Layne, there are such posters for both the Union and Confederate Navies (officers' ratings only) shown on pages 144 and 145 of the William C. Davis volume, REBELS & YANKEES: THE COMMANDERS OF THE CIVIL WAR, published by Salamander Books, in 1990. You should be able to obtain a copy of this volume from any decently stocked library in your area.
Several other volumes also include images of such rank insignia for Naval officers, and I have a reprint volume of an 1864 publication titled: SCHUYLER, HARTLEY & GRAHAM ILLUSTRATED CATALOG OF CIVIL WAR MILITARY GOODS, which provides several excellent pages of Union Naval ornamentation for caps, shoulder straps and sleeve insignia, all in poster type pages. This reprint volume was published in 1985 by Dover Publications, and may still be available for sale. Their contact address is at 31 East 2nd Street, Mineola, NY 11501.
I have several xerox pages of Union Navy rank insignia, for both the officers and enlisted personnel, sent me some years ago, by a fellow researcher, though there is no indication of which volume or publication this originated from.
I have also seen images of such rank insignia in several other publications, but cannot currently recall exactly where.