Has anyone been as surprised as I have over the speed at which the Hanson family has been dumping shares of Winnebago Industries Inc., the motor home maker that Hanson-pere founded and the family rode to fortune?

Since John K. Hanson’s widow, Luise V. Hanson, died on Oct. 19 last year at the age of 90, Hanson Capital Partners LLC, which is controlled by the surviving members of the family, has sold a great deal of the company’s stock. About $186 million worth, according to some calculations I’ve made. That’s a rough figure. The real numbers are likely quite a bit more.

It’s a considerable sum, and piques my interest for a few reasons.

First, Winnebago’s stock has been on a tear lately, doubling in price from a year ago. Next, generational change has always been fascinating to me. Since John K. Hansen died in 1996, his family has unloaded about 8.36 million shares. It’s impossible for me to calculate how much money the family has made in total from those sales, not having access to the Hanson’s brokerage records. But it is possible to calculate the more recent transactions.

We do know, however, that the family controlled about 41 percent of the outstanding shares in 1997. Today, its stake has been whittled down to 13 percent, and stands to drop further.

The family says the stock sales are part of a strategy “to diversify its investment portfolio in an orderly manner.” That is no doubt true.

However, it’s also likely true the family wouldn’t be selling the stock if it thought Forest City-based Winnebago was the best place to make money. And in that sense, these large sales of stock would indicate an ebbing confidence in the company’s prospects on the part of the surviving members of the Hanson family.

That’s curious because things appear to have been breaking Winnebago’s way over the past few years. Sales have been rising. Indeed, demand was so high for its motor homes, some of which cost $250,000, that it built a new factory in nearby Charles City. Profits, though down from the last fiscal year, were up from the year before that. It recently announced it would split its stock, usually a bullish sign.

No doubt part of the reason the company’s share price has risen is related to Winnebago’s efforts to buy back its own stock. In the past 22 months, it has announced plans to repurchase at least $140 million of its shares.     A recent history of transactions involving Winnebago and the Hanson family:

April 8, 2002: Winnebago Industries Inc. announces plan to buy 2.1 million shares from Hanson Capital Partners LLC, which is owned and controlled by Winnebago’s founding family, for $77.7 million.

Oct. 19, 2003: Luise V. Hanson, widow of the company’s founder, dies at the age of 90.

Oct. 20, 2003: Winnebago announces plan to spend $64 million buying 1.45 million shares at $44.1235 each from Hanson Capital Partners. After the purchase, the Hanson family is left with 3,846,306, or 22.9 percent of the company’s outstanding shares.

Nov. 12, 2003: Hanson Capital Partners announces a plan to sell 700,000 shares on the open market. At that time, Winnebago said Hanson owned about 3,383,606, or about 20 percent of the float.

Jan. 6, 2003: Hanson Capital Partners says it has completed the sale of 700,000 shares that was authorized on Nov. 12. Between November and January, Winnebago’s stock price ranged from about $50 per share to $70. Hanson Capital Partners is left with 2,662,006 shares, or about 16 percent of Winnebago’s float.

Feb. 12, 2003: Hanson Capital Partners announces plan to sell up to 1.25 million shares in daily amounts on the open market. The sales will end on July 31. As of Feb. 12, Hanson Capital Partners owns 2,262,006 shares, or about 13 percent of the float. Assuming a price of $70, which is where Winnebago was trading last week, the sales will fetch about $87.5 million.