Messing about in boats since 1975.  Online Since 1997.

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The 49' Low Profile Steel or Aluminum Trawler Yacht

'Double Eagle'

The 49' Trawler Yacht - DOUBLE EAGLE - Kasten Marine Design, Inc.
Interior Plan | Interior Profile | Larger Perspective Aft | Larger Perspective Forward | Perspective Above Aft

Copyright 2004 - 2011 Michael Kasten

General Concept

The 49 foot 'Double Eagle' has a displacement hull form, essentially borrowed from the Vagabond 50. This hull type provides an excellent combination of speed, economy, and seaworthiness. Relatively short overhangs maximize WL length and therefore vessel speed and the room for accommodations below.

Particulars are: 50' LOD x 45' - 7" DWL x 13' - 7" Beam x 4' – 11" Draft light and 5' - 2" Draft loaded. Displacement will vary from around 45,500# light to a full load capacity of around 59,700# with tanks full, stores aboard, and the boat ready for a voyage.

Hull, decks and cabin are planned for steel construction with scantlings according to the ABS Rule. The house top is cold molded plywood, laminated into a single large structure then sheathed in GRP. Plating, framing and other internal structures are intended to be detailed for NC cutting, including integral tanks, engine girders and bulkheads.

Power and Range

The engine specified is a John Deere 6 cylinder diesel for 175 hp at 2,400 rpm, mated to a Twin Disc gear using a 3:1 reduction to drive a 34" propeller. The "cruising speed" for long range voyaging with this hull is assumed to be around 8 knots. Theoretical hull speed is around 9.5 knots, however due to having relatively light displacement the hull should reach around 11 knots with the planned horsepower.

Using 1,250 USG of fuel and keeping a 12% reserve, the Beebe algorithm shows range in the average load condition to be around 3,200 NM at 7.8 knots. Other range prediction methods yield a slightly higher result but we have noted the more conservative Beebe results here.


To review the interior in greater detail please see the Interior Plan and the Interior Profile preliminary sketches. The sketches in these links show the interior that we worked out for the Rhumb Runner. It is an exact fit for this hull form and cabin configuration. In fact, with the displacement hull of the Double Eagle, there is quite a bit more headroom in the engine space and storage below the saloon / galley.

Beginning forward, the layout below contains a large owner stateroom with head and shower to port and starb'd respectively. A ladder on center leads upward to the Pilot House.

The pilot house is quite spacious, with a nav station to port and pilot seat to starb'd. The pilot house also contains the galley and dinette seating. Below the Pilot House sole is the engine room and the bulk fuel tanks.

A companionway leads aft and down to another large stateroom which contains a large berth, cabinets and an en-suite head. Both staterooms are equally well appointed and have nearly the same area, so really it's tough to decide which should be the "master" stateroom. This is the ideal layout for two couples - possibly for co-ownership...

Motor Yacht prototypes using this same interior layout:
Black Jack | Double Eagle | Rhumb Runner


On the aft deck, there is a seat that offers a great place for fishing or just watching the wake. The aft seat also provides a bit of extra headroom for the head of the berth below. Just forward of that, the top of the aft cabin is envisioned a 'chariot' style exterior bridge, therefore the aft sweeping 'wing' walls. The overall rationale there is to keep the height of the house and coamings below the EU canal clearance limits, but to also allow there to be an exterior steering station. It is like a flying bridge, but just not 'flying' as it would be if located on top of the Pilot House...!

Design Summary

The intent of this design has been to fit the maximum accommodations into a seaworthy long range cruiser under 50 feet LOA. The height to the top of the Pilot House is under 11 feet, which opens up access to most of the canals in France and the rest of Europe.

Double Eagle is so-far a preliminary design, having been modeled by computer and the preliminary hydrostatics calculated. The rest remains to be detailed in order to create a completed set of Building Plans. For further information, please inquire.

The 49' Trawler Yacht - DOUBLE EAGLE - Kasten Marine Design, Inc.
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