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Make mine a Magnum

by Dougal Henshall 27 Jun 12:00 BST
One of the all time iconic dinghy designs - the Magnum 6 © Dougal Henshall

In almost every respect, 'Magnum' was a 1970s classic, but 50 years on the Magnum design of International Moth is about to get a 21st century make-over. Sailors wanting to join the growing Lowrider fleet just have to ask themselves, "Do you feel lucky?"

Those readers who enjoy following the many articles I've written on the topic of our domestic dinghy development timeline will know that there is one class that stands out head and shoulders in terms of helping the sport modernise from the days of the clinker-built local designs. Some historians like to champion the restricted developments classes, but ultimately these do what it says on the box; they are 'restricted' in their development.

This means that the 14s would quickly ban the trapeze, then place tight restrictions on the use of hollows in the topsides (a move prompted by the arrival of Thunderbolt, a boat whose DNA would go on to help create the Coronet before reaching peak potential with the 5o5), whilst the Merlin Rockets would put Barry Dunning on the naughty step and his boat back into the workshop at Spud Roswell's for daring to experiment with a dagger board.

Weight restrictions, rise of floor constraints and a list of what you cannot do that's much longer than what you can has seen development all but snuffed out; any changes are minor and along the lines of evolution rather than revolution. The only place that the opposite is in force has to be the International Moths, who have gone from a boat slower than a British Moth to the fastest thing in the dinghy world. This means that many of the steps taken by the fleet have been radial in the extreme and when these were seen to be successful, the boats that, just the season beforem had been race winning successes were suddenly obsolete.

Thankfully no one seemed to mind, as by the 1970s the hulls were being built ever lighter (just one spin off from that lack of a minimum weight limit) with 3mm tortured ply being the build material of choice. Radical, yes, but robust, no; that wasn't a term much in use within the Moth fleet. A hairy breezy capsize, or even a misplaced knee in light airs could result in some serious structural damage.

All this was taken as part of being in such an exciting fleet, one in which the ability to 'throw something together' (the more patient helms even waited for the resin to cure) was highly prized. One innovation even used cardboard honeycomb as stiffening which was light, stiff and a good idea until the hull leaked, the core got wet, whereupon it became heavy, soggy and with little in the way of intrinsic strength.

But, as will be revealed in another article that will soon be cluttering up your inbox, what was a good idea 50 years ago in the mid-1970s might not be such a success now, even if any examples had survived for 50 years. Incredibly though a number of these iconic Moths have survived through to the modern day, and it is these boats that are at the heart of the wonderful revival of what is now known as the Lowrider Moths (to distinguish them from their foiling cousins).

This might not be such a surprise for boats such as the Hungry Tiger, which was the last of the Lowriders and is close enough to the first generation foilers to have seen a number of boats modified for take-off, but the vast majority of the current batch of Lowrider Moths are the superb variants of the Magnum design, from the drawing board of inspirational designer Mervyn Cook, allied to the skilled boatbuilding of John Claridge.

Incredibly, even after 50 years of being 'lost', barn-find Magnums (and other designs) still turn up from time to time, with many requiring extensive rebuilds. It says much of the skill set found amongst the Moth sailors (who, like their boats are equally subject to the passing of the years) that what some might have seen as a wreck soon reappears at an event looking as good as new and with race-winning potential.

All this might sound very jolly and there's a real sea story to be had surrounding the romance of restoring a fast boat from yesteryear to a winning boat of today, but the harsh truth was soon laid out for the Lowrider fleet that turning the clever notion of a Lowrider 'classic' fleet into something more solid (and with the potential for a robust future) would require a better supply of boats than just the diminishing trickle of barn finds.

Some new 'old' boats were already being built, with the Mistral design proving popular as this is about as easy a stitch-and-glue as it is possible to get: you end up with a vee-shaped hull that's wobbly on the water, but this is the Moth fleet after all.

Clearly what was needed was a supply of hulls made to a known design that would allow the Lowrider scene to grow, but here the arguments soon bordered on the philosophical! On the one hand there were those who felt that going down the CNC cut kits of ply parts would keep the Lowriders true to that earlier ethos, whilst at the other extreme were the speed merchants who wanted a super skinny hull that would be the Subaru Impreza of the dinghy park.

Then thankfully reality broke through, for if the Lowriders were to attract new blood then the boat had to be accessible. Nobody expects Moth sailing to be easy, but whilst sailing the boat might make you stressed, you shouldn't be distressed. Attention quickly focused down onto the Magnum range, with the wiser minds promoting the delights of the Magnum 6.

This is far from a step-in-and-sail boat, yet neither is it beyond the skills of a reasonable helm who is prepared to endure some early days pain (or at least, getting very wet) before mastering one of the best-designed all-round dinghies out there.

