This is a fairly complicated question and one for which there is not one universally correct answer. In broad general terms, Coastal Cruisers are intended to be used in areas where there is a lot of places to duck in for refuge from a storm. They deck and interior designs that are optimized to be comfortable at anchor
. Cockpits tend to be larger and companionways more exposed. Coastal cruisers tend to have more and larger operable portlights and hatches
. Coastal cruisers will have brighter more open feeling interiors with wide open cabin soles and fewer hand holds. Seakindliness is less important and voluminous interiors are more important.
Because they are sailing in and out of tight places, pointing ability, speed and reasonable draft become more important. Load carrying capacity is not as critical. To control price, and because sophisticated engineering is not as necessary to survival, the engineering and construction on purpose built coastal cruisers tends to be less robust. On the other hand they tend to be more well rounded sailors, sailing well in a wider range of conditions. They tend to have more gizmos for sail handling such as in mast furling
or roller furling
Boats designed to be used offshore (I really don''t like the term ''Blue water boats'') are designed to take prolonged periods of being thrashed by bad weather. Interiors are simplier with fewer sharp edges, more handholds, narrower tighter cabin soles with more places to get a grip with your feet. They should have more seaberths. Carrying capacity and seakindliness are mush more critical. Offshore boats tend to have large tankage, and good storage. They either have very large refrigerated ice boxes or almost no icebox at all. The interior layout pulls main functions (sleeping, cooking and using the head) close to the center of the boat and out of the ends of the boat where motion is greatest. The interior is designed to work while bouncing on a steep heel angle. Everything has a hold down so that it can''t go flying during a major knock down.
In the past offshore boats tended to have much higher displacements that coastal cruisers but modern engineering and understandings of weight distribution and form stability have allowed substantially lighter boats, pretty much on a par with coastal cruisers, with adequate strength, seakindliness and carrying capacities. Offshore boats tend to have smaller cockpits with larger drains in case they are pooped. Portlights tend to minimized in size to reduce the chance of being broken. Deck gear like lifeline stanchions, and the like, tend to be heavier duty and a few inches taller. Everything, including dorade vents, is designed so that it can be dogged down to prevent downflooding. Sail lockers typically have automatically latching hatches
and have watertight bulkheads to prevent a flooded locker from flooding the boat.
There is a divergence of thoughts on rigging
design. Offshore boats need to be able to quickly switch to heavy weather mode. For this reason multiple head sails or split rigs
tend to be popular. Sloops are often fitted with a removable jib
stay that can be set up quickly with a storm sail. Offshore boats will often start out with less sail area, so that they don''t need to reef as often but in doing so give up sailing ability in light going. Today you see more and more offshore boats goint to fractional sloop rigs
because of the ability to quickly depower and end up with a well rounded heavy weather rig
Offshore boats tend to have simplier more fool proof hardware with fewer gizmos and down to basics hanked on jibs, slug mounted mainsails, and slab reefing.
To somewhat obscure this issue further, there is a whole class of ''value oriented boats'', boats that are designed to provide ''a lot of boat for the dollar''. To do so, a certain amount of robustness gets compromised. They often have interiors designed to look great at a boatshow or at anchor
, but which lacks the necessary storage, seaberths, handholds, and compact walking surfaces of an offshore boat. Almost by default the value oriented boats are only suitable for coastal cruising with limited offshore jumps being made only in a carefully sellected weather window.
like Bucaneer,Columbia, Coronado, Oday, Hunter, Catalina, early Islanders and early Ericson''s, Morgan Out Island series, Beneteau Oceanis Series, C&C Landfall series, and Bavaria fall in this category of value oriented boats. It is not that these boats are not suited for many people. In fact they are ideal for the way that most people use their boats. The problem comes when one wants to take them offshore for prolonged periods of time. They are really not suited for the day in/day out knocks, and the need to carry a lot of stuff that is so critical to an offshore boat.
It is not that people have not made offshore voyages in these ''value oriented boats'' but in terms of risk management, it is better to pick a boat that was intended to take the abuse of being offshore for prolonged periods without needing major repairs
or overhauls after every storm.
The other point is that not coastal cruisers are ''value oriented''. Boats like Tartans, Dehlers, Sabres, C&C''s and the Canadian Express''s are better built coastal cruisers. They tend to have better gear, and engineering, making them more robust and often permitting better sailing abilities. As a result, these boats are more suitable, even if not optimized, for offshore work.
Dehler offers as variety of designs varying from stripped out racers to good offshore cruisers. The Dehlers that I have been aboard are really well built for their purpose and have included nice details. Depending on the model these can be very good modern style offshore boats.