Hi,
my thinking is that Albin's 25 Hull is SD.
The second engine option for the Albin 25 has been a Volvo 36hp and this engine gives it a cruising speed of 8 knots, which far exceeds the hull speed.
I have seen the Albi 25 move much faster than the 15 knot class, after the owner replaced an even more powerful engine.
Aricle
Early 25s had a 20hp diesel built by Albin themselves (the company originally manufactured some of the smaller models in the Volvo Range). This engine was a touch underpowered, giving a top Speed of just over eight knots, so in 1971 the builders switched to the 36hp Volvo MD3B, which lifted the Speed to around ten knots, depending on load. In 1975 the MD3B was replaced by the similarly rated MD17C, which became the standard engine for the rest of the boat’s production life. The Albin 25 might not win any races, but she won’t bankrupt the owner either: at nine knots, with an average load, she will use about 1 12 gph.
Although designing a hull to suit both power and sail can sometimes result in an unhappy compromise, on displacement motor boats it can have its advantages. To improve the sailing Performance of the motor sailer version, Brohäll carried the hull down to a deepish keel. The same keel, in the motor cruiser provides good directional stability whilst also protecting the propeller.
https://www.mby.com/motor-boat-news-boat-reviews-pictures-and-videos/archive/albin-25-11729
NBs