A sand bagger - strip-planked

[DanishBagger]

Hi everyone,

I have finally found the boat I want to build.

In the latest edition of Water Craft (the UK-one), there's a feature on a scaled down version of an New York Bay Sloop. It's scaled down to 15 ft (or so it says, although it looks bigger) from 20 ft.

It's build in strip planked epoxy, and I want to do the same. I like strip plank, although I will propably get to hate epoxy from what I can tell from reading these forums.

Anyways, Since it's scaled down, from what I can gather, the bulkheads is about 45cm apart, and they're made from plywood. My first question is in rregards to this: Under the sidedecks, how thick plywood would you think would be enough for those bulkheads? Should thicker plywood be used oner the foredeck? I'm asking this because I don't want to overbuild it (I want it lighter than the original), on the other hand, I don't want to go sailing and everything falling apart.

Then there's the deck, how thick would you consider reasonable, keeping in mind that there's a mere 45cm between bulkheads, and I could add stringers beneath it.

Okay, then just one more question:

Books.

I have ordered the book, the original is in, namely, Chapelle's "American Small Sailing Craft", and I will most likely buy the 5th edition of the "Gougeon Brothers on Boatbuilding".

Any other books I should consider to get me through the hull-aspect?

I'm thinking it could be chappele's "boatbuilding", but I'm not sure how relevant that book is in this context - I will make my mast with epoxy etc.

I hope you can help me.

Sincerely,

Andre

Btw, I have spent the last 12(!) hours reading threads on this site. It's a very nice site!

[Raggi_Thor]

Take a look at our Backman 18 :-)
It's weighing aprox 150kg without rigging, hardware and ballast.
You can use 6mm okume for the bulkheads/frames, but that's hard to fasten a nail to, so you might go for 8 or 9mm, not becase it's needed, but it's more practical.

[DanishBagger]

Heh, thanks for your reply. I took a look at it. It's a very nice little boat, although a bit modern in comparison, albeit very alike building-methods wise. I won't be making my hull from plywood, though.

Let's see if I can get the only picture I can find of the one I want linked to:

http://www.watercraft.co.uk/contents/current/cover.jpg

(It will propably change in a month or so, as it is called "current" - I wish I had a scanner so I could scan the better ones in the magazine).

6mm will be enough? That's great. So everything above that would be "to my own taste". Things are looking better by the minute.

Now, allow me to ask a stupid question: Nails? My intention is to glass as much as posssible, and screw the rest (as in "with screws"), or both.

My "backbone" (hope I'm using the right word here - the one where the keel goes into, the long "thing" that goes all the way from the back to the front") will propably be made the old-fashioned way, although epoxied. I don't really know why, except that it has to be quite thick, and if I use "real" wood, less end-tree will be exposed.


About the okume - I have found one (1!) place here in Denmark that makes marine-plywood, and they make it teak, ,mahogany, Oregon Pine, and gaboon. Should I go for one of those, or perhaps even try getting some okume from abroad?

I'd prefer not to go with the teak for frames and bulkheads as it's three times the price of, say, the mahogany. On the other hand, if that is the best for this, it's a small boat, so even three times the price isn't that much.

Btw, even though I think your Backmann is a bit too modern, I'm not that old-fashioned. Even though the rig will be a gaff rig, I might make it a bit more high peaked (that's only a "perhaps"), it will be precourt (http://www.precourt.ca) standing rigging, and although I will begin with tufnol blocks and hollowed out spars, I will propably be going to Ti-lite blocks and carbon spars when I get the money for that. But that's way out in the future.


Andre

[Raggi_Thor]

We strip planked the bottom in B18 with 8mm Norwegian pine.
Temporary nails is a fast method for fastening the strips while the glue cures.
Joubert is a large french manufacturer of Okume plywood, and they have one danish distributor. Robbins Timber in UK is also a good source.
Okume is very light, 9mm weighs 4.2kg/m2, spruce would be 4.9kg.

