Michalak's IMB: "Birdwatcher" Style

 Many years ago, Jim built Bolger's Birdwatcher.(Do a Google search on "Bolger's Birdwatcher" for lots of information.) One of the interesting concepts of the Birdwatcher design is that the cabin is almost the full length of the hull and is surrounded by clear waterproof windows on the sides and partially on the ends. The center of the top of the cabin is open as well as the center of the cabin ends. The result is that the boat can be laid over on it's side (on purpose or inadvertently) and no water will get into the cabin. 

The boat is sailed or rowed from inside the cabin and crew is the ballast.

Since his time with Birdwatcher, Jim has designed a number of boats that include its concepts. One of those designs is "IMB". Using Jim's plans, I built this model. 

Jim Michalak's IMB, a "Birdwatcher" Style Sail/Row Cruiser

Modifications:

• Replaced the designed rudder with a Michael Storer style holster enclosed rudder that I've used on two of my sailboats (and will continue to use in the future).
• Added racks on the cabin top for spars (mast, boom and yard) for the lug rig sail and oars; required tie-downs not shown.
• Jim uses ropes to control the leeboard. Based on Jerome Delaunay's Scow 244, I decided to use a  long handle to raise and lower the leeboard.
  
  One of the advantages of building a model of your boat before you commit to the full sized boat is that you catch your own 'brilliant' ideas before you invest time/money in the full-sized boat.
  
  For example, the handle on the outside of the lee board (as shown in the photo above) will NOT WORK on IMB. One would not be able to reach the handle without climbing on the cabin top (not a good idea) or by doing an awkward and dangerous stretch from the after deck.
  
  The handle WOULD work if it were attached on the inside end of the leeboard pivot shaft. Thus the leeboard would be adjustable from inside the cabin.  
  
  

IMB Showing Holster Style Rudder in the "Up" Position.
Tiller extends under after deck about 13" into the cockpit.

Oars Extended Through Oar Ports with Covers Removed 

Specifications:

• Length: 13' 6" (4.1 m)
• Beam: hull: 5' 3" (1.6 m)
• Water Line Length: 13' (3.9 m)
  
  
• Cockpit length: 8' (2.4 m) (bulkhead to bulkhead)
• Cabin top opening: 8' by 2' at midships (2.6 m by 610 mm)
• Span is 5' 3" (1.6 m); Oar's shown are 8' (2.4 m), which I believe are adequate for the small amount of rowing that would be done with this sail/oar cruiser.  
  
  
• Freeboard: 1' 6" (457 mm),  2" (51 mm) less midships
  
• Water Line Width: 5' (1.5 m)
• WLL/WLW Ratio: 2.6:1
  
  
• Hull Speed: 4.8 Knots, 8.9 kph, 5.5 mph. Given the large wetted surface and low WLL/WLW ratio, sailing in good wind could reach these speeds, but not rowing.
  
  

Summary-Pros:

• Based on the Birdwatcher concept, IMB provides a safe and comfortable sail/oar cruiser.
• Oar ports enable her to be rowed (from within the cabin) when maneuvering in close quarters or when the wind dies.
• The lug rig provides a powerful sail that is set with little rigging and hardware.
• Plenty of dry storage in the 2 under-deck compartments.
• All sail handling, steering and leeboard control is done from within the cabin.
• Sailed heeled at 15 to 20 degrees (lee bilge panel is about horizontal), wetted surface would be reduced by approximately half and she would be really fun to sail.
• Able to be transported with a light trailer.

Summary-Cons:

• Rowing speed will be lower than "Hull Speed" noted above.
• Though plans are straight-forward, there are a lot of closefitting parts, especially around the windows and bulkheads, none of which are difficult to create and install, but do take more time to build than an open sailboat such as Jim's Mayfly series.
• The open top (and ends) of the cabin are really comfortable and safe in sunny/cloudy weather, but would require closures for inclement weather. Such closures are typically made with either waterproof cloth and/or hatches.

If we're looking for a comfortable and safe sailboat for both day-sailing (for a small family) and occasional overnights for one or two (very close friends), this would be an excellent choice that you could build for yourself.

Michalak's "Marksbark", a Day Cruiser

 Jim's long, narrow "Marksbark" is a fast day cruiser that can carry a passenger safely and yet provide an invigorating single handed row with a hull speed of 5.4 knots. 