Selecting a design would only be the first step, there was then the bigger issue of how to take that forward, but here the Lowriders were lucky, as the builder of so many championship-winning dinghies, Ian Ridge, had returned to the Lowrider scene where he had first carved out an enviable reputation as an innovative boatbuilder and as a top helm. Having built more than his fair share of radical Moths, Ian was very much of the mindset that said that whilst others were still talking, he would already be working!

And so, it came to be! Ian located a set of plans for the Magnum 6 out in Australia and whilst these were being airfreighted to the UK, he was already getting stuck into the detail, with more advanced planning taking place. Back in the day all of the Magnum 6s had been made from tortured ply, but Ian's plan was to go the whole hog, first building a plug, then creating a mould in which high-tech hulls could be turned out on demand.

Even as the newly arrived plans were being pored over, construction of a hefty rigid frame was under way, onto which would be placed wooden hull profiles at 1ft intervals. Stringers and a hog would be laid onto the growing hull form, but now the advantage of that early planning time came to show its worth.

The Magnum 6 has something of a lipped chine running for the aft 4ft or so of the hull, which would preclude the use of a conventional mould. Instead, Ian devised a clever series of flanges that would allow the mould to be eased open, allowing the completed hull to be released. He also arranged for the gunwale flange on the hull to incorporate a curved rebate, with the deck mould having a corresponding male section so that, once laid up, the two mouldings would almost self-locate.

By now the part-complete hull form was being planked up, which finally revealed the true brilliance of Mervyn Cook's design. The hull has very little rocker and what there is looks like three joined straight lines. At rest, both ends of the hull are in the water, but as soon as the boat starts moving it creates a dynamic lift allowing the hull to all but take off. It is clear to see just how for many years the Moth fleet would defy the best efforts of the PY Number setters, as just a year or two earlier they would have been rated in the Firefly/Enterprise area, yet now they had reached the point where they could be quicker than a Merlin Rocket with the speed to take a Fireball on a reach.

It would be easy to think that with the hull shape complete that it was 'job done' but it soon became clear that to date only the easy work had been done. Now, after being coated in a single layer of 300gm/m woven glass mat, a highly repetitive process of sprayed on high build paint that was then longboarded away saw the minor imperfections taken out, with any hollows being filled before the process started all over again. Just one small hollow, all but invisible to most eyes, was highlighted by Ian's soft pencil, so that it could be filled again, longboarded, more high build and another three days, before moving on to the next one.

Next up the whole plug had to be flipped upright, so that a similar process could be taken to create the deck mould. The scalloped recesses for the wing bars, mounts for the kicker array, kick bars and supports for the rudder gantry were all factored in before... yes, the longboarding started again.

Progress up to this point had been steady and at times almost spectacular, with one target being to get the first hull out of the mould in time for the Dinghy Show, only for fate to play a cruel hand. As the saying goes... to lose one member of the team 'crocked' may be regarded as misfortune, to lose another looks like carelessness! It certainly wasn't the latter, but without going into detail the build project would effectively grind to a halt for the best part of three months. Even when work restarted, there was little option but to proceed at a lower tempo than before.

Even so, the end of the beginning was now in sight, as the hull was once again sprayed then cut back. The final task was to start laying on the Mirror Glaze release wax, coat after coat and now all that work in filling and longboarding was seen to have paid its way, as, after six full applications, the gleaming plug looked very fair without any of the 'rippling' that could be found on the old tortured ply hulls. No sooner had the finished hull form reached the point that you could see your face it in than it was covered in gel goat, before the worked started to lay up the mould over it.

The first layer was 300gm/m, then over the next few days a half dozen layers of 600gm/m cloth were glassed in, but care had to be taken as a degree of flexibility was required at the flange points, to allow for the chined area in the aft sections.

One of the great advantages of the Lowrider scene is in the way that they have embraced racing under PY rules, so there should be nothing to stop a 2024 version of a Magnum 6 happily racing on a level playing field with a near 50-year-old version. However, amongst those who know and have sailed the '6' there is a growing sense of excitement and anticipation as now, so many decades after the boat was first launched, the 'ultimate' in Magnums could soon be tested afloat.

Little surprise then that a number of helms of yesteryear are looking at the prospect of an all-carbon Magnum as, if they were exciting before, the new boats could be rocket ships.

In Part Two of this series, we will see the hull turned back up the right way so that the deck mould can be made, then comes the moment of truth for the flanges and the mould is released from the plug. After that, it is but a short step before the first hull is laid up, with some projections putting the hull shell as weighing in a little more than 8kg.

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