Unless you have a large boat, it's difficult to arrange that the dinghy is big enough for use, but small enough to store on the boat. It's always a compromise.
Storing a dinghy on deck
How big is your deck? You might want to consider a two-piece nesting dinghy.
This dinghy was designed by Evan Gatehouse. I bought the plans and built the dinghy in my spare time last winter. It weighed 88 lbs before painting. The front half is about 40 lbs, the back half is about 48 lb.
There is a fair bit of rocker in the hull which makes for a sweet rowing displacement hull form. The down side is the hull isn't intended to plane and therefore it won't tow as well as a flat bottomed boat. That compromise works for me because I want a nice rowing boat. I seldom tow it, and never when the sails are up. I don't have an outboard for it, but I eventually plan to buy one. - John, Blue Teal
For a commercially available nesting dinghy, check the NN10 by Nicolls Lite.
Davits on the stern
Generally only practical on larger boats.
Towing a dinghy
Works great for short passages in settled weather, but can get dicey when the wind pipes up. Generally the painter should be long enough so that the dinghy can ride one wavelength behind the boat.
We have never had the dink hit us while under weigh but once it surfed far enough along that given time it might have. Our cure is to thread a large plastic funnel onto the tow line which we fix with knots at a point about 12' from the dinghy. When the dink is being towed normally the funnel skips along but it the load comes off the line, as it would if the dink surfs up, naturally bringing its end of the towline with it...the funnel gets pulled through the water the other way and it acts as a drogue. This tends to slow the dinghy and also spoils its aim. It works very well. - Gord #426 Surprise