new but ambitious

Mr Efficiency
Well, looking at the basic information of the Sorrento, it should be possible to sheet the entire hull with 4' wide material.

Though I'm still researching and studying myself, I'm now contemplating to simply create a list of everything I actually want from the boat (anticipated use, desired length, desired speed, desired style,.......) and order a customized design/construction plan, depending on how much that would cost me off course!
Just a matter of not having my hull brake in 2 when I take it on a fast spin, hahaha!
I'm not sure yet, we'll see.

 

The "Sorrento" has a bottom that requires double diagonal planking, does it not ? The topsides can be sheeted in ply. Big job for anyone, especially a newbie.

 

Haven't checked that out yet.
What's special about double diagonal planking?
I suppose they speak about 2 layers of plywood strips, crossing each other diagonally yes?

 

It's like a student in medicine saying: I want to be a heart surgeon, so I go to school just to study heart, since I don't care about the rest of the body.
Is that clever or what!
As an aside: planning hull are the most difficult design to make it right.
You are really starting on the wrong foot, and your chance of success with that train of thought is zero.

 

I hear you, dskira, and you're right off course!
I may have oversimplified my thoughts.

But to use your analogy: a heart-surgeon doesn't need to know "everything" about the feet, hands etc.., to be able to perform heart surgery, does he?

Off course he needs to know much more then only the heart, but I'm just saying: if you focus on simplifying things and you don't expect to obtain the highest possible quality (top speed, top balance, top agility,...), you'd be amazed on how many things you don't "absolutely" need to know in order to reach your goal.

That said, I must admit that I'm now aware that what I'm trying to do is more difficult and complex then I originally thought.
Which is why I've changed my goals.
They now look something like this (don't laugh yourself to death while reading this!):
step 1: building 1 or more objects (that have nothing to do with boats) with plywood and fiberglass/epoxy, to get some experience with the materials and fresh up my technical skills.
step 2: build a 20' boat (speed boat model, but without the real speed performance) for river/lake and experiment with some ideas I have. I'm hoping to start construction by November 2014.
step 3: if step 2 is successful, build a 36' - 45' cruiser, based on an existing design, but strongly adapted to my liking. I hope to start this project 1 year after completing step 2.

All the same, I'll keep on gathering information and learning about what it takes to not only build, but also design a boat.

 

This isn't as practical as it might appear, simply because to optimized build methods and/or shapes, you do have to understand them fully, before you can take advantage of physical properties or engineering principles.

Getting familiar with build techniques is always good practical experience, which helps tremendously with build and engineering issues later.

Building a runabout, without the "real performance" aspect will not teach you much, unless the build style is similar to what your dream boat will be. Currently I know of zero 36" - 45' (an unreasonable swing in vessel size BTW) designs in taped seam (stitch and glue), though adaptation is a logical option, particularly if you can accept the hydrodynamic realities, but upgrade the layout and aesthetics.

There's a monstrously large difference between a 36' and 45' yacht. A 45' vessel can easily and quite literally be twice the size, even though the boat is only 20% longer than a 36'.

 

PAR,
thanks for that reaction.
There are several reasons I want to build the runabout "without the real speed performance".
1: the places I'll be using it don't really allow high speeds, unless you're only gonna follow straight lines
2: not being a marine engineer, I'm not able to calculate the necessary hull strength (thickness of the plywood) for any given (high) speed, so I prefer to stay safe. I'll just copy the basic plans of a similar size boat and keep the power under controll.
3: both for the runabout as the cruiser, the looks of it are much more important to me then the speed performance, but I'd use the same building techniques.
4: I want to do some experimenting by using a converted car-engine, which will automatically reduce speed potential.

I have some trouble really understanding this long sentence of yours (English not being my native language), so could you please cut it in smaller pieces?

"Currently I know of zero 36" - 45' (an unreasonable swing in vessel size BTW) designs in taped seam (stitch and glue), though adaptation is a logical option, particularly if you can accept the hydrodynamic realities, but upgrade the layout and aesthetics."

You're probably right about the 36' - 45' being too much of a difference. It's just that I'm not yet sure about the exact size I want, and I like a lot of space. I'd have to see some similar boats from the inside to get a decent impression about the space they provide, but that's easier said then done here in Thailand!

By the way: do you think 36' or more is too big to make the hull entirely out of plywood and fiberglass?
I'm not sure I fully understand the difference between "stitch and glue" and "plywood over frame", because when I look at the way the're build (video youtube etc.), it looks almost the same to me. The all have wooden framing, the plywood is stitched (screws) and glued, so what's the real difference??? Is it the number of frames/beams that's being used?

Thanks for the help!

 

Most marine engines are automotive derivatives with modifications for marine use. No lose of power will be noticeable.

It's generally not wise to build a boat designed for 40 MPH operation and only drive it at 10 MPH. Most boats have an operating range, where handling and maneuverability is predictable. If you grossly under power one, the boat usually just acts like a pig and wallows around, sometimes uncontrollably. Build a boat designed for your intended use, rather then force a boat to do what you want.

My long sentence was saying I don't know of any taped seam builds on large yachts. Most taped seam builds are for small craft, though I do know of a few around 30'.

I own a 65' all 'glass hull so yes, it's possible. I've seen 55' plywood hulls, so this is possible too. It's all about engineering for the materials you have, which (again) requires an understanding of the build materials physical properties.

As you gain experience with boats, you'll find you don't need nearly the internal volume you currently think you do. This is a classic novice misunderstanding, thinking you need a floating condo. In reality, learning to make do with less is the practical way to have a life afloat. You thoughts and desires will be dramatically different a few years from now, assuming some sea time. You'll generate like and dislikes, with specific preferences for various aspects of this lifestyle. I can't emphasize enough how important it is to just focus on getting real experience and sea time now. This is the only way you can refine your ideas and needs, developing an ever evolving sense of what suits you best.

 

As far as I know heart surgeons take lessons and probably start on something simpler like trimming toenails, so they probably know about feet I like to think my one did

I think it's good that you are taking the same graduated approach, but step #1 can still be a boat, something simple like a canoe or small rowboat, doesn't have to be perfect - you'll just be learning to read the plans, use the tools and handle the material. Step #2 can be smaller - it doesn't have to be a size midway between #1 and #3, what you really want is to add more complexity like deck, motor bearings, seats etc., and concentrate on getting the quality of fit and finish you will hope for in step #3. Then you'll be ready for the big one without spending an unnecessary amount of time or cash to get there, and will be happy with the result.

There will be significantly different approaches to hull shape, construction details and fitting out as you progress through the steps and even by the time you reach step #3 you will not have the knowledge you need to design such a vessel. Unless you intend to have a career in boat design the investment in time, cash and disapointment that will result from learning boat design by trial and error will not be cost-effective. Having said that I think it is good that you taking the time and effort to understand what is involved in boat design and how weight, power needs, and cost/time vary with the size, type and performance of the boat.

As some of the other posters know I chose that route but then I wanted to be able to design and build just simple canoes, so it didn't cost a lot and the rate of learning was fast, but I do understand the drive of curiousity and desire to learn.