Where are the mid sized multis - the case for a class 40 trimaran

Who remembers trimaran Financial Times? Well I'm old enough to qualify. The 1970's were heady times for multihull sailors with trimaran design evolving rapidly and a host of new designs competing on the European race scene. David Palmer's 35' Kelsall design Financial Times shown here was launched in early 1974 and competed in the Observer Round Britain Race and the OSTAR of that year. The decade that followed saw a burgeoning of multihulls on the European and Transatlantic racing scene up to the establishment of the short lived Formula 40 racing circuit.

In recent times we’ve had the one design Extreme 40’s and now the GC32’s active on the inshore racing circuit. But what of offshore racing in the sub 60’ size range?

 In the 2015 Fastnet Race high performance multihulls dominated the elapsed time results but multihulls were poorly represented in the under 60' LOA size range.  The French trimaran Olmix was pretty much the only high performance multihull in the sub 60' size range to show her paces.


Her performance was impressive enough. 

Olmix sailed the course in 3 days, 9 hours and 40 minutes give or take a couple of seconds, just 22 minutes behind Tales 11, the first boat home in the Class 40's. Olmix has ten feet of hull length over a Class 40, but she's the nearest thing we have to make a multihull - monohull comparison in the fleet in this size range. 

She was built in 1991 entirely from wood epoxy and has a published displacement of 5800kg. A state of the art Multi50 trimaran by comparison comes in at 3.8 tonnes.


The Class 40's, just ten years since their inception as a class, were the biggest non IRC fleet competing in the Fastnet with 22 boats, most of them highly competitive and some with top ranked crews on board.


After nearly three and half days of racing the two fasted 40's in this year's Fastnet, Thales 11 and Concise 8 fought a 200 mile match race to the finish and crossed the line just 19minutes apart, an incredibly close result condsidering a high percentage of the race was sailed in drifting conditions with strong tidal currents.

The 50' French trimaran Olmix was the only Multi50  trimaran in the 2015 Fastnet race and the only competitive multihull under 60' LOA

So why no high performance multihulls in this size range in the fleet? What is it that’s attracting competitive crews to the Class 40’s in preference to multihulls, especially given that a number of the Class 40 sailors are professionals who also sail the larger trimarans, some of them sponsored by the same sponsor as their  Class 40 counterpart?


I expect there’s a number of factors involved but the success of the Class 40 box rule and the competitive race scene that has evolved as a result is possibly the dominant factor here.

What about the Multi 50's?

The Multi50 rules were established to a philosophy similar to the Class 40's at a time when the ORMA 60's were losing favour due to their cost and some rather compromising design features that had evolved as a result of the rules.

The basis of the Multi 50 Rules (15.24m LOA)  includes the prohibition of canting masts and a limit of six sails including a storm sail.

Titanium is prohibited and the use of carbon is limited to particular components.

Nine yachts are currently listed on the Multi50 web site including Olmix. We've seen some spectacular performances from these boats in events like the Transat Jacques Vabre, but they've failed to set the yachting scene alight as a class. 

Could it be these boats are too big and expensive for most amateur yachtsmen, and too small to attract the backing of sponsors who appear to prefer to invest in the more high profile maxi multis like Mussandam-Oman Sail, Prince de Bretagne (who previously sponsored a Multi50 trimaran), and Spindrift 2.


Irens designed Multi50 trimaran Nootka

There is no doubt the Class 40’s are exciting boats to sail. Skipper of Tales 11 Gonzalo Botin reported on the sailing on the return leg of the Fastnet;  

“At one point we were doing 15-18 knots – it was some of the best offshore sailing I’ve done – really excellent,” said Botin. “We were going very fast but the guys (on Concise 8) were matching our speed.”


And Jack Trigger, skipper of Concise 8 reported;

“When Tales II caught us up we started to really think what we could do so we hoisted our high clewed reaching sail and we were doing consistently 16-17 knots of boat speed at 100° TWA with one reef in. And the race was incredible! The question was – who could hold the biggest sail and could we get high enough to get around Bishop Rock and still stay fast. You could catch some nice waves and we did a nice job of staying fast - we came alongside them but they hit another gear again and were off."

(Quoted from the official web site of the Rolex Fastnet Race)

Class 40 Concise 8

It sounds like the kind of sailing multihull sailors lust after. And while we can’t be sure what the sea state was like there’s no reason to believe that a well designed and well sailed 40’ multihull would be going any slower than the speeds quoted here.

You can find any number of Class 40 polars on the web and most of them max out somewhere between 18 and 20 knots at a wind angle of about 150˚.

The polar on the right on the other hand shows a Seacart 30 trimaran maxing out at a clip over 24 knots at a wind angle of 120˚. We can verify this figure is realistic from racing in Australian waters.  And the 30's curves are lot more rounded between about 50˚ and 80˚ wind angles - not much doubt who has the advantage here.

