Fill the tub with water that you can just barely put you hands in without getting burnt. Add a scoop or two of tide. Insert sail. Swish the sail around every 15 minutes or so for an hour. Add more hot water. repeat swishing every 15 minutes for another hour. Drain tub. You will be surprised how dirty the water is. Add more hottish water. Swish sail around, drain. Add water one more time. swish and drain. Hang sail on the clothes line or over a fence and hose off (both sides). Let dry.
They should be much cleaner now. I have done this twice. Made a huge difference.
The people who find fault in what you build typically don't build anything at all.