Total noob. Small plywood sailboat questions.

[unseen wombat]

Hey guys. I'm new here and I have some stupid questions.

I'm in the first stages of looking into building a little wooden sailboat. I'm deciding on a plan, and I think this one is the one I'm leaning toward: http://www.svensons.com/boat/?p=SailBoats/Falcon. What do you think? Does it look seaworthy? Any difficulties in that plan I should be aware of? I expect to take it out on Lake Erie and stay near the shore (Nice days only)! or maybe to Mohican State Park.

Now my stupid questions deal mostly with the plywood.

1. When the sides and the bottom come together at the chine, one of those plywood sheets is going to have exposed edge grain. Isn't this bad for plywood, even marine plywood? Don't you need to somehow seal that edge? Is paint sufficient? Would gluing on a solid hardwood edging be good, or is that overkill?

2. Also, doesn't water come up between the plywood and the chine? Or do you expect the glue between them to be watertight? I know it's dumb, but that's the first thing I wondered when I saw that corner and no instructions for what to do in the way of sealing it.

3. Should I use douglas fir plywood? I hear it develops cracks in the paint over time because of its grain, and I don't want that. Are there any better alternatives? What about oak plywood? Or do I need to get that expensive scandinavian company's mahogany stuff if I don't want cracks?

4. Are stainless steel screws and bolts good? Or do I need silicon bronze if I don't want rust stains? (I've never built anything to be so exposed to water as a boat, so I don't know how stainless will hold up over time, but silicon bronze is expensive). We do expect to store it in our barn, so it won't be constantly afloat. Is there anything in the plywood that will react with the steel, like there is with treated lumber?

I'm really looking forward to building this. (My mom and wife tell me it's going to sink, but I'm gonna make sure it doesn't, and take sailing lessons before I go out on my own). I have all the woodworking equipment I need, even a shopbot (which I just got and haven't set up yet), and have some experience with other projects, (like this: http://finewoodworking.taunton.com/item/10815/walnut-shaker-crib-and-nursery-set) but no boat yet. :)

Thanks for your advice, guys.

[jmolan]

http://www.devlinboat.com/

I would start here, Sam has a great video on modern ply contruction. i would not want to build from that old of plans. New methods are far better at time and labor and using epoxy. Old ways are not always better in plywood constructions.
There is a lot of info out there on modern ply contruction. Google stitch and glue and you will have a ton of info to comb through.

[marshmat]

Hi 'wombat', welcome aboard :)

I'm not too familiar with this particular boat. From the drawings you linked to, she appears to be of fairly traditional ("old school") construction. Not especially complicated, but she'll demand some skill with cutting bevels and that sort of thing. If that furniture in the other link you posted is your own handiwork, you're definitely capable of doing a boat like this one.

Seaworthiness in a 14' sailboat is almost entirely a function of the crew- do they handle her well, do they bring her back to the marina when they should, etc. When the boat weighs less than the crew, the boat's inherent seaworthiness is somewhat less of a factor than the crew's skill and intelligence.

This boat appears to have a structural member at the chine, that the bottom planking and side planking are screwed and glued flush with. Hence the watertight seal. Exposed edge grain on plywood is obviously a weakness, as is checking; there is also the issue of abrasion resistance if the boat is being hauled out a lot. Hence why sheathing the hull in fibreglass/epoxy is such a popular method among more modern designs. In 1978, when the article on the "Falcon" was published, the technology to do this was still quite experimental. Today it is easy and common.

There have been a number of good threads on here over the last few years regarding stainless vs. bronze fasteners, and regarding the various grades and types of plywood. Careful use of the "advanced search" function on this forum (or Google with the qualifier site:boatdesign.net ) should bring them out of the abyss for you.

[unseen wombat]

Hi guys, thanks for the responses. Yes, me and my mom built the nursery set for my daughter. It took us a long time working only nights and weekends, but we finished it just before my wife went into labor. :P Except for the mini step-stool. We did that later with the leftover walnut.

From what I see in other discussions, it looks like stainless steel is no good. I guess I'll have to shell out the money for silicon bronze if I want to do it right. For plywood though, I found a place near me in Sandusky that sells the good stuff, so I won't have to pay for shipping. That makes me really happy. :D

Thanks for the link and suggestion on the stitch and glue technique. It does look easier, though I don't think the traditional method would be too hard either. But it will save on weight, which is a good thing I think. 100 or so lbs versus 475 is a strong argument in its favor. Is such a light hull on a sailboat less stable though? Will I need ballast? How much do I add? :eek:

I have one more stupid question. Suppose I wanted the hull to be bright finished. Could I still sheath it in fiberglass? In fewer words, is fiberglass clear? Sorry so dumb. I've never worked with fiberglass before in my life.

