Questions about catspaw dinghy.

[nickajeglin]

I am about ready to start lofting one, but I have several initial questions. But first, I'll tell you what I have:

I got the Barry Thomas book "Building the Herreshoff Dinghy" and the wooden boats "How to Build the Catspaw". I'm planning on trying to do glued lapstrake construction so I also got John Brooks and Ruth Ann Hill's book "How to build Glued-Lapstrake Wooden Boats".

Any thoughts on the glued lapstrake thing? I live in Nebraska, where the humidity flies around wildly and the boat will live on a trailer, probably outdoors, covered in tarps.

I have not much woodworking experience (read none) but have time to learn, and am planning on spending several years building, since I also have not much (read no) money. I just finished making several 8' pine battens 2 millimeters thick which I hope to use for lofting. Is that an acceptable thickness? I did get my plane sharp enough that it makes nice long thin curls off of them so I think I could go thinner if necessary. I don't think they're long enough, but could one scarf them together and still have a fair curve? Do you think I will need a book specifically on lofting? The John Brooks book goes over it cursorily, but it's a little shady on specifics.

The wooden boats book specifies building in carvel, but the original was lapstrake. Do you think it's possible to go to glued lapstrake using the wooden boats plans? It seems like the challenge is calculating the number planks one would need per side. Any insight on that?

Thanks for any help you can give me, I need as much as I can find. There's not many boatbuilders in Nebraska.

Nick

[Candyfloss]

I can talk you thru, step by step, how I built mine if you like.


http://pic50.picturetrail.com/VOL458/12377907/22018548/368295438.jpg

That,s the finished product with the mold in the background, built on the skinniest budget I could manage.

[bob easton]

That's an ambitious, but completely achievable. project for a first boat. You might be making it more difficult by wanting to use a construction technique different from the one in the WB reference book.

My only contribution is a few suggestions:


You're probably already doing this, but study very carefully the construction differences between the carvel planed boat and the glued lapstrake boat. There are differences that will affect the lofting of the forms you use. For example, ribband placement and plank lines. Once you reach a point of confidence with the differences, get to the lofting.
You might want to consider yet one more book Greg Rossel's "Building Small Boats" describes both carvel and lapstrake boat building by traditional (planks and frames) methods. The contrasts within that book help understand the first point above.
Take Candyfloss up on the offer for "step by step" guidance, and take a look at Candyfloss' "My New Boat" thread at:
http://www.woodenboat.com/forum/showthread.php?t=96479

Oh yeah, those 8 foot battens are too short. 3 to 4 feet longer than the longest lines on the boat would be better. Scarfing pieces together will work as long as you don't need them to form tight radius bends, and you can make the scarf at a 12 to 1 ratio. That should give your sharp plane something to practice.

You're starting on a new journey, one that I can attest (from a recent first build) will be very rewarding. Some have said that boat building is often a serious of problem solvings. There are lots of us here willing to help when you hit a problem that doesn't have an obvious solution.

[nickajeglin]

Candyfloss, thank you for the offer, I'm sure I'll have quite a few questions for you very soon :p

For starters, I'm going to need some type of building jig to which the molds will be attached, yes?

To find out the size of this jig, I need to make some sort of full sized patterns of the sections.

If that is so, then those would also be the patterns for the molds.

If all of that is correct then I have several questions about lofting the sections (stations?). They mainly concern where they run into the sheer, and where they run into the keel.

Am I on the right track here? If so, I'll get back to you with those lofting questions.

[almeyer]

As stated above, get Greg Rossel's "Building Small Boats." It will be money well spent. He has an excellent chapter on lofting, and by the way, the example he uses in that chapter is the Catspaw Dinghy. He's also got a good chapter on lining off the planks.
Al

[nickajeglin]

Thanks, I will do so. I'll get back to you guys when I've researched more.

