Design, and some thoughts on how I go about the process of designing a wooden boat.
A while back I was asked a series of questions about how I go about my design work. I think it’s worth posting as I get many of these questions, so, here goes.
I’ve not long ago moved ashore after close to a decade living in my old motorboat, she’s 43 ft long and just under 15 tons so not a small craft in our sense. But that meant having to round up all of my possessions including a huge library and a large collection of woodworking ( read “boatbuilding” ) tools and machinery, and bringing it all to my new home on dry land. I’m enjoying gutting then rebuilding the 88 sq metre workshop here to suit my needs and am very much looking forward to completing my own Long Steps sail and oar boat and trying her out on the lake just along the road, then in the open sea.
I do have a need for a really nice rowing boat, about 4.5m (14ft 9in ft) would be nice and I’ve started the preliminary sketches for that, and it’s the next build on my list. Out there with my friend, rowing on a mirror calm lake, late on a warm moonlit summers night is something that I’m very much looking forward to.
I do have a need for a really nice rowing boat, about 4.5m (14ft 9in ft) would be nice and I’ve started the preliminary sketches for that, and it’s the next build on my list. Out there with my friend, rowing on a mirror calm lake, late on a warm moonlit summers night is something that I’m very much looking forward to.
First of all, my definition of “performance” is “suitability for purpose”. So a racer will be as fast as possible within the constraints of the rules for the event, while a cruiser will be suited to the clients need for comfort, seaworthiness and manageability and so on.
After much study, much “if it looks right it must be right” which is a misnomer if ever there was one, I use “numbers” a lot. There are particular “numbers” which can be used to describe performance characteristics. Displacement, displacement to length ratio, prismatic coefficient, sail area to displacement ratio and on and on, about twelve of those “numbers” are sufficient to describe the shape and weight of a given boat.
In order to design a boat, I talk to the customer, often many times, then go through the process of compiling the brief. From that I work out those “numbers”, and I check the drawings against those numbers at each stage of the design work.
In this way I am able to reasonably accurately predict the behavioural characteristics of a new design, and to ensure that it meets the expectations of the customer.
After much study, much “if it looks right it must be right” which is a misnomer if ever there was one, I use “numbers” a lot. There are particular “numbers” which can be used to describe performance characteristics. Displacement, displacement to length ratio, prismatic coefficient, sail area to displacement ratio and on and on, about twelve of those “numbers” are sufficient to describe the shape and weight of a given boat.
In order to design a boat, I talk to the customer, often many times, then go through the process of compiling the brief. From that I work out those “numbers”, and I check the drawings against those numbers at each stage of the design work.
In this way I am able to reasonably accurately predict the behavioural characteristics of a new design, and to ensure that it meets the expectations of the customer.
Not so much, although the lightweight recreational sailing craft that are so much of New Zealand’s heritage are certainly a factor, but it wasn’t until I returned to boating after some years racing motorcycles that I really developed an interest in what made boats tick, so in my childhood boats were just boats, and they went along through the water pointy end first. Whereas the second time through I was as competitive in sail as I’d been on two wheels, and was studying why the boats went through the water the way they do which lead to the passion for design.
New materials have certainly made a huge difference to design, we can today achieve shapes and weights that were, if not impossible with traditional construction methods, extremely difficult to build.
With plywood and epoxy its possible for a person who is modestly handy with tools to build a boat of lightweight but strong construction, using materials that are comparatively easy to source, and the possibilities for designing within this medium, which is where most of my work is done, are much wider than say, traditional solid wooden carvel or clinker designs.
Plywood and epoxy is unique in that it is so accessible in terms of materials source, tools and skills required and the wide range of possibilities it presents, so is very well suited to the home boatbuilder.
There is too the move to roto moulded plastics for fleet boats, high strength composites for those wanting very light weight with high strength, strip plank using lightweight woods reinforced with variously woven fibreglass or carbon fibre or other cloths, even foam core with composite cloths are there to be used.
Each of these presents a slightly different range of possibilities in terms of design, foiling boats with scow bows, canting keels, canting rigs, carbon and Kevlar sails, each new material, added to developments in sails and hulls, opens up a whole new range of possibilities.
With plywood and epoxy its possible for a person who is modestly handy with tools to build a boat of lightweight but strong construction, using materials that are comparatively easy to source, and the possibilities for designing within this medium, which is where most of my work is done, are much wider than say, traditional solid wooden carvel or clinker designs.
