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The 49' Motor Yachts

"Vagrant" & "Migrant"

49' Vagrant Trawler Yacht - Kasten Marine Design, Inc.
Click for Larger Image

Exterior Profile | Exterior Deck Plan | Interior Profile | Interior Plan
Perspective Forward | Perspective Aft | Perspective Far Aft

See Larger 70' Vagrant Below

Copyright 2004 - 2014 Michael Kasten

General Concept

The original design assignment for this vessel was to create a robust and classic displacement type long range steel trawler for a couple with guests, having two equal staterooms - the purpose of the vessel being long coastal cruises as well as ocean passage making.

An additional requirement was to have a generous but secure and comfortable flying bridge, yet to stay within the height limits for travel on the canals of Europe. As it turns out, this was quite a challenge, but the resulting layout is excellent.

The primary canals of France ( Freycinet Standard) have a limiting air draft of 3.50 meters (11' - 5.8"), a limiting water draft of 1.80 meters (5' - 10.9"), and a limiting beam of 5.0 meters (16' - 4.9"). The main German canals have a limiting air draft of 5.25 meters (17' - 2.7").

In the half load condition, with Bimini top, mast, poles and exhaust stacks down, the Vagrant 49 has approximately 10' - 9" air draft, leaving several inches to spare even in the French Canals, opening the door to nearly all of the European canal system.

Hull, decks and cabin are steel, with all scantlings according to the ABS Rule. Plating, framing and other internal structures have been detailed for NC cutting, including integral water and fuel tank faces, engine girders, etc. The house top and flying bridge coamings are cold molded plywood, laminated into a single large structure then sheathed in GRP.


The Vagrant 49 makes use of Paravanes for roll stabilization. The mast and the paravane poles are detailed to be economically built of aluminum pipe. In all, the whole design is intentionally quite simple, so should be economical to build, to maintain, and to travel with.

In order to minimize the drag inherent in most paravane designs, and to maximize lift for the greatest stabilization effect, we have created a design for foil shaped paravanes. Machined out of aluminum, they can be NC milled out of billet stock. The paravane body, wings and fin are accurate NACA foil shapes designed for low drag and high lift.

The paravanes are balanced and are adjustable for different speeds. The "weight" in the nose (so that the paravanes will dive) is achieved by machining out a hollow part in the nose and loading it with lead shot, then welding the nose back onto the body. We developed a size that is appropriate for boats up to around 35 feet by up to approximately 11 feet of beam, and a larger size for boats up to around 60 feet by up to approximately 15 feet of beam.

Reports in-use are that these foil shaped low-drag paravanes cut the amount of drag in half as compared to typical rudely shaped steel paravanes made out of flat plate and a cylindrical weight chamber.

Vessel Particulars

The Vagrant 49 and the Migrant 49 share exactly the same design particulars, as follows:


The engine specified is a John Deere 6 cylinder 6068 TFM 75 emissions compliant diesel, which produces 178 hp at 2,500 rpm in the M-2 rating (2010 updated spec). The engine is intended to be mated to a Sabb HVP-85-E controllable pitch gear using a 3:5 reduction to drive a Helseth three blade 34" CP propeller. At maximum power, the maximum calculated speed is 10.8 knots - an S/L of 1.58.

One might question whether that hull speed can be achieved in a displacement vessel... After all, that is well above the usually assumed "theoretical" hull speed of S/L 1.34 (theoretical maximum in knots equals 1.34 times the WL length in feet). In other words, theoretically the maximum speed to length ratio is 1.34. This is the same as the speed of a wave train of length "L" in the open ocean. For the Vagrant, an S/L of 1.34 would equal close to 9.2 knots using the average load condition WL length of 46.8 feet.

So we have to ask, "Is this an excessive amount of power...?"

To answer that question, we also must consider the fact that Vagrant has an average displacement to length (D/L) of around 245, in other words medium to light displacement. With the relatively light D/L we find the maximum theoretical hull speed to be more on the order of around S/L 1.50, or approximately 10.2 knots...! In actuality, this "theoretical" maximum will be further enhanced by the overhang given to the stern, which will make for a longer WL under way and will push the actual maximum hull speed higher yet.

