When the SIs specify that certain government marks bound legs, while others must be honored / passed on their correct side but do not begin or end a leg, are these other bouys marks or obstructions? From the definition of "mark" it would seem that they are marks. "An object the sailing instructions require a boat to leave on a specified side.." It would also seem that if they are not mentioned in the SIs then they are no tmarks, but could be obstructions. Is this correct?
If an object fulfills the definition of obstruction it is an obstruction.
Obstruction An object that a boat could not pass without changing course substantially, if she were sailing directly towards it and one of her hull lengths from it.
Thus, for example, navigation tower structures and large buoys are obstructions to most boats.
If an obstruction is also a mark, unless it is a continuing obstruction, rule 19 does not apply and rule 18 does (rule 19.1a) If a mark is a continuing obstruction rule 19 applies and rule 18 does not (rule 19.1 last sentence)
Unless there are two or more that have to be passed on the same side. Then you can use them to define an exclusion zone in the SIs. Then that zone becomes an obstruction.
If they are not mentioned in the SIs and there is no reference to government regulations or IRPCAS in the SIs either, then a protest committee would have a hard time enforcing them.
Otherwise a boat must pass the marks on the correct side but otherwise can sail where she pleases.
If anyone remembers that thread and can put their fingers on it, please post a link here. Thanks. Ang