Plywood and epoxy is unique in that it is so accessible in terms of materials source, tools and skills required and the wide range of possibilities it presents, so is very well suited to the home boatbuilder.
There is too the move to roto moulded plastics for fleet boats, high strength composites for those wanting very light weight with high strength, strip plank using lightweight woods reinforced with variously woven fibreglass or carbon fibre or other cloths, even foam core with composite cloths are there to be used.
Each of these presents a slightly different range of possibilities in terms of design, foiling boats with scow bows, canting keels, canting rigs, carbon and Kevlar sails, each new material, added to developments in sails and hulls, opens up a whole new range of possibilities.
I do use a computer, mainly spreadsheets to do my calculations rather than drawing. My design work started as a hobby, and I very much enjoy drawing, pen on film, downloading from my brain to the paper through a , H4 pencil or a Rotring pen, and although I will eventually change, I don’t enjoy drawing on a computer so prefer to avoid that.
I have only recently retired from an absorbing day job, so my design routine has been to make notes of thoughts during the day, details and new ideas, refining a design mentally before drawing those thoughts in the evenings.
But I’m now able to do that as my “dayjob” so although I don’t have a set routine, I do tend to work full time, long hours when I have a project on the go, I prefer to get it completed while it’s still fresh, it’s very hard to pick up the flow when I’ve been away from it for a while.
I have only recently retired from an absorbing day job, so my design routine has been to make notes of thoughts during the day, details and new ideas, refining a design mentally before drawing those thoughts in the evenings.
But I’m now able to do that as my “dayjob” so although I don’t have a set routine, I do tend to work full time, long hours when I have a project on the go, I prefer to get it completed while it’s still fresh, it’s very hard to pick up the flow when I’ve been away from it for a while.
There is a lot to learn, but the real question for each “contemporary amateur” is “how would that learning be of benefit? Studying design as I’ve outlined in the first question could lead to that person making much better choices of a boat to build, much improve their chances of building a boat that will perform well in the conditions in which they’ll use it.
But the structures themselves, are really quite different, today we’re building monocoque stressed skin structures that are more like aircraft in the way that the loads are carried within the hull and rig, whereas the old style vessels were limited in their construction by the materials available to the builders so there is much to be interested in, and I encourage people to be interested in the traditional craft but its only of limited value if not building a traditional boat.
But the structures themselves, are really quite different, today we’re building monocoque stressed skin structures that are more like aircraft in the way that the loads are carried within the hull and rig, whereas the old style vessels were limited in their construction by the materials available to the builders so there is much to be interested in, and I encourage people to be interested in the traditional craft but its only of limited value if not building a traditional boat.
I did see more activity on the various social media where amateur boatbuilders converse, but I’m not sure if that were just that they had the time to converse or if there was an increase in the building being done. We did see a slight lift in plans sales, but again, I’m not sure if there was more building going on, or if it were more just feeding dreams of freedom.
I’m one of the admins, and as it’s a group focussed upon “my” boats, I monitor the posts, answer questions, write small articles and contribute suggestions where appropriate. Between the other moderators and myself, and the general good manners of the membership it’s a very pleasant group and one that is often very helpful to those with questions. Here’s the link. https://www.facebook.com/groups/JWDesigns
I’ve not long ago moved ashore after close to a decade living in my old motorboat, she’s 43 ft long and just under 15 tons so not a small craft in our sense. But that meant having to round up all of my possessions including a huge library and a large collection of woodworking ( read “boatbuilding” ) tools and machinery, and bringing it all to my new home on dry land. I’m enjoying gutting then rebuilding the 88 sq metre workshop here to suit my needs and am very much looking forward to completing my own Long Steps sail and oar boat and trying her out on the lake just along the road, then in the open sea.
I do have a need for a really nice rowing boat, about 4.5m (14ft 9in ft) would be nice and I’ve started the preliminary sketches for that, and it’s the next build on my list. Out there with my friend, rowing on a mirror calm lake, late on a warm moonlit summers night is something that I’m very much looking forward to.
I do have a need for a really nice rowing boat, about 4.5m (14ft 9in ft) would be nice and I’ve started the preliminary sketches for that, and it’s the next build on my list. Out there with my friend, rowing on a mirror calm lake, late on a warm moonlit summers night is something that I’m very much looking forward to.