[Bruce Hooke]

2mm sounds way too thin for a batten. You want something that you can bend to the curve required without a whole bunch of force, but you don't want something that bends so easily that it has to be held in place every few inches because then you will have a very hard time getting a fair curve. I'd think you'd want a batten that is more like 6mm (1/4" thick). For the tightest curves you may well need a very thin batten so don't get rid of the 2mm batten but also don't bother making it long enough to draw the long, gentle curves.

How wide is your batten?

[Bob Cleek]

Get Alan Vaites' book "Lofting" from the WB Store. It's not expensive and it will tell you everything you need to know about lofting and then some.

Read the "Building the Herreshoff Dinghy" book over and over until you can build the boat in your head with your eyes closed. Seriously. It is a really great little book. Just about everything you need to know about building this type of boat is in that book.

Forget about what you've read about battens. All you need is something that will spring a fair curve under tension. You can make wooden battens, but you'll soon find you'll need several sizes... small thin ones for tight curves and heavier ones for the long sweeps. Be creative. The world's dumpsters are full of good battens. I've used broken bandsaw blades for laying out tight curves lots of times, for instance. Long lengths of fibreglass, metal and similar materials work just as well as wooden battens, too. Often, you can go to the Big Box store or the lumberyard and get a long 10' or even 12' length of trim molding material that will be perfect for a batten for very little cost. That approach allows you to select a clear straight grained piece that will lay a good fair curve.

Finally, after you've wrapped your head around how Herresoff built those dinghys, seriously, very seriously, consider building your boat that way rather than trying to cob together the same sort of thing out of plywood and hold it together with hardened epoxy. A properly built clinker hull, using good dry wood, particularly if you run a small bead of caulk on your seam and let it set up so it acts as a gasket, will do just fine out of the water. That construction technique was designed by the Vikings exactly because they hauled their boats out of the water all the time. Done correctly, any shrinkage will swell up tight in short order.

As for plywood versus "real" wood, take a 3/4" piece of plywood and run your plane down the edge of it. Then do the same with a piece of naturally grown lumber. Then consider how much planing you will have to do to shape the plank bevels on your boat. Buck bet you'll decide against the plywood!

Don't freak out because you can't find boat building wood in your local Big Box store. You're considering a small boat. Even if you have to travel a bit to get yourself some nice Alaska yellow cedar or a similar wood, and pay a little bit more for it, your labor is the biggest "cost" and there's no point in putting a lot of time and care into any project if you aren't going to use the best materials you can find. In the end, the natural wood won't cost more than the plywood anyway, since you are going to have WAY more waste using 4x8 sheets of plywood than you will using standard planking stock.

If this is your first build, then make yourself a model first at, say, a scale of an inch to the foot. Loft it to scale from the offsets and plans in the Herreshoff book. Build it out of basswood from the hobby shop, just the way the book says they did it. (You'll have trouble riveting at that scale, but cyanoacrylate glue does as good a job on a model.) For your trouble, you will have made and corrected many of your mistakes at a scale of 1:12 and have a nice model for your mantle to inspire you as you tackle the full sized boat.

Things to consider. Don't give up. "Experience starts when you begin."

[Mrleft8]

Double the length and width of your lofting battens. Think through every stage 3 times before cutting anything. Read the "How to build a Catspaw Dinghy" book 5 times before throwing it out. (I found it less than useful, and actually contributed to having to reinvent the wheel a couple of times)
Ask specific questions here as often as you need. Get a decent digital camera, and learn how to post pictures, so that we can "see" the questions you have as they arise.
Good luck! It's a wonderful little boat.

[nickajeglin]

Bruce, the battens are the width of the short side of a 2X4, in this case just under an inch and a half. I'll keep it around for the tight things and check out home depot/lowes for some materials for the long curves (thanks Bob).

