The Ajman jam jar lable shows a French N300 hovercraft. The ships and hovercraft set was issued in 2 mini sheets 210 x 147 mm and 82 x 100mm
with stamps 46 x 32mm and 17 x 23mm. I tried to show these sheets but they wont be accepted because they are more than 90KB.
Other Cinderella's you might like are here.
The Sao Tome & Principe mini sheet (which shows Famous Bridges of the World is 128KB so too big but the single hovercraft stamp shows an Australian-built Mustang craft. There is no logic sa to why the background shows the Oresund Bridge which links Denmark and Sweden! This craft has no connection with the area, though 3 AP1-88 craft (similar to the craft on your Madagascar stamp) operated for SAS linking Copenhagen and Malmo airports until the bridge was built.
Have you noticed on the Madagascar stamp that it seems to show two different values; 300FMG and 60ARIARY? The craft is UK-built AP1.88/100-008 "North Wind" which was operated by the Northern Shipping Company in the far north of Russia on round trips from Archangel. The trips lasted for 2 to 3 days. Because of the length and remoteness of the route, a satellite communications system was installed. Seating in the passenger saloon was reduced from 100 to 64 seats which allowed crew accomodation and a galley was incorporated. It was sold to Cuba in 2003/4 and had the cold weather stuff removed and A/C installed!. Sold in 2006 to Hoverlines International for a service in Bahamas and renamed 'ACV Falcon'. I'm not sure but I think it is one of 5 or 6 used AP1.88 craft currently in the UK for refurb and resale.
The other mini sheet is from Guinea Bissau and shows, what they call, Hydrofoils. Top right stamp shows an SR N4 cross-Channel craft (UK-France) and the bottom left shows the first man carrying craft - the SR N1. The SR N1 was a test bed for the hovercraft theory and was shipped to France for the return to Dover on the 60th Anniversary of Bleriot's first crossing by air (25 July 1959). The Guinea Bisau stamps were available in single stamp sheetlet and a mini sheet with one stamp (not on the mini sheet) showing a Russian-built hydrofoil of Greek flag, but the surround shows an SR N4 and a Japanese MV-PP 5 hovercraft.
I hope you are still awake and I haven't bored you!
Regards from a sunny (for now) Wirral, UK