Marsh Pirogue ? (Keith, Seedtick? Anyone?)

[FlaMike]

KJ,

I can tell you what I think now, tomorrow I can tell you what I know. 8)
I suspect my notion that I would need the extra 5* angle on the stems was not only wrong, but completely bass-ackwards. It probably did add to the rocker, but I'm pretty sure that it is only part of the problem.

From watching what happened as I moved that jig into place, I'm thinking that the amount of flare to the sides had a lot to do with it. This model has the sides flared out at 35*, where I think the average swamp pirogue would have quite a bit less, more like 20* to 25*. As I moved the jig into place, I could see the ends curving up.

Tomorrow, I will make some changes, but just one change at a time so I'll know for certain what did what. I'll probably change the stems to either a 45* which is what my UJ pirogue has, or maybe take it a bit past that, and do a 40* stem. (Later on, I'll see how a curved stem changes things.) I don't want to change the flare at this time, as that is part of the difference between a marsh and a swamp style pirogue.

beekeeper,

You are quite right, I've not cut an arc in the bottom of the side panels. After I finish trying different stem angles, the side arc is next. Right now, the model is of a 12' pirogue, but with 12" sides. From what I've seen, that would be considered quite high. But I did that so I would have some height to play with. (Almost said "wood" instead, but remembered how some of the less cultured might react. ) Anyways, With most pirogues I've seen on this (and other) fourms, having 10" sides, I thought I'd first try a (1/2 scale) 2" arc, just to see how much that lowered the rocker, leaving the minimum side measurement at 10". Then, if I still need to reduce the rocker, or just adjust one end or the other, I'd have no qualms cutting the arc even deeper, where the low point of the side would be a scale 8" or so. For a 12' pirogue, I don't think that would be out of line.

Of course, this would be after the stem experiments, and if I need to, I can go back and make a change at one or both stems to dial it in. Like I said, just one change at a time, until I better understand what each change will bring. And at least for right now, I think I'm going to keep it more-or-less symetric. Might be wrong, but I *think* that it might be more important on a larger boat, anyway. (As usual, could easily be wrong!)

seedtick, (if you made it this far, I mean. . . )

Understand about two jigs giving a fairer curve, but I have to ask, when using two like that, should they both be not quite as wide as a single jig would be? Instinct tells me that would be true, otherwise I'd expect a straight line between the two jigs, and don't think the wood would let that happen. On the other hand, this does fall under the "easy enough to try out" category. Just the reason for the 1/2 scale model to begin with.

tx river rat,

How you doin' Ron? Nice to hear from you. I think I've seen this one before, not just because it's a great looking one, but also because it's sitting on a doggie crate!

Thanks for the info, but let's see if I really understand what you did there. . . Sometimes, I'm kind of thick. . . Actually, now that I try to ask, I realize I really don't quite get what you said. Or, maybe. . . Did you cut a 3" arc in the bottom of the side panel, and then cut a 2" arc in the top of the side panel? No, I don't think that's what you are saying, as I think that would put a lot of rake in the deck. (What I used to call it when a boat had high freeboard fore and aft, low freeboard midships.)

Ron, can you give that explanation another shot? I promise I'll pay attention this time!

Much thanks, everybody! 8)

Mike S.
Spring Hill, FL

 

[tx river rat]

To the bow a 3 inch curve top and bottom of that panel ,
to the stern a 2 inch curve top and bottom of that panel .
this leaves your sides the same height ,
Ron

 

[beekeeper]

I'll probably change the stems to either a 45* which is what my UJ pirogue has, or maybe take it a bit past that, and do a 40* stem.

Why not just change the stems to the look you want, curved marsh pirogue style. Set the sides like you like. Cut the arc from the sides and it will make the adjustments in the rocker you need, no matter what caused it.

model is of a 12' pirogue, but with 12" sides. From what I've seen, that would be considered quite high. But I did that so I would have some height to play with.

The sides are 12" now, but after you cut a 6" to 7"+ (est.) arc off the bottom edge, you will probably need an even wider board to get 10" sides. Don't worry about the side height now. Once you get the arch cut you can make the sides any height . The marsh pirogue side is not the same width at the stems and midship. The top edge is not parrell with the bottom edge.

