General boat design for a Motor sail-boat

I am relatively new to boat building and I have high ambitions of designing and building my own motor sailing boat.

I am wanting to build a 55 ft long & 16 ft wide sailing motor boat. It's function will be long ocean voyages (from Europe to the Carribean f.e).

My main problem is what materials should I use? I thought plywood firstly because it's cheap, easy to use and light-weight (which would help with fuel economy). HOWEVER I can find no plywood-built boats exceeding 34'. Is there a reason for this? If it is unsuitable what boat building methods and materials are available to me?

My second problem is what rig set-up should I be using for ocean travel on a larger ship? I'd prefer to have a cutter or sloop rig but all larger ships tend to have twin-mast rig set-ups such as yawls or ketches ( or larger), why is this?

Thirdly what style of hull should I be using for ocean travel and what should it be made out of?

Thanks guys.

 

Rogers,

You have proposed a massive undertaking. To design a boat this size you really need at least a few years of schooling, then spend a few more years with a qualified designer to learn how to put book knowledge into experience. Figure 8-10 years to be able to really design the boat you want.

After that you should be able to answer the rest of your questions reasonably well, and get to the design phase, figure 6-8 months of designing followed by a 4-5 year build cycle if you are doing the work yourself. Though it could be longer if you have to work for a living. So from start to finish figure about 15 years or so to do it right.


The alternative is spend a few thousand dollars on a good set of plans, a few more to modify them to fit your desires, and then you just have the build time. All for probably less than one percent of the total cost of the materials a boat like this requires.


As for your specific questions...

Plywood becomes less desirable with size, as it's advantages in small boats (easy to work with) become eclipsed by the other materials superior stiffness. And the complexity of the build is no longer in the hull.

Most boats of this size are build in either carbon fiber (too expensive for your use, and the weight savings would be meaningless), or steel, aluminum, wood, fiberglass, or cores composites. All have significant advantages and disadvantages but all are suitable building materials depending on design, usage, and owners preference.

As for rigs, likely the best option is either a sloop rigg, or a cutter. Though a ketch or yawl are also reasonable. The split rigs have the advantage of shrinking the loads on only one line or control surface, but at the cost of complexity, and space ( and cost). With modern rigging, and winches I would recommend a cutter, but again that it personal preference, others can reasonably disagree.

As for hull type... It depends, probably a non planing hull sailboat hull, with lead ballast. Though you could go to the other extreme and convert an open 60. Traditional motorboat hulls are generally unsuitable for putting sails on since they have the wrong stability curves, but it would be possible to design a motorboat hull with a keel I guess



Honestly I think you need to get some experience on boats similar to what you are considering, and there are a lot of them out there. Most of the questions you have asked indicate a lack of real understanding about the complexity and trade offs all boats must make to be any good. Just remember a boat this size is about as complicated with as many systems as your entire house, plus everything in your car, plus the ability to tilt 90degrees without anything failing. Boats are the most complicated machines a normal person will ever control, and one of this size is not an easy undertaking.

 

Well I'm not intending on building it anytime soon, so the time-scale or the price which you have said isn't that overwhelming.

I am wanting to know then, bearing cost in mind, what are the best materials to use to build this boat and what methods of boat construction are required to use them?

Thanks

 

Rogers,

My point is there really isn't a best material or a best method. They each have their advantages, and disadvantages, and trying to go through them all is really a book, not an answer on a forum. It really depends on what you want to do, what capability you want out of the boat. Upfront coat sensitivity, maintenance sensitivity, any special desires, special limitations, the size of the boat, ect. This isn't an exhaustive list, just a partial list of the issues.

Again I would really suggest trying to get some time on different boats of this size, and get a batter feeling for them. Failing that a detailed description of what you want out of the boat, what your plans are, and your cruising profile.

 

what are the best materials to use to build this boat and what methods of boat construction are required to use them?

USED MATERIALS , already assembled as a boat.

The used market is fantastic , probably 1/5 the cost to purchase instead of build new.

Saving as well as a dozen years of heavy sweat ,and ending a boat with resale value, that home builts seldom have.

Since your requirements are common , although the beam desired would make her really slow , your boat IS out there waiting for your checkbook.

Go for it ,

FF

 

FF, I think that that idea IS a possibility providing that there is no way I can build the very boat I want effectively.

Stumble, What I would like out of my boat is something spacious enough to accommodate (bedrooms, kitchen and living area) myself and 5 others, nothing OTT though! and it to have very good mpg and gph (hence why I'd like sails), mph isn't that important. I'd like to be able to sail for long voyages for weeks at a time so a good sized food store would be necessary. It would be an ocean faring vessel so a relevant hull would be required.

