I'm Lucy, and I'd be happy to answer your questions today.
The town has some discretion in determining which laws they choose to enforce and which they do not, as well as when to enforce them. For example, if I'm stopped for a speeding ticket, it's not a defense if there were 10 other cars speeding and I'm the only one who was stopped. This is a similar situation. If you really are in violation of the law, you can't claim that you're allowed to break it because everyone else does. Selective enforcement is only illegal if the enforcement itself is based on discrimination - like if you're a member of a minority group.
For example - harsher penalties for people who are convicted of crack cocaine usage than for regular cocaine are considered discrimination, because many more black people are convicted of using crack, whereas cocaine is primarily used by relatively wealthy white people. If police went to a party and arrested everyone using crack but ignored everyone using cocaine, that could be the basis for a discrimination claim against the police. In this case, that means it really comes down to whether you can prove that there's some ulterior motive for not enforcing those two laws, and if that reason has to do with unlawful discrimination. Discrimination is unlawful when it's based on a person's status as a protected minority. Boat owners with side yards versus those without typically wouldn't be considered unlawful discrimination because neither boat owners nor property owners are a protected class of persons.
Harassment is a legal term that has a much more specific meaning than how most people use it, and it's never harassment for someone to be doing their job. Harassment requires a pattern of conduct that serves no legitimate purpose, like calling someone repeatedly (and not talking to them when they answer) or making a habit of calling very late at night or early in the morning. There's nothing in your question that supports harassment.
You can choose to report other boat owners who you know are breaking the laws. It's possible that they choose to only enforce the law when it comes to their attention that someone is breaking it, rather than going house by house and checking every boat to see if it's drained (which could use significant police resources). But there's no ability to make police ticket someone, and the fact that they didn't usually doesn't mean your ticket isn't valid.
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