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  #1  
Old 05-12-2009, 10:13 AM
unseen wombat unseen wombat is offline
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Total noob. Small plywood sailboat questions.

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/i...nd-nursery-set) but no boat yet.

Thanks for your advice, guys.
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  #2  
Old 05-12-2009, 10:33 AM
jmolan jmolan is offline
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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.
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  #3  
Old 05-12-2009, 10:46 AM
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marshmat marshmat is offline
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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.
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  #4  
Old 05-13-2009, 02:20 PM
unseen wombat unseen wombat is offline
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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. 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.

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?

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.
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  #5  
Old 05-13-2009, 03:06 PM
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alan white alan white is offline
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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.
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  #6  
Old 05-13-2009, 03:35 PM
unseen wombat unseen wombat is offline
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Quote:
Originally Posted by alan white View Post
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.
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  #7  
Old 05-13-2009, 04:18 PM
jmolan jmolan is offline
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http://www.systemthree.com/index_2.asp

Lots of pis an info on finishing bright or clear.

Have fun!
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  #8  
Old 05-13-2009, 04:53 PM
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alan white alan white is offline
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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.
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  #9  
Old 05-13-2009, 05:02 PM
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marshmat marshmat is offline
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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.
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  #10  
Old 05-13-2009, 09:04 PM
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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.
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  #11  
Old 05-14-2009, 10:16 AM
unseen wombat unseen wombat is offline
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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).
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Old 05-14-2009, 10:44 AM
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marshmat marshmat is offline
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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.
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Old 05-14-2009, 01:30 PM
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alan white alan white is offline
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Quote:
Originally Posted by unseen wombat View Post
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.
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Old 05-14-2009, 01:46 PM
unseen wombat unseen wombat is offline
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Quote:
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.

Quote:
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.

Quote:
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?
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  #15  
Old 05-14-2009, 02:30 PM
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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.
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