Can someone explain how beersmith is calculating my boil off and losses??

My boil off in my equipment profile is currently set to 6.50l for a 60 minute boil, with the 'use boil off as an hourly rate' ticked. Then there is a loss to trub and chiller figure off 1.50l. I figured this should mean that for a 60 minute boil by pre-boil volume should be 8.00l more than my batch size. I also would assume that for a 90 minute boil it would then increase my boil off by 50% but the trub loss would remain constant at 1.50l, so for a 90 minute boil it would be 9.75l boil off (6.50 x 1.5) plus 1.50l trub loss, so a total of 11.25l more than my batch size? Please correct me if (in theory) this is incorrect?

When I type in 60 minute boil in a recipe, however, it says a pre-boil vol of 31.04l for a 25l batch, and when I increase the boil to 90 minutes the pre-boil volume only goes up to 31.99l? My last brew I ended up 2l lower than my target going into the fermenter? I understand that if I increase my boil off this will help in 'real life', but the numbers beersmith is giving me just don't seem to make sense?

Can enable help clear up how this all works please?

Thanks

Ok, ill take a stab at this and I have to apologize up front im going to have to convert this to gallons. so your final batch size into your fermenter is 25l or 6.6 gallons. BS is telling you to collect roughly 8 gallons of wort or 31.04l preboil. When you finished you ended up with with 2l sort or .5 gallon. was your preboil at 31.04l? how much did you end up in your fermenter? Theres also a chance your boil was too vigorous that you lost 2l.

I'm subscribed because I'm not completely sure what's going on with the water calcs in Beersmith myself, however one thing I always consider is that the equipment profiles must be an approximation. I have two 70l pots, one tall and thinner than the other. Boil off is greater on the one with a larger surface area and neither of them boil off at the pre-defined rates in Beersmith. Thankfully you can create your own equipment profiles.

First, the equipment profiles in BeerSmith are meant to be used as templates for you to customize to your particular equipment. The targets for boil-off rate are most probably based upon what Brad gets on his equipment and has no relationship to what you get with yours.

As for the OP issue, I would need to see the recipe (save it as a .bmx file and upload it here) to try to figure out what might be going on.

Thanks for the replies everyone. I appreciate that my equipment profile may not be 100% correct, so perhaps I should not have said about my previous brew as it may have confused matters.

My concern is that my profile says a 60 min boil should lose 6.5l, yet when I change it to a 90 minute boil it suggest that I will only lose 7.45l, when I would assume it should be 1 1/2 times the loss of a 60 minute boil? I am nervous to start my 90 minute boil with this amount as if I lose the 9.75l that I believe I will, but have used the amounts that beer smith is giving me I am going to come up short.

Oginme, I will upload it when back at home as I'm just on my phone at the moment. Thanks