Z40 Roadster (Its a sailboat, not a car)

I’ve muddled on designing and building a boat for many years. Several years back I started the mental explorations of how to achieve my goals and started reading books, researching on forums like this and started the learning curves on the tools to help in the design process. I enjoy the daydreaming, designing and analysis. I also enjoy wood working and working with fiberglass and I enjoy sailing. Will the Roadster ever see the wind in her sails? I don’t know if I like fiberglass that much. However, for the cynics in the audience, I don’t expect to press the print button and get any satisfaction either.
I am not an artist. I am an aerospace engineer specializing in structural analysis using composite materials. Meaning, everything has been thought out till I’ve drilled down to China. HOWEVER, I am not a marine architect and I don’t have the practical sailing, designing and building experience that is the gold mine of this forum. There are almost no details that have a cosmetic only reason, so you might find the design rather bland compared to other artist renderings on this site. On deeper inspection you may find a beauty in its Teutonic detail, multi purpose utilization of components, its Transformer abilities and its absolute efficiency of using every cubic inch to the fullest. It is by no means a fully realized design and has some challenges to overcome. But that is part of the enjoyment for me.
Some of my ideas are rather radical and come directly from the aerospace industry. That doesn’t mean I’m certain they’ll work, but I’m willing to air them here so practical minds can throw darts… hopefully constructively!
So here we go…

My Criterion – in order of importance are…
1. Safety
2. Trailerable
3. Largest boat possible.
4. Able to single hand.
5. Speed
6. Comfort

My early inspirations were the designs by Woods. Strong, beautiful boats from an architect with a great reputation. How could I go wrong? Unfortunately, his Skua at 30’ and Sango at 25’, although trailerable, were just not something I’d want to live aboard. Any of his larger designs have to be planted in the water to stay.

Trailerable – Here are my thoughts on trailerable. I live in the United States. And I can imagine wanting some variety to my sailing grounds. I’d like to sail the Bahamas and Caribbean in the winter, Penobscot Bay in the summer, the Mexican Rivera in the winter and the Inside and Outside passages between Seattle and Denali in Alaska in the summer. Maybe throw in some Great Lakes time and even put in, in Jackson Lake in the Tetons. Anyway… you get the idea. From a safety standpoint, I also want to get it out of the water and head inland during the hurricane season. I don’t want any cordwood of mine on the shores of Louisiana! For those of you not familiar with these places… well they’re a long ways away from each other… and some not by water!
Well, trailerable gives me some definitive maximum dimensions. It must fit within 40’ x 8.5’ x 13.5’ when on the trailer. Apparently, there is some wiggle room on the width here, but in some locations here… there isn’t! So, for the moment, I’m sticking with 8.5’. Among many other reasons (for me) this pretty much rules out monohulls and trimarans.

Comfort - Although down on the list, here is what I mean for comfort. I want to be able to live on it… period. Not camping, not roughing it. A shower I can stand in and a bed I don’t have to crawl into are a must. I don’t want to duck much but I’m only 5’7” so that isn’t much of an issue anyway. I want to entertain guests… basically, I want to live 2, sleep 6 and entertain 20.
This requires a hard bridge deck! This drove me toward the Sango’s articulations. Unfortunately, they just simply won’t scale and still fit into the box given the 7’ head room requirements I want. I briefly entertained the scissor scheme, but again it takes up way too much volume for that articulation when the only time that volume is used is during the expanding. So, I decided on the sliding beam concept similar to the Skua.

Speed versus Single Handing versus… well SPEED
This one burned the midnight oil many times. I like speed. Although I want to race it, I want to live on it and that means single handing most of the time… or assuming, at least, that in the worst of conditions, it still must be single hand able. I also want to be able to use it for as long as I can stand up… 70’s, 80’s… Maybe I can still push buttons into my 90’s. I’ve daydreamed over the likes of Hydroptère, Orange, Playstation, BMW’s America’s cup and just about every architect who offers plans or techniques. Nothing had the exact combination I wanted. And my 401k plan isn’t what it used to be. So, here I am… rolling my own. If I get everything down on this thread, you should see a lot of different influences. In the end, I centered on two designs that are my driving force for realistic speed… The Z40 Roadster is based mainly on parameters gleaned from the Extreme 40 and the Gunboat 48. By aiming high, I hope to at least break 20 knots in ideal conditions.

