Steel hull thicknesses 34'

[Confused Object]

Is a 34' constructed with 5mm hull plate effectively a motor sailor? Despite being of a classic true sailboat design with bowsprit and cutter rig it is very overbuilt.

I think I know the answer but if anyone has any experience or knowledge to input, that would be much appreciated.

ta

[Breaking Waves]

No. Not necessarily.

Some well designed mid-30s steel boats with that plating have sailed 'relatively well,' and no one would call them motor sailors. They will be heavy and will certainly not be rocketships, but can sail at all angles in almost all wind speeds without motor. But some sailors have sailed them to all sorts of places.

ofc, if the design is 'less good', inefficient keel and rudder and rig extra heavy topsides, and short waterline, etc it will sail less well.

and ofc, it the owners prefer to motor rather than work at sailing, it will act as a motor sailor.

But heavy boats can sail relatively well (in cruising terms).

[Briis]

Do you know approximate displacement fully laden and an approximate sail area? Engine hp and fuel tank size?

Only with this info one can say if it’s a sailboat or motorsailor. Sometimes the line between them is very narrow or even hybrid depending on the boat design and bulild.

Sub 50-60-foot steel boats are never fast boats in modern terms with plastic ultralight bumpy-ride racing boats comparison, apples and oranges. But they tend to be mighty comfortible boats motion-wise, especially in rough conditions. 5mm thickness is very good for a steel boat. Gives you strenght and longetivity. And yeah, even the ultra heavy displacent boats sail well in cruising terms when rigged right.

With very subjectively and roughly 34ft boat, you’d need 50hp+ engine and 300 liter+ diesel tank, sub 40 square meter sails to call it a true motor sailor. Anything less motor and better sail terms goes toward to a proper sailboat territory.

[Fore and Aft]

Confused Object the steel yachts I survey in that size usually have a hull thickness between 4mm-6mm. Like it has been said there are lots of other factors that determine the boats performance. Even if she's been designed as a yacht, adding a generator, air conditioning etc can badly affect a boats performance.
Cheers

[Tillikum]

Heavy? You could put ballast in the bilges, or you can hang it off the keel, or you can build it into the hull. Yes, of course the effect on stability is not identical, but then the durability isn't either.

There was a gent from the UK mentioned on here previously; a sailor of long experience who IIRC had built a replica of the the famous Bluebird of Thorne. His bottom plating was 1/2" (12.7mm) thick. Might as well put the weight where it will do some good was his thinking.

Of course some people never run aground so wouldn't need that kind of insurance.

[Scorpius]

Scorpius has only 10 guage steel topsides - but the bottom of the keel is 3/4" steel plate. Very comforting on this rock-strewn coast!