Bob, here is what concerns me about the traditional construction: Steam bending oak frames, and riveting. I'm probably only afraid of those methods because they are so unfamiliar to me, but it seems like they would be very complicated. Am I mistaken? I also am concerned about the availability and cost of good wood, a problem which you already addressed to some extent. It's not that it's impossible to find around here, it's just that I am utterly inexperienced as to what I'm looking for. I couldn't tell Alaska yellow cedar from Douglas fir from mahogany. (Ok, maybe I could identify mahogany) It seems like having my local lumberyard order me a few sheets of marine ply is the only option I have. Speaking of which, they want 80$ a sheet for marine ply. That seems crazy to me. Is that fairly standard or are they just charging exorbitant prices so I'll shut up and leave them alone?

[Bruce Hooke]

Bruce, the battens are the width of the short side of a 2X4, in this case just under an inch and a half. I'll keep it around for the tight things and check out home depot/lowes for some materials for the long curves (thanks Bob).

Two thoughts: I prefer a batten that is not so wide and thin. I find it very hard to keep something that wide and thin bending smoothly, square to the surface, and in nice contact with the surface.

It sounds like you used a 2x4 to make the batten. Try bending that batten into a curve and sighting down it. I'd bet that it won't take up a smooth curve. If so, toss it. When you bend a batten in a gentle curve and sight down it you should see a nice smooth curve with no bumps in it. A standard 2x4 with knots, lots of grain runout and so on will almost certainly have humps when you try to bend it. For a traditional wood batten you need nice reasonably straight-grained wood that is totally free of knots.

Once you start using a batten, if you are paying attention to what is going on it should become more clear what works and what does not.

Alternatives to wood are good if you need a fairly tight curve. I still like wood for longer gentler curves.

[Candyfloss]

Twelve foot eight is a big dinghy, especially for a newbie. You will need a good workspace & lots of time. You will also need to make friends with a joiner or cabinet maker for the use of a bench saw, planer & thicknesser, or get him to do it for you. Lumberyards do not stock timber in the sizes you will need. You local lumberyard will probably not stock timber in the quality you need. You will also need at a minimum, a jigsaw, a 4" grinder, a trimmer router, & two (yes two) 12v battery drills. You already have a hand plane. You will need a good work bench with a vise and a sturdy shelf 14ft long for handling your planks. You will need lots of clamps.
I live in New Zealand so I cannot help you with your choice of timber, but a mahogany transom always looks good. The wisdom on this forum is that white oak does not glue well with epoxy. Oh, yes, you will need a 5 litre pack of West System epoxy with dispensor pumps, slow hardener & glue powder. Accept no substitutes.
At a guess, your planks will take up one and a half to two sheets of ply wide by two sheets long. That's six, maybe eight sheets of 6mm marine ply. You live in the middle of nowhere according to my Atlas, so Lord knows what it will cost.
Still want to build this boat? Not trying to scare you off, just point out the size of your project. Hell, my wife & I built a 25ft cruiser/racer in a shed at her Mom's place in 18 months, while we both worked full time. Anything is possible.
Graeme.

[Bruce Hooke]

Twelve foot eight is a big dinghy, especially for a newbie. You will need a good workspace & lots of time. You will also need to make friends with a joiner or cabinet maker for the use of a bench saw, planer & thicknesser, or get him to do it for you. Lumberyards do not stock timber in the sizes you will need. You local lumberyard will probably not stock timber in the quality you need. You will also need at a minimum, a jigsaw, a 4" grinder, a trimmer router, & two (yes two) 12v battery drills. You already have a hand plane. You will need a good work bench with a vise and a sturdy shelf 14ft long for handling your planks. You will need lots of clamps.
I live in New Zealand so I cannot help you with your choice of timber, but a mahogany transom always looks good. The wisdom on this forum is that white oak does not glue well with epoxy. Oh, yes, you will need a 5 litre pack of West System epoxy with dispensor pumps, slow hardener & glue powder. Accept no substitutes.
At a guess, your planks will take up one and a half to two sheets of ply wide by two sheets long. That's six, maybe eight sheets of 6mm marine ply. You live in the middle of nowhere according to my Atlas, so Lord knows what it will cost.
Still want to build this boat? Not trying to scare you off, just point out the size of your project. Hell, my wife & I built a 25ft cruiser/racer in a shed at her Mom's place in 18 months, while we both worked full time. Anything is possible.
Graeme.