Of course, this would be after the stem experiments, and if I need to,

Please tell us the changes. I think I see that it could change the rocker, but I'll be surprised if it is very much.

Question?
What angle did you cut the stem? Not the angle that controlls how verticle they stand, but the angle that the sides meet.

beekeeper

 

[seedtick]

"Understand about two jigs giving a fairer curve, but I have to ask, when using two like that, should they both be not quite as wide as a single jig would be? Instinct tells me that would be true, otherwise I'd expect a straight line between the two jigs, and don't think the wood would let that happen"

You are correct, two jigs - fore and aft of the center - will be narrower and some what less angled than a single jig. When you bend the sides around the jigs, the sides will continue to bend outward between them. You can adjust jig placement until you have the bottom width you want.

Beekeeper is right, you'll be looking at something like a 6 or 7" arc, so don't worry too much about side panel width right now. Get the contour of the bottom of hte side panel where you want it then worry about the top. And another thing , make a template of the full size side panel so you can nest them (like spoons) when you cut them out of the good wood. Otherwise you won't make the sides from one sheet of plywood

 

[FlaMike]

I just keeps getting better and better. More and more information gets posted, the little half scale model makes it easier for me to understand, and I am having a ball with it all!

This is one time I am glad that there isn't a plan I can simply download or buy, and then build. This way, I get the chance to learn how many variables there are and how they work together. A little change at one end can make a BIG change at the other.

That is kind of why I seem to be taking the long way at times, like with the angle of the stems. I started with the "standard" angle (45*,) then changed it to a sharper 50*, and next I'll cut it back to a more sedate 40*. Once I get it settled in my head what the differences make, I'll settle on one and convert it into a curved stem, as I know in the long run, that's what I'll want.

Right now, there is NO stem in the model. I could be wrong, but I'd think the hull shape will be dictated by the building jigs that will set the flare of the sides, that shape being "locked in" by the installation of the chine logs and shear rails (outside rub rail and inside gunnel or inwhales,) plus the breastworks and deck, (if any.) I think the stems are designed to fit into and support that shape, more so than to set that shape.

I also suspect that it seems like so many pirogues are built the exact same way, the exact same shape, differing only in length, that the basic stem design doesn't change, so it's design seems to be "fixed," making it look like it dictates the shape, rather than it's shape being dictated. (A simple thought becomes complicate when it's put to words!)

The best thing to come out of this so far is the use of models. I'm having fun with it, it's cheap, and will save money in the long run. It's not a new thing, just something that hasn't been discussed very much lately. I guess design software has replaced it to some degree, but a lot of us here seem to have something of a "retro" streak in us and the model building should fit right in there.

I probably won't have time to get the "test" done and pictures uploaded today.

Here's the deal, it's kind of complicated, but while recovering from surgery, waiting to go back to work, and this building project, I'm also learning what I need to know so that I can take over my father's business within two years. For him, it's been a side business, a hobby, and a source of "extra income." I'll need it for other reasons and it will have to be less of a "hobby," and more of a source of needed income.

In short, I'm learning to write code for some specialty business software, and to maintain it. I don't have a background in this, so dear 'ol Dad is having to teach me, so he can retire (again!) in a year or two, his business will go on (to his current customer's relief,) and I will go on as well, being a more-or=less productive member of society, taking care of my wife, my cats, and myself, and be able to continue "messing about in small boats."

So for today, I'll have to work on that, so I'll be able to afford this. Besides, it just started raining again, making that decision easier!

The funny thing about this business deal is that his customers were beginning to worry because he is over 80 and recently recovered from a heart attack and pneumonia, so he's announced that the younger guy will be taking over. The "younger guy" (me,) just turned 60, and is now recovering from bypass surgery!

I think the Wicked Witch of the West put it best when she said, "What a world, what a world. . . " as she melted into a puddle. :shock: :lol:

Mike S.
Spring Hill, FL

 

[Kayak Jack]

Mike, let this boat building be therapy, not a chore. Keep it light (both in wood and in your mental concentration), and you will be better for the activity. AND - will finally get a boat.

 

[FlaMike]

Mike, let this boat building be therapy, not a chore. Keep it light (both in wood and in your mental concentration), and you will be better for the activity. AND - will finally get a boat.

