Yes, Winair has weight restrictions; sometimes enforced, sometimes not...here's what we tell clients:
Weight Restrictions... Windward Island Airways " Winair" has an official weight restriction of 20kg per person (44 lbs.); however, there is an additional 10kg (22 lbs) allowance for diving equipment. If you are ticketed through to Saba on USAir, Delta, Air France or KLM, the luggage restrictions of those airlines apply. American Airline passengers must re-check bags in St. Maarten. Some suggestions:
o take your regulator in your carry-on luggage
o minimize the extras (we sell great t's, tanks, shorts, the works
o smile and be polite at the St. Maarten Winair counter--
remember, you get more bees with honey
o put essentials (medications, a change of underwear, a prescription dive mask, etc.) in your carry-on luggage in case your checked luggage is delayed.
Hope this info is helpful...taken from
http://www.seasaba.com/NewWeb/TravelTips.htm#Baggage