The 48' Schooner, JASMINE
Perspective Aft |
Perspective Forward
Larger Sail Plan |
Deck Layout |
Interior Profile |
Interior Plan
Copyright 2006 Michael Kasten
The
48' aluminum schooner Jasmine is a fine example of combining
classic form with modern thinking in terms of materials and in terms of
propulsion. This is a motor sailor in the purest sense of the
term. In other words, Jasmine is
designed to be equally capable as a sailing vessel or as a motor vessel, and to
do so in style! Please have a look at the Perspective Aft
and the
Perspective Forward, and I think you will
agree. The propulsion and structure involve modern thinking for several reasons:
- Use of all aluminum construction,
- Use of a medium to high aspect Junk Schooner Rig,
- Completely free standing, un-stayed masts, and
- Electric Drive...!
I will describe a number of the unique features of this vessel below.
Particulars
The dimensions of the schooner Jasmine are:
- 48' - 3" Hull Length including bulwark and
rub rails
- 47' - 6" Moulded Length On Deck
- 13' - 5" Moulded Beam
- 42' - 7" Approximate WL Length in the Half Load condition
- 6' - 1" Approximate Draft
- 49,900 lb Displacement in the average Load condition
The Structure
I have referred to the materials of construction as being modern because the
entire vessel will be built in aluminum, including the free standing masts
and the upper and lower yards.
It takes a while to actually let that concept sink in... Yes, with free
standing masts there is no rigging and there are no chain plates. This
dramatically simplifies the rig, and almost entirely eliminates chafe.
The cost...? Slightly greater weight in the spars. The
benefit...? Zero standing rigging, therefore zero maintenance of it!
The intent is that the exterior of this vessel will not be painted, except below the
waterline, and at the boot stripe. With a fine-grit sandblasted
surface elsewhere, the exterior will look like it has been painted a flat
light gray. In the long run, this will weather to a uniform soft gray,
and the surfaces above the boot stripe will require zero maintenance.
The Layout Above & Below
The Deck Layout is very
straightforward. The cabins are kept low intentionally, in order to keep windage
to a minimum.
A cockpit is located aft, with a binnacle placed on the bridge deck just
aft of the aft cabin. This is the primary steering station, from which
all sails are clearly visible. A tiller is mounted directly to a
transom-hung rudder. The aft deck is intentionally kept as un-cluttered as
possible. All hatches are flush to the deck and water-tight. This
allows complete freedom for placement of deck chairs or sleeping /
sunbathing mats, etc.
A second cockpit is located amidships. The seats that flank the
midship cockpit are generously sized for comfortable sleeping or lounging on
deck as well. An optional second steering station is located
here. From this midship cockpit, one can go below via the
companionway.
Below, as can be seen in the Interior Profile
and Interior Plan views, there is first a
very ample head compartment to port which includes even a bath tub! To starb'd
of that is a large galley. Forward of these spaces is a full sized
saloon, complete with heat stove and coffee table. Also, there is a large bureau right
forward that spans the width of the forward end of the cabin. This is
the perfect spot for a stereo, or books, or entertainment center, or maybe
just to accommodate a bar service.
If, after descending the companionway ladder, one were to instead swing
around to starb'd, a passageway is found which leads aft to the owner's
stateroom. The aft cabin is generously sized and contains a large
island-style berth on
center, two hanging lockers outboard, and a long shelf / cabinet that
extends full length on both sides. Very roomy indeed!
Within the stateroom, forward and to port is the entrance to the engine /
motor room. In the motor room are the twin electric motors, generator, batteries,
diesel tanks, and whatever else makes noise or generates heat.
There has been no attempt to crowd in more accommodations such as another stateroom, which on a
vessel of this size is often very tempting. Instead, guests can be
accommodated in the saloon by the simple expedient of placing a curtain
forward of the galley. The result is that in all, this is a very
un-crowded layout. It is an interior which will be a joy to inhabit.
The Rig
As can be seen in the Larger Sail Plan
image, we have used a medium to high aspect modern
junk schooner rig in order to maximize sailing performance. Both fore and
main sails are geometrically exactly the same. The junk sails are cut
flat, and span between top yard and boom. There are four intermediate
battens as well, which lend excellent support to the sail. A brief
list of some key advantages of this rig are;
- The battens prevent flutter at the luff and leech
- The weight and stiffness of the battens make reefing extremely easy,
panel by panel
- The battens - and the whole sail - extend forward of the masts,
helping to counter-balance the sail in the event of a gybe
- The boom, and each batten, are controlled by "sheetlets" that are
set forward of the leech, thus the forces on the sail are extremely well
distributed.
