At one point we considered offering the Manta 44 powercat as a motorsailer,
and as Malcolm said we figured it would probably be faster than our sailcat
when reaching in higher winds because of the reduced rocker, though albeit
with compromised light air performance due to the higher wetted surface and as
Malcolm says reduced tacking ability.  One thing Malcolm didn't mention is
what kind of appendage for the lateral resistance needed for sailing.
Certainly the drag of fixed keels would not be good for powering at higher
speeds. Dagger boards would work, but I think a single large centerboard in
one hull or two smaller ones in each hull, would be less problematic when
grounding and more in keeping with the motorsailer look.

Back in the  late 70's Lancer made a 44ft. monohull motorsailer, that had a
hull form with fine sections fwd and wide aft sections with a chine above the
water and little or no rocker.  It had a furling main and jib and all
sailhandling lines led back to a single winch at the helm, this boat was
actually the inspiration that lead me to rig future designs this way including
the Manta sailcat.  It had an option for large single or twin diesel engines,
and could motor top speed at close to 20 knots and reach under sail at 10-12
knots in a stiff breeze. The problem was once the owner new they could get
where they were going at 15 plus knots, they NEVER pulled the sails out!
Though very innovative and ahead of its time it had limited commercial
success, and the conventional sailboat and motoryacht industries continued to
thrive.

Whenever the price of fuel goes up, you will see a new injection of new
motorsailers come out, look at all the new monohull motorsailers being
advertised currently (Nordhaven, Island Packet etc) They are pushing them like
they are some kind of new idea and breakthrough in design, when it's it all
has really been done before, by the likes of Ted Hood, Schucker and Vince
Lazzara of Gulfstar back in the 70's. Of course non of these monohulls can
offer the stability of a cat underway or at anchor still.

As I see it the big question when considering the possibilities is how fast do
you want to be able to motor? If it is in the 10-12 knot range, a conventional
sailing design in the 45-50 ft. range with slightly larger engines could do,
if its 18-20 knots than that then something like the CS hull form would be the
way to go.

Pat Reischman.

Dear Pat,

On the Cordova we actually had hydraulically operated "tandem" dagger boards
originally because nobody knew how the boat would perform to windward. After a
year the owner removed these and blocked off the holes. The reasons were
twofold. [1] the engines needed to be run to power up the hydraulics when
operating the boards as the hydraulics very quickly drained the batteries. [2]
they were simply not needed. because there was no rocker in the keel, and the
very fine hull shape, the Cordova went to windward better than all but the
most extreme racing catamarans. And, as the owner said- "if I want to beat the
raceboats to windward I just turn on the engines".  You have to keep
remembering that we are talking about motor sailers, not racing sail boats,
and that this leads to different expectations and a completely different
performance envelope. Most sailers motor in light weather and we all know that
"gentlemen" do not sail to weather.

Even in the 10 to 12 knot range the CS hull is still more fuel efficient.

All sailing catamarans suffer a wetted surface/sail area penalty in light
winds. It is the nature of the beast. You just put on a bigger rig or turn on
the engines.

Malcolm Tennant.

MALCOLM TENNANT MULTIHULL DESIGN LTD
PO Box 60513, Titirangi.
Waitakere 0642
NEW ZEALAND
Ph: +64 9 817 1988
e-mail: malcolm@tennantdesign.co.nz
www.tennantdesign.co.nz
www.catdesigners.com