Basically I want to design the boat myself, and make it cheaply. If the former fails then I'd like to design the superstructure at least.

So what resources are available to me to assist me design my own boat and-or it's superstructure. Also how much would it cost for me to buy/someone to build me a compatible hull of this size? Only an approximate guess required

Thanks guys! =D

 

Not really enough details here, but I'll try to extrapolate.

First, the math says that in this size range a boatman be more economically run under power than by sail. Take a look at the Dasher's logs. The cost for them per mile traveled was actually less on their powerboat than their sailboat. Remember the purchase price of sails, rigging, mast, hull reinforcements and the like can make up a significant purchase price of the boat.

Assuming sailing is a requirement then there are a few boats that come to mind as options. An Irwin 54 at 14 foot abeam is quite livable for a family of five ( I did it for monthsat a time) and has the storage capacity for long duration cruising away from resupply. Cost new (well they are out of production...) 2-3 million. Cost used about 3-400,000.

Assuming sailing isn't a requirement, then the dashes 64 runs 2.25 million used, no used sales yet though. There are other boats available I am sure with their efficiency numbers, but I couldn't suggest one.

Both of these boats have a reasonable cruising speed of about 8kn, and long distance offshore capability. And can easily go weeks if not months without resuply.

Designing the hull. Again this is a highly specialized field, and requires a huge amount of knowledge that you simply don't have (neither do I, this is just stating a fact). Similarly designing the superstructure is part of the design of the hull, as the superstructure is part of the reinforcing necessary to design a strong hull. Working with a designer though it is possible to have a design layout like what you would like, but to do the layout work, and reinforcing calculations yourself is not reasonable.

As for cost. What is 'cheap' for you, is not likely to be considered 'reasonable' for others. An actual real price must be given. As I calculate it a vessel of this size will have a huge percentage of the final price just in the materials, for the Dashew this comes out to something like $200,000 in scrap aluminum prices. Though of course the cost to buy aluminum plate is higher than the scrap value. The Irwin 54' probably has about 2-300,000 in material cost just for the hull.

Now add the systems including engines, generator, AC, Rigging, Sails, Anchoring system, electronics, ect. And just the purchach price of the systems on these boats will add another 200,000 to the construction price of a boat.

Now consider a professional boat yard can build around 10 lbs of boat per man hour. A home builder can normally expect around 5. The lighter of the boats wer are discussing weights in at 60,000lbs. So figure 12,000 man-hours of construction time for a home builder.

Honestly these are the unavoidable costs, you might beagle to save a few dollars using poor used electronics, perhaps a few thousand eliminating something like AC. But at the end of the day the major cost of a boat is going to be in raw material, and labor. A used boat on the the other hand is likely to have depreciated below the purchase price of just the material, let alone the additional systems.

Now I don't consider this a reason not to build your own boat, but instead part of the realities you need to accept. The advantages of home building are that you get to design and build exactly what you want (though this is also available in a custom boat yard). You get to save the price of the labor ( by trading in your time instead). You get to watch the boat grow from the ground up ( this can be awesome).

On the other hand home building has cost people wives, careers, and huge amounts of money. Often without finishing a boat that can ever be used. Then without a designers name on it, and without a finished boat, the hull (or what there is of it) gets sold for pennies on the dollar to someone who finishes it off and finally goes sailing.



To be honest Roger what you are asking for just isn't that unique. You have yet to mention anything you would like to do, or design issue you would like to implement that cant be found in hundreds of commercially available boats, many on the used market for a fraction of the build/new price.

When people come on the forum and say "I love building boats" and need help, I am more than happy to encourage them. But you seem to be under the impression that building it yourself will be cheaper, or give you more control, and that honestly is not true. It is significantly cheaper to hire an Archatect to modify an existing boat, or an existing design to suit. And likely not any more expensive to pay a custom yard to build a custom design than it is to build it yourself. In large part because they get much better deals buying in bulk than a home builder could ever hope to see. Have the manufacturing experience to do the work without waste, and honestly if something goes wrong have the resources to pay to fix things.

 

Rogers: You need to make a list of requirements. Some will be conflicting, which will force to modify or delete some items on the list. Other requirements will force you to add more equipment, which may or may not conflict with other items in the list. What you are asking is akin to "how much will a plane ticket cost me?". To design a boat that size, you can go take a Naval Architecture or Yacht design course. They are three to four years. Building it is a matter of either apprenticing or taking a course of at least two years. If, as you say, you got the time and money is not such a problem, that should do it.

 

Stumble/gonzo

I'd give more details but I don't really know what you want me to tell you precisely about my the design I have in mind. =/

Also I'm surprised that a sailboat would be less cost effective than a powerboat but okay =/

]

What you have said here has interested me though, Is it plausible to buy a "cheap" used boat and get an architect to modify it? Could that be "cheaper" ??

