From dinghies to the Architectura Navalis and back

It’s funny how some things in life go round and round in one’s mind.

This morning over my porage I idly read a copy of Cruising & Ocean Racing by EG Martin and John Irving that I managed to buy for a song at the weekend. I turned to a chapter by John Irving about dinghies and their design, and found that he had some remarkably trenchant things to say about pram dinghies as tenders. He strongly dislikes them – so much so that one might think he was frightened by one at a young age.

Now the people who wrote that book could afford sizeable yachts, and could perhaps live with with tenders lashed to their decks that were long enough to have sharp bows – but that isn’t true for most of us. Prams can be a fact of life, so I was interested in what he had to say about what made a good and what made a bad pram.

The most important features, apparently, are strong sections that bring quite a lot of bouyancy right to the ends of the boat, and a good sized skeg. In the drawing below, he says the solid line shows how such a dinghy should be, while the dotted line shows a pram that would be ‘one of the most treacherous in any weather, and will be easily upset by overloading’.

John  Irving pram

All very interesting, I thought, as I sipped my morning tea, and wondered what he would have thought of a pram I designed some time ago that has several of these characteristics. The boat hasn’t yet been built, but I’ve often wondered whether in drawing it up I was guilty of bringing the bouyancy of the central section too far forward and too far aft.

At lunchtime, I found myself musing that there might be some interesting comments to be found around the web about the Architectura Navalis, to which I posted a link last evening, I thought it might be interesting to Google around see what people say about it.

I didn’t get very far. The first link I found was to Hannu Vartiala’s website. Hannu, I should explain is a very bright and individualistic Finn who loves developing interesting small boat designs, publishes them on the Internet and often builds them also.

Plate 48, boat 11

Just as Chapman did long ago, Hannu decided this was an interesting hull form – even though it was much too long for the purposes of anyone he knew. So Hannu drew up a much shorter version to be built in plywood.

The boat got built (see his page on the project), and seems to work. But have you noticed how much it has a lot in common with the version of the pram that John Irving advocated years ago in Cruising & Ocean Racing? It’s not too far from the Auray punt form that Claude Worth noted either.

And then I got to musing again about what might be the merits and otherwise of the Light Dinghy I designed some time ago, and mentioned in this post . The FREE BOAT PLANS can be downloaded here.

Light Dinghy
I’m surer now than ever that the little boat is a good one and deserves to be built, but more than that I’ve had quite a few minutes of pleasant musing about small boats today that I wouldn’t have had if the grumpy British naval architect, the sublime Swedish naval architect and the Finnish plywood experimentalist hadn’t happened by to provide the entertainment.

And if anyone does build my little Light Dinghy, please tell us all about it! Meanwhile, I think I’ll turn to musing about what Chapman’s long punt might have been like on the water under oars, and about those curious crooks people used for oarlocks in those days…

http://intheboatshed.net/2006/12/25/tempting-plans-for-the-boat-dreaming-season-part-iii/

3 thoughts on “From dinghies to the Architectura Navalis and back”

  1. Gav,
    I continue to learn from you! All these years I have wondered what a transom bowed boat gives someone that a sharpy doesn’t. I have never thought about shorter length on deck! Makes so much more sense.

    Ron

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