Ideal Vessel Size – Less is More

There is a lot of interest expressed in larger vessels in the 50’ (15m.) range, so we undertook some preliminary investigative design work to identify features we may be able to offer in a 50’ vessel that would be specifically applicable to our liveaboard customer base.

for cruising customers, however, we came to the conclusionThere can be little argument that the 50’ vessel has a strong position in the charter market, being able to offer separate accommodations with separate heads for four cruising couples. There are lots of hands, eyes and pocketbooks sharing in the duties attendant to such a craft. Its “fair weather fun” application can turn much serious impracticality in the arrangement of things into a genuine positive.

For cruising customers, however, we came to the conclusion that the compromises made on voyaging with these large vessels using a limited crew can be a definite liability to enjoyment, safety and piece of mind.

The 50′ developmental exercise was informative in that it identified a number of controlling factors that may not be immediately apparent at a boat show or on the dock.

1) Visibility from the helm

If you actually keep the desired bridge deck and headroom clearances in mind, you are led to some accommodation configurations and a deckhouse envelope that has some serious interference with the line of sight from any practical enclosed steering position.

For the sake of this exercise, we took the altitudes from our current 44’ design, with some upward adjustment to raise the bridge deck proportionately, and doing a 2-dimensional expansion of the plan approximates a 50/44-like configuration. From the helm, you now have to see over a much greater expanse of cabin top and deck with no height advantage. This could be the single most serious controlling issue of the size envelope and at least partially excuses some of the bizarre helm configurations to be seen in the market. At 50’ the corners of the vessel are a long way away; difficult to see over, and more difficult to get to from any helm position.

It is significant that the otherwise comprehensive CE rules requiring minimum visibility from the helm of a powerboat have no like application for sailboats, the presumption being apparently that you will never be able to see where you are going. We just don’t find this premise acceptable as a design parameter for a limited crew cruising vessel.

2) “Split levels”

The relative heights of accommodation decks, weather decks, bridge deck and water surface are all exaggerated as the vessel size goes up. What works well in the mid-40’s vessel size as regards step and seating heights becomes very problematic if you wish to avoid an Escher-style exercise in staircases and landings.

Escher staircase

There is a tendency to abandon recognized ergonomically correct step proportions to disguise this effect in many current designs, especially in the transom area, a dangerous practice for any vessel. If a design works well, you should be able to move around the vessel without much thought and without any head impacts, knee injuries or fatigue.

3) The individual in relation to the vessel

Evaluating a cruising vessel’s capacity in terms of its “floor area” is misleading when considering its functionality. A vessel of this type that is 50/44ths the size of a 44’ vessel in terms of length will be approximately 45% larger in terms of structurally supported surface area. This is a vast increase in terms of windage and weight, all of which has to be driven through the water. Mechanical systems, spars, sails, ground tackle, etc. must all go up in size accordingly and rapidly exceed the capacity of an individual’s (couple’s) handling effort.

Reliance on powered systems becomes not just convenient but critical to operation. All cruising vessel tasks should really be planned for one or two individuals in possibly very arduous circumstances. This is a limiting factor and a fresh design exercise therefore demands that the “mission profile” be fulfilled in the most economical manor, without superfluous space or volume. The application of this maxim is not particularly important for vessels which receive casual holiday use but for a voyaging vessel, the benefits to be achieved are critical.

It is evident that cabin separation and privacy is a big advantage with any catamaran design over a monohull. The lower hull accommodations can be placed in the vessel extremities and common living spaces can be centralized. It is hard to reason that simply “more of the same” however will be worth the price to be paid.

There has to be some identifiable “extra” that is achieved by floor area alone to justify going larger with the design. We have yet to identify any sufficiently attractive extra features available with the 50’ vs 44’ potential floor plan, especially when working to retain the practical considerations essential for a couple’s liveaboard vessel. You could end up with more vessel than you can comfortably handle.

Bigger is not in fact necessarily better and may constitute a serious liability. It appears to us that concentrating our design efforts in the mid-40’s range of vessel size will produce the most rewarding results for our customers and by doing so we will continue to offer the most efficient cruising vessels available in the market.