Therapy it certainly is. But I can do a better job of keeping the build light that keeping it light in my alleged "mental concentration." :roll: In fact, I'd have to say I'm already in full Obsession Mode. :mrgreen:

Oh well. . .

It won't be a surprise to many, but I just turned up what is for me, a new data point. But when something is revealed to you so simply and clearly, you kind of want to talk about it. (What the heck did he DO?!!?) :shock:

I didn't want to re-cut the ends to try a different angle on the stems, as that would shorten the sides a bit and I wanted to try whatever I could without doing that just yet. So, I had the 1/2 scale in the living room, on the rug, and thought I'd see how much effect different bottom widths would have, with the same amount of flare in the sides. I'd been thinking that what I'd seen so far was going to make the boat too wide to paddle comfortably, and thought that the original 28" bottom was too much.

I put a tape measure down and set up the side pieces across it, and put the 35* template (jig) in place. With the straight sides, meaning no arc cut in the bottom edge, (just parallel top and bottom,) that gave a top of the sides beam of 40". Like I said, a bit wide for a 12' boat. Also, I couldn't help but notice the excessive rocker! A full-size boat built like this would have 8" of rocker at each end.

So, I lifted the jig and let the panel bottoms move it to a scale 24" and was rather disappointed to find the rocker only changed a scale inch or so. Looks like simply going with a narrower bottom (which I most likely will, regardless,) won't make much of a change in that excessive rocker. While pondering this, Ii removed the jig, but held the sides more or less in the same place. When I that, the bottom of the panels stayed in place, but the flare changed. And when it did, the stem ends of the model moved like an elevator!

What I mean to say is, just a little increase or decrease in the flare angle produced larger changes in the rocker. just a few degrees reduction in the flare had the rocker almost vanish! Push the tops of the sides back out and the ends would lift up off the floor a full 6", real measurement, not scale. On a full size boat, we're talking a FOOT of rocker. (A bit much, for my taste.)

OK, I knew it would make a difference, I just didn't know how *much* a little change would make. For me, a new data point. For most of you, probably more like "Duh! What'd he expect?" :lol:


So, I can reduce the rocker by decreasing the side flare. . . NOPE! No can do.

The amount of side flare is characteristic of the marsh style of pirogue. At least, that's my understanding of it. Sure, in the end I can manipulate that angle a bit to "tune" it in, but mostly, I want to leave the angle alone.

So, next I try two other things that should reduce the rocker, possibly the stem angle, but more likely, cutting that arc in the bottom of the side panels. Since both changes will mean altering the side panels and eventually will lead to having to cut new ones, I think I'll do the stem shape changes first. Once done, then I'll cut a new pair of side panels out, cut the stem shape that won that "contest," and start with a minor arc cut into the bottom edge, try it out and then increase the depth of the arc. If I don't over=do it, I should arrive at a suitable amount of arc and then start altering the shape of the top edge once or twice, without having to cut a new pair of side panels.

But if I do have to make a new pair, it only takes a couple of minutes and for this model, they com about 4 pair to a single $9 sheet of luan!

And that's cheap enough that seedtick's mention of making a full-sized side panel out of the luan in order to figure out how to get the sides cut out of the expensive ply without having to buy a 3rd sheet, a real good idea.

Right! Now I'm going to sit in a nice, comfortable dark place for a while and pretend I'm all calm and collected, and not at all excited.

Mike S.
Spring Hill, FL

 

[FlaMike]

Remember that part where I said I try different stem angles first? Well, I changed my mind!
Remember that also said I would not have time to mess with it today? Well, I changed my mind!
Remember I did say I would not be able to post any pictures either? Well, guess what?

I changed my mind about that too!

I figured I could make more than one cut on the side panel arcs without having to cut out new panels. Each re-working of the stem would shorten the sides. So, I cut an arc in the sides.

After a little hemming and hawing, (aka: procrastination,) measured and cut a 1 1/2" arc, which translates to a full scale 3 inch arc. And pretty much along the lines predicted by both the Piper and seedtick, this reduced the rocker to right at one half of what it was. (No, that doesn't surprise me, either.)