I'd disagree on quite a bit of this. As long as he has enough work space, I don't see a 12 footer as really THAT different from say a 9 foot long boat except that when done the 12 foot boat will be an all around much more useful boat. For the plywood version, the amount of lumber that will need to be taken down in thickness is relatively modest so it should not be that hard to get that done. The count on the number of sheets of plywood also sounds a little high to me. Yes, building would be easier with a tablesaw and a thickness planer handy.

I would also disagree on a lot of the specifics of the tools. I've never felt the need for two cordless drills. In the very rare cases where two drills speeds things up I use my cordless drill and a corded drill, and I've never felt like I needed to have two drills. I waited years before I got a trim router. I almost never use my angle grinder for boat work. If a 14' bench is a problem I've done fine with sawhorses and some planks to make a temporary long working surface.

There are a variety of good epoxies out there besides West System. I would certainly stick with a name brand and I do like West System myself, but that is not the only good choice when it comes to epoxy.

[gazzer]

I was scanning the book, "Building the Herreshoff Dinghy - the Manufacturer's Method" last night for the great insight it provides on spiling and dimensioning planks. I was thinking at the time that it would be very useful for glued lapstrake as well.

Good luck

-G

[bob easton]

Bob, here is what concerns me about the traditional construction: Steam bending oak frames, and riveting. I'm probably only afraid of those methods because they are so unfamiliar to me, but it seems like they would be very complicated. Am I mistaken? ... It seems like having my local lumberyard order me a few sheets of marine ply is the only option I have. Speaking of which, they want 80$ a sheet for marine ply. That seems crazy to me. Is that fairly standard or are they just charging exorbitant prices so I'll shut up and leave them alone?

I'm probably not the same Bob to whom you directed the questions, but I do have a couple of thoughts. Steam bending and riveting can seem intimidating, but once lerned, they aren't. They require some learning and practice, and understanding a few tips (i.e. use lumber that is as green as you can get it, not kiln dried (most stuff at the home center is kiln dried)). That book by Greg Rossel will give you more info on both techniques. One thing to consider is that you'll need a helper for riveting, and it's handy to have a helper for bending. If you are a lone builder who can't rustle up an occassional helper, these jobs will be very challenging.

On the cost of marine plywood, yes, it is expensve and the $80 price might not be out of line ... depending on the variety and thickness. This is definitely an area for shoping around. By the way, there are a number of lumber vendors who have web sites, and who can arrange deivery almost anywhere.

[nickajeglin]

@Bruce, I spent a loooonnnnggg time searching for the right 2X4. It has no knots except for one bad one about 5 inches in from one end. The grain is really straight, and as far as I can tell, it's bending nice and fair, except for that part with the knot. For future reference though, where would one find nice knot free wood like you are talking about?

@Candyfloss, middle of nowhere indeed:p I doubt there's much you could say that would scare me off, but your points are well taken. Luckily I have access to a fairly well outfitted shop (my father runs an art framing business), I believe the only tools mentioned that I can't come up with are the planer and thicknesser. Are these tools that speed up hand work? Because I'm not in a great hurry, if I have to spend a week making a part then I'll spend a week.

@Bob Cleek and Gazzer, I just finished seriously reading the Building the Herreshoff Dinghy book cover to cover several times, and you're both right, it's pure gold. I'll check out "Building Small Boats", read up, and I think I'll be almost ready to get started!

Any last thoughts on traditional lapstrake vs. ply before I bury myself in books for a while? I think I'm still leaning towards ply for now, but I'll probably have to do some reading to be sure.

Thanks,
Nick

[Bruce Hooke]

@Bruce, I spent a loooonnnnggg time searching for the right 2X4. It has no knots except for one bad one about 5 inches in from one end. The grain is really straight, and as far as I can tell, it's bending nice and fair, except for that part with the knot. For future reference though, where would one find nice knot free wood like you are talking about?

