever works for your Saga/SG/Troupe.)
But that only "triggers" every sunrise and sunset, and then only against targets that it was touching at those moments - if a passenger boards mid-day, or if they are carrying some luggage that gets unpacked later, or somehow are not touching the actual "boat" (as defined by the enchanted object) at that precise time, then they are not protected.
(Base 5, +1 Touch, +1 Group, +1(?) Size, +1 Conc, +5 Lvls (item maintains conc), +3 Lvls Env Trigger, +5 Lvls x50/day)
ReAu 38 (maybe more with more size)
And that is better, as it casts the spell anew every half hour, according to the passage of astrological time.
But that's still not perfect. We want a safe environment, a "bubble" against wind, so anything and everything on deck is simply "safe", so the wind just doesn't affect anyone/anything who comes up on deck. And so the wind is stopped long before it reaches a mage with their Parma up. Shouldn't be that hard...
What is wanted, is a "bubble" like the Rego wards against Fae of a certain Element. But Ring Wards won't work.
Simply bumping it up to Voice won't work - "the Target is the thing protected...", and the Range is the range to the Target, to the thing protected from that Form.
Hermetic breakthrough the only way?
(Short of a breakthrough, "penetration" is the obvious solution to Parma - but the effect as listed isn't completely satisfactory, so...)
Next question - an effect to keep folk from falling overboard! A ReCo(?) effect to act as magical lifelines, so that even if someone was thrown overboard, they would simply "bounce back", or something equally effective.
Some of the same problems as above - I think anyone with MR is just SOL on this one. (This is not like keeping water away from the deck!)
Base 5 is "Hold a target motionless" and "Move the target slowly in any direction you please" - back into the boat, thanks! This sounds good.
(Base 5, +2 Voice (to catch those falling from the rigging, etc), +10 infinite/day)
= ReCo 25
Would that do it? Define the trigger and target area as anyone outside the boundaries of the deck? You'd have to bump it to "Group" if you were worried about more than one at a time.
(Hmmm - maybe hard to leave the boat... have to define a way to turn the item on/off. Details like that can be important to remember, esp for a mage who has a Parma running while working on the effect in the lab. Really annoying if it's not realized until after launch!)
(edit - math correction)