Prime rib roast

I am planning to SV a prime rib roast that is 3 ribs, but weighs 10 pounds. My wife will only eat medium, so I am planning to set the temp at 138F. How long to I need to SV it/?

Size? Dimensions matter, not weight.

Hey Doc, please see my response to workerbee.

You realize the temeprature you selected is at the low side of Medium.

Ember, the roast is roughly oval, with 8" in the long direction and 6" in the short direction. It is 7" long. I guess the controlling dimension is 6". Most of the things I can find about “thickness” don’t include a dimension of 6".

Chatnoir, How do I find your response to workerbee?

OK. Thank you. Sous vide (in fact all cooking) is about heat penetration. It is thickness that will be your guiding factor for calculating the duration of cook. A prime cut like a ribeye roast will require being brought up to your doneness temperature and little more. You’re going to be looking at over 14 hours just to get your roast up to temperature at the core.

Doc, it’s this one.

20 Lbs Prime Rib Roast - Boneless

I regret the confusion. I’m a forum novice and it certainly shows.