Well done on finding a clear, straight-grained 2x4!

At least around here, my local lumberyards carry clear pine 1x stock. It is a lot more expensive than #2 pine, but for one or two battens the price is pretty reasonable.

I believe the only tools mentioned that I can't come up with are the planer and thicknesser. Are these tools that speed up hand work? Because I'm not in a great hurry, if I have to spend a week making a part then I'll spend a week.

A planer is mighty useful. If you otherwise have access to a pretty well-equipped shop I would consider spending a few hundred dollars on a portable thickness planer. It is not too bad to true up the edge of a board with hand plane but taking a pile of boards from 3/4" thick down to 1/2" thick is a job only a masochist would take on by hand. That said, you should first look over the plans carefully and figure out how much wood you have to take down in thickness. If you go the plywood - glued lap route there may be so little wood that needs to be thicknessed that it does not make sense to get a planer.

Note that the perfectionists will say that a thickness planer is not much good without a big, wide jointer to first true up one face of the board that needs to be thicknessed. In theory this is true but it is not too bad to at least roughly true up one face of a board by hand so you can thickness it and end up with a flat board, and quite frequently, if the rough board is reasonably true you can get away with skipping this step anyway.

[Candyfloss]

I also have a picture framing business. There is nothing there that I would consider useful for building dinghies. Well, I have occasional use for a battery drill. My fourth. Anyway, the studio is a dust-free zone. No dinghies allowed.
I could not build my dinghies without access to the bench saw, planer & thicknesser at my mates boat shed, even tho it is a half hour drive (a big deal in NZ) from where I live. I take him beer. Everyone is happy. I never said you should buy those things.
The rest of Bruce's post is too depressing. I can't be bothered arguing. I stand by my advice. All of it.
Graeme.

[Mrleft8]

Steam bending the oak frames is easy. Riveting is easy once you get the knack, but you will need an assistant.
Drill the hole in the centerboard trunk for the centerboard pivot pin before you install the centerboard trunk into the boat.

[Candyfloss]

I'm planning on trying to do glued lapstrake construction so I also got John Brooks and Ruth Ann Hill's book "How to build Glued-Lapstrake Wooden Boats". Quote.

Rivets? Who said anything about rivets?

[nickajeglin]

Rivets? Who said anything about rivets?

Bob Cleek was recommending that I consider the traditional building methods in the "Building the Herreshoff Dinghy" book. I was simply bringing up what methods most scare me out of that book.

[nickajeglin]

Ok, I've been studying, saving money and studying more, and have a few more specific questions now.

I've decided on the glued lapstrake plywood construction method, so:

Concerning molds, should I make one for each station? For a boat this small this seems sufficient to me.

Concerning ribbands, I see that candyfloss did not let them into the molds. Should I just take their thickness into account when lofting my stations? What if I don't know their thickness yet? It seems that I should just loft to the inside of the planking and then cut notches in the molds for the ribbands. Is this correct?

Concerning frames, it appears in the pictures of candyfloss' boat that he has none? Is that right candyfloss? Do they get added later? The John Brooks book hardly even mentions them, while the carvel planked version in my plans has them every few inches. How many do you think I should have, and where would be good places to put them?

Thanks for all of your help, sorry if I'm asking silly questions.

Nick

p.s. I've also managed to locate a large heated shed to work in not to far from where I live. It even has almost every tool that I need, including a nice woodworking bench. So now the only problem that I have is locating materials. Does anyone happen to know of any sources for someone as landlocked as me?

p.p.s. Gah, every time I close my browser I remember another question. What is the common wisdom on plank thickness for a dinghy of this scale in glued ply? John Brooks says 1/2" should be sufficient, I've seen Ian Oughtred designs that specify 6mm. Would 3/8" be sufficient?

