Jul 282013
 
Sections of the ketch Presto by Commodore Munro (1885)

Sections of the ketch Presto by Commodore Munro (1885)

The Presto design was developed by Commodore Munroe in the 1880s on the US Atlantic Coast. The boats sailed up and down the coast some distance offshore and were confronted by the frontal weather systems and the influence of the Gulf Stream found in that part of the world.

The first time I came across the lines of the Presto was when an old friend pulled out a dusty set of large wooden moulds he had once built from lines lofted on the floor of his shed. I was immediately intrigued by the flare in the sides and the flat bottom. Sadly, the project never progressed further and some years later he passed away.

When I saw the lines above at the time of my first visit to New Zealand, I was fascinated. It is one of the few hulls I have ever seen that was so obviously designed by a highly experienced seaman for seamen. Nothing else came in the way. All the design decisions made come together consistently, there is not a hint of design trends, beliefs or conformism perspiring through.

It was a revolutionary design in 1885 and it took over 80 years before yacht hull design as a discipline started just edging closer to it, increasing beam and reducing hull depth. It took another 20 years almost until we saw broader aft sections appearing on displacement vessels, finally letting go senseless shapes and beliefs that had originated from Scandinavian lifeboats.

Today, one should check the fore-and-aft volume distribution achieved and – if needed – correct it based on what we have since learned about hull hydrodynamics and wave-making resistance, but the general shape of the sections is still just as perfect for the displacement achieved. It demonstrates an outstanding grasp of stability and hull shape versus seakeeping characteristics. I never imported the Presto lines into 3D CAD – no doubt many others have; it would be quite interesting to see what comes out.

There are a few modern and “damaged” versions of the Presto hull around, a case of name-recycling for marketing purposes. They seem to have a different waterline beam-to-hull depth ratio, a different relative displacement and they are just different boats.

  4 Responses to “The 1885 Presto Hull Design”

  1. I’m confused, are you saying you saw munros presto lines in nz or are you talking about the early nz boats?

    • Guy,

      Yes, I am saying I saw frames for Munro’s Presto design in New Zealand. The boat was not built and I am not aware of any true Presto ever built in New Zealand.

      Best regards,

      Eric

  2. Hi Eric

    I am interested to know where you saw the frames for Munro’s Presto Design (just out of curiosity)

    I am reminded of a conversation I had with Jack Cropp about hull design and efficiency…he had a reputation for designing fast sailing and fishing boats.

    I recently saw a newly built traditional East Coast (of the USA) fishing boat and was struck by its width aft…it reminded me of the Volvo 70’s being used today…I understand that these fishing boats were also (like the Presto) designed to be seaworthy (enough to fish off the coast without motor)

    I lack the technical expertise to make a full assessment of these boats…do you have any knowledge of them?

    Greetings,

    New Zealand Sailor

    • Roger,

      I discovered them in Otatara near Invercargill in 1999. They were in an old shed. Some years later the property was sold and the frames stayed behind. They may still be there today.

      Narrow and pinched stern lines were always a mistake, they gave boats that were unable to accelerate in following seas and became unmanageable as waves caught up with them. I never specifically heard about the fishing boats you are referring to, but they may well be related to the Presto hulls. I would expect so due to the geographic location.

      I am particularly uninterested in traditional designs in general due to them so often being hydrodynamically senseless, based on misconceptions and ultimately unseaworthy when you take them to the limit (you just can’t sail them any more), but the strength of materials and construction methods constrained what could actually be achieved for a long time. The evolution in design hasn’t just been one based on new ideas and understanding.
      In this context, those boats from the US East Coast are quite remarkable, because their design was excellent from a seakeeping point of view at the displacement that was imposed by their traditional construction and they could be built strongly enough. They weren’t designed according to beliefs like almost everything else that went on for almost 100 years on both sides of the Atlantic.

      You may remember that when Francis Chichester commissioned the design of Gipsy Moth VI to sail around the world, the brief he gave to the design office represented what would have been an early Open Class racing yacht: “I asked for a scow-shaped hull, that is to say of broad beam, shallow draught, and flattish bottom, with a deep keel”. Such a hull would have been very stable and powerful and most interesting. He was told that he was wrong and the boat he got instead was narrow, deep and also basically a heap of garbage. What a missed opportunity…

      I sometimes work on designs with fishermen and commercial operators. It is essential to listen to the people who go and spend time at sea and work the boats. They have interesting things to say. What they believe and the conclusions they draw are one thing, but their raw experience is something that can’t be touched. Looking at the Presto boats, some people clearly had an outstanding grasp of both stability and dynamic seakeeping. These people not only understood marine design and construction, but they also spent plenty of time at sea in bad conditions or they wouldn’t have come up with these hulls.

      Kind regards,

      Eric

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