Messing about in boats since 1975.  Online Since 1997.

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A Compact Blue Water Motor Yacht

The 35' "Big Ferdinand"

35' Big Ferdinand Trawler Yacht - Kasten Marine Design, Inc.s
Larger Aft Perspective | Side Perspective | Forward Perspective

Copyright 2015 Michael Kasten

General Concept

Here we have a much larger version of the 24' mini-trawler Ferdinand, which is therefore called "Big Ferdinand". The all aluminum "Big Ferdinand" has much more room throughout the interior. As with the 24' Ferdinand, this is a displacement hull form which favors maximum carrying capacity and long range. Short overhangs maximize WL length and therefore vessel speed as well as accommodation space below.

Particulars are as follows:

Draft is mainly a matter of deciding the expected shoal water limitations versus the preferred propeller diameter for best propulsive efficiency. Larger propellers are better...  


Having been stretched without increasing other dimensions, the Displacement to Length is dramatically reduced, in this case to a D/L of 167.  Theoretical hull speed for a 33.5' WL length is around 7.75 knots.  However due to the light D/L, with 55 hp, it should be possible to sustain a steady 9.5 knots... But that is fairly wasteful, so a more modest engine of around 40 hp is indicated. 

With 40 hp on tap, 9 knots is achievable. At voyaging speeds of around 6.5 knots, with 250 US gallons of fuel, using the Beebe range algorithm, the range is calculated to be over 4,000 NM, assuming a 10% reserve. At this speed, power use will only be around 8 or 9 hp...! At 7 knots, range would drop to something like 2,700 NM in the average load condition. At this speed, around 12 to 14 hp will be used.

A Lister Alpha 40 diesel would be ideal, especially if mated to a controllable pitch gear and propeller.


Below the pilot house sole is the engine space, in which the engine will be on center, flanked by integral fuel tanks on each side which extend from the pilot house sole to the hull bottom, and from bulkhead to bulkhead. Approximately 125 USG per side is the target.  Below the forward settees will be integral water tanks. Below the forward sole will be heavy duty polyethylene tanks for black and gray water. It may be possible to also place a small clean fuel tank there.


Some means of stabilization will be desired.  Ideally this will be in the form of a simple paravane rig, which can be managed from inside the pilot house.  See the article on Roll Attenuation for more information about this option...


The proposed Interior Arrangement is so-far planned to be similar to that of the Boojum 30, but there are several other options... Since Big Ferdinand has a large flush fore deck, there is an enormous amount of space in the forward cabin. Right forward is the forepeak for chain and lines.  Just aft of that is a generous stateroom with double berth on center.  Aft of that is the 'saloon' with settee on either side of a central table.

Up and aft of that is the pilot house, with pilot seats both port and starb'd.  Aft in the pilot house to port is the galley.  Aft to starb'd is a hanging locker and head / shower compartment.  Aft of the pilot house either...

What gives "largeness" to the interior is that the cabins extend all the way outboard to the edge of the bulwark. The aft portion of the pilot house is therefore wider than it is long.  

Heat would ideally be provided by a Wallas forced air furnace or circulating water system. Alternate possibilities are Kabola or the excellent Hurricane heaters. Cooking would be on a two burner stove with oven. My own preference on a vessel of this size would be to use kerosene. Yet another option is to simply use a Wallas diesel range. Though the Wallas range does not have an oven, it is an excellent little stove. 

With well-placed kerosene lamps, the interior would be very cozy indeed.

35' Big Ferdinand Trawler Yacht - Kasten Marine Design, Inc.
  Click for Larger Image    

On Deck

The fore deck will have a hatch leading to the 'saloon' below.  Access to the fore deck is also via an 'awning' window on center.  There is intended to be a large opening portlight on center aft, plus a hatch in the overhead of the sleeping cabin and the pilot house.  Combined, there should be very good ventilation.  On the foredeck there will also be a windlass, and right forward rollers for a good sized anchor.  If sun-bathing is a priority, there is plenty of room on the fore deck, and the pilot house top is clear.  If sunbathing is not so important, the house top provides ample area for solar panels...

Design Summary

The intent of this design has been to fit the maximum accommodations into a compact cruiser of 35 feet LOA. The requirement for excellent sea keeping has encouraged keeping the cabins low in order to minimize windage. Additionally, with a beam of 8.5 feet and a "dry" weight of around 12k lb., the boat could be trailered from one cruising site to another, and then stored ashore when not actively cruising - a big savings in marina fees and storage yard rental. Yet another benefit of this arrangement is that the boat when sitting on a trailer will function perfectly well as a camper...! 

As a prototype, the Big Ferdinand design is as yet unfinished. If this concept is of interest to you, please inquire for more information.

35' "Big Ferdinand" Trawler Yacht - Kasten Marine Design, Inc.
  Click for Larger Image 

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