Thanks Dave. I've now replaced that image.

Portfolio of JRA Dinghy Design Competition Entries

An illustrated write-up of all 10 designs (together with five concept designs which were not officially entered), has been compiled and collated into one PDF document which can be downloaded by members of the JRA.

It comprises drawings, photographs and introductory articles from each of the designers.

We can call this a “Portfolio of Study Plans”.

If it is the wish of the committee, this document could go into the website “Documents” section, but in the mean time I have just put it into my own blogsite, so if anyone wants to have a look and provide any feedback, make suggestions etc. please do so. At the moment, together with a couple of other PDFs about the models, it can be downloaded from https://kenyonz.com/page-18

Jan is currently working on a shortened version, edited and laid out in a form suitable for publishing as a magazine supplement, if the JRA committee decides to go ahead with that. I have seen some sample pages of what Jan is doing, and it looks very good and I think it would be great if Jan’s work could be published and souvenir copies sent out to all subscribers to the magazine – that’s my hope anyway.

Dinghy fun

such a photo would cause much "tut tutting" where I come from...

Im looking forward to such a complete collection of all the dinghys of the design competition and especially the design of David Tylers Tender to Sibling which I want to build. At last I found a shop which can waterjet cut the 3 plywood sheets according to Davids dxf files with his newest adaptation of a higher bow for 360 Euros. I will let You all know about my progress of the build. I especially like that I can use the daggerboard on PS or SB and store it at the bottom for rowing the dinghy which I will often do on a nearby slow flowing river.

Anonymous wrote:

PS: as the series, at one dinghy per magazine issue, would stretch out over a period of more than a couple of years, I personally think it would be more useful to print a magazine supplement dedicated to the dinghy designs - with a copy sent to each of the members who subscribe to the paper magazine - and a digital copy to the other members, and to be added to the digital magazine archive. That, of course, is a matter for the Editor and the committee to decide. I have no idea what other members think of that idea.

I think that's an excellent idea and have been thinking along those lines myself. As you may know, I'm helping the magazine editor (in a very minor way compared to the effort she puts in to the magazine, I must say) with getting to grips with new desktop publishing software, our current modus operandi is that the next issue is being produced by Lynda on the old software that she is used to and I am replicating it from scratch on the new software and then the October issue will be fully on the new software. Due to a recently broken arm all my boating, gardening and work projects are on hold and I'm taking the opportunity to really get to grips with the software, I'd be delighted to take on this dinghy supplement as long as it happens in the next month. Whether or not it is physically published is another discussion, a .pdf version might suffice. 

I have just come across this discussion.   I was pleased to hear that I won the competition and I have transferred the prize money to Sailing Horizons,  a charity that offers a chance to try sailing to young people who might not otherwise have such opportunity.  

A few comments:

Since submitting my entry to the competition I had the thought that my design might be better with a single wheel at the bow rather than two wheels at the transom.  Pic attached shows how it would look with a single wheel at the front, the oars could be drawn back through holes in the transom to become handles like on a wheelbarrow.  I think this would have some advantages. A possible dissadvantage is that if you have to land on a beach under oars with any waves breaking I think you are best coming in stern first in which case strong wheels under the stern would give some protection to the hull.  Maybe not a big thing but if anyone wants to build my design and would prefer a wheel at the front I would be happy to modify the dxf files.  Alternatively the wheels could be left off althogther, its hardly worth altering any files for that since the changes are fairly obvious.  I would say though that we have wheels on a longer row boat that I built and we find those wheels very useful.

There is a sugestion that the mast of my design should be further forward and that if the bow storage compartment should be smaller to make that possible.  I wonder why it is thought that the mast should be further forward - is it that the helm balance is wrong or is it something else?    The mast and centreboard positions as drawn are my guess at what is needed for good helm balance and having a pivoting centreboard does allow for some adjustment of helm balance.   The bow storage compartment may be larger than some people may need but I see very little gain in making it smaller - with the bow storage as drawn there is still room for three, or maybe four, people to sit in the boat, albeit that would be a heavy load for any boat of this size.

