Keeping Up With The Cal 40

The Lockheed C-130 Hercules first launched in 1955 as a cold war crusader but has gone on to become a staple of modern aviation. Because of its unique adaptations and innovations including upgraded engines, revised wing shape, and avionics, it will become the first military aircraft to stay in continuous service for a hundred years. Photo credit: Lockheed Martin

It’s been a while since we had a good stir-of-the-pot to get us fired up about something other than politics and the news for a minute.  So we figured why not throw our paw in the familiar beehive of that argument for a full re-imagining of a dear, beloved classic: the Cal 40.

This isn’t our first soiree into the merits of putting new life into a design released the same year that JFK was assassinated, and the Sabin oral Polio Vaccine was first distributed with a lump of sugar to kids across the US.  In fact, we’ve jumped into the deep end twice and received a massive response (the good, the bad, and the ugly) each time.

In our first article, we put Cal 40 owners on notice that it was time to address the lingering design issues and suggest a path to update these treasured boats for the 21st century.  We outlined an array of points in our brief that called out details including wide-ranging weights across the fleet, dated sails and rigs, cumbersome deck layouts, the (OMG) kooky cockpit ergonomics, and quirky mechanical choices.  We also identified some rigging problems that continue to make us a little seasick when we think about the prospect of amateur sailors taking their Cals hundreds of miles offshore… even on a good weather day.  Other than that, great boats!

The overwhelming response to this first piece (one of our biggest ever) prompted us to draft a follow-up response, where we doubled down on the details and costs of a full Cal 40 reboot. Our full menu of updates included new rigging, sails, keel, rudder, cockpit and sailing hardware, interior, propulsion/systems, and paint.  The whole enchilada, including design fees and labor, came to $350-$375K all in.  A big pill to swallow until we compared it to the price of a comparable custom racer like the The Solo 38P (also a great choice).

Originally created as a daysailer, Solo is all about style, charisma and high performance. A slightly tuned down racing yacht, Solo has conservative draft and a punchy sail plan that promises a lively sailing experience.

So, if our first article outlined the ingredients of the design brief, and the second article the recipe for success –consider this a reveal of baking the cake, itself… at least a rendering of it.

Your Cal 4040 Cake

The Cal 4040 Concept by Stephens Waring. Note, the cockpit arrangement, updated underbody, and the boost in plumage.  

Deck and Cockpit

Almost all practice of design most certainly involves the necessity to iterate and refine. It’s not lost on us, here, that if given the chance perhaps the creator of the CAL 40, C. William (Bill) Lapworth, would have revisited many details of the boat to bring all enhancements possible to the table.  As we carve up this turkey, the way in which we’ve learned to experience sailing and how we aim to dovetail the work with the pleasure of sailing, it’s important to point out that it’s only natural to learn from what has been done before you.

Having that history is a great power.  One of the most important improvements we can make to a design is to focus on the comfort of the crew and operators aboard the vessel.  This has a direct relationship to safety concerns and ergonomic comfort that are intrinsic to the health and stamina of people on board.  We pointed to the Cal 40’s flawed cockpit in our first story, and this project gave us the opportunity to re-imagine how the handling of the boat improved by simply tuning in a thoughtful sailing platform.

The original layout placed a lengthy tiller in the middle of the cockpit well, and positioned the helmsman forward. The parallel and poorly shaped settees leftover then become quickly filled with feet and lines and the remaining elbows flailing about on all sides makes for a glitchy situation – generally causing all kinds of traffic flow and work area issues, at best.

Comparison overlay of the Cal 40 and Cal 4040 Sail Plan.

Our thought here was to parse out a cockpit that shelters the helmsman out of the way of traffic and gives a proper pit area for the management of sail handling.  Note, on the drawing, how we have almost 3 separate sections: settees forward, winches and line pit to the middle, and steering/navigating aft.  All sailing hardware is organized throughout the deck arrangement to provide good access to halyards, sheets, trimming tweaks with good visibility and elbow room for all.

Sails and Rigging

The design of the sail plan is the larger departure in the campaign to update the CAL 40. In our article we propose a taller rig where, proportionately, we have most of the sail area concentrated in the main and a 105% working jib for easy handling and quick tacking.  In light air, or close reaching, a Code 0 or Windseeker style sails are hoisted on top-down furling outside the headstay.  The idea with this  rig configuration is to get away from burdensome sail inventories–those days of multiple overlapping headsails are gone (gladly). And significant handling advantages are realized from the low-drag-high-lift nature of a trapezoid wing shape from the sq. head in the main. Reducing sail inventory is easier work on the crew and this matriculates into a simpler streamlined design brief for the rig — the lower drag wing shape in plan-form greatly reduces heeling forces on the yacht and are able to translate the lift energy more directly into driving force that benefit sailing angle and speed.

