The riders met at the visitors center and were briefed about SP5 Seaman and how the mission would be conducted.  The family asked the PGR to serve as pallbearers.  There were several other missions ongoing at the same time and with the poor weather only 9 riders were present.  Six pallbearers were assigned and all but the ride captain departed for the shelter to prepare the flag line.  The ride captain moved his bike to the lane to lead the family to the shelter.  As he waited for the family lightening and thunder occurred.  Riders were told NOT to stand on the flag line but to be under the shelter.  The rain came down hard as the procession moved to the shelter but let up just as the service began.  At the conclusion of the service the flags were stacked in the storage area to dry out, the riders debriefed and dismissed.