There is a sugestion for a daggerboard rather than a pivoted board. (I will call it a 'pivoted board' rather than 'centre board' since it is not on the centreline).   I do think that a pivoted board is much better than the daggerboard arrangement and not really much harder to build - basically the difference for the builder is drilling a hole and fitting a bolt or a pin, with something to seal the hole.  I think it is a big advantage to be able to sail into shallow water with little risk of serious damage.  Also a pivoted board looks after its own storage when it is not in use. When a daggerboard is partially raised it is sticking up and very much in the way, when fully raised you have to find somewhere to put it.  I think there is only one reason why daggerboards are popular for the smallest sizes of sailing boat, this being to minimise the space taken up in the middle of the boat. However, with this design the pivoting board is built into one of the bouyancy tanks so takes up no usuable space in the centre of the boat.  So I sugest that a pivoting board is the best option for this design, but if a daggerboard is really preferred the changes to the files would be slight and are fairly obvious.

I dont recall the rules of the competition requiring a junk rig but I chose a rig that from a distance looks a bit like a junk rig.  I expect the JRA will know what is and what is not a junk rig - is it to do with the number of battens or the sheeting being taken to the ends of the battens?    Certainly the design could have another batten or two and a pole could project behind the transom to allow sheeting to the batten ends. It might even sail better that way but I think it would be a bit fiddley for this size of boat.

It seems that some people would like a boat design to include a table of offsets.  If someone actually wants to build this boat and are sure they would prefer a table of offsets then I can make one. Since it is a chined hull the offsets presumably would be measured from the chines to the centre plane and from the chines to a nominal waterplane. So for this '5 plank' hull that means 3 pairs of numbers for each cross section - not too hard.  How many cross sections? I think 10 cross sections is fairly normal but may be more than necessary for such a short boat.  But I would say that I would much prefer to build a plywood boat from .dxf files defining the shape of every piece of plywood rather from just a table of offsets.  Ideally one would start by getting all the plywood parts cut out automatically from the dxf files, although this is not the only way.  This adds cost certainly, but it also bypasses much of the more tedious parts of boat building, leaving the builder with the more enjoyable work and reaching the launching point much quicker.  As I think someone said, if you havent tried it this way you may not appreciate the advantage it offers.  I fairly recently built a 15 foot plywood rowing boat from dxf files and I got a price quoted for waterjet cutting and for cnc routing - the waterjet cutting turned out fine and was about half the cost of cnc routing but perhaps another firm would price these options differently.

When I sent in my design I did include all the dxf files and I dont mind these being published.  If they are not going to be published I can email them to anyone who wants to use them for building. I cannot gaurantee that all this data is actually correct - to the best of my knowledge it is but I dont think anyone can be certain of that without building a complete boat.  Do let me know if you find any mistakes so that I can make corrections for any future builders.  And if you view or print out the files and think anything looks wrong ask me about it before you cut out material.  I can say that I fairly recently produced a set of .dxf files for our 15 foot row boat using a similar design procedure and that boat all fitted together as intended with no problems. In that case, since I knew just what fittings I was going to have on the boat, I included every fastener hole in the dxf files - nice not to have to do any marking out at all - just bolt the fittings on with bolt holes already cut out by waterjet.

At the present time the dxf files for this design are not 'nested' - they are at somewhat random orientations.  If automatic cutting is envisaged, or even plotting at full size, the next step would be 'nesting' the shapes so that they can be cut out with minimal wastage.  I think it is unlikely that there will be any great demand for this design, there are so many small boat designs already available, but if there are a few people wanting to build to this design then maybe I could do some nested files.  For our 15 foot rowing boat I did this with software called 'mynesting' which you pay for each time you use it, not too expensive though, at least not compared with overal boat building costs.

Talking about boat building costs, I dont think you should build your own boat to save money - if you just want a boat as cheaply as possible get a second hand one, if you look around I expect you will find a good one for less then the cost of materials, or even for free from someone who just needs to clear storage space.  I think the only justifiable reason to build your own small boat is for the satisfaction of doing it, which I have found can make it very worthwhile.