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Cherubini Classic 20

Built by:

CHERUBINI YACHTS

Factory and sales:

51 Norman Ave.

Delran, NJ, 08075

Tel: (856) 764-5319

http://www.cherubiniyachts.com

Cherubini Yachts has continued development of the Cherubini Classic 20 speedboat.  Originally conceived as a jet boat, market reaction was a little lukewarm to the idea of a jet in a classic speedboat.  Cherubini Yachts decided to adapt in I/O drive to the hull which actually works very well, if you can get beyond the modifications to the transom to accommodate the drive unit.  Actually, Cherubini Yachts has done a marvelous job.

The new I/O configuration can be equipped with either gasoline or diesel engine.  The gasoline engine is a Mercruiser 220 HP 4.3 liter V-6 going to an Alpha I outdrive.  Speed has hit 60 mph at 4500 RPM.  The diesel version is equipped with a Yanmar 220 HP 183 cubic inch in-line 6 cylinder diesel going to a Mercruiser Bravo I outdrive.  Speed has hit 57 mph at 4100 RPM with a 4-blade prop.  The hull had to be modified to take out the jet pump flat and keep the hull design as a full deep-V shape, 20 degrees deadrise at the transom.

Another option is a 5.0 liter gasoline V-8, 375 HP with closed cooling with a Bravo I outdrive.  Top speed to date is 57 mph.  This may be a little low, and some propeller tuning might be in order to improve speed.

The two-cockpit Cherubini Classic 20 is the more popular arrangement of the design, simply because you can carry 5 people in the two cockpits versus 3 people in the single cockpit version.

In the image above of the current production design, all the wood that you see is real.  The Classic 20 is built with a cored fiberglass deck over which is added the mahogany deck overlay and all other wood trim.  Real wood was not in the original concept of the boat.  In the article below, you will see the first prototype of the Cherubini Classic 20 with its computer image wood deck and transom.  We had anticipated that we could scan the image of wood into a computer and print it out on a fabric that we could place right in behind the clear deck gelcoat in the mold.  The result was absolutely remarkable.  At the Cherubini Classic 20 world premier at the Annapolis Boat Show in 2002, we had all the marine carpenters and cabinet makers totally fooled.  Nose to the finish, they could not tell that the "wood" surface was fake.

Ultimately, however, we met with a few problems.  The red dye in the ink of the printed image reacted with the catalyst in the gelcoat and resin, and the image started to fade.  This was not good.  We surmized that this was the problem at the time, but financial considerations led my original client, Independent Classics LLC, to go out of business before we could prove the source of the problem and find a reasonable solution.  Another problem we faced is that with all those stripes on deck, workers had to get the image placed absolutely correctly the first time every time.  If there was a slip up and some of the stripes were squiggly or out of line, it was really obvious and not easily corrected without damaging the image.  By the time Cherubini Yachts Inc. took over production, they made the decision to stick with the tried and true--real mahogany with any of a selection of white wood strips over a fiberglass deck.   Built by hand, the wood and the strips are always exactly right.

Another development that is going on at Cherubini Yachts is a lengthening of the hull to 24'.  As is typical sometimes of new boat development, the crew is kind of cutting and pasting hull and deck bits together, putting in a big engine, and seeing what happens. You may read the story of the Cherubini Classic 24 by clicking here: Cherubini Classic 24

Ultimately, what would be nice to see is a conventional prop drive under the hull as in a classic inboard arrangement.  Because of the way the tooling was set up with the engine aft, a 4.3 liter V-6 could fit into the hull backward and go to a Walter V-drive which would be situated under the aft-most seat.  New development always takes financial investment, and that is always made easier if a customer is ready and waiting.  Any takers...???

 

The following article appeared in the December, 2002, issue of Soundings magazine, page 28 when the Cherubini Classic 20 was a brand new design. Extra photographs have been added below.

The Designs Of The’20s Come Roaring Back.

Why and how the Cherubini Classic 20s were designed (originally created for Independence Classics, LLC).

By Eric W. Sponberg, Naval Architect, P.E. (CT)


Designer of the Roaring Twenties by Cherubini YachtsTop management at Independent Classics had a very clear idea of a new production speedboat: Design an affordable 20’ speedboat with the latest boat design and construction technology using infused fiberglass, but make it look like a wood speedboat of the 1920’s. And it can’t look “kind of like wood;” it has to fool you. The boat has to look so much like the real thing that you have to be told it is fiberglass. Power it with a jet pump for shallow water running and the increased safety that goes with eliminating an exposed propeller. Design a single cockpit “roadster” model (the “sports car” version) as well as a double-cockpit family model (the “sedan” version). The boats not only have to look fun to drive, but they have to be fun to drive.

What a challenge! I couldn’t say no!  A number of factors make this boat right for the market. The leading edge of the baby boom generation is on the verge of retirement. The children are out of the house and out of college. Discretionary income is increasing, in spite of the recent recession. We can afford to pick up our childhoods where we left off. Retro-style products are in high demand, as evidenced by automobiles such as the Chrysler Prowler, the PT Cruiser, the VW Bug, and the Ford Thunderbird. These cars are fun, new designs in the “old style” of the early 20th century, but build with the technology of the 21st.

We could build a reproduction of the real thing, a genuine wooden speedboat to exact designs that were popular 80 years ago.  But they would be expensive to build, buy, and maintain; they are not the best performers compared to todays modern speedboats; and other companies are already doing that.  And, while many of us may be wooden speedboat enthusiasts, we are not aficionados, nor do we care to be.  So wouldn't it be nice to capture the romance of the 1920s at an affordable price with the minimum of maintenance?  This is the market for the "Roaring Twenties" speedboats.

