Heat loss uninsulated MLT

I've got my new 15 gallon keg all plumbed with welded outlet on the bottom, and a welded inlet on the side for my thermometer. I haven't leak tested it yet, but I'm sure it's fine.

However, my beer supply is getting low, and I've got to brew! If I use my keg as an uninsulated MLT (I'm going to insulate it and cover the whole assembly with wood, so I can set it up with a tippy dump, soon.) how much heat will I lose? How often will I need to add hot water?

Or, if I just wrap it in a couple of packing blankets for the duration, will that be enough insulation?

If you are heating the whole keg on a burner you will not lose much, but also will have the ability to raise or maintain the temp with a trickle of the propane burner. I always planned to insulate mine, but never got around to it. If you are not heating the whole keg (adding hot water and grain into the keg), you will probably see conciderable losses that a blanket might help in reducing.

This will be a totally unheated MLT. I plan eventually to fabricate a large electrically heated HLT, from which the hot water will flow into the MLT.

On your way to HERMs. Go propane (IM a RIMs guy). Occasionally Ill overshoot the temp and have to shut of the burner. When that happens, Ill lose 5 degrees in about 20 minutes. And that is in a heated Mash tun, inside, at an ambient air temp of probably at least 90. If you plan on an unheated mash tum of the sanke type, you would want to insulate it. Or better yet realize your perfect excuse to go all out and build a HERMs (or RIMs).