So, now the scale rocker is still high, so I'll guess I'll have to go the rest of the way tomorrow and cut the arc deeper yet.
And the top view:

This view confirms my thinking that I'll want to reduce the width of the floor from it's scale 28", at the very least down to 26" and then think seriously about 24". The question will be, do I think I can deal with the 24" bottom. . . Personally, I think so. I will be getting some help from the widely flared sides, and my balance is pretty good. I think with some practice, I can adapt to it. But, still a lot of time before I actually have to make that decision, plenty of time to talk myself into or out of it.

beekeeper, I WILL get to work on the stem thing, and soon. I will note and post what difference the angle makes, be it little or large. After that, and the arc question is settled, then I guess I need to work on the shape of the sides, including regaining some of it's height.

Mike S.
Spring Hill, FL

 

[beekeeper]

Floor width:
28" floor = 40" beam for 12" sides,
24" floor(did not change rocker because the flair stayed 35*) = 36" beam at 12" sides = a more managable width, lower the sides to the 10" you spec. and the beam will be less. Since you will sit behind center and the boat will be stable enough for you to have a higher seat, the width won't be a problem.

Each re-working of the stem would shorten the sides.

True, but it is only changing the overall length of the sides, not the floor. If latter you reduce the rake of the stems, but you want the boat to stay at the same overall length, you will have to streach the floor and this will change the shape of the boat(rocker, and form). That is why I mentioned making and installing the stem to match the look you wanted and then adjust the rocker by cutting the arc, not being conserned with what caused the rocker.

Food for thought:
If you change the shape from symetrical, after this next cutting of the sides, the arc will need to change shape also. You will have to build another model.

beekeeper

 

[jdupre']

Mike, I didn't see this angle being addressed. You can decrease the rake with heavily flared sides by cutting a bigger arc in the bottom edge. No problem. BUT, if you're using using sides with a a straight top edge, you will end up with a boat with very high ends and not a whole lot of freeboard in the center. You might want to actually try curving the bottom AND top edges to give a more balanced side view with more freeboard towards the center. Seedtick and keith have a post somewhere that shows this.

If you run out of cheap ply for 1/2 scale models, just use the same pieces and cut them to 1/4 scale. Pretty accurate and a lot faster to experiment with.

You're doing fine! Looking forward to the rest of your build.


Joey

 

[FlaMike]

keeper of the bees,

You are right, of course. The different stems will not shorten anything enough to make a real difference, besides, I'm not planing on taking any measurements of this particular model. When it's all done, though, the stems will be curved. (You are right, that is an important part of the look.)

jdupre'

Nice to hear from you, Joey!

Yessir, I will be making another cut to make the side panel arc deeper, and it will bring the freeboard down to the scary range, too. But one I get the rocker where I want it, 1 to 1 1/2", then I will transfer that arc to the bottom edges of the next set of side panels where I will be working on the height and the shape of the side panels. The few pics I've seen of the marsh pirogue seem to have a distinctive sort of "hump" in the forward section on the sides.

I've collected several pics that show this shape quite well, and seedtick has sent a CD with pictures from the marsh pirogue build thread that got me interested on this project to begin with. And then the one beekeeper started really got me going. . .

Good idea about keeping the parts around so I can drop down to 1/4 scale. Somethings you don't have to see Large, just to see how it works. And some parts will likely get a full-sized model made.

As for going asymmetric, I'm still thinking that it might not be quite worth the effort on a 12' pirogue. As usual, though, I am still open to the idea.
I'll get back working on the 1/2 scale in the morning. The CD with the pics should be here any day now and I definitely want to give them a good going over before I commit to too much on this. (Other than the full size pirogue WILL get built, and soon!)

Mike S.
Spring Hill, FL

 

[jdupre']

Mike, I think you have a good idea about not going with the asymmetrical shape. With a 12 footer, you can use the extra flotation. The assym. shape won't give you any big increase in speed or manuverability.

Joey

 

[FlaMike]

This morning, I increased the depth of the arc cut into the bottom of the side panels. The first cut was a 1 1/2" arc, which would have been a 3" cut on the full sized boat, this time I cut another 1 1/2", which is what both beekeeper and seedtick predicted that it would take, that is a total of at least 6", full scale.