Design
I am still relatively early in the design spiral and have only made several cycles. My analyses include simple closed-form solutions, mechanics of materials methods, LPT theory and Dave Gerr’s scantlings in spread sheets. Yes, I know, he clearly says his scantlings do not apply to catamarans. I am mainly using it for ball park sizing, weights and cost analyses at the moment and no more. However, if anyone is willing (and able) to quantify that disclaimer, I would greatly appreciate it. A single hull falls within his acceptable dimensions, so I’m assuming (for the moment) that his disclaimer is due to the high stress concentrations incurred by cross beams that his scantlings do not address.

So without further fan fare here is how it stands (at the moment)…

LOA = 40’
BOA = 23’ (Collapsed 8.5’)
Hull Beam = 4’
Maximum displacement = 13,000 lbs - I want to make sure it is possible to tow with the Dodge/Ford/GM 350/3500 class of pick-up trucks using a 5th wheel configuration. As you’ll see, the 5th wheel configuration will be required as I have to move the trailer wheels far back from the balance point for height reasons and thus too much weight would be on the hitch.

So far weight is a growing target. I am currently experimenting with resin infusion methods to try and get the fiber density up. At the 35% number Dave Gerr states the boat is just plainly not feasible. However, if I can get near the fiber percentage claimed by resin infusion, and with the following accounted for…
• All fiberglass
• All Epoxy
• Foam core
• Windows (probably UV protected Lexan)
• Teak or artificial teak decking (may have to go)
• Engines
• Batteries
• Water
• Fuel

…AND the optimistic resin infusion fiber density, I have a gross weight before people of about 8500 lbs.

TP Mast Design
If you’ve already seen the pictures, you’ve probably already noted the masts (Plural). To my knowledge, I’ve not seen this configuration before, but I’m sure if it’s out there, someone here on this forum has either designed it or knows about it. Please let me know. I’ve seen many free standing (Schionning) and some with cross pieces (Yves Parlier’s “Médiatis Région Aquitaine”) so I’m coining the phrase TP Mast. The configuration solves many problems.

Pros
1. No huge support structure to hold a center mast.
2. No huge support structure to hold free standing bi-plane masts
3. Triangulation (strongest form in nature or man-kind)
4. Wing masts have no supporting shrouds for lateral stability.
5. Masts can rotate 360 degrees as many times as necessary.
6. Main sails are furled AROUND the masts.
7. 150% Genoa are furled around dual forestays.
8. Redundant forestays and backstays for safety and strength
9. Masts are stepped on rigid posts above the deck.
10. Masts can be stepped using the booms and dual anchor lasses. (Usually something in the size range requires a crane)
11. Due to the lower center of wind pressure and tilt of masts, more sail can be carried than a conventional single mast.
12. Lower windage with less shrouds and weathervaning of mains when sails are lowered.
13. Masts can be lowered to clear bridges while motoring.

Cons
1. Interference of multiple sails decreases efficiency of sails
2. Wind speeds are lower at lower heights. Sails aren’t as tall as a conventional design.

Just to give perspective for item 10 above. At the full gross weights and each using 100% foresails… the 13,000 lbs Z40 Roadster can carry slightly more sail area than the 17,700 lb Gunboat 48. They will both start lifting the windward hull at the same wind pressure. In this configuration the Z40 Roadster can carry 1650 square feet of sail! Hopefully, this will overcome the inefficiencies described in the Cons.

