The island with the channel around it sounds like the mash is compacting. This happens when the transfer is being conducted too quickly, and the grain bed pulls away from the sides of the mash tun, allowing the fresh sparge water to run down the side of the vessel instead of through the grain, resulting in lower efficiency (sugars left in the grain). The sparge and transfer process should take 30-45 minutes, even up to an hour depending on your equipment. This sounds like a long time, but it allows the grains to remain in suspension, so the sparge water will travel through out the grain, bringing as much sugar as possible along with it. About efficiency inputs in brewing programs: The previous poster was correct, in that to adjust your gravity, add more base malts and corresponding specialty malts. One nice tip: Start to think of recipes in terms of percentages of the grain bill, instead of .5 lb of this and 1 lb of that. This allows you to make adjustments more easily, and you can compare contrast recipes much easier, because they will be in common terms.