I wouldn't know how much of the lead plating you'd need on your body armor, sadly. Though, when I went in, I wore the Hazmat Suit and Power Armor and had no issue. Hazmat Suit is good for radiation, but Power Armor gives great defense (I think it blocks out rads, too...?).
Stocking up on RadX and Radaway gets you through just fine. There's also a quest providing you with a serum, making you almost immune to radiation, if you choose the right outcome.
Most base power armor sets get your rad resist to 1000+. At this level, two-three doses of Radaway over the course of the entire trip (assuming getting hit a lot by Bloatflies and Ghouls) and you'll be fine. Even if all you're wearing is the T-45 suit from Concord, assuming you've kept it fully repaired which requires no specific skill, you'll have 1050 rad resistance with all 6 pieces slotted.
I guess because I wore the Hazmat Suit underneath PA made it so I had no issues with rads during my entire excursion through the Glowing Sea. At least PA made it easier to survive Deathclaws, Mirelurks, and Radscorpions.
You don't need any of that. No complicated preps, no special armor, just the right chems.
I went in in leather and the Rads never went over 2. Well, unless you get attacked by ghouls on the way. Which can happen anywhere.
Like any other "armor" the hazmat suit's properties are disabled when you're in a power frame. The PA itself protected you.
The radiation in the Glowing Sea is not all that it's built up to be.
I went into the Glowing Sea with T-45a lead-plated power armor and never once worried about rads, even walking through those wonderful pools of water. I didn't use Rad-X or Radaway and walked from Fort Hagen to the crater, then down to Virgil's cave. Once I exited, I even explored the sea until my power core started getting low and I bailed the area.
Plenty of YT videos show people walking about without leaded armor or PA, and the highest dose I saw given was 24 rads/sec while the person crossed those irritating puddles (stay out of them).
I forgive Amani's description of the Glowing Sea. After all, she was never there.
It's not that you can't get radiation damage in power armor, it's just that it's hard to do a lot of it without extremely long amounts of exposure. (The exception is Raider level 1 power armor, which is literally junk scrap metal welded to a power armor frame -- Raider II actually is real power armor with normal resists, just very fragile in comparison to even base T-45, and is broken off easily by small arms fire due to this.)
I also have Aquaboy on most of my Power Armor focused characters, so don't take a lot of the extra damage from stomping through puddles.
I waited until I had a fully upgrade Leaded MK VI X-01 Power Armor set......really didn't need to but I could spend hours in the Glowing sea without any Radiation problems.
Just get the Hazmat Suit, take good guns and a companion and it's fun with no rad worries
Prefer power armor rather than haz suit, since haz suit won't protect you against deathclaws and radscorpions.
Anyway without power armor you shoud be fine with 20 Rad-X and RadAway and some plating.
But why going there without power armor when you can get access to 2 power armor really early in the game ? (SPOILER : at Concord follow the Minutemen questline and west of USAF Olivia station there is some parts too)
Radiation in The Glowing Sea is not that bad, you get tons more if you go near nuclear waste barrels out in the wasteland.
A power armor suit will be just fine, as you'll need it for protection, is the creatures there that you are supposed to prepare against, not the radiation. Specially if you're playing on survival. PA provides protection against them (except for radscorpions poison damage over time) and you will also want to be able to do some consistent damage, some enemies there are bullet sponges. Level 30+ would be a starting point, to get some decent hp, damage perks and good weapons (and X-01 PA that spawns at lvl 28).
I went there farming for some hours. Being suddenly surrounded by 3-4 (legendary) scorpions is intense if below level ~50. They act like mole rats, shooting off the ground behind you.
Oh, and there's no need to increase your radiation resistance past 1000, I saw someone tested if the radiation resistance increase is linear and it's not, it's more like logarithmic. Meaning when you increase your rad resistance from 0 to 100 it's not the same as increasing it from 1000 to 1100, it's way less in the second case.
ALL damage resistance is logarithmic. That's why you can run around in X-01 armor with a ballistic defense well above 1000 and still take damage.
I made it just fine with T-60 power armor and maybe five each RadX and RadAway.
Another option: One of the early Railroad quests nets you a Hazmat suit, which has very high rad protection (but very little damage resistance).
Make the game a challenge, use hazmat suit + good weapons, rad away and stimpacks.
-klevs
I went in with T-45 not lead lined and took hardly any rads in the glowing sea and I explored most of it. The Glowing Sea is the only place I really use PA. Unless I want to rampage a building for fun.
Zero pieces are needed. If you go in with power armor or a hazmat suit you'll get 1000 resist, more than enough to survive the glowing sea. You can also just use a lot of Rad-X, instead of selling it to a vendor.
The radiation in the glowing sea doesn't really live up to it's reputation. I went in with a hazmat suit in my last playthrough, exploring all the map markers and only used a single Rad-Away.
When you go there the game provides places that are free of radiation.
There are numerous places to pick up chems too.
Also there are plenty of foes who will do rad damage to you.
If you go there without Power Armour it will make returning those suits of Power Armour hidden in the Glow easier to return to home base, if you so desire.
Saves doing a double trip.