Planners said the economic benefit would be "fairly minor" and the industrial plant and machinery would have a "harmful impact on the open character and appearance" of the rural area.
The council's conservation officer is concerned about the impact on the character, appearance and setting of the marina but says these need to be balanced with the benefits of the scheme.
Legal proceedings were lodged as the cottages fell in an English Heritage conservation area and the local council deemed the demolition to have caused "substantial harm" to the village's character and appearance.