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Naiad 3. Survival of a water Nymph.

The Naiads were water nymphs that lived in the wells, springs and fountains of Greek mythology. Whilst they could travel through the watercourses, if they left their aquatic environment they would dry out and die. Naiad 3 is a water nymph that has avoided this fate and survived for more than 50 years in perfect condition, although it has certainly dried out by now.

In the years immediately following the second war, there was rapid development in the design of tethered hydroplane hulls. The scow or ‘kipper box’ was giving way to the three-point ‘prop riding’ hull. Numerous routes were followed including a narrow hull with the sponsons on outrigger bars, which is now universal, or the American ‘Ventnor’ trend with the sponsons or other running planes integral with a ‘boat shaped’ centre section. Whichever design was used the aim was to get the boat riding on the sponsons and prop without getting so much air underneath the hull that it took off. Most of these designs led to very boxy and slab sided boats, easy to build but no so easy on the eye. One group of competitors, many of them from the Bournville club, eschewed this path and produced some beautifully streamlined and graceful designs. One of the most elegant was George Stones 5cc Lady Cynthia, but Tom Dalziel from Bournville produced Naiad 3, which was equally fascinating.

Tom Dalziel was a gifted engineer, well ahead of his time in design thinking, which suited his work as a prototype engineer for Morphy Richards, the appliance manufacturer. The first of the Naiad boats was described in 1948 as (an) "interesting new ‘B’ class boat". That it certainly was, with an almost perfect aerofoil shape in plan yet very shallow. The motor had been built by Tom in his small garden shed, and was a 15cc two stoke with twin exhaust ports, looking every inch a miniature motorcycle engine.

The boat was a delightful shape but that was probably its downfall as the shallowness and lack of lift caused it to nose dive, finally causing severe damage when it hit the lake bottom.

Naiad 2 followed in 1949/50 with the same engine mounted in a very deep hull, rectangular in plan and an inverted wing section in profile. 2 sheet metal planes took the place of the sponsons and such was the depth of the hull that the complete exhaust system was under the deck.

With this boat Tom won ‘B’ class awards in the 51 and 52 Model Engineer Speedboat Competition at 46.5 and 48.9 mph respectively. George Lines’ ‘Sparky II’ was some 10 + mph faster and had a stranglehold on the class at that time.

In reality, although superbly constructed, the hull and engine design were outdated so Tom set to and built an entirely new and quite extraordinary engine and hull that was to be Naiad 3.

The third boat in the series appeared in the 1956 season and proved to be significantly quicker. In the ME competition for that year a speed of 58 mph was recorded which was a major achievement as Tom Dalziel had avoided the route taken by many fellow competitors of building a ‘Sparky’ clone motor.

The hull of Naiad 3 is elliptical in section and a sleek, streamlined, airfoil in plan and profile with sponsons attached solidly and faired into the hull rather than on bars.

The 15cc motor is a work of art with no surplus metal anywhere. At first glance it may look like a Lines motor but the similarities end with the twin silencers.

The porting arrangement is the most fascinating as it uses the 360 degree principle but in a quite unique way. Instead of the transfers being milled into the inner surface of the liner there are 6 conventional passages that match up with windows in the piston skirt but rather than the transfer ports opening into the cylinder directly as on all other engines, it becomes even more interesting. 
 

The piston crown is extended to form a combustion chamber but then 6 ports are cut into the side of this space to match up with the transfer ports. A very clever design seemingly intended to scavenge the exhaust gases by opening the transfers very much earlier than conventional porting would allow.

Naiad 3 proved to be both successful and long lived being run regularly into the 1970s. At some stage new, longer and deeper, sponsons were added, although the stark rectangular shape of these detract from what would otherwise be one of the most attractive boats of the period.

When Tom Dalziel finished competing he passed the boat to a fellow club member, Arthur Wall, holder of the British record at that time and first person in Britain to achieve 100 mph with a tethered hydro. Arthur in turn passed the boat to Dave Scarnell, another holder of the British record, and that is where it currently resides. In 1997 the boat made a ‘guest appearance’ at the St Albans International Regatta.

Update Nov 2007. Almost as soon as this article was published, Stuart Robinson recalled seeing Tom running a twin hulled boat, but a search of all the records failed to produce a reference to this 'mystery' craft. In an amazing coincidence, just four days later, a collection of photos came to light, and in one of them, Tom Dalziel was holding the very boat in question.

A close look at the print shows that the15cc motor featured above had been fitted to this 'catamaran' style hull, probably in the early 70s. The fate of this experimental hull is not known, but the engine was obviously put back into Naiad 3.

Update March 2011

Having stripped down Naiad for the photos, Dave Scarnell made the decision to put the boat back into running order and rebridle it. It was first taken to Kingsbury, where Arthur Wall and Ron Hankins, seen here on the right, were co-opted into getting it running. The engine proved reluctant to pick up fuel, and after some more attention was taken to St Albans. Here Dave was back in waders, but again the engine would run out a prime, but no more. Frustrated by this, Dave dug his A3 boat out, and came out of retirement. Naiad was returned to the shed, but has now been passed on, in the hope that the fuel problems can be ironed out so that it can be made to run reliably again.

Along with Naiad was another of Tom Dalziel's 15cc 'B' Class boats, seen to the left. The engine shows his normal superb level of craftsmanship and is yet another design variation with the single rear exhaust port. Unusually, the boat is rigged to run in either direction, which must make the fuel feed interesting. A look inside this motor could prove equally interesting.

Thanks to Dave Scarnell for the very detailed pictures, to Arthur Wall for information about Tom Dalziel and Peter Hill for original photos

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