In this plan, the rig supports that square-top Main by eliminating the backstay and positioning heavily swept spreaders that locate shrouds and chainplates further aft at deck level and out to the rail of the boat – this wide-angle geometry actually reduces loads delivered into the hull and provides a nice wide shroud base for good support of the spar.  The reduction of all these stresses on the hull and up the rig mean lighter stays, turnbuckles and tube weights. With that staying arrangement, and the lighter, stiffer carbon spar, the overall weight aloft is further reduced compared to the original Cal 40 rig specs. When we match this to a more practical sail inventory, the net result of all these tweaks moves the vertical center of gravity downward, drives the weight of the craft downward, and generally reduces or mitigates certain highly loaded areas on hull and rig. Now, what is wrong with that picture?


The Cal 4040 replaces the inefficient original underbody design with a modern foil-shaped fin with bulb and foil shaped rudder.

The antiquated, under-specified spade rudder is swapped for a deeper, higher aspect modern foil. A plan form like this is a strong and efficient solution for steering under the boost of canvas we have in the proposed sail plan. A rudder like this delivers precision handling in all conditions and is intrinsically linked to the balancing of the boat and drive provided by interacting between sails and keel.

The original keel on a Cal 40 is a monster. By modern-day approaches, its lateral plane area represents nearly 2.5 times the area we would normally anticipate matching to the sail area in the original design. Additionally, that old keel is not fashioned into a quality foil shape, but is more a crude imposter: the unfair surfaces show little symmetry to centerline and appear bent and warped to an approximate foil curvature that is paired to a poorly shaped leading edge. These bullet points add up to a terrible solution that mostly results in drag on the boat.

Cross-section comparison of the Cal 40 and Cal 4040 keel and rudder design.

In the proposal, the dated keel is removed and the boat is fitted with a modern foil-shaped fin that’s more suited to the job of responding to the sail area above.  The design effort becomes two-fold: first is to increase the efficiency of the fin through proper foil-shaping and reduction in the plan-form area; then,  carve a refined bulb shape that concentrates the ballast as low as possible.  The result produces a significant decrease in wetted surface and a more capable fin on all points of sail. Going towards this deeper-draft, updated, keel, we not only reduce ballast weight and retain righting moment, but the added benefit of increased handling capability improves maneuvering and sailing across the board.

An interesting aside: analysis of the fleet illustrates a glaring, wide-range of bare-boat hull weights –nearly 4500 lbs difference across extremes.  This is certainly an issue for racers thinking about viewing the class as a one-design and is most certainly a headache for handicapping. We suspect most of this resides in loose construction management over the production years. Yet, it’s always best to approach the design and build by specifying sensible materials approaches and build techniques that can give us good light structures.

The Stats:



Cal 4040 Updates by Category:

  • Rig: Mast/rigging
    • Revised geometry in hoist and boom length.
    • Carbon mast, SS rigging, no back stay.
    • Square-top main for more efficient horsepower.
    • Solent head, Code zero Headsail in outer position, 105 working jib on inner stay.
  • Sails: 4 sails
    • top Main, 105 Jib, Code Zero, A-sail launcher.
  • Keel: Fin/bulb/structure
    • Not too finicky, yet very efficient updated foil with shorter chord.
    • All lead concentrated in the bulb.
    • Revise structural hull grid for new keel.
  • Rudder: Blade/shaft/steering
    • Again, not too finicky, yet efficient, updated plan form.
  • Cockpit and sailing hardware:
    • Fine-tuned for single/dbl-handed racing, some reconstruction required.
    • Sheets & halyards lead to helm for sailing with minimal crew.
    • Consider: add wheel steering, and definitely an autopilot.
  • Interior:Materials
    • Revise layout to remove all unneeded structure. Very light and spare is key.
    • Suited for dbl hand racing, no frills.
  • Propulsion/systems
    • Sail drive, 30 hp Volvo or Yanmar.
    • Small fridge, with cooktop and galley area.
    • Upgraded navigation gear.
    • Integrated flywheel genset (IFG)
    • Light lithium batteries.
    • Consider electric motor/hydrogenerator! Like the big boys and girls in the Open 60’s.

Borrowing from our friends in the aviation industry who brought us the C-130 Hercules (first flight: 1954), the Boeing B-52 Stratofortress (first flight: 1952) and the Boeing 737 (first flight: 1967), all of  which remain aviation stalwarts with no foreseeable plans for retirement, we too believe the Cal 40 can live on in perpetuity.  But like its aircraft brethren, the Cal 40 future requires updates and upgrades to remain relevant, reliable, and radical for the next generation.


Links to previous Cal 40 Articles

The Cal “4040”

Cal 4040 or Solo: You Decide