Marksbark as a Day Cruiser

The Safety Features of this Day Cruiser

1. Water proof compartments at each end of the hull, approximately 2' (210 mm) long.
2. The hull is fully decked except for the cockpit opening.
3. A 3" (76 mm) coaming surrounds the cockpit opening. 
4. The deck extends beyond the hull width by 8" (200 mm) midships and then becoming narrow fore and aft. Fastened to the bottom outside edge of the extended deck is a 2" (51 mm) wide 'plank' that runs the length of the hull on each side. Filling the space between this plank and the hull is 2" thick foam. This provides approximately 33 pounds (15 kg) of additional flotation on each side of the hull. Thanks to John Welsford for the idea of extending the deck beyond the hull as he did in his "Kiwi PDR".
   
   
   

   

   Underside of Deck Extension to Hold Foam Board Flotation 

 

The cockpit opening is long enough (7', 2.1 m) to accommodate rower and a passenger. Two positions for the oar locks enable a single rower or a rower with passenger without affecting trim. The cross-slotted floorboards enable the rowing seat and foot rest to be shifted as necessary.

Set-up for Rower and No Passenger

Added Passenger Seat & Moved Footrest/Rower's Seat Forward

Two storage compartments (in addition to the water proof compartments at the ends of the hull) provide  dry storage with access through deck hatches. The aft compartment is 2' (610 mm) long and the forward compartment, pictured below, is 3.5' (1069 mm) long. Both hatches are 12" x 18" (305 x 457 mm). The after hatch supports the reverse reading compass. 

Bow Showing Forward Storage Compartment, Anchor Cleat & Anchoring Fairlead

Use of the 'anchoring fairlead' (see end of post) enables anchoring without going on the deck, which is dangerous in a hull this narrow.

Specifications:

• Length: 18' (5.5 m)
• Beam: hull: 3' (0.9 m), edge of deck: 4' (1.2 m)
• Water Line Length: 16' (4.9 m)
  
  
• Cockpit length: 7.5' (2.3 m)
• Cockpit opening: 7' by 2.5' midships (2.1 m by 762 mm)
• Span is 3' 10" suggesting 8' (2.4 m) oars.  
  
  
• Freeboard bow: 12" (305 mm)
• ... midships: 6" (152 mm)
• ... stern: 9" (229 mm)
  
  
• Water Line Width: 3' (0.9 m)
• WLL/WLW Ratio: 5.3:1
• Hull Speed: 5.4 Knots, 10 kph, 6.21 mph
  
  

Summary-Pros:

• A straight forward build based on Jim's Toto design.
• Hull is built as Jim designed. The changes noted in The Safety Features in this Day Cruiser are all additions to his design.
• Fast: A cruising speed of 4 mph (6.4 kph, 3.5 knots) for ten 45" sessions per day results in 30 miles (48 km) a day cruising. Jim states in his write-up for the plans "...she'll hit 6 mph in good conditions and cruise forever at 4 mph."
• Carries a passenger comfortably without affecting trim.
• Could be cruised in, but may require shelter. See this post on "Shelters" for alternatives.
• Abundant dry storage.
• Seaworthy based on waterproof end-compartments, full decking, coaming and under-deck flotation.

Summary-Cons:

• Narrow hull at the water line results in a 'tippy' hull which is offset (somewhat) by the under deck flotation.
• Heavy to car-top, although boats this long are easier to car-top than shorter boats of the same weight. See these posts on car-topping and this one by John Welsford.

If most of your  rowing is 'day-cruising' and relatively little of over-night cruising, this design, with its ability to carry a passenger and it's speed, is an excellent option.

Bolger's Japanese Beach Cruiser

Phil Bolger's Japanese Beach Cruiser (JBC) is a 12.5' (3.8 m) seven panel sail boat.  

The JBC has a transom bow. Ross Lillistone's Whimbrel, Matt Layden's Sandflea and John Welsford's Scamp are three other examples of transom bow boats. Ross wrote a post about transom bows which incorporates some of Bolger's views. They make a case a for transom bows if there is a design constraint of LOA. 

The plans from Bolger's Boats with an Open Mind (pg. 127)

Using those plans, I built a 12:1 scale model pictured in the two photos below.

Bolger's Japanese Beach Cruiser

Bird's Eye View

Specifications:

Length: 12.5' (3.8 m)

Beam: 5.5' (1.8 m)

Mainsail Sail Area: 89 Sq. Ft. (8.3 Sq. m)

Mizzen Sail Area: 24 Sq. Ft. (2.25 Sq. m)

The success of John Welsford's Scamp, which is similar to Bolger's Japanese Beach Cruiser, is a testimony to how successful a transom bow boat can be. Key is that we get a lot of boat for a short LOA.