the boat I want to build (a sailing dinghy design)

Here is the starting thoughts on a sailing dinghy I would like to design and build. The main goal of the project is to have a boat that I enjoy sailing and is easy to build. I wont lie, I am not an engineer and I would really appreciate some help on the math necessary to make this vessel a success. This project is pure hobby and is not under any time schedule. Now while I may not be an engineer I am a good builder of many things including a very successful 16' stitch and glue power dory. The ease of that project makes me lean towards the plywood construction but my initial sketch dose not favor it. I will probably compromise the design to accommodate.

The list of constraints on the design

16' LOA
around 250 lb
free standing mast with a single sail (no jib or spinnaker)
comfortable cockpit for two
unsinkable hull (maybe, depend on ease of construction)
easy and cheep to build (well, cheep as far as boat building goes)

I basically want a bigger version of my Force 5 that has more room for two people. In fact the sketch below is very close to the force 5 shape. The force 5 was the first boat I ever sailed and after many years of sailing catamarans I have learned the value of minimalist sailing. I can set up or take down the force 5 in 10 minutes, it so easy a caveman can do it.


Any ways on to the sketch. I now need to learn how to get this sketch into a hull design program of some sort and start hammering out the math, that's where I hope to find some help from the members.

 

design programe for stitch and glue at www.pagesperso-orange.fr/robert.laine bottom of the page "carene" very easy to use and then export to freeship (not delftship it will not print ) to adjust the lines and print out the developed panels ( google to find freeship)

 

Lots of folk want to design their own boat, for some reason, more than want to design their own car or house. I will start with the customary cautionary note that for an amateur a lot more $$ and effort goes into the build than the design, and success is more likely using a design from a professional. You can also expect to get detailed construction, possibly full-up instructions and, if the designer is alive, valuable support. A typical professional puts far more effort into a design than an amateur. If you wish to go the home-design route I recommend you start small and cheap. OK, that's out of the way.

It looks at first glance like a design that is suitable for ply construction. I think the stitch and glue method would suit you well given your recent successful bird''s mouth mast build including glass and epoxy.

There are several useful free hull design applications "out there" on the net that work well with plywood construction including -but not limited to- the stitch and glue method.

Carene is probably the easiest to use but the most limited as far as hull shape is concerned: To start, you enter a few dimensions to define the bottom shape: length, beam, deadrise (Vee) angle, twist at the bow, bow and stern rocker etc. Carene generates the bottom shape and then you add the planks: less choice here, just height and flare angle at 3 locations. Carene will provide the plank developments needed for stitch and glue. As far as I know Carene supports only hull shape design, not topsides.

FreeShip and DeftShip are more or less the same with minor differences. Both support topsides design but not accommodations. I am more familiar with FreeShip which will provide plank developments whereas the free version of DeftShip does not. Both are based on control points that you move around to control the hull shape, which behaves something like an elastic membrane being pulled into shape. There is a learning process to this and tutorials are also available to help you learn; the effort IMHO is worth it.

 

The fact is I really don,t want to design the boat. On the other hand I do want to build one. But I want a design I like. I looked at a lot of the plans offered from Glen L and Bateau and some others. I completely agree that I am not qualified to design something that would compare to a professional but none of those plans really inspire me.

I have now downloaded feeship and delftship and I will spend some time learning them. I can't seem to get Carene.

You say that freeship has the ability to develop the ply sheets so I will start there.

I suppose that if I get enough opposition to the project that I will pretend to give up and continue my mad experiment in the lonely seclusion of the shop with only my insanity to keep me company.

 

Here...this will give you a start. Most folks have trouble getting a chined hull when they first start out in freeship. Open it, save it as something else then work on that something else. As a precaution...set the attributes of the file as read only too. To do that...right click in Explorer, go to properties and put a check mark in read only.

 

They actually have house design software that figures all your framing if you simply draw the plan.
A house can be any shape and still it can perform nicely.