Maybe you should let me make a precut kit for the frames and backbone :-)

[Raggi_Thor]

I forgot to mention....

Nails? My intention is to glass as much as possible, and screw the rest (as in "with screws"), or both.

You do not want to leave any metal in the wood.
Use composite nails and a "gun" if you find one or temporary screws and nails.
You can use polyurethane glue between the strips if you plan to cover everything with glass and epoxy. Many canoes are even built with white carpenter glues (snekker-lim).

My "backbone" will probably be made the old-fashioned way, although epoxied. I don't really know why, except that it has to be quite thick, and if I use "real" wood, less end-tree will be exposed.

You can laminate the backbone in pine, fir or larch or...
But you can also use plywood as the end grain will be covered with the hull skin.

[DanishBagger]

We strip planked the bottom in B18 with 8mm Norwegian pine.
Temporary nails is a fast method for fastening the strips while the glue cures.
Joubert is a large french manufacturer of Okume plywood, and they have one danish distributor. Robbins Timber in UK is also a good source.
Okume is very light, 9mm weighs 4.2kg/m2, spruce would be 4.9kg.

Maybe you should let me make a precut kit for the frames and backbone :-)

8mm that's quite thin, methinks, but that's okay since it obviously must be strong enough.

Joubert? Do you have a link for them?

Thanks for the offer about the precutting, but I prefer to loft it myself, even though it will take some work. I like to be the builder, and not an assembler.

I won't be using plywood for the strip-planks, but then again, that isn't what you're suggesting, is it? You just used "normal" norwegian pine, right? Guess I could use the danish pine (it's the same thing, afaik), I can also easily get hold of "lærk" ("scandinavian larch"), scandinavian fir, Douglas fir, and "Giant thuja" (same tree as western red cedar, except grown in scandinavia - a little lighter).

I forgot to mention....



You do not want to leave any metal in the wood.
Use composite nails and a "gun" if you find one or temporary screws and nails.
You can use polyurethane glue between the strips if you plan to cover everything with glass and epoxy. Many canoes are even built with white carpenter glues (snekker-lim).



You can laminate the backbone in pine, fir or larch or...
But you can also use plywood as the end grain will be covered with the hull skin.

Ah, so temporary nails - good thing I'm buying that book :p

"Snedker-lim"! It's so nice you're scandinavian as well, makes it so much easier to understand these things.

I don't plan to cover everything with glass. The hull, of course, and as much needed as to make the flotation-rooms. Perhaps using "see-through" glass-mats/cloth (haven't figured out the difference yet, but that will come when needed).

Although I like strip-plank, and to a certain extent plywood because of strength/weight/stiffness, I do not want to make something where the idea is "modern materials negate the reasoning for making something "properly"". (ah, I'll get a whipping now). It reminds me of how you cannot buy a proper window-frame these days, because nobody remember how to build them properly, with the advent of plastics, pressure impregnated woods etc. I know that will sound awful, but I need and want the essense of the boat as I see it to be what it was. That is not to say that I wont take advantage of modern materials, as "they" would, had they been living today.

Some of the "rooms" in between the bulkheads under the deck will be used as storage, as will some of the space under the foredeck. I will not cover everything in epoxy and have it painted white. I want wood - idjit as I am.

I'm also thinking that I want stringers under the deck, if the original design "demands" it, although I propably will make them thinner - reason is, I have seen way too many plywood decks being a bit too "bouncy and flexible.

About the laminating of the back-bone, I will see if I can get hold of thick enough "stock" so I don't need laminating, and if not, I will have to laminate, but I won't go the plywood route for it. To me, I might as well make it out of metal or carbon fibre - it won't be "real". I know, I know, awkward thinking :(

One thing I _will_ be laminating, though, is the bowsprit (you can't see it in the picture, but the round plug on the deck is another mast hole, it's build and designed to be able to do with one sail in winter, two in summer - or as I think: one sail to begin with, two sails and bowsprit when I get the money).

