Many wooden boats readers identify with a philosophy of wooden boats and their craftsmanship. A niche in the vast recreational boating market, that works.
It would be hard to track free magazines but the actual # out is not always that accurate of reader loyalty, even for sold subscriptions.
Consider online magazines. Subscriptions tell numbers, but what about reader loyalty? Free ones can only count 'hits'. 'Hits' are gospel today, but what do they really mean? They're not an accurate gauge of reading and not at all for reader loyalty. Same with periodicals that are on a decline. The numbers of actual sales will simply follow the decline and be the last indicator that the magazine is sunk.
Actual reader loyalty such as GOB readers display regularly on forums(and I hear word of mouth), is the best indicator of the magazines vibrancy. Maybe that is GOB's secret, they listen to the readers?