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32' Skipjack Schooner
Starb'd Aft View | Portside Fwd View | Starb'd Fwd ViewCopyright 2014 Michael Kasten
General Concept
The request in this case was to design a fast, light, trailerable schooner, no larger than 32 feet on deck, no wider than 8'-6" and as shoal draft as possible, ideally less than 3 feet, but also capable of blue water ocean sailing... An additional requirement was that it should be easy to build, ideally in aluminum alloy. Oh, and it must be able to sleep four in comfort, five in a pinch, have a pilot house, and be fast under power...
Well, thankfully there was not a requirement for 7 feet of headroom...!!
The starting point was to come up with a salty, classic looking, larger replacement for the now discontinued Macgregor 26. Needless to say, the Macgregor is quite a different vessel than the design we have created here..! Two strong requirements were that the client did not want a tupperware boat, and he wanted retro / traditional styling... the concept being to develop a design for his own use, but which could easily be put into production should the concept prove to be of interest to investors, and of course, to the market.
With those goals in mind, and trying to avoid any similarity whatsoever to the Macgregor except for the concept of ending up with a fast trailerable sailboat, it became a matter of trying to imagine what would satisfy all of the requirements...
It seemed that the V-bottom Skipjack types might be a good paradigm, so that's where I started. Of course the original Skipjack types were very wide, very shallow, did not have much freeboard, and were not designed for ocean sailing... but what that vessel type did offer was classic styling in a chine hull form, as well as shoal draft and a very simple shape to build.
Hull Form
Dockside wags may well ask, "Why did you bother fooling around with a dowdy old-fashioned sailing type, and one that was not even intended for open ocean sailing...?"
- First: I wanted to start with a traditional type that could be easily built in aluminum (or any other flat sheet material) thus having a single chine hull shape for ease of construction. The Skipjack is perhaps the ultimate in terms of being an aesthetically refined traditional sailing vessel which has always had a single chine hull shape. No one argues with the shape, since these vessels have never been otherwise.
- Second: I was told in no uncertain terms by another Naval Architect that a Skipjack would never be safe as a yacht that was intended to venture offshore... Well of course with the original flat, wide, shoal-body, low-freeboard Skipjack form - I agree totally! But never say never..!
Naturally I took exception to the claim that the Skipjack type could not be adapted to being a safe and seaworthy yacht... The overall benefit of the Skipjack shape is its highly refined traditional aesthetics, combined with an economically built and easily driven hull form.
So, I decided to develop one that could sail in the open ocean, and still preserve the aesthetic character and general shape of the original Skipjack types. Thus, as the result of the implied 'bet' that I could not, I developed the 50' to 70' Skipjack concept design, and the 100' Bermuda rigged Skipjack concept, both of which contributed greatly to this much smaller version.
Inevitably comes the question then... 'Isn't a rounded hull faster..?'
We answer this question the same way every time: A single chine shape has slightly more wetted surface, therefore more sail area is provided, making it the equal of a rounded hull in light airs. In section, the single chine shape has just a bit more 'shoulder' below the waterline which allows the boat to carry that extra sail area without penalty in terms of heel. At speed, in particular when surfing down wind, the chine shape is actually faster due to being able to develop substantially greater dynamic lift.
The single chine shape has other advantages... Primarily it is quite simple to build, and therefore requires considerably less labor and effort to build. If thought of in terms of "boat speed per dollar" it becomes obvious that one can afford to make a single chine vessel longer than one could afford to do with a rounded or multi-chine hull form, thereby realizing very real performance gains...!
Seaworthiness...?
Is the resulting design shown here faithful to the aesthetic of the original Skipjack types...? Yes, to a large extent, however in order to become a good yacht this design has included the following changes:
- The modified Skipjack shown here is much less wide in proportion to its overall length;
- The V-bottom hull body has been made deeper;
- The topsides have been given quite a bit more freeboard, especially amidships in way of the cabin house, which extends the full width of the ship.
The additional freeboard was accomplished without aesthetic penalty by raising the deck up to the height of the rather substantial bulwarks characteristic of the original Skipjack types, and then introducing a modest bulwark and house side above that.
