Because holding tank
systems only add cost to the builder
, they don't increase the boat's value one bit...and double vents + a fan would only add MORE cost. Odor
isn't a safety
issue or a legal
issue...which makes it your problem, not the builder's.
However, it shouldn't take two vents and fan to solve the odor
problem on your boat...it's sailboats that are challenging because people insist on sailing laying 'em on the sides to sail 'em!
Shoot me an email
and I'll be glad to help you figure out what you really need to do to fix it.