With a boat, no design software actually designs anything. What you input gets measured and saved, gives you something to look at.
It's fun to design your own boat but it's closer to designing an airplane than a house or a car. Of course, I'd rather sail my own design than fly it.

 

Phil Bolger wrote some remarks with philosophical wisdom. Among them, here loosly quoted : People want their boat to look like they want their boat to look more than they want a boat that works well. Just a tag line for Ancient Kayakers astute remarks. None of this is intend to offend.

Your drawing makes a good looking boat. It seems to have a scooped rear deck, two footwells, and a lot of decked area. This is all very well but it will be heavier than you want it to be on account of all that detail stuff. Built with ply, it will be much more subject to deterioration because of all that non ventilated air space. You can incorporate closed volume sections but your drawing has too much of it for a 16 foot boat. There is little or no space to store water, sandwiches, beer, fishing or snorkle gear, suntan lotion...and.....well you can see the point. No place to lie down for a snooze either.

If you must design your own, then there are many of us who will offer some input, including the math if needed. If you have been sailing a beach cat then you may well be a speed freak. If so tell us that. If leisurely sailing is your bag then the boat will be a little different from the hot rod. We also need to know what kind of weather and water conditions you anticipate.

 

carene is at http://pagesperso-orange.fr/robert.laine or google it its at the bottom of the page that comes up.
I draw my boats in carene then transfer to freeship ,adjust he bow and then develop the plates and print out the dimentions for transfer to ply. I dont find the deeloped panels in carene are as accurate as those in freeship.

 

I would like a balance of performance and simplicity. I love to sail beach cats but I don't like setting them up or storing them. I want a beach launchable boat with adjustable draft centerboard. I live in Clearwater FL where we have a lot of shallow water. For the most part we have crap wind but a great environment to sail, lots of beautiful little keys and fantastic beaches to explore. I also want the boat to be simple, good control over the mainsail but nothing else, no stays, halyards, jib, spinnaker.
A mainsheet, rudder stick, and a nice cold beer will do.

The sketch implies a sealed hull but I was thinking of some removable hatches that would stay open when stored.

Anyways I have pick up on DelftShip pretty fast so far. Have a Look.

 

I think ,with guidance, you may be able to pull this off. But just in case you want to consider other options here is a 14 footer(RYD 14.6) by Paul Ricelli. His company is Ricelli Design and is in Eustis, Florida. He is an extremely knowledgeble guy and would probably work with you on the 14 footer design or any of his designs.

Ricelli Yacht Design
352-357-1248
34539 Marshall Road
Eustis FL 32736

 

Your boat looks a lot like John Welsford's latest, the AWOL. Graham Byrnes has some that also are close cousins of yours in his BRS series. The Core Sound series are all great sailing and beach cruisers and both series have the lockers and air chambers you show. I have had great success with plywood air chambers with no danger of rot for many years. Proper use of epoxy solves this problem. Paul's boat looks interesting but may be more advanced than you want.

Drawing a boat that has the look you like is only a small part of the design process and is not the most important part. This is more true of sailboats than most, but not all, powerboats. The two designers I mentioned are experienced sailors and their boats are well tested and respected. Not all can say this. You may sometimes be the guinea pig and doing the designer's beta testing for them. Even good designers have been known to put out a failure now and again.

 

If you want to go ahead with FreeShip or DelftShip feel free to post questions and problems and we’ll do our best to guide you through the first steps. But I’m not sure it is wise if you just want to build a boat.

DelftShip does not as far as I know provide the plank developments needed for stitch and glue work. FreeShip is harder to find but it's out there, try this
http://freeship-plus.land.ru/downloadsE.html

There are many good designs out there: if what you want can’t be got by slightly modifying a similar design, chances are there’s a good reason why you should not proceed with it, but your design does not seem outside the range of existing boat concepts. If you’re looking for a balance between ease of build and performance you are clearly not trying to slide down the razor blade of extreme design (ugh) so what you want has almost certainly been done several times already.