- Being cut flat, there is relatively less heeling force generated per
given wind pressure
And the disadvantages...? There are not many. Windward
performance is generally considered to be on par with other rigs of similar
aspect ratio and hull form. Performance on other points of sail is
often better, a side-benefit of the rig being so easy to handle.
The rig is
heavier than a standard gaff or Bermuda rig of the same sail area (but not
by much). The sails are heavier, and that is one of the reasons they
are so easily reefed, but they require a greater mechanical advantage to
raise. Given that raising sail is an act performed in favorable
conditions, and reefing typically is not... in my view this rig definitely
has its priorities straight!
More can be read about the advantages of the
Chinese junk rig by following the links provided below.
Electrics & Propulsion
We have provided very ample power for motoring via a 16kw permanent magnet 144v DC
electric motor made by the grand master of electric propulsion technology, David Tether at Electric Marine Propulsion. The EMP motor we've chosen has the capability
to re-charge the battery bank whilst sailing, very much as with a hybrid
automobile which re-charges while braking or coasting down hill.
The motor and the electrical system are entirely designed and supplied by Electric Marine Propulsion. Dave Tether really know his stuff when it comes to electric propulsion,
having designed the motors as well as the entire control, power supply, and
battery charging systems as an integrated approach.
We have provided sufficient diesel fuel for long range motoring, or
virtually unlimited range while motor sailing (in combination with
re-gen). You will find more information about the excellent advantages
of motor sailing by following one or more of the links given below.
For intensive periods spent motoring, a
22kw permanent magnet 144v DC generator provides power to the 144v DC propulsion battery bank. This generator is provided also by EMP, and makes use of a Perkins
diesel... thus quick and easy parts and service availability.
The rationale for use of a DC generator is that the propulsion and
house electrical loads can be served easily by a variable speed
generator. That's right... the generator need not scream along at
full speed when the loads are light. Instead, the gen can adapt
its speed to the load being demanded. The benefit here is that
the diesel is always fully loaded...!
For shore power, we have specified a large 144v DC battery
charger / isolation transformer (an EMP component), which is able to
receive 50hz or 60 hz, and from 110v to 240v AC current - much like the
power pack for your laptop computer... The advantage of this
arrangement is that there need be only one shore power inlet, which is
completely shore power agnostic with regard to frequency and voltage -
allowing the vessel to plug in anywhere in the world without any
worries about power compatibility.
House 12v DC demands are provided via the 12v DC house
battery bank. The house batteries will be charged by solar
panels, and also via a cross charger from the 144v DC battery bank and
/ or 144c DC generator. House AC demands are provided by an
inverter in order to create 60hz 110v AC from the 12v DC house bank.
One might imagine that electric power on an aluminum boat is asking for
trouble... Due to the prevalence of improperly wired marina
power systems and faulty wiring or incorrect wiring practices onboard other
vessels which may end up in a nearby slip, we have the benefit of an
extraordinarily well integrated electrical system design which assures that
the electrical system is able to remain entirely isolated from the hull.
A
further benefit of this approach is that there is no connection
whatever between the shore side AC power and the onboard AC system, nor
to the onboard DC system. In other words, shore power (110v to
240v AC) is converted to 144v DC in order to charge the
batteries. A cross-charger also provides charging to the
12v DC house bank. Power from the 12v DC house bank then provides
onboard AC power via an inverter.
By this means the endless
arguments regarding how one should properly connect the shore power AC to
the onboard AC are entirely side-stepped... there is no connection at
all...!
Whilst disconnected from shore power, the 144v DC charger is
energized by either the generator, or by re-gen from the propeller and
electric motor. The 12v DC cross charger is energized either by
solar panels, or by the 144v DC side. All the electrical
components required to interface to shore power and to the generator
are designed by and directly supplied by Electric Marine Propulsion -
extending all the way to the breaker panels and the electric
motors.
This is an unusual, but also a highly integrated approach - one which is
extremely successful.
Summary
The best introduction
to this design is to have a look at the layout drawings linked at the
top of this page. Please also check out the 'Perspective' image
links above which provide a three dimension look at the shape of this
design. For the most complete review of the Jasmine 48 design, we recommend that you obtain Study Plans or Estimating Plans. Please see our
Plans List page for plans cost and ordering information.
For a brief introduction to the benefits of the junk rig, please see our
Junk Rig
web page. For more information about various rig choices, plus some
background information about the rationale behind the schooner rig,
please see our Sail Rig web page. For an overview of the benefits of motor sailing, please review our
Ideal Motor Sailor web page.
If you'd like to know more about the Jasmine 48, please inquire.
