BeerSmith Hops Use Selector

Hey guys, anyone know anything about the Hops Use selection box in BeerSmith? Here's a picture of what I'm talking about:



The reason I ask is because I want to use an ounce of Simcoe for Aroma. Well I know that you're okay adding aroma hops any time during the last quarter-hour of the boil. However, if I select Aroma in that Use box, BeerSmith's Timer tells me to add it at flame-out, and furthermore, the IBUs go way down. If I set it at Boil and say 15 minutes, the IBUs shoot way up into IPA range.

I don't mind a high-IBU beer, but I'm trying to figure out what's right here. Do I ignore that drop-down option? And if so, why is it there? In this particular case, I'm not going for a bitter beer. Any advice?

edit: I also circled the Hop Type Selector, but I think I understand that function. It doesn't change anything but your records, anyway.

The time that the hops are boiled relate to how much bitterness is added to the brew. If you boil for 60 minutes most of the effect is bitterness if you go toward 30 minutes approximately half goes to bitterness and half to flavor and aroma (not exact). If you add at flameout almost no bitterness is added and you get aroma and flavor from the hops.

So you can use the selections as a tool to adjust the effect the hops will have. If you use the aroma selection and do not have enough IBU's you can add an addition of hops to the boil also to increase the IBU's

I just adjust the additions during the boil until I get the IBU that I want then make late additions, flameout additions, or dry hop for flavor and aroma.

So if I boil an ounce of Simcoe (~14 alpha) for 15 minutes, will it really bump it up 30 IBUs? I guess what I'm saying is, is that software accurate in that regard?

I used Beer Calculus on hopville.com before using Beersmith and have always adjusted my boil times to get the IBU's I was looking for and trusted them. They seem to be accurate.

I then add late additions for aroma and flavor while checking that the IBU's are still within range. I haven't compared my brews to anyone else's so I don't know. I have not been disappointed with any results as far as bitterness or aroma/flavor. I have been working on a pale ale and trying to get more aroma. I have not gotten as much as I want yet. The flavor and bitterness is good though.