Based on the fairly conservative algorithm we use for speed prediction, it is entirely possible that the vessel will see 11 knots in regular use with the JD 6068 TFM at maximum power. So if maximum performance is essential, or an extra "weather factor" margin is required, the JD 6068 does not seem excessive. But... certainly it will be hungry at that speed..!

Engine Options...?

In order to address inquiries regarding whether the new emissions compliant John Deere 4045 TFM 75 four cylinder diesel would be up to the task for the Vagrant 49, I have run a new set of calculations to discover the answer... To run this calc, I have used the M-3 rating for the new 4045 engine, but I have pulled the engine back to a more friendly 1,850 rpm, approximately 71% of its 2,600 rpm maximum. This is just beyond the 1,800 rpm peak torque, the sweet spot for any working diesel.

At 1,850 rpm, the 4045 TFM engine produces approximately 125 hp. In order to transmit the engine's full power at that rpm, we have assumed it will be mated to a Sabb HVP-65 gear with a 34" x 3 blade controllable pitch propeller. With these assumptions, the results show that the 4045 TFM will be able to achieve around 9.6 knots in the average-load condition. This is approximately S/L 1.40... or approximately 4% above the S/L 1.34 displacement vessel "maximum theoretical hull speed."

In consideration of the above notes regarding the Vagrant's relatively light displacement to length ratio, the increase in WL length underway, and the fairly conservative calculation we use, there is little doubt this speed would be readily achievable. Although the 245 average displacement to length shows a potential for S/L 1.50, the upshot of this investigation is that, yes, the 4045 TFM would indeed be adequate to the task... in particular for voyaging where vessel speeds and horsepower requirements are considerably less in order to achieve the requisite range and fuel economy.


The "cruising speed" for long range voyaging is usually presumed to be between S/L 1.05 and 1.15. If we strike at the middle for an S/L of 1.10, in the average load condition the voyaging speed for this hull will be around 7.5 knots.

Per the Beebe algorithm for range, using the Vagrant fuel capacity of 1,200 US Gallons and a reserve capacity of 15%, range is predicted to be approximately 3,200 NM at 7.5 knots. This yields an "endurance" of 17 days under power at that speed, with 15% reserve.

The Beebe algorithm uses a very conservative fuel rate of 16 hp / gal / hour in order to over-compensate for a WX factor. The Beebe algorithm "power factor" at 7.5 knots calculates that approx 39 hp are required for that speed. Other algorithms predict up to 45 hp for 7.5 knots... but they also use the engine's actual published fuel rate which is usually closer to 21 hp / gal / hr, and if a WX factor is applied the net result is approximately the same or slightly greater range.

Either way, it is very apparent that for voyaging under power, either engine would be suitable. In fact high horsepower is not only not a requirement, it is possibly over-kill. If the engine will only use some 45 hp on average, it is being quite under-utilized. This is usually not optimum for a diesel, which expects to be working hard.

Here we have revealed one of the primary reasons that we advocate in favor of controllable pitch propellers, with which one can dial in greater or lesser pitch as needed in order to work the engine hard at nearly any rpm.

Exterior Arrangement

The aft deck, side decks, and interior pilot house deck are all at one level. There are two exterior water tight doors entering the pilot house. The side and aft decks are surrounded by substantial bulwarks, and the fore deck by a toe rail. All decks are surrounded by lifelines, with welded steel pulpits forward and aft.

Right aft in the cockpit area is an aft-facing seat. Wing plates are arranged to flank the aft deck, and allow the cockpit seating area to be easily enclosed by screens and / or vinyl - canvas, depending on the season.

49' Trawler Yacht VAGRANT - Kasten Marine Design, Inc.
Click for Larger Image

A ladder on center leads up from the aft deck and into the well-protected flying bridge area above the owner's cabin. The flying bridge is arranged with two long seats outboard. The whole idea of the flying bridge is to allow outside enjoyment, accommodate occasional outside sleeping, and for lounging and dining with a 360 degree view. The flying bridge contains a second helm seat and control station forward. A mast and paravane rig are located just aft of amidships with all control lines operable from within the flying bridge.

