I have used Lanocote Prop and Bottom which is lanolin based. In actual use it lasts about 3 months. I had a friend whose boat
sat idle for two years and had no growth on the prop with the product. The product can be used under water
but I have only had success in warm Florida
water while in Maine
it wouldn't stick to the prop. Also the metal of the prop has to be extremely clean before applying. If there is any growth or slime on the prop at all it won't stick. We use a scotchbrite pad to get it clean before attempting to apply it in the water followed by wiping with a cloth just before applying. I find it is much easier to apply out of the water. If the water is full of particulates you may have to apply the Lanocote immediately behind the cleaning
cloth. I cannot tell you how plain lanolin would work
, but the Lanocote product seems to be a bit thicker than plain lanolin and even their anti-corrosion product for dissimilar metals.