Wire brush tend to require brute-force angle-grinder rather than drill
- and remove a fair bit of metal too.

3M Clean N Strip XT (purple) discs are very good.
2-3 will strip an entire car of paint, corrosion, pitting to bare
steel without removing much steel which might be important. Frost's
Auto Restoration and probably fleabay do them.

Hammerite is good until water gets under it.
Protection is how much are you willing to pay.
True cold galvanising paint like Galvafroid works surprisingly well -
you need to get to Sa2.5 (good 3M clean n strip, no dark mill-scale,
not likely if corroded steel). It does require a primer on top &
suitable paint since it is mechanically very weak - it is pure
virtually nanoscopic zinc (and ridiculously heavy and priced
accordingly).
Zinc loaded epoxy works well, 2pk is available; commonly used in
marine applications with micaceous oxide and so on.
POR15 is good if you never intend to weld.

If this is a long boat, hire a media blaster - or perhaps see if you
can get an attachment for a pressure washer, in theory they should
exist but I have never bothered. That keeps the material wet which
reduces the mess.

The 3M clean-n-strip in Purple XT form are like a sand blaster in
their speed - very effective removal of everything except the steel.
Best product for auto or similar "thin sheet metal" repairs ever.
Galvafroid is pig ugly for auto use because it is thick and requires a
suitable galvanised-metal primer because conventional car paint has no
chance of sticking on top.otherwise.

Another alternative would be a metal-prep with suitable primer & paint
on top. Comes down to the application. The zinc-epoxy can be roller
applied and will at least give a good life. I assume the 40sq-m it
can't be dipped?