Sagittarius 60
A 60' (18 Meter) Enlarged Yacht Version of a Colin Archer Redningsskoite

Lines by Colin Archer with Slightly Adjusted Sheer for Better Appearance in 3D
Concept, Construction Scantlings, Accommodations Layout, and Supervision by Thomas A. MacNaughton
Drafting and Renderings by Michael Chudy

Put Picture of Accommodations Drawing Here.
Family voyaging with crew for those with substantial resources to devote to the lifestyle.  With a different interior she could also be a school ship or passenger carrying vessel. This is just one possibility, intended for a client, his children, and their nanny or governess, to cruise and perhaps voyage with the help of paid crew.

We have always loved the Colin Archer types, and have been very amused at how many people have not understood that the original Redningsskoites, which were very powerful vessels designed to sail only in the winter, were vastly underrigged for summer sailing or cruising.  Therefore somehow people have thought that these vessels were inherently slow.  Nothing could be further from the truth.  These are very powerful, extremely seaworthy vessels which sail well and fast in everything from light winds to incredibly heavy weather if they have plenty of sail area in an easily reefed rig, which the originals did not need.  We were all extremely please to get an opportunity to design a Colin Archer type vessel.

In the night sky "Sagittarius" is the constellation known as The Archer.  This constellation is represented as an centaur with a bow and arrow.  This fusion of man and horse seems a good reflection of the ideal union between the vessel and her crew.  I think there is good potential for this sort of union with a vessel like Sagittarius.  My brother's Colin Archer derived ketch is about half this length.  Her original owner loved her so much that he kept her the entire rest of his life, over 60 years.

This vessel was originally designed for a gentleman and his two children, with additional accommodations for guests and a professional crew.  She was intended to be of straight forward, simple, yacht finish in general arrangement, although she did end up with more complex equipment aboard than we personally would use.  A teak overlay on the wood and epoxy deck is specified and all the hardware so far as possible is bronze.  In addition to family cruising she was intended to be used for businessmen's fishing and scuba diving trips.  She is intended to be an excellent performer under sail and has a full power auxiliary capable of pushing her at hull speed with a 1/3 power reserve.

From forward in the interior there are two large chain lockers with grates in the bottom with mud pans under them.  Aft of these there is a a double cabin for the crew with its own hatch to the deck and a very small head, with a wash basin in the cabin itself.  The bulkhead aft of this is watertight.  The master stateroom is just aft of this bulkhead and contains large lockers, two large settees, a sizable office area with library, a double berth and a gun rack.  It has its own en suite head with a small tub and shower. Across from the en suite head aft of the master stateroom is a large head with a large tub and shower for use of those who may be sleeping in the guest cabin or in the main cabin.  Aft of these heads there is a large dining area to port for at sea or in port entertaining and sit down meals.  One of the settees here is suitable for sleeping on.  There is also a very large freezer and a washer drier.  To starboard is a sizable double guest cabin with lockers a small desk and its own library.

Aft of the main cabin is the engine room which is quite large and has a water tight bulkhead at both ends.  It has seating around the engine and has a workbench for the engineer.  The fuel tanks and all plumbing for them are contained in the engine room as is an additional refrigeration unit, a hot water heater, air-conditioning and heating equipment, a generator, etc.  Above in the wheelhouse there is a large inside steering station with a chart table area to starboard of the wheel, seating for the watch just aft of the wheel, and then on the port side a large galley area with a double sink and a oil fired cooking range.  To starboard there is a large dinette area where the whole crew can gather when not under way and they wish to look out at the harbor and passing boats while eating or relaxing.  We would interject here that if someone were building this vessel entirely for voyaging we would prefer a smaller wheelhouse with all galley and dining areas down below.  When living aboard and voyaging, too much light and visual reminder of motion can be very tiring for both cook and crew at meal times.  Retiring below to a dimmer light and the comforting limits of the cabin is much more restful.

Aft of the wheelhouse there is an aft cabin with two berths and its own head with small tub and shower.  This was originally intended for children, which is most people's thought for an aft cabin.  However we have found that many people, as their children get older and may want to entertain young people from other yachts, will often make this their in port stateroom.  In the case of people who may be operating this vessel to carry passengers, this may be a good place for the couple running the vessel to get some separation from their paying guests.

Aside from the wheelhouse the vessel is entirely flush decked except for the raised hatch coamings.  Instead of a cockpit, which we regard as dangerously easy to fall into, especially on a boat this size there is  very comfortable deck box seating in the helm area.  The windlass should be capable of manual operation but will normally use hydraulics for everyday operation.  Steering is via conventional Edson cable steering systems to retain good "feel" under sail.  You will note that we have shown a very low toerail under the bulwark with a gap above it to let water off the deck immediately.  The low toerail keeps pens, screwdrivers, etc. from rolling overboard under the bulwark.  The bulwarks are supported by bronze knees.

The rig is a Marconi cutter.  The first "reef" will normally be to bring the headsail inboard, which is done from the deck.  You then have an all inboard rig from then on and no one need ever go out on the bowsprit.

Construction was to owner's preference and consists of stip planking, lightly sheathed on the outside with glass cloth and epoxy for neglect resistance, over laminated ring frames.

Years ago in the process of saving and partially restoring one of the most famous of the original Colin Archer Redningsskoites, we acquired a copy of the original lines drawing, done by Colin Archer's own hand.  Sagittarius's lines have been carefully reproduced and scaled up slightly, from those of this fabulously seaworthy and historic vessel.  We were given carte blanche to "improve" the lines wherever we were sure that there had been improvements in our knowledge over the years. 

Periodically people have decided to "improve" these lines.  I, myself, though tremendously impressed with these vessels, felt the need to very carefully analyze everything about the vessel on the theory that I should be able, after more than a century, to make at least some improvement.  So when this project came up I dug into these lines in great detail.  I put the original lines into the computer and carefully faired them.  I applied my own analysis techniques.  I also compared her to Marchaj's analysis of the factors going into making up a seaworthy vessel (see "Seaworthiness - The Forgotten Factor).  Finally I came to the conclusion that if I was only going to change things where I was sure I could make an improvement there was nothing in the lines themselves to change.

We did refine the sheer.  In the days of drawing lines entirely on flat sheets of paper, it was difficult to draw a beautiful three dimensional sheer on a two dimensional surface.  You did your best but the illusions of three dimensions often produced some un-anticipated angle at which a sheer looked too flat or lumpy.  A truly well drawn sheer tends to look a little exaggerated on paper and a sheer that looks good on paper tends to look too flat in three dimensions.  We avoided these problems in Sagittarius by keeping the sheer height the same at bow and stern and almost exactly the same height and position for the lowest point of the sheer as Colin Archer's lines called for.  Then we constructed a plane which passed through those three points and projected the plan view of Colin Archer's sheer line onto that plane.  This guarantees that the sheer, though very close to that of Mr. Archer, avoids some serious optical illusions which greatly improves her appearance in full perspective.  It is close enough to Archer's original sheer that it is possible that when building from the original lines Mr. Archer simply corrected the sheer, by eye, as he was building  So it may well be that our sheer is closer to what Colin Archer actually built than what he drew.

The particulars for Sagittarius are given below in comparison with the original Colin Archer Redningsskoite:

  Redningsskoite Sagittarius 60
Length on Deck 14.3 meters 18.3 meters
Length on the Waterline 13.23 meters 17.53 meters (includes rudder on this design)
Beam on Deck 4.85 meters 6.42 meters
Beam on the Waterline 4.53 meters 6.00 meters
Draft 2.31 meters 3.06 meters
Volume Displacement 30.8 cubic meters 71.64 cubic meters
Displacement to Length Ratio 380 380
Prismatic Coefficient .54 .54
Center of Buoyancy 6.03m, -.58m 7.98m, -.77m (forward of aft station, and down from LWL)
Wetted Surface Area 67 square meters 117.73 square meters
Working Sail Area 168 square meters 311.6 square meters (working sail)
Sail Area to Wetted Surface Ratio 2.5 (minimum desirable) 2.65 (actual working sail ratio)
Sail Area to Displacement Ratio 17 18.04
Waterplane Area 38.06 square meters 66.82 square meters
Center of Flotation 6.18 meters forward 8.19 meters forward of aft station
Kilograms/Centimeter Immersion   3,311.7 kilograms
Moment to trim 1 Centimeter   500.7 meter kilograms
Scantlings Numeral 10.28 13.6

Stability is increased immensely in Sagittarius over the original Redningkoites not just because larger models of the same hull will be more stable but also because all the ballast is placed outside, and the hull construction, though as strong as the original, is somewhat lighter.  Because she has more stability she can carry a lot more sail area.  Even if sailed in winter like the originals she could have more sail area.  With the sail area we have shown she will have good performance even in the lightest winds.  Given the hollow aluminum spars and lack off gaffs, this larger rig weighs less than 1/4 the weight of the original rig.  This further increases stability and also further increases the amount of ballast that can go on keel.

Under this rig the power of this moderately heavy, deep, beamy vessel will be extraordinary in any conditions.  This is one of those vessels which is so powerful under sail that she could actually make reasonably comfortable open ocean passages to windward.

Contrary to popular belief heavy displacement vessels like Sagittarius have a natural advantage of low wetted surface relative to their sail carrying power.  This is because of the shorter girth measurements resulting from the deeper bodied sections and heavily filled in hollow garboards.  Therefore heavy vessels don't require the severely cutaway profiles that lighter vessels need to keep the wetted surface down.  This relatively low wetted surface, added to the tremendous sail carrying power derived from her great initial and ultimate stability, means that she carries enough sail so that even just the main and staysail will allow her to perform well in moderate winds.  Therefore, unlike the gaff rigged originals, the bowsprit has a somewhat different function.  It is less a support for the working sail than it is a support for light sails.  Just as many of today's boats that are heavily influenced by today's racers tend, because of rule changes, to have abandoned conventional spinnaker poles in favor of bowsprits from which all sorts of downwind, reaching, and light wind sails can be set, on Sagittarius we will use the bowsprit primarily to set a very light drifter, cut like a genoa, but made out of spinnaker cloth.  This will be set flying and can be taken in when the wind picks up by pulling a release that lets the tack go so that the drifter comes back into the lee of the other sails and can be retrieved easily simply by pulling in the sheet while slacking the halyard.  Alternately you can pull the tack back to the stemhead and use downhauls and brailing lines to bundle it into a ball which can be stowed in a sail bag.  This very large sail can be carried in fairly strong winds, yet is light enough to be taken in easily at any time.  When the drifter is taken in you are left with an all inboard, all self-tending rig.  Since the tack of the drifter is drawn in to the stem head or out to the end of the bowsprit by lines, there is no need for anyone to go out on the bowsprit at any time.  When beating to windward in dusty going the only action needed to tack ship is to put the helm over.  No tending of sheets is necessary.

Complete Plans

Profile & Rig
Construction and Accommodations (Inboard Profile & Plan View with Midsection)
Sections & Opposite Profile (Inboard Profile of Starboard Side & Sections)
Chainplates & Rigging Details #1
Chainplates & Rigging Details #2
Chainplates & Rigging Details #3
Control Station and Forward Hatch & Cleats and Handrails Drawing
Yacht Joinerwork Details #1
Yacht Joinerwork Details #2
Typical Workboat Interior Joinerwork Details
Salon Table
Chocks & Lever Windlass (lever windlass not applicable to this design)& Pulpits and Stanchions
Watertight Door

Study Book

The Study Book consists of an article on the design and pdf based drawings of the the Profile and Rig, plus the Construction and Accommodations Inboard Profile & Plan View.

Study Plans $66
Complete Building Plans $733

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