From the 1959 deed to all the property owned by Hammond Acres Club, Inc.
The paragraph that begins with "Tract 10" on page 3 reads as follows:
Tract 10: There is also hereby conveyed the fee to all land in the bed of the water of Hammond Lake shown and designated on said maps aforesaid, and there is also hereby conveyed a three-foot strip of land along the shore of said Hammond Lake as shown and designated on said Maps No. 1, 2 and 4, recorded as aforesaid, subject to the rights of way conveyed by the grantor to the purchasers of lots abutting said Hammond Lake"
Rule #11 grants an easement to lake front property owners for the exclusive use of that three foot strip provided they are members in good standing. I vividly remember John Gare saying that if lake front property owners failed to pay their dues he would put up a rusty old fence on that three foot strip of land between their property and the lake and leave it there until they did.
The deed references maps in Plan Book 49, page 40, Plan Book 50, page 2, Plan Book 50, page 20, and Plan Book 50, page 24 in the Hampshire County Registry of Deeds.