I suggest you consider investing a few dozen hours searching the net rather than the many hundreds needed to learn the art and science of boat design, use of several design applications (they each offer different advantages) and then go through the complex and reiterative process of producing the detailed set of engineering and build drawings needed to proceed with procurement, planning and construction.

Messabout gives some of the reasons why the design is a much longer process than you might expect; there are lots more.

Doug mentioned Paul Ricelli: I second that based on my own pleasant experience of building one of his designs, which I shamelessly customized with his support.

Tom has a point: any reputable designer will tell you how many of each of his designs have actually been built. Note that this is not necessarily the same as the hull number, since not all sets of drawings sold result in an actual build. I have a couple of boat plans that will likely not get built, for example.

As well as detailed drawings meant for actual construction, many sources provide much cheaper “study plans” that show an overview of lines and accommodations so you can compare several designs when you are zeroing in on your final decision.

 

Powers; I have a suggestion for you. You live in Clearwater, there ae plenty of boats in you home town to look at and discuss with the owners. Some weekend soon, bop on down to Sarasota Sailing Squadron and hang around their boatyard and clubhouse for a while. Plenty of ideas and boats there. Boats; you can touch 'em feel 'em.

Check out the goings on at Lewis Boat Works in Bradenton. (Call Dave Lewis. He is in the phone directory.) A bunch of amateur builders hang out there and they always have two or three boats in progress. Pretty good bunch of opinionated guys too. They are big on the Cortez Melonseed. A wonderful little gaff rigged 15 footer that has a big following. Plenty of other types in evidence too. The Manatee Maritime Museum, at Cortez, has a boat shop where there are some very seasoned old pro boat builders. Good guys there as well. Visit the museum boat shop.

The summum bonum of all small boat events is upon us. This is said to be worlds largest gathering of small boats and almost none are power boats. The annual Cedar Key gathering will take place the first weekend in May. There you will see hundreds of boats of every description. Many of them, most of them really, are home built. The Gougeon Brothers usually show up there with whatever far out design they have done over the past year. This event is completely without organization. No fees, no schedule, no rules. Just show up and make friends with as many strangers as you want to. If you contact Dave Lewis before hand he will almost surely offer you a chance at sailing a Melonseed at Cedar Key. You'll get other offers to sail other boats if you are good at networking. Cedar Key is not too far from Clearwater. Consider going for "research".

I may start an argument here.... Forget stitch and Glue methods. S&G will take longer and be more labor intensive than traditional methods of construction. What is more, the traditional methods will produce a more precise copy of your design than S&G can. More than that, you do not need panel layouts and the tedium of measureing and drawing and splining all those ply components. You will not need to drill a zillion holes nor have to fill them up later. You wont cut or nick your hands on all those wire bits either. If you are not up to speed on standard building methods, you might do well to get Tom Hills' little book titled; Ultralight Boatbuilding. Another simple book is Lapstrake Canoes by David Nichols. Either of those books will guide you through the building process without getting too complicated or intricately detailed. Plenty of other boatbuilder books are available but these two are quick and easy reads with gobs of pictures. I mention all this because from a purely practical standpoint, your new design will deserve assesment in terms of building practicality or difficulty. That is the kind of thing that may well influence your final boat choice.

 

I formed the same opinion about S&G watching a buddy huilding a S&G canoe; he hasn't finished and I have built at least 4 boats since he started. Messabout didn't even mention the worst part which is the sanding.

 

Well I want to stay focused on just the shape and dimensions right now. This is how I came up with my sketch


as you can see my sketch is more of a trace over a known design except for the obvious shortened aft section. Then you have to take into account that the sketch represents a larger boat than the original as it is scaled up to 16 foot LOA The forec 5 is 13'10”.


Here is what the boat would looks like if were the same length as the original. I dont know if this means much.



And finaly here is the boat (16' LOA) at the same scale as the original. So far i was planning on scaling the sail, mast and boom by the same ratio.

Wow it a lot bigger maybe I should scale to 15' instead.