Estimating

[joshuamccoury]

If I'm adding fruits and what not how do I figure displacement and final yield?

 

[Johnny2]

Use a mesh bag

 

[Dan O]

If I'm adding fruits and what not how do I figure displacement and final yield?

Displacement will be challenging at best to figure out as well as final yield.
Yield will depend on a few things.
Firstly, your lees (yeast cake) will vary from batch to batch, therefore it could be more or less with each batch, so, no way of telling from that.
Secondly, whether you decide to use a brew bag makes a pretty big difference. No brew bag will yield less just because you'll have to rack less due to the fruit floating around. With a brew bag, yield will be much better as all the fruit will be contained for easy removal.
Lastly, if you're making your mead in a glass carboy, the bag is pretty much out of the question. If you're using a food grade bucket, the bag is the way to go.
Depending on what fruit you're adding & the quantity of fruit will depend on how much liquid it adds, as some fruits contain more water to extract than others.
I hope this helps you.
Happy meading

 

[Raptor99]

In the primary, put your fruit in a mesh bag and do the primary in a food grade bucket, not a carboy.

As for displacement, if I am adding fruit to the primary, my recipe uses honey, fruit, and enough water to bring the total volume up to X. I target a initial volume higher than what I want in my carboy for bulk aging. The amount of the increased volume needed depends on the type and amount of fruit, and how much lees you expect. For example, peaches produce a LOT of sediment, while most berries produce far less. Generally I would aim for 1.5 gals initial for a 1 gallon test batch, or 4 gals initial for a 3 gal. batch.

Once I add the fruit (frozen, thawed, mashed) and given it a few hours to stabilize, I check the SG to see if it needs more honey. Once the SG is right, I add the yeast and nutrients.