Oh! Almost forgot the amenities…
• Two queen size births in the hulls.
• 108 sq ft for the Master stateroom with King size bed forward in the bridge deck. Most Admirals (that I’ve read about) clearly dislike the “living in a cave” feel associated with living down in a monohull or even worse in a claustrophobic catamaran. This Master stateroom has panoramic views of your favorite anchorage.
• 120 sq ft in the Galley
• No, interior sitting, dining area – a deficiency to some, but then I don’t plan on sailing in cold climates WHEN it’s really cold. My suth’n blood would freeze solid.
• 120 sq ft in outside sitting, dining area with seating for 10 and another 10 could easily “join” the conversation on top of the hulls.
• 34 sq ft main head with full size standing shower (30” x 30”).
• 36 sq ft Master head with shower (and maybe whirlpool bath) if weight can be balanced. The Admiral likes baths!
• Full walk in Master closet… guess who?
• 32 sq ft shop / office / dual bunk beds area.
• 3’ bridge deck to water clearance for reduced pounding
• 6.5 to 7’ headroom throughout
• The bridge deck roof lowers for “spirited” sailing for reduced windage, structural stiffness and looks. It can be raised while sailing, but the windward foresail cannot be fully extended (only about 100%). Hard windows fold into roof. “Think” modern hardtop convertibles (BMW 3 Series) NOT popup campers.
• Hardtop Bimini
o Can be slid forward atop roof for full sun into the seating area.
o Can be slid back and fastened to hand railing when the roof is lowered… have to see the pictures.
o Can be slid back and fastened to the traveler when the roof is up… again see the pictures.
• Dual cockpits in rear corners. Unrestricted sight lines (when top is down) to all points.
• All control lines will be below decks and lead aft to the cockpits for single handing.
• Steering, I’m thinking about an aircraft joy stick type arrangement. Requires less room than a wheel, and with more feel. Also will be able to have multiple places for “joy sticks” that are mechanically attached… both cockpits, one inside the Master stateroom… maybe others.
• Also, emergency tiller can easily be attached to the top of the rudder and still sail from the cockpits.
• Rudders are offset to the outside of the hulls for egress and for improved efficiency when heeling. They also flip up if struck.
• It also uses swing keels instead of dagger boards that also swing up if struck.
• Engines are electric (so far) and will be housed near the fore/aft centerline to
o facilitate turning on its center point
o protected props. Props should be fully above the bottom of the hulls.
o Permit backing and beaching the stern and allow dry walk off/on.
• Hard dingy is stowed forward under the bridge deck.
o No ugly dingy hanging off the back
o Doubles as reserve buoyancy in case the wave piercing designed main hulls pierce too much wave.
o Doubles as a racing dingy using TP Mast design also.
o BOA 6’ (fits under King bed in Master stateroom)
o LOA 15’

That’s about it… so far. I have plenty of details and if there is any interest, I’ll be glad to share some of those details.

Right now, the biggest technical challenges are:
1. Getting all the pieces on the trailer
2. Sealing between pieces – gaskets, tang and groove.
3. Transform on trailer or in-water. Both have their Pros and Cons.
4. Getting assembly time down – I want it to be assembled with little technical knowledge (owner) using a check off sheet and a couple of men (hired help) and to be assembled or disassembled within about a half day. Idea being…
a. Sailing in Penobscot bay
b. Day 1 - Trailer and transform (or transform and trailer)
c. Day 2 and 3 – Travel to Southern Florida
d. Day 4 – Transform and launch
e. Day 5 – Bahamas and beyond.

Here are some views of the model. I will be uploading a low-resolution video of the Z40 Roadster to YouTube shortly and a 720p video is being generated now and should take about a month.
Let the darts fly! And if you insist on saying my baby is ugly or stupid… at least be descriptive to the area that offends your sensibilities. I’d like to learn something.

 

Space cadet

 

Low resolution video...

This computer generated video (480x270 at 15 frames/second) shows the Z40 Roadster docking on a pier on a secluded island.

It highlights…
• Sailing under full sails upwind
• Furling the sails
• Lifting the roof up
• Sliding the Bimini out
• Rotating within its own length
• Backing up to the pier.

*** Z40 Roadster ***

Although you are seeing a lot of focus on the computer generated graphics, the design and analysis and re-redesign amount to several orders of magnitude more work than these simple graphics. The 3D models are more for analytical use and will be used for detailed finite element analysis. It just so happens that they lend themselves to generating these “pretty” pictures in the background.