[alan white]

That last question has been asked before. Whatever plywood you use, it will likely be peeled ply, meaning wild grain, though some tropical plywoods look okay finished bright.
It's been said many times, you can use light glass and it will be invisible, but go heavier. like 6-8-10 oz per yd and you can see the weave. Mistakes can't be covered. That means you have to do a good job and avoid visual clues that you screwed up. Then the epoxy you used has to be protected with a varnish having good UV inhibitors, and further, that finish has to be kept up because neglecting it will cause epoxy yellowing below the glass, indicating degradation. 6-8 coats of varnish will do, and a couple of new coats each year, sanding between, and so forth...
Personally, I don't go for that kind of masochism myself, but you may wish to do so. It's done all the time with canoes, but then they don't sit out in the summer sun at a mooring either.

[unseen wombat]

That last question has been asked before. Whatever plywood you use, it will likely be peeled ply, meaning wild grain, though some tropical plywoods look okay finished bright.
It's been said many times, you can use light glass and it will be invisible, but go heavier. like 6-8-10 oz per yd and you can see the weave. Mistakes can't be covered. That means you have to do a good job and avoid visual clues that you screwed up. Then the epoxy you used has to be protected with a varnish having good UV inhibitors, and further, that finish has to be kept up because neglecting it will cause epoxy yellowing below the glass, indicating degradation. 6-8 coats of varnish will do, and a couple of new coats each year, sanding between, and so forth...
Personally, I don't go for that kind of masochism myself, but you may wish to do so. It's done all the time with canoes, but then they don't sit out in the summer sun at a mooring either.

Ah, I see. That must be why most boats I see anywhere are painted some solid color. Probably then I'll just leave the coaming and molding bright. But I plan to store my boat at home and just trailer it out when I feel like sailing. I'm not going to moor it. Do you think I'll still have so much trouble?

This is where I'll be getting my plywood from, most likely: http://www.marine-plywood.us/ Probably the meranti or okoume.

[jmolan]

http://www.systemthree.com/index_2.asp

Lots of pis an info on finishing bright or clear.

Have fun!

[alan white]

If you cover the boat at home, after washing off salt water if present, and paint the interior and bottom, then maintaining the sides, if nice okoume or meranti, is not going to be a big deal, since you're only doing a stripe around the boat topsides.
I'd be doing you a disservice if I didn't tell you the work involved. Also, small dings and scrapes (what boat doesn't get those sometimes on their topsides) can't always be hidden by a maintainence coat. That means that the nice original finish (unlike paint) will never look as good as new.
I like doing the tiller, coaming, spars, and guards. Nothing more. that wood tends to show up more if not buried in a sea of varnished surface.
I see an old Chris Craft in all of its shining glory, and instead of drooling, my carpel tunnel acts up.

[marshmat]

I am quite proud of the complete absence of even a single drop of varnish on my runabout. Everything's done in marine enamel- bright red topsides, blue accents and gunwales, grey inside. Eight seasons later she still looks new, with only about an hour of work every couple of years to touch up scratches.

I do like the look of a bit of wood here and there, but it's quite possible to get beautiful and practical in the same package with a good choice of paints.

[PAR]

Interesting Matt, I'm proud of the complete absence of any paint on my runabout, not a drop, just varnish, soon to be replaced with clear LPU. Of course I don't recommend this treatment for anyone. My boat is housed in doors, lots of ventilation and is kept clean. Most folks couldn't care for a boat like this.

Falcon is an old design (quite old in fact). She'd be a good candidate for taped seam conversion, which would make here much lighter (around 30 - 40%), much more water tight, easier to clean, less parts to make, stronger and faster under sail.

An experienced builder could make the conversion other wise you'll have to hire someone to work out the details.

Lake Erie on a good day will be fine for this boat, but she doesn't have a lot of freeboard so run for shore if the weather turns on you.

She could stand some updating if you elect to have a construction upgrade preformed. Appendages and rig both could tolerate some modern thinking. This is one of the problems with these old free plans. First of all they're not usually very comprehensive. Also they don't incorporate modern materials or techniques. Lastly, dealing with a living designer is a handy thing, especially if you have a question. You can try the "crap shoot" of a discussion forum, hope for the best or call a living designer.

