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65' Ketch 'Rachel'

A Fast Blue Water Sailing Yacht in Aluminum

Copyright 2008 - 2016 Michael Kasten

65' Aluminum Ketch 'Rachel'
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Rachel Aft Perspective | Rachel Far Aft Perspective | Rachel Forward Perspective
Rachel Side Perspective | Proposed Ketch Sail Plan
 

The Concept

The 'Rachel 65' has been developed as a variation of our 96' Zebulun design. In keeping with the names given to the other vessels in this series, the Zebulun, the 50' Sarah, the 112' Leah and the 120' Leah II, this design has been named for another member of that family, Jacob's first true love, Rachel, Leah's sister.

Planned for fast ocean voyaging, the Rachel 65 design is configured with a single skeg hung rudder and a single fin keel with ballast bulb. The purpose of the bulb is to concentrate the ballast, as well as to provide an 'end-plate' effect for the fin keel, which allows a relatively shallower keel having the same effective aspect ratio as a keel of greater depth. The skeg hung rudder in combination with this kind of keel will provide excellent windward ability and accurate tracking at sea.

The hull shape is planned for easy construction in Aluminum, including deck and house structures. The radius chine shape is easy to plate, with the majority of the surfaces using flat panel material. If steel were to be considered, it would only require an increase in beam and hull depth in order to achieve sufficient displacement to carry the structure.

As shown, the aluminum version has a beam of around 16.5 feet; a draft of around 7.5 feet to the DWL; and a waterline of 59.25 feet. Displacement is around 75,000 pounds in the light condition. Beam, draft and other dimensions are very much a variable until an actual interior is planned; structure is determined; equipment is specified; the rig detailed; and all weights have been calculated.
 

The Hull Shape

Many fast cruising designs tend to mimic all-0ut racing sleds rather than wholesome cruising yachts.  For example, the older IOR racing types are well known for poor handling, in particular when off the wind.  And as the Fastnet tragedy has amply shown us, neither are they safe in heavy weather.  As a contrast to the older IOR racing types and their 'cruising boat' counterparts, the Rachel 65 is not overly fat in the middle... 

These days, the trend is toward extreme wedge shapes in plan view, resulting in a sharp entry and a very wide stern.  Contrary to those so-called "cruising" yachts, a significant feature of the Rachel 65 is that the stern is not too wide.   Allow me to explain...

On sailboats with an overly wide stern, the water-plane outline (looking down at the heeled water plane) will move off-center to leeward in the aft part of the boat, whilst remaining more or less on center forward. This effectively moves the heeled centerline to leeward in the aft portion, and therefore out of parallel with the upright centerline.  The heeled CL is thereby canted to windward causing excessive weather helm.  This can be tolerated to a small extent, however if the CL moves out of parallel by very much there will be excessive yaw when rolling under power, and excessive weather helm under sail.  As insult to injury, the stern at the centerline will be lifted and the bow will be depressed.

With a very wide stern, a centerline rudder would be lifted too far out of the water to be effective, exactly at the moment when it is desperately needed to maintain control due to the excessive yaw induced by the wide stern…  This is the very reason why modern racing sleds and the so-called "cruising boats" that emulate them must make use of twin rudders…!   This is not at all conducive to steady course keeping, nor is it safe... The person at the helm must remain extremely vigilant and fatigue becomes a very real issue.  In heavy conditions these factors can quickly get out of control and readily induce broaching.  A broach can even result in less severe weather conditions when carrying a spinnaker.

Far better is to have a balanced WL shape, both upright and when heeled.  In other words, the WL outline should not be excessively wedge shaped.  In general, the transom width should be no more than half the overall beam.  Narrower yet is even better.  This will keep the aft portion of the WL shape from being lifted, and from being shifted so far to leeward when heeled.  Here, the CL will not become out of parallel by much when heeled.  The result is that the vessel will have much greater directional stability, whether heeled or just simply rolling… 

In addition to having a more balanced WL outline, the Rachel 65 also has a modest counter stern, i.e. a slight overhang.  In other words, the hull bottom extends beyond the end of the upright WL.  A modest counter stern allows the heeled the effective WL to lengthen, providing greater speed potential.  The transom is not a true "sugar scoop" and quite intentionally so.  Instead, most of the transom is enclosed.  This is for the sake of added reserve buoyancy, and to deny a boarding sea the ability to depress the stern.

