The navigation lighting on a 13-footer never uses a sternlight--well, at least I have never seen one set up that way. In order to use a sternlight a masthead light would be needed. On small boats like a 13-foot Boston Whaler the normal lighting is to use a white all-round lamp. The lamp is carried on a pole, mounted at the port or starboard corner of the transom. The pole mounted with two brackets. You can see details in the image below of the mount:
Typical two-bracket mount as seen on a 1976 SPORT 15. The upper mount has a threaded portion, and a knurled retained tightened down on the pole to hold it in place.The lamp fixture itself seems to vary. Here is a typical Boston Whaler white all-round lamp, which I think is a Perko lamp fixture. Sometime it was mounted to the pole at a slight angle:
Navigation lighting was an option. I don't think every 13-footer had navigation lights. Here is one that did:
http://smg.photobucket.com/user/Yiddil/media/DSC00130.jpg.htmlToday I'd look for a suitable aftermarket white all-round lamp and see if a suitable mount could be worked up for it. Try a search on GOOGLE with the arguments ( Perko white all-round pole light base ) to see what is available as a new lamp and mount.