[Richard Jones]

I've built a number of glued lap from old carvel-plank plans. A lot of hit and miss, but they came out fine.
Molds: one at each station is fine.
Ribbands: I don't notch them into the molds. This lets you adjust them on the molds to get that perfect eye-sweet curve. 1/2" thickness should do. Just subtract from molds.
The beauty of glued-lap is the absence of ribs. The properties of plywood, plus the epoxy holding the laps together, makes for incredible stiffness and strenght. Depending on the design, you might want a couple to avoid oil-canning (bottom of boat flexing in and out while under way.
I'm a carpenter by trade, but learned all my boat-building from books. Lots of fun and a great challenge. Good luck!
p.s. plank thickness: again, with plywood it can be a lot less than carvel. 6mm (1/4")should do. Marine ply is measured and sold in mm thicknesses.

[nickajeglin]

If I do decide to put a few ribs in, they would go above the ribbands, under the backbone, correct? If this is true it seems largely like a matter of many ribs or none. If I am to put any ribs on it seems that I must let the ribbands into the molds to allow room for the ribs between ribbands and planking, which seems like quite a bit of work for just one or two. Could a person add ribs after planking and removing from the mold? Steam them and press them in from above?

[Mrleft8]

Yes you can install the "ribs" after you pull the hull off the molds, but I would build over them. And I would put more than just a few in. As for letting the ribbands into the station molds.....I would. The closer the mold is to the inside dimensions of the hull, the less math you have to do, and less math means less mistakes and head scratching (for me anyway).

[Richard Jones]

Your main challenge here is understanding the difference between carvel and lapstrake construction. Ribbands notched into molds or not? Your choice. In carvel construction, (small boats, anyway)the ribs are bent over the ribbands and the planking attached to the ribs. In lapstrake, whether traditional or glued lap, the ribs are bent in after the boat is off the mold. This is because the laps are attached to each other and the hull is self- supporting. In traditional lap, you need those ribs every few inches. In glued-lap, you don't.
If it gets all too confusing, perhaps choosing a similiar boat designed for glued-lap with a complete building manual might be a good option. I've been building boats as an amateur for 30 years and I still lie awake at night scratching my head over problems, converting 100year old plans to glued-lap!

[nickajeglin]

Ok, so here's my plan as of now: I'll loft the stations to the inside of the planking, use those for molds, position the ribbands to my liking, notch them into the molds, and leave frames (not ribs, sorry for my linguistic faux pas) out until I get it off the molds. Then I will check out the stiffness of the hull and see about bending in frames. Does this sound like the correct way to go about it?

[GRussell]

This may sound really stupid, but if the frames go in after the boat is off the molds, what do the ribbands do? I'm building LIZ and it's not too late to add them if I need to. Please forgive my ignorance.

[Mrleft8]

This may sound really stupid, but if the frames go in after the boat is off the molds, what do the ribbands do? I'm building LIZ and it's not too late to add them if I need to. Please forgive my ignorance.

They'll stiffen the whole assembly. Aside from that, they'll certainly get in the way, and make life difficult! ;)

[Thorne]

More nautical nomenclature: in small lapestrake boats you can have two types of frames - sawn and steamed/bent. Some have both, like my Chamberlain dory skiff.

http://www.luckhardt.com/backrest1.jpg

Here are some pics of a fancy Catspaw build by a friend of mine with lots of uber-trad additions, including bent frames, hawse-holes, a bowsprit, etc. He needed bent frames because he built the hull from doorskin material (not anything I recommend), so it was too light to hold shape without frames, even when glassed inside and out.

http://www.luckhardt.com/big-lagoon-06/images/DSCN7504.jpg


http://www.luckhardt.com/big-lagoon-06/images/DSCN7505.jpg

http://www.luckhardt.com/big-lagoon-06/images/DSCN7507.jpg

http://www.luckhardt.com/big-lagoon-06/images/DSCN7506.jpg

[Richard Jones]

This may sound really stupid, but if the frames go in after the boat is off the molds, what do the ribbands do? I'm building LIZ and it's not too late to add them if I need to. Please forgive my ignorance.

