The aerial photo below is from the vintage Warships in Profile volume on Seydlitz and is captioned as showing the ship in September,1918. There are very few boats visible on the decks, in fact I can only make out two for sure, one under the barrels of E turret's guns and one on the port side of the forward superstructure. There may be another, stowed at an angle, next to the one under the guns.
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Another interesting thing the photo shows well is the arrangement of the hatches and skylights on the ship's quaterdeck. This is something that every plan, rendering and kit seems to show differently and most do not get right.
The rendering below, also from the Profile, purports to portray the ship as she was at Jutland and shows three boats stowed on deck and one on the roof of D turret. The boat on the turret shows up in the after-battle photos of Seydlitz and, remarkably, it appears to have survived the battle intact.
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The totally bare expanse of wood deck from A turret aft to C turret looks odd and is not correct as there were skylights, hatches, coal ports, decklights and other equipment located through out this area. Also, from what I understand, to show th ship correctly at Jutland the aft funnel should be painted red.
I was fortunate to recently acquire one of the old Classic Warships 1/200 semi-kits of Seydlitz and I have been trying to accumulate as much infromation and resources on the ship as I can. It appears that building an accurate model of the ship at a particular point in time is going to be very difficult as reliable plans and dated photos seem to be rather scarce.