 

How much do they charge for that marina berth? W-lan included?

Wow and those fishnet sails! What a nice invention, you´ll never heel too much, no nagging wife, great.

 

Rhetoric...

Although, I was looking for a little more technical discourse on the design… along the lines of… have you thought about this… or even… that will never work, or even WTF? Where the this or that was something specific.

However, in the humorous light of you kind responses… I’ll return in kind…

Mani – You might still be on the Manic side if you had read about “hull speed” or even pressed the “Resistance” button on your FreeShip. Come on – you actually rationalized better than 10 knots?... waterfall, right... planing in 40 knot winds?

Apex1 – Really don’t have a come back for you. Your ship is just plain beautiful… on the inside. I wish I could afford such joinery and the hull to put it in. My ten million dollar company went down with 9/11 and now I’m employed by someone else. But the tug boat is not my cup of tea. But it’s obvious you know more about marina berths than I with that 72+ footer. I didn’t plan on staying in berths or giving one-tinker's about getting free Internet. However the Roadster will fit in a double birth (at small Marinas that wouldn’t even be able to support your behemoth) if need be and if you had read one word… trailerable. I’ll be pulling it out of the water when I’m not actually sailing to some exotic destination.

Fishnet - We have a small monohull now… I think the Admiral will be ecstatic about going from the 40 degree heel commonly seen to a maximum of 5 degrees with the catamaran. Plus – I’ve promised that I will NOT fly a hull. Oh! Although I’m sure you know… the rendering was meant to simulate a Mylar sail with Kevlar and Carbon tows for reinforcement. Mainly, so that more of the boat could be seen through the sails. In reality, I’ll be using something far more mundane… probably Dacron.

 

my thoughts on "biggest trailerable sailing cat" idea.

Here is my idea for modular big trailable sailing cat
.
The "Cat in the Box" would be a 40' cat with 40' x 4' hulls connected by poles or box beams decked with either a tramp or some sort of solid removable decking.

I'm thinking of a aft wishbone mast cutter rig with a third windsurfer type sail aft. I'd use spare sails to construct a 3 sided tent on deck.

In either boat I'd consider using the trailer frame as a aft wish bone mast. I'd even have provision for detaching the wheels and tires and mounting them on the flat on the deck as fenders so nothing would need to be left on shore.

I think it would be possible to carry the tow vehicle itself on the deck of a Cat in the Box, including ramps for on-off loading. The 'killer app' would be to tow the boat to the beach, launch the boat, expand the scissors (poles) to separtate the hulls, use the trailer as the mast, drive the tow vehicle up ramp (or pull up with winch) and sail away. Reverse at next land fall."



I'd also want it to be Containable with standard 40' x 8' box....while still on the trailer. No "standard boat yard operations" needed to launch or pack for shipping.

I'd want a generic simple way of connecting the hulls to the beams, so more hulls could be added, or even use 8' wide hulls. I figure once you are into towing one 40' trailer, another trip isn't a big deal.

I'm aiming at a 'system' that could go from a fast, bare bones cat with only accommodations in the two narrow hulls, to a "Fat Cat" with 8' wide hulls, to a 40' x 30(?)' flat platform onto which a 40' x 30' x 10' tent could be erected for massive temporary living space.

My target market would be everything from:

Weekenders wanting a big fast cat they can tow with normal big pickup and use without berthing fees,

to resort/special event operators who would like a modular shippable system with additional dedicated Head and Shower OR Kitchen and Dining hulls,

to work/business boats.

One BIG draw back would be no obvious built in pilot house or helm, as the deck would start off being flat across the beams, so this might not be good for cold weather.
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Old 07-19-2009, 01:23 PM
Squidly-Diddly Squidly-Diddly is online now
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PS-as part of the "system" I'd have the 8' wide hull
able to be used as the center of a tri, possibly with the amas stowable inside the main hull for trailering/shipping.

Also, a single 4' wide hull could be used with same amas, and collapse down to 8' total with amas.

If the 8' wide hull could be trusted on its own, then turn the two amas into a 20' cat! I think stowing the amas inside an 8' hull is doable.

