To learn how to manage your passage of human solid excrement, you need to spend some time learning your own body's characteristics and you have to avoid doing all the right things that most everyone should do to encourage good "flow-through" of foods consumed.

(Please note that these suggestions are exactly opposite to those suggestions on how to remain healthy!)

Starve yourself of fluids, water.

Consume salts and other things that will de-hydrate your body.

Dehydrating your body will make it very difficult for your stool to attain the proper volume and hydration level to promote bowel movement.

Eat a low-bulk diet. Avoid pulp (fruit, vegitables).

How to avoid "bulk" and get enough caloric intake: Eat eggs!

Eat a steady diet of what you think that you should eat while on the voyage. Study your results for a few days.

Re-enter this diet on occasion to learn how long it takes your body to react to the change from a normal diet.

Timing is everything. Learn how to time yourself.

Use mass quantities of water to provoke a bowel movement when convenient to do so.

When choosing to be on a boat for 24 hours, pick a boat that has a way to take a crap. Don't ever embark on a long trip without at least an alternative way to relieve oneself; you never can know what the body may decide to do.