I took inspiration for the “Roaring Twenties” from a couple of good coffee-table picture books on antique speedboats. The overall “long nose” look of the single-cockpit boat is similar to a Gar Wood. The barrel-back transom is reminiscent of a Chris-Craft. And the black-enameled perimeter plank in the deck appeared on some Hacker Craft. The hardware was inspired by a variety of boats, consistent with what is available on the production market today. Lots of the original hardware was chrome-plated bronze, but these days it is a real mixture of materials. Independence Classics is endeavoring to get all the hardware sourced out in as few materials as possible, preferably all in stainless steel. This will mean custom tooling for some items.

The hull design had to incorporate the most modern design sense. For example, the original boats of the early 20th century had very hollow, concave bow sections running back to very flat sterns. They were fast, but they pounded in waves and were very wet. Today’s generations of fast runabouts have convex sections forward running back to a constant-deadrise V-section aft. Just about any transom deadrise angle between 16° and 24° will work, and the trick is to get the right amount of deadrise angle that is consistent with overall beam and the boat’s intended weight. For any given weight, as the beam gets wider, the deadrise angle has to reduce. We chose a beam of 6’-10” and a deadrise angle of 20° which gives us good flotation for the weight we want to carry.

Lifting strakes at the chine run the full length of the hull with a slight downward angle forward and a horizontal run aft. From our current powerboat design science we know the proper relations between center of pressure, center of profile area, and center of gravity. We seem to have hit a home run with this combination because the “Roaring Twenties” are fast, stable in turns, and squish softly through on-coming waves. Driving one is like driving a Porsche with Rolls Royce suspension.

Naval Architect at 40-Eric Sponberg enjoying his first try at the helm of IC 20 prototype #1. That’s 40 miles per hour, not his age!

Industrial regulations demand that fiberglass manufacturers clean up their act. We cannot release VOCs and toxins to the environment. In addition, we have to squeeze the most strength and stiffness out of the minimum of materials. And we have to be efficient with labor-time is money-and the less time in manufacture the more affordable the product. One answer to all of these demands is resin infusion technology, one of the cleanest fiberglass manufacturing processes ever developed. It produces laminates with the strongest and stiffest mechanical properties, and more consistently, than any other wet FRP process. It requires a minimum amount of labor, and workers love it because they don’t get covered in resin as in traditional wet processes. To get production off the ground quickly, Independence Classics is beginning with wet lay-up production using multi-directional E-glass knitted fabrics and epoxy-based vinylester resin. Ultimately, they will endeavor to shift production to resin infusion.

The wood images for the hull, deck, and other parts are created by scanning real wood master patterns into a computer and printing them onto a thin fabric. This image layer is laid into the hull and deck molds behind crystal-clear UV-inhibited gelcoat, wet out with more resin, and allowed to set. In the infusion process, the structural laminates and internal framing are laid into the molds dry, topped with the infusion bag, and infused with resin to a predetermined glass content. During final assembly of the boat, the hardware is strategically located to hide all the molding seams, flashing, and joints. The boat’s finished appearance is beguiling.

As for power, Mercury Marine’s jet is a 6-cylinder outboard powerhead mounted on their own jet pump. Standard power for the “Roaring Twenties” is their lowest rating at 175 hp, but we can offer the maximum at 240 hp. This power package is inexpensive and lightweight, and installation is simple. Owners do have to fill an oil reservoir in addition to the fuel tanks for the fuel-injected two-stroke engines, so if you don’t want that, we can offer other powering options.

All in all, the “Roaring Twenties” were meant to create and fill their own niche. Production has only just begun with the first prototypes making their debut at this autumn’s Annapolis and Ft. Lauderdale boat shows and other selected winter shows. Dealer inquiries are invited and can be directed to Independence Classics LLC in Delran, NJ. Other designs for Independence Classics are under consideration for future development, so dealers and owners can expect a range of sizes in these unique craft.

The IC20s as they appeared with designer Eric Sponberg at the Annapolis Boat Show in October, 2002.

 

A note from Eric Sponberg about drafting, artwork, and design.

This project was interesting in that I started designing the IC20 the old fashioned way-with paper, pencil, splines and weights. Don’t forget the eraser! I needed to sort out certain hull shape ideas quickly, and these materials offered the fastest way to achieve my design goals. After I settled on the basic size and shape of the hull, I recorded offsets from my hand-drawn drawings and entered lines and shapes as templates into my hull design program, ProSurf. When the computerized hull shape was finished, I exported hull lines information into AutoCad and began the detailed design process for the construction drawings. In all, I produced 24 sheets of drawings at 11”x17” to fully document the design.

Some of these drawings were the general arrangement plans for the single and double cockpit versions, as shown below in their profile views:

I then hired a local marine Newport artist, Joe Comeau, to produce the renderings. Using my line art drawings as a guide, he “painted” the general arrangement renderings in his computer. Independence Classics then used his artwork to produce the first brochures for the IC20 for the boat shows. Joe’s arrangement plans for the single and double cockpit versions are shown below:

IC20 single cockpit profile view, the original design.

 

IC20 single cockpit plan view.

IC20 double cockpit profile view. We think this boat, fitted with the 240 HP jet pump, will be the best selling model.

IC20 double cockpit plan view.

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