The fore deck spans the full width of the boat from bulwark to bulwark. This provides a very large volume within the forward accommodations below. Davits port and starb'd allow placing a shore boat onto the fore deck. A dual capstan horizontal anchor windlass is located forward.

Interior Arrangement

The accommodations are intended to provide comfortable cruising for four people. Deck structures provide 6' - 6" standing headroom throughout. See the links above for a comprehensive view of the interior and exterior layout.

49' Trawler Yacht VAGRANT - Kasten Marine Design, Inc.
Click for Larger Image

Beginning forward, there is a generous guest cabin, arranged for maximum privacy. The guest cabin has a queen size berth, plenty of shelves and a big hanging locker. A door leads directly from the guest cabin to a combination head / shower. Another doorway leads aft to the galley and saloon.

The large L-shaped galley is located to starb'd at the base of a spiral stairway. The galley contains a large refrigerator / freezer aft, large sink, and three burner propane range. In the saloon to port is a large wrap-around dinette and table, sized for six. The intent is that this will be the primary entertainment space. With the full width raised foredeck, the galley and saloon will be light and open and will have unobstructed views to port and starb'd.

At the aft end of the saloon / galley is a spiral staircase leading to the pilot house, and a WT door leading into the engine room below the pilot house. Access to the engine room is also via large opening hatches in the pilot house soles.

49' Trawler Yacht VAGRANT - Kasten Marine Design, Inc.
Click for Larger Image

The pilot house has a WT entry door to port and starb'd. The helm station is located on center, and a large bench seat is located to port, aft. There is a narrow table with a drop leaf, allowing occasional meals to be taken there, or just for observing and conversing with the helms-person.

Just aft of the pilot house and below the flying bridge is the owner's cabin, accessed by a companionway ladder to port, aft within the pilot house. The owner's cabin contains a private head and shower, queen size berth, rather large hanging locker, and wrap-around shelves and storage.

MIGRANT - Variation on a Theme...

We also co-developed the same design without the flying bridge: the Migrant 49. Migrant has exactly the same hull form and interior layout, but the flying bridge is deleted in favor of keeping a lower profile with less overall windage. Other slight differences include a smaller overhang all around on the pilot house roof with a visor forward, plus a faceted forward face on the pilot house. All other aspects of these two designs are identical.

Migrant Starb'd Aft | Migrant Starb'd Fwd

Design Summary

Overall the primary goals for the Vagrant 49 have been to fit two nearly equal staterooms into a sea-going boat of 15 meters or less on deck (for the sake of easier ownership and piloting within the EU). The layout has worked out very well, and the boat is not at all crowded. Easy canal cruising throughout the EU is made possible by the relatively low profile, even though there is a generous flying bridge...!

If the flying bridge is not important, the Migrant 49 provides the same layout and hull form with less windage and better visibility from the helm.

Design Genesis

As with our other designs in this series, the hull form for this vessel has been adapted from real trawlers - US West Coast fishing vessels which have to operate in all weathers - including in the Gulf of Alaska, a place where the ocean is... well, not so nice. Our aim has been to retain the excellent sea keeping qualities of those working craft, and to refine their lines into 'yacht' form to achieve a more easily driven hull with relatively light displacement. See the following links for vessels in the Gulliver / Greatheart series...

Greatheart 36 | Vagabond 36 | Gulliver 46 | Greatheart 48 | Greatheart 54
Greatheart 60 | Swallow's Nest 60 | Braveheart 53 | Braveheart 63 | Swallows Nest 70

In order to achieve a proportionately longer waterline and more interior space without increasing boat length, we developed another series of designs based on the same hull form, but with a more upright stem and transom. Combined, this reduces the overhangs and increases the WL length to gain more interior space with less overall hull length. Check out the following links for boats in the Vagabond series...

Vagrant 49 | Vagrant 70 | Vagabond 50 | Voyager 52 | Valdemar 53 | Valdemar 70

70' Vagrant trawler Yacht - Kasten Marine Design, Inc.
Vagrant 70 - Click for Larger Image


Vagrant 49 | Vagrant 70 | Vagabond 50 | Voyager 52 | Valdemar 53 | Valdemar 70 | 37m Peri Laut

For more information on this or other designs, please inquire