I also think their could be a market for 8' x 40' trailerable fuel efficient day cruiser for calm waters.

Mix and match.

For resort operators and floating hotels I'd want hulls to be able to be added or subtracted 'on the water', by slipping them under the deck, so refreshed bathroom and kitchen hulls could be exchanged without main boat heading for the docks.
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Big boat...lots of open area...very wet under the right circumstances...don't consider the roaring 40's as a destination. otherwise...luxurious and decadent...love to have the excess cash to play with it

 

Liability, petty people and Lawyers

I am wondering if the concept of this forum (Boat Design) is even possible in this day and age. The whole concept of this forum is for people who want to design a boat… dah! It is not a professional forum for Marine Architects ONLY to discuss their designs as a mutual consultation forum. It IS for amateurs. Most of the members are amateurs.

A professional Marine Architect’s input is always desirable! No doubt about it. And, I can understand that many professionals have offered input and have either been snubbed or sued. Either the recipient took their input out of context or miss used it or plainly has no personal ethics and sued just because they wanted to steal someone else’s money in addition to using the freely offered advice. Personal responsibility has flown out the window in this country (particularly) and now seems to have crept into the ethics of the rest of the world. It’s so sad! Many want someone ELSE to pay for their own irresponsibility.

It has jaded many, very experienced members from even putting in words the thoughts that might save someone some grief. Because they become liable… or so it seems. Many have stopped contributing to this forum. Others have become just petty, en-bittered word slingers. Really… take a look at yourself… if you’re only purpose is to tell an amateur how “stupid” he is… you need to get out of the house and get a life.

I, personally, have a pretty thick skin about my attempts at boat design. I know my limitations. I can even take a condescending tone, but a constructive, thought-out argument will be more instructive AND far more likely to encourage me to hire you to formalize and correct my design. Do you really think of your clients with such contempt? Or is it because you think by offering your advice you have the right to talk down to someone? Be careful - there may be potential customers here. I already know some of the "professionals" I wouldn't give the time of day... much less my hard earned income.

 

Release of Liability

I here by freely and publicly proclaim any advice offered to me by any professional will not be used against them by me!

That includes advice offered for this thread or for any I have posted in the past or will place on this forum in the future.

As a practical understanding… any advice I receive will not be used by me until I fully understand the theory behind said advice. This is not for lack of trust of you (the professional), but because, I will be certain that I can defend MY decision to incorporate the feature. I will do the research required for me to fully understand the concept as well as the feature.

With that said, please offer any advice you are willing… either through a response on this thread or if it would be more comfortable, to me directly in a private message.

Any moderator... please lock this message so even I can not edit or delete it.

 

I would like to offer this as constructive criticism. I, for one, would not want to carry my tow vehicle on the boat. But, I assume you have reasons of your own. From an engineering standpoint, I believe, you will find it is not possible… and even if it is, it will be closer to a barge than a sail boat.

First off, catamaran’s performance is extremely susceptible to weight! You don’t need to take my opinion on that. Experts have said it many times on this forum. I have found it extremely difficult to get the Roadster down to 8500 lbs. And there is no way it could handle supporting the weight of the 6000 lb truck that would be needed to tow it anyway. By the time you added the structure and extra buoyancy required to hold up the truck, it would far heavier than the truck could tow.

That does not even include the problems you will have with the windage and top heaviness of the having the truck on the boat. In any seas (at all) you are likely to be in a very dangerous situation. Then you could probably not fly enough sail to even get it over a couple of knots.

As a suggestion, you might want to see apex1’s thread on the design 101…
Apex1 101 Design Spiral

With a few hours, you should be able to convince yourself that any boat that can hold itself and a truck up is just not practical... even if is feasible. The software's free... so its just your time required.

Good luck on your adventure.

 

Inquisitor, really nice job, and why not that tropical moonlight movie we like
i have very similar thoughts, have a look into my gallery, but short on cash
forget about mapping the steps, the idea is there, going for inventor FEA?
i'm thinking new hardfoam on spaceframe looking for rock bottom cost
still have have to read your specs but hey, thats just about the idea

 

constructive comments?
i think your light weight is way to low and have some more points
but see the anticlimax allready and dont want to argue or fight

again, i like the concept and presentation, just build it (after consult)

 

Double vision...

