That IS a problem - smoke alarms are very sensitive and the danger is that with repeated false alarms people either become accustomed to ignoring it or else they remove the battery to stop the nuisance - the problem then arises that the smoke alarm is now completely non functional.
I wouldn't put one in an engine room because any fumes at all are likely to set it off (smoke alarms are often actuated by steam from kettles, over-enthusiastic toasters or even aerosol deodorant or hair sprays). A smoke alarm outside the engine room would be better but it would need to sited where it would be out of the path of fumes or else you will have a false alarm every time the door is opened.
In the daytime most people are going to be alerted to a fire by their senses especially their nose, and they are already up, dressed and mobile so they can escape quickly if necessary.
It is at night, when people are at their most vulnerable, that a smoke alarm comes into it's own.
I can see that in a boat, which will probably have a (relatively) large open combined cooking and living space that false alarms could be a problem. Particularly if the ventilation in the living space is limited. I haven't heard of adjustable smoke alarms but they must be worth a go.