Combined, these features provide the greatest speed under sail, the best balance when heeled or when rolling, less fatigue at the helm, far less tendency to broach, and much greater peace of mind for safe blue water sailing.
  

The Interior

A variety of interiors are possible, however at 65' the interior is able to greatly expand upon the interior planned for the Sarah 50.

The layout for the Rachel 65 is planned to be as follows:

The reason to locate the galley and nav station aft in the Pilot House is that they require more width to the cabin sole, the space for which would not be missed all that much if taken from the overhead in the engine room, but definitely would be missed if it were to encroach on the twin staterooms below. 

That layout would provide the flexibility for chartering, as well as for family ownership, say for a couple and two children.  In charter mode, the owners and children would move into the aft cabins so that they could charter out the forward owner’s stateroom and twin forward guest cabins.  When not chartering, the guest cabins would occupied by the children, and the aft staterooms would be used for storage, office space, study area, project room, etc. or even for carrying occasional cargo. 

This concept was quickly done so I’m sure it could be optimized in various ways, but it illustrates approximately the size of vessel that will be required for a family of four on a circumnavigation who also want to occasionally charter the vessel in order to earn their way.  If the boat were made another 3 feet longer, the guest cabin head compartments could become larger, making them a bit more comfortable.  But if those cabins are mainly used as a refuge when chartering, that’s probably not necessary.   

When chartering, the main thing is to make the guests comfortable.  In this case they would be sharing the forward head and wash-room, but everyone would also have access to the day heads in the aft part of the house.  If it were considered important to have en-suite head compartments for the twin guest cabins forward, then the heads could be moved to the forward end of the saloon, with an access door from the centerline hallway as well as from within each of the staterooms.
 

Alternate Interior

An alternate cockpit / pilot house configuration is illustrated in the following images.  In this case, the cockpit is slightly larger, the pilot house shorter, and the transom differently configured.  Additionally, since this vessel is much larger than the Sarah 50, it is possible to have a pair of identical head compartments just aft of the forward owner's stateroom, with each of them having access from the owner's stateroom as well as from the guest cabins.  In this case, the saloon would be much larger, and there would not be any staterooms below the pilot house sole - that region being reserved for the engine room and machinery.  

In this alternate layout, there is a third possibility which would be to use the entire "lazarette" space for a second "owner's cabin" complete with en-suite head and shower, in which case the boat would be ideal for two couples and four children, or two couples plus guests.  There are many options...!

Alternate Interior Perspective Port | Alternate Interior Perspective Starb'd
 

The Rig

For this size vessel, the ketch rig is ideal.  As proposed, the rig would be configured as shown in the Proposed Ketch Sail Plan. Another rig possibility would be a two mast schooner, much like the rig of Zebulun - minus one mast...!

It is ordinarily preferable to place the masts according to what works best for the interior, rather than according to some pedantic notion as to their 'perfect spot'.   For this model, if it were a ketch the main mast would be close to the middle of the forward head / bath, with the mizzen somewhere near the aft end of the pilot house. If it were a schooner with approximately equal fore and main sail sizes, the fore mast would be at the aft end of the forward stateroom and the main mast at the aft end of the saloon - more or less at the forward end of the pilot house windows.
 

Summary

As described, the interior fits nicely into a length of 65' overall.  In all, I think this would be an ideal platform for a couple with two older kids, a couple with four kids, or for a couple to charter using the three forward cabins for charter guests, taking refuge in the aft cabins while chartering....
 

Other Designs in This Series:

45' - 60' Zeb | 46' Dinah50' Sarah | 65' Rachel | 96' Zebulun | 118' Leah  |  120' Leah - II
 

65' Fast Aluminum Ketch Rachel - Kasten Marine Design, Inc.
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