In order to verify the seaworthiness of these modified Skipjack designs I calculated the hydrostatics according to the rather rigorous criteria of the EU-RCD, specifically the STIX criterion as outlined in ISO-12217. The result...? Provided that the VCG is located as I have intended, the Skipjack model shown here and in the above links achieves a STIX score well within Category A, i.e. all ocean.
Further, the McCurdy Stability Index is 1.58, well within the preferred limit of 2.0 max, and the Motion Comfort Index is 32, well above the norm for boats of this size.
Particulars
Dimensions and weights of this design are as follows:
- 32' Length on Deck
- 27' Design Waterline
- 8.5' Overall Beam
- 2.6' Draft - boards up
- 4' Maximum Draft - boards down
- 10,000 Pounds Displacement in the Light Load condition
- 225 Displacement to Length Ratio
- 475 sq. ft. Sail Area Target
Due to having light displacement to length, sailing speed should exceed 8 knots in the right conditions.
Construction
Even though quite shallow, the long straight keel provides the ultimate in tracking at sea. This combination is the very best at avoiding being tripped by a sea, and will therefore lie ahull safely.
In aluminum, the keel box is hollow and can conveniently contain the ballast, essentially located as though it were "external" ballast. For the sake of improved windward sailing, a centerboard could be used in order to provide additional 'bite' to windward. However in this case, we did not want the intrusion of the centerboard box in the midst of the cabin, and we did not want to have a CB trunk to pick up stones on the beach and the associated maintenance hassle of having a difficult to access recess in the hull...
What then...? We looked toward Holland for a solution, and we've decided to use leeboards. With the bulwark / cabin sides having substantial tumblehome, we can mount the leeboards onto the cabin sides and they will be canted to just the right angle for sailing.
If such extreme shoal draft were not a requirement, naturally the keel could be shaped differently and the ballast lowered further. This would not necessarily make the keel deeper overall, it would just become level on the bottom, but still raked back at the forward end. In other words, starting aft, the keel could remain at the full depth of the rudder heel for approximately 2/3 of the keel length, and then would slope upward to the depth of the stem forward.
Sailing Rig
With a relatively narrow and shoal draft hull form, the rig should be kept rather low-aspect, but it need not be shy on sail area. A gaff schooner rig was another request, and it fits the requirement of being low aspect, but of generous sail area admirably. In order to make good use of modern materials and to reduce labor and hardware costs, the spars will be fabricated using welded aluminum pipe. The sail materials are to be Dacron, and a performance oriented sail cut is intended to be used.
Interior Layout
Although I did not bother to model a pilot house as yet, it can easily be added. The layout that will work best is as follows, starting forward:
- Forward is a forepeak for anchor gear and other goodies
- Just aft of the forward bulkhead is a large wrap-around settee with table mounted on the foremast
- Aft of the settee is the galley, both sides
- Aft of the galley is the head to port and shower / washroom to starb’d
- Aft of the head / shower is a pair of quarter berths which tuck under the bridge deck
- A pilot house could sit above the middle of the quarter berths, and spill onto the aft deck some
- Between the quarter berths and below the bridge deck is the perfect spot for a lightweight diesel
- Maximum interior headroom is 5 feet...! The galley and other locations are arranged so they can easily be tended while seated.
- On the aft deck is a large cockpit, aft of which a flush hatch can provide good lazarette access
- Steering is by tiller or by wheel, or both
- Leeboards are assumed
A layout that is quite similar is that of the 36' Ketch GRACE. Differences are that the forward wrap-around settee in the 32' Skipjack would end at the forward end of Grace's cabin as shown in that drawing. Otherwise it would be essentially the same as the Grace.
Click for Larger ImageSummary
Overall, this is precisely how the US working sailors of yore would have adapted such a vessel to a new purpose - that of a safe, easily built ocean sailing craft. Then, whether it is an "exact" replica of a fat old oyster boat... no one will care. Nor for that matter will anyone even notice...! For an understanding of the rationale being applied here, please see our article on New Materials vs Classic Yacht Design.
Classic styling, seaworthiness, ruggedness, fast cruising, windward ability, simplicity of construction, a reasonable cost to build and maintain... these have been the primary goals of this design. In my view, each of those goals has been superbly met.
For more information, please inquire.
Please see the AVAILABLE BOAT PLANS web page.
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