Ths is a very sheltered anchorage. The normal anchorage is to the north of the islet, but there's far more shelter between the islet and the island, as long as you have the draught (there's probably no more than two metres at LW springs). Recently a raft has been moored in my favoured spot.
If you have a shoal draft vessel, then from Crinan you can cut across the south of the islet, and if approaching from Dorus Mor you can use the entrance between Eilean Macaskin and Eilean nan Gabhar with care in calm conditions. The passage north of Eilean nan Gabhar is just as shallow, but there are more submerged rocks.
There are reefs to the south of Eilean Macaskin that should be given a wide berth. Fortunately, they are usually populated with seals making them a little more noticeable:
We saw our first white-tailed sea eagle soaring over the mainland opposite Eilean Macaskin: