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The Tug Yacht
"BOOJUM 25"
Image © 2004 Charles Vollum
Boojum Profile | Boojum Interior | Boojum Sections | Boojum Stack Detail
Side PERSPECTIVE | Side Above PERSPECTIVEBoojum...?
Many may wonder where the name "Boojum" comes from... It is from Lewis Carroll's Hunting of the Snark...
"He remarked to me then," said that mildest of men,
"If your Snark be a Snark, that is right.
Fetch it home by all means -- you may serve it with greens,
And it's handy for striking a light."But oh, beamish nephew, beware of the day,
If your Snark be a Boojum! For then
You will softly and suddenly vanish away,
And never be met with again!"
General Concept
The original design requirement was, "It's got to be cute!"
Along with that, the intent of the design has been to create the smallest possible trailerable pocket 'trawler yacht' capable of long range offshore voyages, whether sailed handed, as a couple, or with an occasional guest.
Particulars are: 25' LOA x 22.5' DWL x 8' 6" Beam x 3' 9" Loaded Draft. Displacement will vary from around 13,500# to a full load capacity of 17,500# with all tanks full, and the boat ready for a long voyage, complete with stores for two people. Boojum's extreme load case is around 18,500#.
Range is in excess of 2,600 NM at S/L 1.15 in order to permit trans-Pacific voyages. Slowing down will offer greater range, as usual. The ideal engine will be in the range of around 35 hp at its M-1 continuous rating. Sabb Motor of Bergen Norway supplies an excellent engine, the Lister Alpha, mated to the Sabb HVP 15 gear and CP propeller.
Hull and pilot house construction are aluminum. Portlights are glass. Pilothouse windows and portlights are Lexan except for the center forward window which is glass to permit a wiper. The pilot house top is cold molded wood for lightness and for ease of mounting hardware.
Hull Form
Boojum's hull is modeled after working tugs, in order to get the largest carrying capacity within the smallest overall length, therefore the plumb stem, etc. Boojum's hull has been optimized for ocean conditions and for the boat's anticipated speed / length range. Beam has been limited to 8' 6" to allow trailering without being a "wide load." Deck structures have been kept as low as possible to provide for a low center of gravity, and also to permit trailering on the US freeway system. Still there is full standing headroom for the owner (who is over 6 feet tall) in the pilot house, a queen size berth aft, and a full size settee forward...!
Boojum is configured with twin keels. Some will refer to these as "bilge keels" however in our judgment that is a minor semantic point. In common usage, the term 'bilge keels' most often refers to long shallow appendages akin to 'rolling chocks' put onto fishing vessels to ease the motion.
Within each of Boojum's twin keels is 1,200 lb. lead ballast, for a total of 2,400 lb. The twin keels provide excellent roll dampening. They also provide lift for windward sailing under "auxiliary sail power." Due to their roll dampening ability, the twin keel configuration offers improved comfort at sea - especially welcome on a vessel of this size...! The combination of external ballast and the vessel's hull form offer an exceptional range of positive stability. In fact, the vessel is fully self righting, there being no negative region of the stability curve.
The twin keels have other functions, too: They are used as "wing" fuel tanks, and also as mud legs, allowing Boojum to sit comfortably on the hard in a harbor that gets emptied by extreme tides, and to be easily hauled up on a trailer. A "dive-ladder" is placed to starboard for boarding from the water, or from land while aground.
For more information on the rationale behind Boojum's twin keel configuration, check out the article Boojum's Twin Keels. For general information on the benefits of twin keels for power vessels, see the article on Roll Attenuation.
Please also have a look at Boojum's larger sister, the Boojum 30, more or less the same vessel with just enough added length to allow a bit more "elbow room" in the pilot house, the engine space, and aft cabin... The Boojum 30, while planned for a single centerline keel, could just as easily be planned for bilge keels. It is only a matter of preference. Yet another similar tug yacht design that makes use of the same interior layout is our prototype design, the Talisker 32, which borrows the wider hull form of the Terrier 32.
Interior Arrangement
The accommodations on Boojum are intended to provide comfortable cruising for two people on extended passages, with the occasional addition of a third crew member for shorter trips.
The layout makes use of a low forward cabin extending from an enclosed head forward, aft to the 'midships wheel house. The forward cabin top extends the full width of the ship for its entire length at the height of the main bulwark top, providing the greatest amount of interior space, the largest open deck area, the greatest forward freeboard, the most reserve buoyancy forward, and the greatest range of stability.
Within the forward cabin is the settee / saloon area, and the head. An overhead sky-light / hatch allows light to enter the saloon, and opens for fresh air and access to anchor and forward mooring lines without having to go outside. This hatch also functions an emergency exit. The settees are very ample for service as guest berths. Water tankage and some storage is provided under the settees.
Within the raised 'midship pilot house, the galley is on the port side, with pilot seat and wheel to starboard. The pilot house offers excellent visibility in all directions. Deck access is via a watertight sliding door to starboard. The door has a fixed window. The pilot seat reclines, allowing a variety of comfortable positions. A small swing-up table is attached to the pilot seat for writing or for using a laptop computer. A "passenger" seat is made to fit the area between the pilot seat and the galley face.
The "dashboard" forward of the wheel holds instruments and engine controls. VHF and SSB radios are mounted near the helm. Some instruments are mounted overhead as needed. Chart stowage is under seats and in back of cushions in the forward compartment.
To port, the galley includes a Wallas diesel range, and a sink with manual and electric pumps for fresh and salt water. There is a refrigerator under the pilot seat (starboard side). A large pilot house window is above the galley sink on the port side. Storage is provided for dishes, flatware, knives and cooking tools, a set of nesting pots and pans, and a small pressure cooker.
A trunk cabin is located aft of the wheel house to house the sleeping quarters, clothing, and library.
The systems aboard Boojum are rather elaborate for such a small boat, even to the point of there being forced air heat throughout! Have a look at the perspective drawing of her heating system as one example!
The ideal pocket trawler...? We think so!
Here are links to several shots of Boojum under construction - and of the completed vessel under way:
Boojum Under Construction | Boojum Painted | Boojum Launched | Boojum Under Sail
Boat Building by Computer...
Designing Boojum was a unique project in many ways, as you can see from her plans and from the above requirements. The design drawings were taken somewhat farther in terms of detail than many larger vessels and also in terms of the arrangements made to build the boat. Owner Charles Vollum elected to have the hull's metal structure thoroughly detailed by computer for NC cutting.
What is NC...? It simply means Numerically Controlled... Boojum was detailed for automated plasma arc cutting so that the frames and plating could be pre-cut and delivered to the builder as a "kit" requiring no lofting and no hull layout, just a grid established on the building floor for assembling the pre-cut parts...
Boojum and many subsequent projects we've done have shown that not only can NC cutting be a highly accurate means of making boat parts, but that it can pay its own way several times over. By this means, we have effected a substantial savings for Boojum in terms of the hours saved during fabrication of the hull / deck / house.
If you're at all interested in the process, please our articles on the NC Boat Building Advantage including the various links provided there to our other NC cutting articles.
Similar Designs and Prototypes in this Tug / Trawler Yacht Series
Tug Types
Boojum 22 | Boojum 25 | Boojum 30
Terrier 32 | Talisker 32 | Nidaros 38
Trawler Types
Sweet Okole 30 | Buster 30 | Boojum 43
Roberta 43 | Roberta Jean 43 | Roberta Jean 47
Far Horizon 40 | Far Horizon 43 | Far Horizon 46 | Far Horizon 50 | Far Horizon 54
Direct Quote from an aluminum boat owner... As an owner since 5 years of an aluminum boat I could not agree more with your preference for this material. She is a great boat and requires very little in the way of maintenance. I do a lot more reef snorkeling than the paint, polish, varnish and wax guys!
--Peter Kminek
Image Copyright 1998
Please see the AVAILABLE BOAT PLANS web page.
Home | Intro | Our Design Process | Stock Design Info | Motor Yacht Designs | Sailing Yacht Designs | Prototype Designs
Plans List | Articles | Our CAD Design Stream | Maxsurf | News..! | SITE MAP..! | Site Search | Design Team | Contact Us