This done, the 1/2 scale model now has the equivalent of a 1" rocker at each end. THAT, I can live with.

View from above:

OH! I think I provided wrong numbers on the scale! The flare jig that is spreading the sides is actually cut to a scale 26" bottom, and NOT 28" as I thought I'd done. I was on the fence originally, thinking 24" being kind of chancy for someone not born in a pirogue, 28" stable but would make for kind of a fat-looking 12 footer, and 26" possibly being the best compromise width.

Well, I did cut that template for the compromise beam (bottom width,) of 26". And I still just might reduce it on down to 24", but that decision will come later on.

I did this for a better look at the rocker:

Now then, the scale here represents 12" wide at the ends of the side plank, curving down to 6" at the center. Call me a "wuss" if you must, but I'm thinking that 6" is just a little low to keep the water out. But, never having actually seen a real, live 12' marsh pirogue, I don't know what the standard might be.

I will be trying a couple of stem shapes first, then I want to cut new side panels, starting with the curved bottom already established, but changing the shape of the top of the panel. But I would like to see the pics that have been sent first. I do want to get the look of that hump on the bow end, raise the freeboard in the middle a bit, and (I think,) keep the stern end a little lower than the bow. Problem is, as of now, the side panel is at a maximum of 12" wide, which doesn't leave much to "play with." Although I 'll have a better idea once I've studied the pics, I'm wondering if I'll still be able to get the panels the correct shape, and still get them out of a single 4X8 sheet of ply. . .

But, I guess I've still got a ways to go before I have to worry about that.

Mike S.
Spring Hill, FL

 

[Kayak Jack]

Mike, it isn't wussy to want freeboard. Seedtick (sadistic son of a gun that he is) once sent me out on Lake Verret with a boat that had 2" of freeboard - - 1" on the left side and another one on the right. I think him and Keith had bets on whether I'd ever return their boat or not. :wink:

You are getting deep into solid geometry with this project. Thinking in three dimensions is an order of magnitude (about 10 times) more difficult than thinking in only two. Changing only one variable produces whole families of outcomes in width, rocker, slope, etc. etc. Plans reduce the number of variables you have to deal with. Designing opens up Pandora's box of variables.

You have the box open in our lap, with stuff dripping off the edges. Pretty soon, you'll begin to become familiar with stuff, begin to reduce options - thus reducing variables to deal with, and begin to narrow choices to a small number. Then, you'll feel more comfortable. Until the next boat, anyway.

 

[beekeeper]

When you remove the side and it lays flat, the bottom edge will be a curved line. Place the side on a wider( width of the max. side height you want at mid point of the boat + 6") piece of plywood and draw a line parrell to the curved bottom line.
This would give you a UJ pirogue look. The marsh pirogue has wider sides at the ends so you would have to start the line midway and let it swell to each end. seedtick can address that.
My "truck" boat's first side panel is 8"(26" floor, 400lb. load) and I have yet to lean water over it. The next panel is tumblehomed for a total depth of 10.5". I would be more comfortable with 10" sides in a open boat.

1" of rocker should track well but I'm not sure if it is enough to be nimble. You will have to decide based on your useage.

The trick to getting the boat from two sheets is to use one sheet for the floor and one side. This might require two splices in the floor. The other sheet will yield the other 3 sides if you "spoon" them and cut near the lines.

beekeeper

 

[seedtick]

looking good and looks like you're getting close to what you want

just my 2 cents -- looks like a lot of rake (or cut back) on the ends, maybe 45 degrees or 12 on 12? Decrease that cut back to 6 on 12 and it'll get you another foot of boat length in the water. That part of the boat that's above water doesn't hold you up

 

[FlaMike]

Mr. jack,

Freeboard is usually, I mean. . . Normally, you don't have to add, uh. . . Just how much money did they have riddin' on the outcome of this, anyway?
Note to self: Do NOT play poker with seedtick, or Friend Keith.

You are getting deep into solid geometry with this project.

