Making the Most of a Minimal Budget. Contact me at: or on Twitter: @skintsailor

Friday, 6 September 2019

Yacht Design.

I know I'm late to the world of yachting, but like all things mechanical, yacht design does interest me.

I've commented before on the plague of insufficiently supported keels snapping off offshore yachts (possibly the worst type of yacht for this to happen to).

This is a more positive post.

Looking at the latest racing yachts, starting with the one most local to me, Alex Thompson's new Hugo Boss IMOCA boat.

Some interesting design features on that boat already. It looks like the philosophy around the bow on racing boats has changed in the past couple of years. The Mini-Transat boats, with their bulbous bows for increased buoyancy up front are no translating to the bigger boats.

Some good picture of the boat here:

If you look at the picture of the box, it's quite bluff and has a whaleback to disperse any water that gets on top of it, so the bow is designed to travel over waves rather than the wave-piercing design previously used.

Makes sense in a boat that is designed to fly or foil, rather than sit on the water. I assume the idea is to get the bow on top of the waves as soon as possible, so the boat can foil. The same bow profile seems to have migrated to a few other racing yachts that have been announced in the paste few weeks.

The bulbous bow design can be seen on the latest Jeanneau IMOCA boats, although they don't foil, I assume the increased buoyancy at the bow helps to stop the bow digging in and slowing the boat. It will also help stop pitchpoling at high speeds.

In fact the new Jeanneau SunFast 3300 has the same bow profile. A very tasty looking boat that... Just need the lottery win...

Finally in the bluff bow category, we have the newly-launched Team Emirates New Zealand AC75 Americas Cup boat named Te Aihe. Maybe not quite as bluff as the European boats, but still has the essence of the design philosophy.

Moving back from the bow, the hull profile has started to flatten out. I assume because the boats (except the AC75) will be mainly travelling at an angle (the bluff bow also makes the buoyancy even along the hull when heeled) or if not heeled, then foiling. Here, drag is the issue, so drag reduction is the key in order to get the boat up to speed quickly. For the foilers, getting up to foiling speed is the primary function of the hull profile.

The AC75 seems to have a flat section apart from the centre, where there is a bulge in the hull. The AC75 has two massive foils that are down all the time and are ballasted. The boat is designed to sail flat and then foil  so reducing wetted area in the centre reduces drag and gets up to foiling speed quicker.

The new Boss Boat seems to be entirely flat, although the long pictures of the hull seem to indicate a long concave to the hull. But that could be due to camera optics. This is definitely designed to sail heeled.

In this regard the Jeanneau IMOCA boats take the design a step further and add concave sections to the hull. Getting the hull away from the water reduces drag.

Finally we come to the foils. The Jeanneau boats are not designed to foil, being a cheaper entry to the IMOCA class.

First it's interesting to look at Charal, Jeremie Bayou's new boat. It can be classed as a transitional design. It has the element of the latest IMOCA design rules, like big adjustable foils able to change angle of attack, but the hull profile (especially the wave-piercing bow and hull bottom) is rooted in the previous designs.

The New Hugo Boss boat takes the New IMOCA rules to a totally new level of design. The boat is currently running large adjustable foils, but I assume they are not the final design.  Interestingly, there appears to be no pictures released of the boat foiling yet. I do know it's been out in the Solent, but I assume the pictures give a bit too much away about the hull's interaction with the surface of the water. Scrub that: seconds after I wrote this footage appeared on Social Media of the new HB boat in full flight.

Of course the AC75 has just been launched, so not pictures of it actually sailing yet. But the test mules run by the different teams across the globe show that the boats will be big, fast, foiling and not too easy to control. It should be an interesting Americas Cup when the final designs run off against one another. I do hope that it will be available on free TV somewhere and not behind a paywall or subscription.

Another interesting feature of the New Hugo Boss boat is the amount of solar panels installed. Virtually the whole boat's top surface is covered by a bespoke solar installation. This allows more electrical kit to be used without having to use diesel to generate it or having to have a draggy water-powered generator. Looking at it, the boat is designed to be run from inside. The aft end of the boat doesn't look to have any equipment for human interaction at all. How that works out when having to trim sails mid-ocean I don't know, but by 'eck it will be fun to watch.

So, there you go. Yacht design at the top end has evolved yet again. The SunFast 3300 looks to take the latest design philosophy and cram it into a 33ft boat. Very, very tasty. Out of my league, but then again so is an old Westerly Centaur!

Still, it doesn't stop me appreciating these new designs and any traits they have filtering down to boats even mortals can afford, even if it's for millionaire mortals. Those flat-bottomed designs would translate well to sitting on mud moorings like mine, all they need is a retractable keel. Now then, I need plywood for a mould and a ton of carbon fibre and resin... anyone got any going spare?