update table through form - vba

Question

This is the next attempt I am making at solving this problem. In my timeline is the prior attempt.
I have three tables BOAT, BERTHAGE, LOCATION. These tables are joined in the following way in a query called Boat_Move
BOAT(boat_ID) joins to BERTHAGE(boat)
LOCATION(Loc_ID) joins to BERTHAGE(location)
This query is viewed on the form as a subform.
When the form opens up I will highlight the vessel which needs to have its location moved/updated
Once highlighted in the subform I click the edit button
Private Sub cmd_Edit_Click()
If Not (Me.Current_Week_Boat_Move.Form.Recordset.EOF And Me.Current_Week_Boat_Move.Form.Recordset.BOF) Then
With Me.Current_Week_Boat_Move.Form.Recordset
Me.txt_Boat = .Fields("BOAT_NAME")
Me.txt_Cur_Loc = .Fields("LOCATION")
Me.txt_Cur_Flo = .Fields("FLOAT")
Me.txt_Cur_Doc = .Fields("DOCK")
Me.txt_Cur_Ori = .Fields("ORIENTATION")
Me.cmd_Add.Caption = "Update"
Me.cmd_Edit.Enabled = False
End With
End If
End Sub
This puts the appropriate information into the text boxes.
I've also did up the following with the idea that this would update the location(field) in the BERTHAGE(table)
Private Sub cmd_Add_Click()
Dim strSQL As String
strSQL = "INSERT INTO BERTHAGE(BOAT, LOCATION)" & _
" VALUES(" & Me.txt_Boat & ",'" & Me.txt_Cur_Loc & "');"
CurrentDb.Execute "UPDATE BERTHAGE " & " SET LOCATION=" & Me.txt_Cur_Loc & _
" WHERE LOCATION=" & Me.txt_Cur_Loc
Current_Week_Boat_Move.Form.Requery
cmd_Clear_Click
End Sub
I'm not sure if in this instance I should be creating a new table to make the update and then overwriting the older table. The issue I see here is the older table is at around 24k records so that doesn't seem like the best way forward.
So at this point I'm facing two problems, and I am unsure if solving either one will solve the actual problem of updating the BERTHAGE(location) field.
View of the from
Any help is appreciated.