(Thread to account for the activities of the knarr and the sailors, with a little in-character interactions thrown in.)
Scoping out the island takes a few days and doesn't reveal anything spectacular, although it allows Pytheas to map out a number of small villages all around the island, as well as a few other places of note.
There are two castles on the island. The first and largest one is the Danish lord's castle, to the east of Oberland. A second castle, much older and smaller, can be seen to the west of Oberland.
There are also what looks like two religious communities on the northern side of the island. One is a small village built around a sizeable church dedicated to Saint Ludger. The second one looks like a monastery, built at the edge of the swamp that Quercus has identified as having a magical aura.
The knarr was unable to make a complete circuit around the island, as the eastern coastline has numerous sand bars and is generally marshland. After beaching the knarr twice on sandbars, Trond (the captain) told Pytheas that this was an area to avoid for the knarr. Perhaps one of the locals may help him explore the area in one of the flat-bottomed fishing skiff, which can be seen in the area.
Finally, Pytheas is able to see the two stone pillars that rise out of the sea to the north-west and north of the island. There is no way to land, however, as the pillars have no beach. They simply rise up from the water as rough towers of stone (one of reddish stone, the other of dirty white stone) about 100 paces in height. Trond indicates that they might be able to tie up to a rock, but there is no easy way to climb unto the pillars. Clouds of birds surround the pillars, with numerous nests set on the side of the pillars. The base of each pillar is coated in guano, making them both slippery and quite fragrant.
After a few days sniffing out possibilities with the local merchants, Trond reports back. "Not much luck with furs and skins, sirs," he tells magi, "that market is locked in by regulars. I was, though, offered a cargo of salted fish to the mainland. There's plenty of that to go around." He shrugs, "It'd be better than sitting idle, at least. That always sells, particularly if I can go further inland along one of the rivers to a big town. I heard that both Bremen and Hamburg have good markets. Fish doesn't require too much money to buy, either, just about a dozen pounds of silver." He grins, "Doesn't bring up much profit, but anything is better than nothing."
He then asks if there is anything specific he could bring back for Japik and the other magi, although he notes that anything they use for themselves would cut down on the profit he could bring back. "Wrong season to bring back grain, as most towns will be low on that, but we'll look for things that the island lacks. Won't be able to sell it for hard silver, but we can trade it for more fish."
When Trond is approached about the idea of his crew helping out on the construction, his face darkens in disapproval. "It'd be better if we were at sea. We know nothing of building houses. And we'll make more money manning the ship and trading than we'll save ya by helping lug around rocks."
Pytheas suggests that the boat take what work it can. Any income is better than no income. And keeping the sailors busy seems a good plan to me.
I am no trader. Just make sure you do not lose our money.
Trond takes a few days to arrange for the purchase of his first cargo, asking the magi to provide the initial capital to do so. This amounts to approximately 15 pounds of silver. The Baltrum departs shortly thereafter for Bremen, under the directions of a local pilot and with its captain expecting them to be gone for about two weeks.
Japik consults with the other magi about the money and unless there are any strong reasons not to give Trond the initial money he will do so and wish the sailors good luck on their travels. He swims with them as dolphin for a while on the day they leave the island.
Pytheas is content to allocate the funds to Trond. We need to do something to make money or we'll starve. 
Same for Quercus. he is no business genius, but he is feeling the rapid increase in expenses.
I'll use this thread to also track how much silver the covenant has. Here goes:
Before the Baltrum leaves from its first trading trip (mid-June), the covenant had 36 pounds of silver. Buying the first cargo costs 15 pounds, leaving only 21 pounds in reserves.
Over the next month, accomodations and food costs the magi 1 pound, while construction of the first small house costs 4 pounds (although it won't be completed until mid-August). But the Baltrum also returns with a cargo of fabric and lumber, and the round trip generates a profit of 5 pounds (over what is needed to purchase the next outbound cargo).
So, by mid-July, the covenant's reserves are 21 pounds.
As the summer advances and closes, the Baltrum switches returning cargo from fabrics to grain, for which there is always demand on the island. The diversion of the Baltrum to help look for the sunken cargo ship proves to be slightly profitable over time, but only a little more than spending that time travelling to the mainland with cargo would have been.
So, for the period from mi-July to the end of September, the covenant's monetary situation evolves as follow.
Income: Trading nets out 13.5 pounds of silver, including the sale of the goods recovered from the sunken ship.
Expenditures: Accomodations and food cost 2.5 pounds, while construction of the second small house costs 4 pounds. Purchase of the inn costed 6 pounds, while restoring it and refurnishing it cost another 4 pounds.
Overall, at the end of September, the covenant has reserves of silver stood at 18 pounds of silver. But of that, Pytheas and Quercus each leave with a little bit each, leaving only 12 pounds for those remaining.
At the end of the year, the covenant's monetary situation is as follows.
The Baltrum lost a bit of income due to the longer trip when Yulia went to Bremen to hire a stonemason. Furthermore, as the season advances travelling begins to take longer and is more risky. The income for the last three months of 1210 is only 12 pounds.
Yulia paid a little advance to the stonemason to secure his services. That cost 1 pound.
Food and maintenance of the former inn costs about 2 pounds, with the departure of Pytheas and Quercus reducing those expenses but also leaving you with more space than you need. Dietlinde takes care of cooking for now, grumbling about it, but she cannot justify hiring a new one with the reduced number of people to feed. Yulia gives her a hand as well in this upon her return from Bremen. Some of the grog's equipment and personal belongings (clothes, shoes, leather straps, etc.) need to be replaced, costing the covenant a further 2 pounds.
Completing the lab to a standard level requires the expenditure of 1 more pound of silver, for those cumbersome or common items that were not worth packing and travelling with.
Overall, at the end of Fall 1210, the covenant has 18 pounds of silver.
EDIT: Bernhard also returned with 35 pounds of silver from the the sale of 2 pawns of Perdo vis. So the covenant ends the year with a total of 53 pounds of silver.