72 COLREGS (navigable waterways, Federal)
"...a power driven vessel under 12 meters in length may (instead of other lights)...exhibit an all-round white light and sidelights." This means that an anchor light and red/green side lights will have you covered in international and Federal waterways under power. You should not also display display a sternlight in this case. I do not know the configuration of your mast head light. In a 26 it's two parts, Foward bulb and rear bulb. Both on is the same as an anchor/all-round white light. Foward on is a steaming light (must use separate stern light). When sailing do not use all-round light or foward steaming light, you must use red/green side lights and a stern light (at the stern, rear portion of mast head light will probably not be considered in compliance.) State requirements in non-Federal waterways may differ. Hope this helps. alan