[1.05] Splashed down ship disappears at 2.2km

[Coam]

KSP Version: 1.05
Mods: Planetshine 0.2.4.2, Distant Object Enhancement 1.6.4 , MechJeb 2.5.6.0.

I have a boat floating around 5km from the KSC. Passing within ~2.3 kilometres of it causes lag, and on exiting the lag and passing within 2.2 it disappears, killing the crew on board it. It doesn't leave any debris behind.

This happens repeatedly, regardless of the aircraft design used.

Two possibilities I can think of are that the ship is being deleted for being too complex and taking too long to load [It contains around 150 parts] or that it collides with the water on loading and is destroyed.

However the ship loads fine without damage when selected and flown from the map view, and it seems to load in reasonable time when this is done, so neither seems particularly obvious as the cause. Does anyone have any idea what's causing this and how it can be prevented?

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