There are several ways to build glued-lap boats. The method I use (the Tom Hill method), uses ribbands (or battens) to define the exact shape of each strake. This is what you see in the picture of the catspaw earlier in this thread. Has nothing to do with frames. Other builders "line-off" their strake shapes directly on the molds.

[Thorne]

I believe that Arch Davis also uses the ribbands/battens method for his glued-lapstrake designs. They are left in the hull, which some folks like and others don't -

http://www.archdavisdesigns.com/ad3.JPG
http://www.archdavisdesigns.com/ad1.JPG

http://www.archdavisdesigns.com/davis_penobscot14.html

[nickajeglin]

Thanks for all of the information and great photos. I see there are many different methods of doing this, especially with respect to the ribbands and frames. I think that I will review what methods the John Brooks and Greg Rossell books recommend and adapt them to my design. Fall break is coming, and I'm about to go get some ply to loft on. I'm really excited to get started on the lofting! :D

[Sailor]

I'll be keeping an eye out on this thread as I plan to start work on lofting my Catspaw this winter. Assuming I can get the house projects struck off the honeydo list.

[Richard Jones]

I'll be keeping an eye out on this thread as I plan to start work on lofting my Catspaw this winter. Assuming I can get the house projects struck off the honeydo list.

I just finished remodeling the master bath. This should earn me a month or two for boatbuilding. My wife was no fool for marrying a carpenter.

[nickajeglin]

Is it all right if I use this thread as a sort of a building journal to keep everything in one place? If not, just let me know and I'll be sure to move such things to where such things go. Anyways, I'm going to try to keep an accurate account of how much money and time I spend, in addition to any mistakes I make, and how they were fixed. I'm planning on putting pictures of steps here: http://www.flickr.com/photos/45050602@N03/ (sorry for the low quality of the first few, forgot the camera at home.])

So for time:
Painting lofting boards...................................1.00 hrs
Laying out grids............................................3 .00 hrs
Lofting........................................... ..............12.75 hrs
Total so far............................................... .16.75 hrs

As for money:
3X plywood for lofting...................................33.93
Plastic lofting battens (failed).........................17.60
2X KNEEPADS!!........................................ ..... 6. 38
Total so far............................................... ....57.91

Today I started the lofting, the only things of significance are that I tried to take a shortcut and use some rectangular cross section pvc for lofting battens instead of wood. It failed. Far too floppy to make a fair curve. I ended up running all around town looking for a relative with a table saw to make some pine ones since the shops was out of commission at the time. I also discovered what appears to be at least a printing error in the plans. The offset for the bearding line at the 11" waterline has the number of sixteenths messed up, but it's only a single digit for sure. Even if you make it 9/16 its still not fair. I adjusted it to 6 and 15/16.

Continued lofting on 11/28 waterline 5 and1/2 appears to be off at station six in the half breadth view.

Nick

[Sailor]

Nickajeglin,
If you find many errors in the table of offsets, maybe you would be so kind as to keep track of them and post them here for the rest of us who plan on building a Catspaw. Mine is still in plan form on the shelf next to me. When I have time to finish the Redbird canoe, I'll set up to do the Catspaw. Can't wait to start though.

[nickajeglin]

Often it's hard to tell what's my inexperience and what's an error. But the one I posted is most definitely an error. Things look all bumpy if you use the printed offset, and if you remove that spline weight (in this case a jack plane) everything straightens out nicely.

[nickajeglin]

Today I continued lofting. I've almost got it finished. All that's left is the inner face of the transom, and the stem rabbet. Projecting the transom was a pain, as I got confused and annoyed by one of the transom intersections with a buttock, and ended up drawing waterlines every inch to try to make sure it was accurate, turns out that I had stopped labeling the ticks on my tick strip and had used the wrong one. Everything turned out all right, but I can't believe that I did that. As for bad offsets, they mostly seem to be diagonals. The other ones mostly were ok.

Nick

[Candyfloss]

Sorry Nick, I don't know how I missed this for so long. I did not mean to abandon you.