[unseen wombat]

I don't think I really want to hire someone to redesign the boat. I'd be happy if I could find a similar design in the stitch & glue style. Though I'm not sure I've given up on the traditional construction. I've been over and over the plans, and I think I could do it. Especially with the shopbot to help me cut the panels. The only thing I'm not crazy about is the weight. A lighter boat sure would be nicer. Too bad there's no free stitch & glue plans out there. I hate to spend $100 for a plan I later decide I don't like.

In searching for information on stitch and glue, I did find the "hulls" computer program, which is perfect for making DXF's of the panels to send to the shopbot.

I probably will go with paint, since upkeep sounds like a real pain in the neck. As a woodworker though, I might have to have nightmares after painting mahogany or white oak. :( (Paint is for poplar or pine, never anything nicer, but I guess boatbuilding is different than furniture making).

[marshmat]

Phil Bolger's "Gypsy" might be worth a look:
http://www.instantboats.com/gypsy.htm
She's a similar size and style to the Falcon, but in tack-and-tape construction (T&T is essentially stitch-and-glue without the wire stitching step). She'd be a lot lighter than the Falcon (about 120-150 lb versus 475), and is reported to be reasonably fast under sail. The rig is free-standing- no stays, no shrouds, no chainplates. There's a light fibreglass sheathing, which is a big durability improvement over bare plywood.
Plans are only $40, and they include nesting drawings to cut the whole boat out of five sheets of plywood.

Shopbots are handy, but whether it would save much time on a build like this is debatable. Most plans in this size will be drawn for hand lofting with a batten, which is frankly much faster and easier than people often say it is.

[alan white]

I don't think I really want to hire someone to redesign the boat. I'd be happy if I could find a similar design in the stitch & glue style. Though I'm not sure I've given up on the traditional construction. I've been over and over the plans, and I think I could do it. Especially with the shopbot to help me cut the panels. The only thing I'm not crazy about is the weight. A lighter boat sure would be nicer. Too bad there's no free stitch & glue plans out there. I hate to spend $100 for a plan I later decide I don't like.

In searching for information on stitch and glue, I did find the "hulls" computer program, which is perfect for making DXF's of the panels to send to the shopbot.

I probably will go with paint, since upkeep sounds like a real pain in the neck. As a woodworker though, I might have to have nightmares after painting mahogany or white oak. :( (Paint is for poplar or pine, never anything nicer, but I guess boatbuilding is different than furniture making).

You certasinly can use the original plans and still improve on the longevity of the original. The hull's exterior joints can be taped with glass set in epoxy just the same, and the framing parts can be bedded in a modern polyurethane or polysulphide. Nothing need change in regard to the parts and pieces specified. Hiring a designer would set you back hundreds, well beyond the point of practicality.
You can also omit glass and epoxy but I wouldn't recommend it. Just that bit of protection on the chines, stem, and keel will go a long way towards keeping the chance of leaks down to negligable.
This process (taping only the exterior seam) is tried and true. It works well with traditional ply construction, and it has been around for decades, first with polyester resin, and later with epoxy, which is so much superior to polyester that nobody in their right mind tapes seams with polyester any more.
Keep going with the project and stick to the plans. Adding those few modern processes will be easy and very cost-effective.

[unseen wombat]

Phil Bolger's "Gypsy" might be worth a look:Is that guy trapezing in the picture? I don't want to do that. I just want to take my family out on it for a leisurely boat ride. The tiny cat though on the same site looks good. I only wish it were a little longer.

I also like the look of the Glen-L 14, but that's traditional construction too, isn't it? It's certainly pretty heavy.

Shopbots are handy, but whether it would save much time on a build like this is debatable. Most plans in this size will be drawn for hand lofting with a batten, which is frankly much faster and easier than people often say it is. Yeah, I'm sure I could do it, but I'd like a project that the shopbot is suited for, just as an exercise to learn how to use it, and this would be perfect.

This process (taping only the exterior seam) is tried and true. It works well with traditional ply construction, and it has been around for decades, first with polyester resin, and later with epoxy, which is so much superior to polyester that nobody in their right mind tapes seams with polyester any more.
Keep going with the project and stick to the plans. Adding those few modern processes will be easy and very cost-effective.Yeah, I've pretty much decided that whatever plan I end up with, I'll be covering it in fiberglass, just to keep it looking nice. I've heard blistering is sometimes a problem though. How can I prevent that from happening?

