Sponsorship on boats and Blades
Extract from Henley Royal Regatta's Notes & Instructions for Competitors & Coaches:-

SPONSORSHIP ON BOATS
Sponsor Identifications may only be displayed upon boats whilst
competing in the Regatta as follows:-
(a) No more than two sponsors may be presented on any boat.
(b) Each Advertising Space on a boat may be no more than 800
sq. cm. in size and may contain one or two Sponsor
Identification(s).
(c) All boat types are permitted one Advertising Space on the bow
canvas and one Advertising Space on the stern canvas. The
sponsor identifications must be identical on both deck areas.
(d) On the sides of the boat the number of Advertising Spaces
allowed is limited by boat type as follows:––
1x, 2x, 2– once each side
4x, 4–, 4+ twice each side maximum
8+ 4 times each side maximum
(e) In addition, a boat manufacturer may display one
identification on each side of the boat with a maximum area
of 100 sq. cm.

SPONSORSHIP ON OARS AND SCULLS
While racing:-
(a) No sponsor identification, whether of the manufacturer or
otherwise, may be carried on the blade or on the outboard
section of the loom.
(b) On the inboard section of each oar or scull, the manufacturer’s
identification (not to exceed 100 sq. cm.) and a sponsor’s
identification (not to exceed 100 sq. cm. with a maximum
height of 5 cm) may be carried. All oars or sculls in a
boat must carry the same identification.