GIGRota allows you to reserve boats (and other resources) and add club members to them. You can also invite groups to join them or other activities. It has an advanced messaging system which alerts users when they are due to row, or for changes in the events. The alerts can be user configured according to preference.
The messaging system can also be used for other club Messages and Alerts. Including for when subscriptions are due.
There is a Stats section where you can download details of your club activities in the form of spreadsheets.