I've been growing beefsteak tomatoes in the same raised bed for three seasons now, and every year about half of them develop that dark sunken spot on the bottom. I water pretty regularly and added some lime last year but it didn't help much.
It's actually a calcium deficiency issue, not a watering problem - the rot happens when calcium can't reach the fruit, usually because your soil's calcium levels are too low or your watering is super inconsistent (even if you think you're regular, big swings between wet and dry will lock up the calcium).
Since you already tried lime, your soil probably has enough calcium now, so focus on keeping moisture way more consistent - like mulch heavily and water on a steady schedule rather than waiting until things dry out.
You might also do a soil test to see if your pH is off (lime works best if your soil's too acidic), and honestly sometimes switching out the top layer of your raised bed helps since after three seasons that soil can get depleted of other nutrients that help calcium absorption.
Blossom end rot is fundamentally a calcium transport problem, but here's the thing people often miss: adding lime to your soil doesn't guarantee the calcium gets where it needs to go. The real culprit is inconsistent watering. When your soil dries out between waterings, the plant can't move calcium up through the vascular system to the developing fruit - so even if calcium is technically in the soil, the tomato doesn't get it. Then when you water again, it's too late for that fruit. You need to keep the soil moisture consistent, not just "regular."
The lime you added last year might actually take a while to become available to plants, so don't assume it failed yet. But here's what I'd focus on instead: mulch heavily around your tomatoes to regulate soil moisture and keep it from drying out between waterings. Aim for steady, even moisture throughout the growing season - aim for soil that feels like a wrung-out sponge. In a raised bed, this is usually easier to control than in-ground, so you've got an advantage there.
Also reconsider rotating out of that bed or at least refreshing the soil. After three seasons of the same crop, your micronutrients and soil structure have probably taken a hit, and that affects how efficiently the plant can absorb anything, calcium included. Even if blossom end rot is the visible problem, the underlying soil health might be working against you too.
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