shipstamps.co.uk

The Sultan of Zanzibar's barge, shown on a current 20 cents stamp, manned by 16 oarsmen, was presented to the Sultan by Queen Victoria who also provided special uniforms of serge to be worn by the barge's crew.
SG361 Sea Breezes 9/58

http://www.gracesguide.co.uk/J._Samuel_ ... ar's_Barge

update:
The following I found on the net:

07 May 2019.
Restoration of The Royal Barge
Zamani has been granted the responsibility by the Peoples Revolutionary Government of Zanzibar to restore the Royal Barge to its former glory and to be a center piece following the restoration and regeneration of the Peoples Palace Museum. This vessel is also considered to be the oldest surviving examples of White’s 19th century workmanship.

https://www.heritageofzanzibar.com/post ... oyal-barge