There is a complication with your intended method of running your ribbands, but nothing that cannot easily be overcome.

Keep up the good work.

[Mrleft8]

There are multitude errors in the Catspaw plans. Keep your eyes open, and trust your instincts more than the written word.

[Sailor]

I've read that the diagonals are the most important of all the measurements. If it's mostly diagonals that are out to lunch...... how to fix it? Will they all present them selves pretty readily once I start lofting?

[nickajeglin]

The ones that are so obvious to me that they could not be my mistakes are the diagonals that would cause sharply reversed curves in the body plan. There's also a few offsets for the waterlines in the half breadth that seem pretty bogus.

I've been thinking about making the keel out a flat board, beveling it and the garboards and gluing on a keelson, ala John Brooks. Any thoughts? My reasoning here is that since I'm going to be using different thickness planking (6mm instead of half inch) the keel rabbet, height, and all that stuff will be different from the plans, so I may as well take that opportunity to use replaceable keelson idea, which sounds like good sense to me. That reminds me. Since the planking thickness is changing, does that mean I will have to adjust the rabbet line at the stem to get an accurate stem rabbet? Or will things work themselves out when I get a plank sample on the lofting boards?

Nick

P.S. No worries candyfloss, I'm sure I'll have plenty more questions.

[nickajeglin]

Dang, I just noticed that there's actual plans on the wooden boats website. All I have is the how to build book, most of which I am in fact ignoring. Would it be advisable to actually purchase the plans? Or now that I've lofted from the offsets is it not worth it?

[jmann652401]

Get the plans.
The plan set comes with full size patterns for the station molds. I believe any errors in the lofting were fixed when the patterns were prepared. I used the plans, the "How to" book and the Rossel book to build my Catspaw. You can see a series of photos I took at different stages during the build process. Go to
http://www.catspawbuilders.com/
then at the upper left under "The Builders" click Joe Manning.
Hope this helps you out. Good luck with your Catspaw.
Joe

[Mrleft8]

Dang, I just noticed that there's actual plans on the wooden boats website. All I have is the how to build book, most of which I am in fact ignoring. Would it be advisable to actually purchase the plans? Or now that I've lofted from the offsets is it not worth it?

It's worth it. The book is................. I'm being polite here....... Er...... Not terribly helpfull..............

[nickajeglin]

Polite indeed! It's hardly useful at all, especially for someone like me who is starting essentially without any knowledge. The Brooks and Rossel books are far more useful.

[Sailor]

Brooks? I have Rossel's and it's great. There are many books out there and you never really can have too much information or too many opinions. If you read about enough opinions, you eventually learn to sort out the BS and accept the good stuff. Great learning. Now who's Brooks?

[Sailor]

I agree that the How to build the catspaw is only good to look at a few pictures. I wonder if anyone has plans on doing this book properly? Mabye I'll start photodocumenting mine more detailed IOT publish one.......

[Steve Lansdowne]

John Brooks is a Maine builder, WoodenBoat instructor, and now also works in Brooklin at one of the yards. His Ellen sailing skiff was on the cover of WB Mag some time ago. His book is How to Build Glued Lapstrake Wooden Boats, which he co-authored with his wife, Ruth Ann Hill. He is a very detail oriented guy and focuses on making patterns for parts so one can easily make more than one boat, maximizing his use of the wood he buys by carefully figuring out exactly how to cut each piece out, etc. I have both his and Rossel's books and frankly, I never had the patience to get through Brooks' book. I bought it after having a class from him at the WB School. Rossel's book covers various building techniques, whereas Brooks' book focuses on glued lap, and his example throughout the book is Ellen.

[Thorne]

Yeah, I've heard folks say that Brooks' book should be titled _Building Ellen_ ...

I like Oughtred's _Clinker Plywood Boatbuilding Manual_ also.

[Candyfloss]

I carefully read Brooks' book cover to cover and ignored all of it. IMO it is an appallingly bad way to build a lapstrake dinghy.