It might be some sort of wind screen that could be raised to protect passengers on the deck, but I don't know that for a fact. The tourist lounge was added in 1936 in that area. Some pictures also show a large framework over the area between the second and third funnels where the name board was placed.
http://americanart.si.edu/images/1983/1983.16.7_1a.jpg
This appears to be later in her life since the lounge is there aft on the boat deck. The name board seems to be replaced with the covering, which might have been over tennis courts, IIRC.
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The New Wolf's Shipyard
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