SOLO RACING / CREWED RACING HULL DESIGN

We have been looking at hull design development following the evolution towards better performance and paying attention to the differences between  hull designs maximized for solo racing and crewed racing. Even if the main point of interest is the evolution of cruising designs the focus, in what regards hull development, is on racing since it is here that the developments are first implemented before being used on cruising designs.

While today main market cruisers are used almost only for cruising, performance cruisers are used many times with a dual purpose : cruising and racing; so it is natural that while on main market cruisers the main hull influence comes from solo racing, on the performance cruiser market the influence is a more mixed one, having the boats different compromises in what regards solo and crewed racing. 

Contrary to main market cruisers they are designed taking into consideration IRC and ORC handicap racing and its particularities. On the recent developments on these boats the increase in popularity of short hand racing on the traditional handicap racing circuit has importance in what regards a bigger balance towards short hand sailing potential.

To have a better idea in what concerns these two different type of hulls, let's look at two recent designs (2011) by a top designer, Mark Mills and look at the differences in what regards design and also at the similarities.

 On the left we will have a 45ft crewed racer and on the right a 38ft short handed cruiser-racer, that is pretty much what the performance cruisers are today.

We can see that in both boats the beam was all brought back and also that they are beamier than what he used to design some years back. If we compare the Mills 45 racer with the Ker 46, we will see that the Ker is even beamier so, no doubt: in the last years, on racing crewed boats pointed to max performance (upwind and downwind), the beam has increased. No doubt also in what regards beam being brought back.

Regarding the differences, the Crewed racer (including the Ker 46) have a single very deep spade rudder while the performance cruiser has two rudders. We can conclude that in absolute terms a single rudder has advantages in what regards performance but that a twin rudder offers a better and easier overall control that, taking into consideration the solo or short crew, will turn itself on a performance advantage.

We can see also that the transom design on the crewed racer is very different and while the 38ft performance cruiser has a much lower chine, working at relatively small angles of heel, the 45ft crewed racer has a very high chine that will only work at very high angles of heel. That will allow it to explore the bigger RM obtained at high angles of heel and the weight of the crew on the side of the boat, without having the chine creating drag.

The lower chine on the 38ft performance cruisers indicates a boat that is designed to sail with less heel, a boat easier to control specially upwind were that chine will help to prevent roll, offering an extra help and extra time to control the boat when the sails are not perfectly adjusted.

 On the Crewed 45 racer the hull will offer a better overall performance, if the boat is always in a tight control, that can only be provided by a big expert crew, at least when the boat is sailed close to the limits. Again, the easier control of the 38ft boats will turn as a performance advantage when the boat is sailed with a short crew or even with a less experienced crew.

Very interesting to note that on the evolution of that 45 design, that is basically the new Summit 45, even that high chine has disappeared, offering all the lateral side of the transom as a plane that is used to sail upwind, providing a huge form stability at a high angle of heel. A similar solution  is also used on Ker crewed racers. We can see that Mills are using no chines on there more recent crewed racers, namely the very fast Alegre 3 mini-maxi.

We could talk about the difference in beam but, having the boats different lengths, that is not very relevant in this comparison since bigger boats tend to be proportionally less beamier. It is true that beam contributes to create a more stable platform, a boat that sails with less heel making it an easier boat to control and that's why solo racers are very beamy. But we are talking here about a 38ft performance cruiser that will be used also in racing and we know that beamy racers rate poorly in handicap racing. Besides most solo racers are designed with Transat in mind and are more balanced in what regards performance to downwind sailing. We will leave that discussion for another time.

For now I can just say I love that Mills 38ft and it is a shame nobody will be producing it since it seems to me very well balanced and a beautiful performance cruiser.:-)
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Mr Pelicano:

Paulo - Your observations regarding the design trends in crewed racers are also confirmed when you look a the TP52 class, such as Azzurra and Quantum Racing. These boats carry about as much beam as you could reasonably expect on a 52 foot boat, brought well aft, but with either no chines at all - Quantum Racing - or a mild chine,carried quite high - Azzurra. We know from the racing results that Quantum Racing is a very fast boat, but also that the level of crew ability is extremely high. So we would expect that chines could be dispensed with because Ed Baird and Co. are able to sail the boat in its sweet spot under most conditions. That is not to suggest that Alberto Roemmers and his talent-rich team aren't just as good as Quantum Racing. J/V obviously have their reasons for retaining the mild chine in the design - perhaps to favor performance off the breeze in stronger winds. Botin & Carkeek may have chosen to make QR more of an all-around performer.