What to use different chef's knife lengths for?

[SailingChef]

I have had an 8" Wushof knife for a couple of years now and love it! Today, I scored a set of Forschner knives (http://www.amazon.com/Victorinox-Cutl...) at a garage sale for $5! Included is a 10" chef's knife. When should I pick up my 8" and when should my 10" come out to play?

[chuckl]

I tend to use longer blades for larger foods. something like a watermelon, say, or a big piece of meat, where you want to cut in one clean stroke

[David A. Goldfarb]

I think the main issues for me are how much I have to chop or how big a thing I'm cutting or whether I can use the weight of a larger knife or what else I'm doing. If I just have to slice one or two cloves of garlic, for instance, I'll probably pull out the 6" chef's knife, but if I'm doing other things with a 10" knife, I'm not going to get out a different knife to slice a clove of garlic.

[Kelli2006]

The size of knife is determined by what you are disassembling, what you are comfortable with, and the size of your cutting board. Your knife should be 3-4 inches shorter than the diagonal dimension of the cutting board in question.

BTW, nice score at today's garage scale.

[Fritter]

"Your knife should be 3-4 inches shorter than the diagonal dimension of the cutting board in question"

I'm not sure where that rule came from but I break it frequently. Since many boards are rectangular it's not a very practical guide and it disregards many applications where one might use a smaller board and a larger knife.

[Kelli2006]

Its always been a rule of thumb fro safety that I was taught from very young because if the board is too small you don't have sufficient work space.

[Fritter]

Maybe I'm not understanding but that just doesn't make any sense to me. Here's why:
I often use a 10" or 12" knife to break down poultry on a 12x12 butcher block. No issues at all because I'm not rocking the blade or really utilizing the board for the full length of the blade.
However if I use my 12x16 cutting board and I follow that school of thought the 12" knife would be appropriate because it is 4" shorter than than the diagonal measurement of the board. I wouldn't normally use a 12" knife on a board that is only 12" deep even though by that "rule of thumb" it would be appropriate.

[Kelli2006]

the 12x12" cutting board would have a diagonal measurement that is just shy of 17" so that would be plenty big for a 10" knife. A 12" knife on the 12x16 should be fine because it would have a diagonal measurement of 20". You can certainly use a shorter knife if you wish.

I have a 16x16" board and I prefer a 6" knife over my 8" or 10" for most jobs simply because the latter would be overkill for only a few veggies.

[Fritter]

I just fail to see the relevance of the diagonal measurement. Even though a 12x16 board has a diagonal measurement of roughly 20" it's still only 12" deep. This really doesn't leave much working space for a 12" knife and seems to negate the point of the rule.
I just can't think of an application where the diagonal board measurement would be a meaningful guide to appropriate knife selection.

[alanbarnes]

I think the "diagonal" thing has to do with ergonomics. If you're standing with hour hips parallel to the edge of the counter, and you're holding the food with your left hand (assuming you're right-handed), you're going to tend to work with the tip of the knife angled off to the left. If you're going to hold the knife blade perpendicular to the counter edge, you tend to have to bring your right hip out away from the counter.

[SailingChef]

Good rule of thumb. Thanks!

[knet]

I believe the different lengths are simply a matter of matching hand size/comfort levels to the knife. For myself, I use 6" Global chef's knives because despite decent knife skills my hands are not big enough to handle 8 - 10" knives with any degree of comfort. I don't think there is anything more scientific than that involved in matching the size of the knife to the task. Good garage sale find for you today.