Oh good, its' not just me! I thought it was getting kind of dark in here. . . :shock:
I have noticed that each piece of the puzzle has a very interesting shape. But when you put them all together, WoW!!!

beekeeper,

I *think* I understand the process for getting the shape of the side panels. (We'll find out, I guess.) I do agree that the sides should be a minimum of 10", but I'm wondering if 12" is going to be enough to produce that "hump" at the bow or not. I know there should be a rise towards both ends, with the bow end being more pronounced, so maybe that end will have to a little more?

This is where I have to wonder about getting it all out of 2 sheets. However, 2 sheets = 16' and the pirogue is only going to be 12'. I keep forgetting that I don't have to have each side panel being scarfed together out of two, equal length halves. Once piece could be 8', the other 4'. (Plus the extra 2" for the joint.) Using the 12 scale sides as templates should show me how to arrange the parts to get the most out of a 4X8 sheet.

Maybe like seedtick said, full-size templates of the sides cut out of the doorskin luan might be the way to go.

Worse comes to worse, I could get with the one supplier that advertises he sells half-sheets. 2 1/2 sheets of ply still better that 3. But, that puzzle will get solved when I get to it.

seedtick,

Yes, getting a little closer every day!

About the ends. . . No doubt about it, I was thinking completely backwards when I had that idea. 45* would have been better, these are 5* towards the sharper. For some reason, I was thinking it would help and right after I did it, I realized I should have gone the other way. More like 5* towards plumb. I will try the "6 on 12" next, then convert that into a curve, just as you demonstrated in another thread a while back.

The reason I want to try the straight stem angle that is much less sharp than my first try is so I can post a picture of what the two different angles do to the shape. Then I'll add the curve and a pic of what it does. All for my own general knowledge, and for whoever else might be interested.

It is the curved stem I'll want for this boat, it is very much a part of the look that I'm after.
Then I get to figure out how to make it without a band saw. I don't know if it can be done on a table saw or not. (I'm thinking "kickback" for some reason.) I do believe I know how to do it without a band saw, but not sure if I can pull it off without it looking like it had been gnawed out by a deranged beaver.

That part of the boat that's above water doesn't hold you up

Amen to that!

Mike S.
Spring Hill, FL

 

[Kayak Jack]

Freeboard is usually, I mean. . . Normally, you don't have to add, uh. . . Just how much money did they have ridin' on the outcome of this, anyway? Note to self: Do NOT play poker with Seedtick, or Friend Keith.<SNIP>

Well, to be perfectly fair, (which runs a bit against my grain) both Keith and Seedtick were being generous, as they always are. But, it did get a bit dicey when a few whitecaps were dancing about. Joey and Piper San snickering in the background didn't help any, either.

I'm thinking that this mental gymnastic exercise is kinda good for your convalescence. Just take it easy physically, and recuperate - heah?

 

[jdupre']

Mike, my usual way of dealing with problems such as this is to exaggerate the variables to an absurd level, first in my mind and then on paper. You want to see what the effect of a little extra flair is? Just give it a LOT of flair. That usually tells you what to expect. The best thing I've found for boat design is two thin pieces of cardboard in the scale of your choice. Cut approx. stem and stern angles and tape the ends together. You can spread the two pieces apart to simulate bottom width and bend it some flair. This trick will tell you in two minutes what models might take days to tell you. Lots of flair does REALLY strange stuff to boat design.

Also, remember that heavily flaired side panels might be, say 10" wide, but they are NOT 10" HIGH in relation to the water.
Joey

 

[beekeeper]

Using the 12 scale sides as templates should show me how to arrange the parts to get the most out of a 4X8 sheet.

It will. Just think in terms of making 4 pieces, each will be 1/2 of a side. Two spliced together that could = up to 16'. Don't think in terms of cutting boards and then shaping. The floor and one half of a side will come out of one sheet. The other 3 other half sides from the other sheet
The floor will have to be cut to shape. One 8' long middle section and two ends. The ends will be cut from the plywood spaces between the 8' floor piece and the side piece. You might have to position the shape of the floor to have enough wood. The middle of the boat may not end up in the middle of the 8' cut and the ends may have to be different lengths.You can see this in my son's boat. The floor ribs are over the joints.

If you make the floor from just two pieces you might end up with the floor splice near the center of the boat.

That part of the boat that's above water doesn't hold you up

At least not until you tip over too far and have one of those oops moments. :lol:

beekeepers