[marshmat]

Just about any small sailboat can get a bit of extra power with a trapeze in a stiff breeze. That doesn't make it mandatory. Gypsy, and boats like her, can be sailed in a leisurely fashion with kids on board, if you so choose. Of course, unlike their heavier bretheren, they also have the ability to get up and go like a scared cat if you feel the need to do so.

Osmotic blistering isn't really an issue with glass/epoxy on plywood. It's more of a concern when you have a polyester laminate (ie, production fibreglass hull) staying in the water all season.

[ancient kayaker]

Speaking for myself, I put my boats in the water for a few hours at a time, freshwater lakes only, I store them insde most of the time, or upside-down on the beach for a couple of weeks at a time on vacation. If this also describes your intended usage then my methods may be applicable.

I dislike glass fiber and minimise use of epoxy. Titebond III is an alternative see http://www.boatdesign.net/forums/wooden-boat-building-restoration/titebond-iii-testing-27019.html. I use marine ply for all planks. For a simple flat-bottomed boat I fasten the chines using chine logs which are narrow wood battens about 4 times the thickness of the ply: these are first glued to the side (sheer) planks while flat using Titebond. When the bottom is glued on I use epoxy as this joint alone is exposed to water and the paint can wear at the chine exposing the wood and glue line; in addition this joint is difficult to fit without at least a small gap, and epoxy can handle gaps whereas Titebond cannot.

I do not glass or epoxy coat my boats, I find paint/varnish is sufficient protection given the conditions they work in. I make sure they are exterior grade: I use house paint sometimes, it lasts for years on a house exposed to far worse conditions than my boats run into. I check for and patch scratches about once a month, don't usually find anything. My first boat ws left outside for an entire Ontario winter; it had only Titebond III, no epoxy, and was fine in the Spring, except the pressure of the snow on top of the boat which was stored on its side caused slight distortion of the gunnel. I protect the "wear locations" on my boats, using brass stem bands on all stems and small skids (skegs) to absorb impacts at corners and edges.

This is not the construction of an heirloom quality boat of course, but they seem to last quite well. And of course, the time saved by not coating with epoxy and glass fiber, with the interminable sanding required for a decent finish, is considerable.

[unseen wombat]

AK, I know what you mean. I used titebond II for the crib and it worked great. (the short open time makes glue ups quite frantic though). I'm just worried about getting water into the end grain of the plywood and epoxy seems like the ideal solution. But yeah, I'll probably only be sailing a few hours at a time, or maybe if we like it a lot, we might cruise along the shore and camp out overnight (we'll see).

I have another question now, one that's less stupid than the former ones. Since I'm not gonna be mooring this, I'd like to get the simplest rig to set up and take down in the fastest amount of time possible. I don't want to spend a long time messing with riggings, I want to get off the ramp and sail! Is the bermuda rig practical for me? Or should I maybe think about something else? I kinda like the lug rig for the fact that you can leave the sail attached to the top and bottom spars and just connect those to the mast, right?

If I do build the Falcon, I assume that I would be highly advised not to change the rig setup without getting a designer involved, because that would mess up the aero/hydrodynamic interactions stuff, right?

Anyway, what rig do you guys recommend for fastest/easiest setup and takedown and trailerability?

[PAR]

The free standing, sprit boomed, Bermudian with a sock luff (sound familiar Terry) is about as easy as they come. The sail can be rolled up around the mast. Of course some will argue in favor of the free standing lug or other arrangements, but the rig I've proposed needs the least amount of rigging and spars, plus produces the best sail plan form to maximize performance potential.

Placing a new sail plan on this design would present no major challenges, but it would require some skill to get it right. You could use the rather imprecise method of installing an adjustable mast step and partners, knowing it will need adjustment come launch day. If you place the CE of the new rig, 8' aft of the stem/deck joint, you'll be close enough to adjust after launch.

This also gives you the option of lopping off the bow sprit, which is a good thing too.

[ancient kayaker]

I am just starting a small sailboat myself (a tiny perfect design from PAR, actually). That is a catboat, one sail, unstayed mast, two mast step locations for small and large sails, initially I will use a spritsail but later ... well, we'll see:) I don't have a lot of experience yet in this field but I can pass on what I have learned so far.