GEEEEZZZZZZZZ… Yipster. That’s just damn spooky! I almost feel like I should ask your permission to continue. I’m going to have to study your Ladybird concept. Do you have any verbiage on the forum or other place that you wouldn’t mind sharing? Specs or speculations?

My current plans are to continue this thread. I have several desires…

(1) That it will be a useful step by step process for other amateurs similar to apex1’s tutorial. I hope he continues his so I can cross check my own system. The main difference being his will be the theoretical and mine will be more the hands-on lab. I want to have the Z40 Roadster running through the process.

(2) That amateurs (or experts in their own fields) will constructively offer advice or at least warnings of a specific nature. No matter how off-beat a suggestion or question, I plan to try to respond in a thoughtful way. Maybe, they want to learn something and maybe I or someone else will be willing to “teach” a small lesson… hopefully constructively!

(3) I am hoping that the more I feed this thread, the more that the professionals will take it seriously versus just another “napkin” design… and that they too will begin to offer advice or warnings of a constructive nature. Maybe this will spawn a more optimistic forum than the ones I’ve been on lately.

(4) Find an appropriate professional marine architect that will find the project interesting and not just a contract to be “processed”. Since finances are tight for me, I half hope, that maybe I can offer a trade… maybe, simply model and render a design of theirs for their clients… (ulterior motive for the nice renderings above) or maybe a detailed composites or FEA analysis or maybe some software development (C#.NET for Windows and Windows Mobile are my current specialties)

In the end the goal is to have a great boat. I could have simply kept it to myself. By running it on this forum, maybe it’ll be better in one or more ways.

 

How I plan on getting it so light...

Your logic is sound... throw out the biggest stumbling block. If he (being me) can't defend that one, no sense telling him about the others. He (being me) is either an idiot or dillusional.

So here follows my technical argument. Anyone can do the Google search, but if you wish, I can provide some references for you.

---------------------------------------------------------------

I can understand your weight skepticism. Does 13,000 pounds sound more reasonable to you for this size of boat?

My reality check: Moxy 37 - 7165 lbs, Length = 37.3 ft, BOA = 22 ft -- Moxie Link --

As hinted above, I do have some spreadsheets started doing some analyses for all composite structures of the boat. Both structural and secondary.

(1) Hull, topsides and decks over the hulls are modeled using Dave Gerr’s scantlings. (His disclaimer about catamarans is noted) However, for the weight analysis it should be fairly accurate. To my understanding, it is conservative.
(2) For all composite beams, bulkheads, masts, mast steps, bridgedeck, bimini, roof, interior walls, etc, I have various closed form and scantlings for sizes and weights.
(3) I have major lump masses identified and sized… engines, batteries, water, fuel, generators.

With all these, I get a disappointing 13,000 lbs. In other words I can’t put any people on it.

I do not plan on skimping on safety factor or using light-weight autoclave cured, carbon/epoxy racer techniques… aka Extreme 40. Or, any high flut'n aerospace analysis techniques. HOWEVER, there is one major assumption that my background can improve on and still be conservative...

Dave Gerr’s scantlings assume that a laminate contains ONLY 35% fiber by weight. I know that laminates with far higher fiber weight percentages can be produced.

As mentioned above, I am currently exploring Resin Infusion. The method purports to be able to achieve 70% fiber weight in a garage environment… not an aerospace clean lab. The composite structure of the Roadster would be lighter, stronger and cheaper than the 35% based design. It’s a total win-win situation.

The bottom line… the Roadster sheds a whopping 4500 lbs of resin (that I don’t have to pay for)!

That is how I believe I can build an 8500 lb, 40 foot catamaran that is as strong as any Dave Gerr boat. Now, the only question is what kind of fiber percentage can the Inquisitor build in his basement.

 

was and am running today so only read your first geeezz post in the email but great, lets keep it wise, i like your concept and look forward to continuation of this thread