Messing about in boats since 1975. Online Since 1997.
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The 60' Sailing Catamaran Variants
"The GREYHAWK Series"
GREYHAWK-II - Click for Larger Image
Above Aft | Side View | Above Forward | Above Side
Copyright 2014 Michael Kasten
GENERAL CONCEPT
The GREYHAWK 60 Series is a prototype aluminum sailing cat intended for voyaging, with sufficient space for a family of four to six, plus enough room for guests. I have shown three preliminary cabin configurations in the images and links here, and certainly many other cabin arrangements are possible.
The GREYHAWK-I model has the house located fairly far aft. Since a sailing catamaran does not need ballast for stability, and ideally will not have any for the sake of performance, this prototoype will benefit from having the engine room and house batteries located forward of amidships, primarily in order to offset the weight of the aft house without requiring trimming ballast.
GREYHAWK-I - Click for Larger Image
Above Aft | Side View | Above Forward | Aft View
The GREYHAWK-II (top and bottom of page) and GREYHAWK-III (below) models have the house located much farther forward, and would likely be able to avoid trimming ballast if long term provisions and the house batteries are placed forward of the sleeping cabins.
INTERIOR LAYOUT
The accommodation plan is intended to be similar in all three versions, with the exception being that the GH-I model would have the Engine Room forward, and a long shaft to the propeller. The GH-I also has a more upright transom and short stairway to the swim platform.
An inside helm and chart / electronics area is planned on center forward in the house. Just forward of that is an exterior open-air cockpit, where a second helm could be located for fair weather sailing or just for "hanging out" and enjoying the sun.
Although I have not shown a flying bridge on any of these concpet designs, there could easily be a pair of elevated steering stations located at the aft corners of the house, peeking out over the top of the house, one on each side. This would intrude the least on the accommodations and the aft deck, and would allow a low overall profile to be retained (as opposed to having a full size flying bridge above the house).
The house will contain a large galley to port aft and wrap-around settee to starb'd aft. Sliding doors on center will lead out to the covered aft deck. Forward of the galley / settee will be two companionways on each side leading below into each hull where there will be two sleeping cabins in each hull, one forward and one aft. Each of the sleeping cabins will each have a head, walk-through closet / dressing area, and a double berth at the end. Alternately one or more cabins could be arranged with twin bunks, or one or more cabins could become a workshop / studio / office according to preference.
Forward of each cabin will be a watertight bulkhead, and beyond that a large forepeak for storage, accessed from on deck. Farther forward will be another WT bulkhead and smaller storage area for light weight fenders and the like.
The engine room in the GH-II (top and bottom of page) and GH-III (below) will be located aft of the sleeping cabins in each hull, and will make use of V-drives. Aft of the engine room in each hull will be a lazarette containing the steering rams and light weight storage. Each hull has a gently sloping stairway, providing easy access and a great place to hang out near the water.
GREYHAWK-III - Click for Larger Image
Above Aft | Side View | Above Fwd | Side Fwd | Aft ViewHULL FORM
Preliminary dimensions of the GREYHAWK 60 Series are as follows:
- LOA 60 ft
- LWL 58 ft
- Beam 31 ft
- WL Beam 6 ft per hull
- Immersed depth 4.5 ft
- Displacement 48,000 lb
- Hull Prismatic .57
- Slenderness Ratio: 9.7
The hull bottom is V shaped with a rounded 'free form' radius chine. In aluminum this is an easy shape to build and provides the advantage of being a sea-kindly hull type especially when sailing to windward in waves.
If long range voyaging were planned, displacement would be increased for the sake of being able to carry a greater load of fuel, water, stores and accumulated 'stuff'. This would be accomplished by deepening and widening each hull to have a WL beam of around 7.25 feet. In that configuration, displacement would be around 60,000 lb or a bit more, and overall beam would be around 32.5 feet.
While the added WL beam and displacement are not considered optimum for high speed sailing, if the slenderness ratio is kept to no less than around 8 there should still be some fast sailing to be had...!
SAIL RIG
The rig ordinarily specified for sailing cats is a high aspect fractional sloop rig. It is deemed the most efficient rig to windward, and the tall mast can be well-stayed on a cat. Ideally the sails will be battened in order have a generous roach and somewhat elliptical profile.
For voyaging, a ketch rig of more modest height would be an option worth considering, and would provide the advantage of allowing more sail area with a lower center of effort, a mainsail of more modest proportions for ease of handling, and much less stress on the rig.
VARIANTS...?
As with any prototype design, the GREYHAWK 60 Series can be enlarged or made smaller to suit one's preferences. For long range voyaging, more displacement would be in order with wider and deeper individual hulls. In any of the above configurations, the keel can be varied, or eliminated in favor of centerboards or dagger boards. We have shown low aspect ratio keels in the above models for the sake of being able to track well, to protect the hull itself on a shoal, and to dry out at low tide without any drama for walking ashore and for easy bottom cleaning..!
GREYHAWK-II - Click for Larger Image
Above Aft | Side View | Above Forward | Above SideFor more information please inquire.
Please see the AVAILABLE BOAT PLANS web page.
Home | Intro | Our Design Process | Stock Design Info | Motor Yacht Designs | Sailing Yacht Designs | Prototype Designs
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