Generally if you don't understand the theory you will be advised not to mess with the existing rig. I would suggest as a general rule, keep the center of sail area at the same location fore and aft, and don't increase the sail area or rig height until you have tried the boat and have a feel for it.

Earlier you asked about stainless steel vs silicon bronze screws and bolts. SB is appropriate for top of the line sea-going boats. I think SS is OK for your purposes. Lots of people have used ordinary galvanized steel screws. I personally prefer brass for appearance, it's much weaker but for me the fasteners are to hold the boat together while the glue is setting. I pay a lot of attention to good joints and you clearly have the skills to do that.

I have noted that an overstressed glue joint, once it has started to open up, can fail catestrophically, virtually unzipping, which could cause a massive leak. I had one start to fail like that on my first boat, a canoe, but when I stopped kicking it the water pressure virtually sealed it again. While that might happen on a canoe it might be a different story on a sailboat, which is stressed more. I believe leaving the screws iin place will limit that to a manageable/survivable leak but it's only a theory. What I do before each new build is to make samples of every critical joint in the boat using proposed materials and test it to ensure that the ply breaks (across the thickness, not just delaminating).

[alan white]

[QUOTE=PAR;274363]
You could use the rather imprecise method of installing an adjustable mast step and partners, knowing it will need adjustment come launch day. If you place the CE of the new rig, 8' aft of the stem/deck joint, you'll be close enough to adjust after launch.QUOTE]

That makes complete sense.

[PAR]

Wombat, the problem with these free or low cost plans are many fold. First off is the plans are usually quite dated. This doesn't mean they're not good, but it does mean the methods and particularly the materials may be difficult if not imposable to find today. It also means newer products, especially adhesives and sealants aren't incorporated into the design. You also don't have a person to call or email if you have specific questions about the plans.

For example, if that was a modern design, one say done by me or other contemporary. It would likely be taped seam construction. This would eliminate the frames, floors and most of the interior structural elements of the design. That's a lot less building to do, not to mention materials to buy.

If it wasn't a taped seam build, it would probably be a longitudinally stiffened build. Using plywood to best advantage you can still have a fairly traditional build, meaning little to no epoxy, but still have no frames. Just bulkheads, partitions and stringers, which the plywood is fastened to.

In this size range there are lots of plans available. Taped seam, plank on frame, whatever build style you'd like to try.

For your uses, stainless steel fasteners will be fine. It'll be dry sailed and on fresh water, so you're okay.

A lighter boat doesn't mean it's less stable. A simple analogy would be to ask if a Mini Cooper is less stable then a big Chevy Impala. The Chevy weighs twice as much, but it's not more stable because of it. Boats are similar. Small boats by their very nature, rely on crew placement to gain needed stability. Some are better at this then others, but nothing by the numbers I see for Falcon would suggest she's a tender craft. In fact she appears quite the opposite.

http://www.bateau.com/studyplans/CR13_study.htm?prod=CR13

This design is much better.

You may also want to look at Glen-L 13, 14 or 15 (www.glen-l.com)

Then again maybe one of mine.

[unseen wombat]

The free standing, sprit boomed, Bermudian with a sock lufIs that what they call the leg-of-mutton rig? or do you mean a sprit rig?

I am just starting a small sailboat myself (a tiny perfect design from PAR, actually). That is a catboat, one sail, unstayed mast, two mast step locations for small and large sails,As I've been looking around at different plans, I really do like the catboat style. It looks pretty easy to sail and I like the wide hull. That's probably why I liked the Falcon, since it was kinda similar to that. I looked at the "Instant Catboat" and I may end up going with that one, I like it so much. The Gaff rig looks kinda complicated, but if I install the mast on a tabernacle, do you think I could just leave the sail rigged while I transport it? I also like the gaff rig because if I'm about to capsize :eek: I can just release the peak halyard and I hear that will right her every time.

Earlier you asked about stainless steel vs silicon bronze screws and bolts. SB is appropriate for top of the line sea-going boats. I think SS is OK for your purposes. Lots of people have used ordinary galvanized steel screws. I personally prefer brass for appearance, it's much weaker but for me the fasteners are to hold the boat together while the glue is setting. I pay a lot of attention to good joints and you clearly have the skills to do that.

For your uses, stainless steel fasteners will be fine. It'll be dry sailed and on fresh water, so you're okay.That's good news! That'll probably save me a few hundred dollars in fasteners.

