While tied to the dock, weigh out all the dry ingredients for a basic birthday cake mix. Trying to use scales underway or at anchor is a mission impossible without a stable boat — weighing scales will not give you an accurate readout.
Put the flour, butter, baking soda, and sugar into individual ziplock bags. Make sure to label each bag. I like to write the weights of each ingredient on the bag as well, plus how many eggs I’ll need to complete the cake. (You can add cocoa powder for a chocolate cake or other flavoring and colorings when you actually make the cake.)
Consolidate these by putting all the smaller bags into a larger one, and write on the bag the total size of the cake it will make or, as I do, which size cake tin to use. Squeeze out all the air and store it in the freezer.
When you get that last-minute call for a cake, you are ready to go.
Perfect cakes every time!