 

You need to write down every detail. That includes plumbing, deck gear, interior arrangements, electrical requirements, etc. Also, the materials and or model numbers for each piece of equipment. The shape and materials of the hull will affect all the rest of the requirements too. I think you don't have the level of knowledge to do that. What experience do you have with long term ocean sailing? If you don't have sailing experience, there are a lot of boats in the 23-27' range for fairly cheap. They will give you experience and also let you figure out what is you want from a boat.

 

I wonder if the airplane forums get these guys?

"I'm going to design and build myself an airplane to carry me and 5 friends across the Atlantic, I don't know anything about the subject but I know I can do this cheap........."

30-40 years ago these folks bought a set of Tahiti Ketch plans or a Samson Sea-Breeze ferro cement design and flew at it......99% of those projects went up for sale as a bare hull sitting in someone's backyard....today folks talk about doing it on the internet......I don't mean to single you out Rog but of the dozens of folks that appear on this site and (always in their first post) announce their monster project (55' boat = 30,000 man hours construction time only)......100% go on to other things and rarely even get around to buying a boat let alone building one.

I don't like to squash dreams...I'm human and have dreams too....but you need to work toward these things....build experience and working capital....build a dinghy (you can find free plans) and see how it goes.....

Or just take gonzo's advice and spend $1500 on a Cal 20' and go sailing.....it will change your world.......

 

I don't appreciate your condescending and belittling comments to be honest with you Tad. I neither find them helpful nor are they welcome.

If you wish to comment please keep your posts strictly about the questions asked and how it is you can help me to become more knowledgeable in this field, NOT how I'm going to fail at boat building and stereotype me. As I'm sure that I could make you feel inferior in other areas of knowledge, but I don't.
So keep it to yourself please.

To the helpful people out there,

Gonzo,
I have plenty of time to build my boat so I think purchasing a "cheap" and smaller boat would be an excellent idea!!! So thank you for that suggestion =].

Also I have a decent grasp of designing, mechanics and circuit diagrams. So I could do most of it probably, it's just mainly the actual structure of the hull which I reckon I'd have a problem with designing around as everyone is making it sound so impossibly complicated!!! SO... I'd be fine designing above the hull ( I think) But what BASICS do I need to know about planning the interior of the hull (not it's structure as such).

No one needs to write pages but I'm sure you won't bother doing that. Bullet points would be just perfect.

Or instead does anyone know of a sea ship which has a similar hull shape to 55 X 16 X 6.5. The latter may be easier.

Thank you very much fellas!!! =D

(Once I have a better grip of understanding the hull I'll do some designing and post them then you can criticise the hell out them for being so unseaworthy!!! lol =] )

 

http://www.eyemouthmaritimefestival.com/htmfiles/emf_boats_inchcape.htm

 

Rogers as a point of information; Yes plywood can be used to build 40+ foot boats of high quality but certanly not cheap. Sam Devlin is a master of stich and glue ply boats. If you google Devlin Designing boat builders you will learn. He is presently building a high end 48 ft boat.

 

Hi Rogers,
Welcome to the forum... You have a very long road to travel and much experience to acquire... I do not feel Tad was being intentionally condescending and belittling in his comments or suggestions... Just HONEST...

I spent the last 3 years building and preparing and before that another 3 years researching and developing a clear picture of what I wanted, made several models, came with a broad based experience on a variety of boats and adventures of another 5 years prior to that...

In the end I decided on an existing design by Bob Oram and built that with significant modifications by the original designer Bob Oram... It worked, but I ran out of money... I wanted a motor-sailer and ended up with a power-cat for sale... Listen to the voices of experience and learn...

The whole process is interesting, a good challenge, a personally rewarding activity and very character building...

I was told to clearly define what I had in mind to do with the finished build - where to sail, what to do, how to survive whilst cruising, learn the geography, seasonal moods (weather), politics, special considerations, what hull type is best suited to your favourite cruising grounds, How will you survive a severe storm, survive the ongoing Global Economic Crisis... The list goes on and on and not much about fitout of the specifics of the most appropriate design yet...

I chose a light-weight catamaran built using DuFlex (end-grain-balsa covered with 400gsm or heavier glass/epoxy) and 'foam-cored', for coach-house roof... The bottom is also reinforced with additional layers of marine plywood and GRP so it can sit happily on its own bottom for careening... 40ft x 21ft and 6 tonnes including a bit more than a tonne of fuel and full stores for extended totally independent cruising...

http://www.boatdesign.net/forums/boat-building/my-little-piece-peace-25962-105.html

Go for the smallest design that will do the job required... You have a lot to learn and experience so open your mind, and enjoy the journey...