I have noted that an overstressed glue joint, once it has started to open up, can fail catestrophically, virtually unzipping, which could cause a massive leak. I had one start to fail like that on my first boat, a canoe, but when I stopped kicking it the water pressure virtually sealed it again.Whoa, sounds like there wasn't enough glue on that joint. That's good you test them now to be sure joint is stronger than the wood around it. The worst thing that ever happened to me like that is a molding came off a cabinet. My wife wouldn't be happy though if a seam just opened up while we were out on the lake.

First off is the plans are usually quite dated. This doesn't mean they're not good, but it does mean the methods and particularly the materials may be difficult if not imposable to find today.Yeah, I figured that when they suggested covering the deck with canvas and painting it.

For example, if that was a modern design, one say done by me or other contemporary. It would likely be taped seam construction. This would eliminate the frames, floors and most of the interior structural elements of the design. That's a lot less building to do, not to mention materials to buy.I definitely do like the stitch and glue method, mostly because it saves on weight. It'll be a lot easier for me and two women to wrestle with a 200 lb boat than one that weighs a quarter ton. That's how big my planer/molder is and it's a monster to move around the shop, even on wheels. The decrease in materials is nice too, but I like working with white oak anyway. It will save money though, which is a really good thing.

A lighter boat doesn't mean it's less stable. A simple analogy would be to ask if a Mini Cooper is less stable then a big Chevy Impala. The Chevy weighs twice as much, but it's not more stable because of it. Boats are similar. Small boats by their very nature, rely on crew placement to gain needed stability. Some are better at this then others, but nothing by the numbers I see for Falcon would suggest she's a tender craft. In fact she appears quite the opposite.I see. I just wondered, because a mini-cooper doesn't have several hundred foot pounds of overturning moment trying to flip it on its roof when the wind is blowing at its side. LOL

http://www.bateau.com/studyplans/CR1....htm?prod=CR13

This design is much better.

You may also want to look at Glen-L 13, 14 or 15 (www.glen-l.com)

Then again maybe one of mine.I agree. That is better. You know, I did look at the Glen-l boats and I liked their shape a lot, but I couldn't figure out if they were traditional construction or stitch and glue.

Yours is nice too. Can that center board be raised though? And what about the rudder. Beaching will probably be something I want to do, if say we go to an island for a picnic or something.

Looking at the sections, I think I may be warming up to the flat-bottom style. I liked the V bottom at first, because I think it probably sails better, (is that even right?), but the flat bottom would sure be easier to walk around on without having to build a floor.

[ancient kayaker]

Chine joints are unlikely to open up using the taped seams construction because they flex a little. Use of screws in the chines does not apply to taped seam construction. Using chine logs provides me with a stiffer hull and lets me use less frames, but can lead to stress concentration at the chines. The seam that failed was on my first boat which was made with door skin, very cheap ($10/sheet) luan ply that I no longer use. I didn't anticipate the seam would react like that to stomping inside it; that put a peeling force on the joint, a glued joint's worst enemy. Everyone told me to use marine ply and I do these days, but back then I wanted to build boats for as few $$ as possible until I learned the craft. I also wanted to design my own boats so I didn't expect my first boats to be much use. Experience, embarrassment and pain have been patient teachers.

Speaking of covering the deck with canvas and painting it, there is an article on that in the current issue May/June 2009 (#208) of Wooden Boat Magazine, so it is still being done.

There are a lot if advantages to the flat-bottom skiff. As you noted, it comes with a built-in floor. It has to be the easiest way to build a boat, although you may get arguments about that from the skin-on-frame faculty members. Stability is a given of course, and I understand skiffs sail respectably since they shed skin area as they heel, and there is more usable internal space than other boats of the same overall size. I have done stability analysis for the tiny 10 ft long skiff I am starting, and that indicates that theoretically I can stand anywhere within the boat without overturning it, except possibly the extreme bow but the deck will make it impossible to stand there anyway.

I have decided to install buoyancy tanks along each side which will double as seats, so in practice I won't be able to stand right at the gunnel, so she should not move underfoot very much at all. The tanks can go all the way up to the sheerline on such a small boat eliminating the need for side decks, they will stiffen the lightly-built hull and prevent me stomping too close to the chine joints.

[oldnwise]

Hi Wombat, if you still interested, take a look at http://www.dinghy.pl/ there are a few free plans easy to build, and they are light weight, you can contact the designer by mail if you do have any questions.
Good luck on your project.