Mod 70 trimaran Paprec - Team Concise

How close is that?

The Class 40 fleet returning to Plymouth after nearly three and half days of racing - a lot of it in light and drifting conditions with strong tides. 

The screen snap top left shows the wind conditions that Tales 11 and Concise 8 were racing each other as described by their respective skippers above - about 20 knots of true breeze and just a tad behind the beam!!

Performance Comparison with Multihulls

So how would a high performance multihull suited to an ocean race like the Fastnet fare for performance against the Class 40’s? Well there is no doubt the class 40’s are fast, but if we look at the primary design critereon of sail area and weight we can make some basic comparisons.

The sail area of the Class 40 main and solent combined is limited to 115sq.m. This is pretty much the same as the 40’ Irens designed trimaran Carbon 3, and similar to the proposed rig for the Grainger R40 trimaran. But the minimum weight of a Class 40 is 4.5 tonnes and about 40% of that weight total is in the bulb and fin keel.

We could realistically design and build a 40' offshore racing trimaran somewhere between 2.7 and 2.8 tonnes, less than two thirds the weight of the Class 40, and without resorting to exotic materials or highly sophisticated build methods . 

A catamaran would be even lighter but not so forgiving for extended offshore racing.

 Further, a trimaran is likely to knife through steep seas in fresh conditions a lot more cleanly than the modern day broad hulled monohull, and might also have an advantage in light and medium air.

Ave-Gitana above. This 40' Crowther trimaran is a sister ship to the well travelled and renown Verbatim/Bullfrog. A contemporary trimaran in this style would make for exciting racing under a box rule of similar concept to the Class 40 Rule.

The Class 40 Rules

The English version of the  Class 40 rules (the Class Association is French based) comes to no more than 21 pages of broadly spaced easy to understand text and diagrams. The introductory paragraphs make the spirit of the rule abundantly clear; 

The Class40 association was formed with the aim of creating a fleet of simple, seaworthy, performance-oriented, ocean-racing yachts, and where possible within a limited budget. These Class Rules aim to fulfil this mission, but no text can anticipate the capacity of human intelligence to exploit the meaning of words in a manner not in line with the original aim of these Rules. 

For this reason, it is highly recommended that any questions on the interpretation of these Rules which might be contrary to the spirit of the Class be put first to the Executive Committee, to avoid the risk of being considered outside the Rules. 


This is not a rule that encourages cashed up owners to employ lawyers and technicians to scrutinise the wording and look for loopholes that can be exploited with intricate design or the use of exotic materials.


Attempts to establish class racing in offhore capable multihulls have met with limited success over the years. But maybe the approach has been wrong. It should be noted that the Class 40 rule is a box rule - not a one design rule. It allows development in hull and rig design similar to the rules for A Class and C Class cats. You can read the class rules in about as much time as it takes to stroll from your car or marina apartment to the end of the dock. And the emphasis is squarely on keeping it simple and keeping the cost within realistic bounds.

Class 40 Racing

Some of the details in the rules include:

Daggerboards, deck spreaders, rotating masts and canting masts are forbidden

All materials other than woven or laminated polyester and nylon (modulus lower than 300g/denier) are forbidden in the manufacture of other sails, with the exception of two sails and the heavy-weather jib which can be made from any material 

The boat weight must not be lower than 4500 kg in measurement trim.

The surface area, mainsail + solent must not exceed 115 m2. 

Building material:

The boat’s hull, bridge, structure and internal fixture shall not be made of the following materials.

Fibres : carbon Aramid. Sandwich : nomex honeycomb aluminium alloy honeycomb

Chain plates: All other materials than steel or stainless steel are forbidden.

The use of titanium and materials denser than the lead is forbidden. 

Carbon, Aramid and honeycomb cores are forebidden in the hull construction, as is the use of pre-pregs.

Batteries shall be exclusively lead (acid or gel) 

You can see the full class rules here:


The Class 40 rules won’t translate directly to a 40 trimaran. Stainless Steel rigging is largely replaced by synthetics in modern multihulls, and stainless chainless might seem a little quaint. Carbon is pretty much indispensible for beams, rudders, and boards and other components where stiffness is critical in multihulls, but in spirit at least the rule could be reinterpreted and adopted to a trimaran class without too much difficulty.

 So what about a box rule for a 40’ offshore capable multihull? Would it attract racing skippers and crews in the same way the Class 40 rule has attracted racing enthusiasts, with over one hundred and fifty boats on the water at last count.

The image at right is the R40 trimaran proposed by Grainger Designs and ideally suited to a box rule like a multihull version of the Class 40.

This article is a work in progress. Happy to hear your views: