Depends on how much you love your boat. I would not use a blue tarp. first of all you would never be able to secure it well enough that if a storm did come it would rip it off and you might be lucky that it doesn't whip around and mar the finish.
I leave it off for the weekend while we are at cabin on the lake if I don't think it is going to rain. If I am unsure about the rain I bought a Ford F150 easy bed cover at Home Depot [think it was like $35] it has claws and hooks that make it very easy to cover the helm and protect my electronics. There are pictures in my gallery.
I have said on this forum before putting on the playpen cover has to be approached as a zen thing, take your time, dangle your feet in the water, have a sip from your beer. I strongly suggest you use the mooring cover