The bowsprit is flat, tapered when seen from above, and I have thought about steaming a single plank of "real" wood to that shape, but I am thinking of laminating a bit thinner ones instead, using dark and light wood, giving it "stripes" seen from the side, or from above, giving it a nice effect, imo.

Andre

[Raggi_Thor]

Please let me know how you are doing. I understand you want to do everything by yourself, reading and thinking and learning as you go. If you are planning to loft the lines full size you can design with paper and pencil which is a real pleasure.

[DanishBagger]

I will let you know.

I am currently looking for a garage or something similar to rent right now, but it's quite difficult as I'm living in two different cities at the moment (Århus and Copenhagen), so on one hand, options are open, yet the place will kind of decide where I will end up for a while.

I hope to have found one by the end of march at the latest, so I can get going. In the meantime I will read as much as I can, make sketches, and get as much preliminary work done as I can. Buy tools, perhaps cast the ducks, and so on.

I will do most things myself, (or try to, haha), but not all, the lines are in the book, although I do not know how explicit they are yet (it hasn't come through the mail), but they will be lofted full size. I think that is best when visualising. I just read that you can do it vertically, but that seems a bit too advanced for me, he he.

[Raggi_Thor]

Joubert in France:
http://www.joubert-group.com/Gamme/Gamme_Marine.htm
or in english:
http://www.joubert-group.com/UK/Range/Range_Marine.htm
You can ask them for danish dealers.

PLease seek some advice before you simply scale down the drawings for one of the original sandbaggers. It's not likely that the result is what you want.

[casavecchia]

This is a modern sandbagger from the board of Sparkman and Stephens I built some years ago . Mahogany bead and cove strips over laminated ribs .
Marco http://www.classicboat.it/writable/upload/photogallery/immagini/20/DSC_5173_web.JPG

[DanishBagger]

Joubert in France:
http://www.joubert-group.com/Gamme/Gamme_Marine.htm
or in english:
http://www.joubert-group.com/UK/Range/Range_Marine.htm
You can ask them for danish dealers.

PLease seek some advice before you simply scale down the drawings for one of the original sandbaggers. It's not likely that the result is what you want.

Thanks for the address, I just send them an email. :)

Downscaling: I know I in theory might run into something, but it's not a scale model thing, I'm scaling down, either from 20 to 15ft (i.e. 25%), which already has been done by a scot, and it seems to work, or by 20%, down from 20ft to 16 ft ( I think I might go for the latter). The thing is, this is more a less a working boat, much like the couta boats of Port Philip Bay (Melbourne, Australia), only able to carry less, and smaller. The couta boats range from 16-30 feet. More or less the same shape. Of course some have bigger forefoot and what not, more or less tumble home and so forth, but to put this in the nicest possible light, I'm not building this to make the fastest or lightest hull ever, if so, I'd sure as hell would go for a more modern shape and rig.

What I want is the essence of this sandbagger/working boat, with consessions to modern times. THis means, in my humble opinion, that I will use whatever necessary to make it to my liking. Make the consessions needed, while still keeping the essence, as I see it,of the heritage. (Good thing I'm not into restaurations, lol).

Am I worried about it? Not really, the shape is not altered, and with the percentage of downsizing I'm intending to do I don't think it matters much - I'm much more worried about the weight distribution (and lack of weight) strip-planking etc. will do, and how much it will mess things up. I'm thinking that if the boat becomes too light (too much "dancing on top") it'll be hell, I don't want to be a cork on top of the water, if it becomes like that I might as well have bought some modern wide bottomed glasfiber thing, perhaps even the skimming board, the swift solo (http://www.single-handedskiffs.com/pages/697520/index.htm), which all things considered is a much faster boat than the one I'm building (btw, this is a much interesting boat, I'm contemplating stealing some ideas from it, for example the way the main is rised by way of "pumping" (stick your foot in a loop, and raise the main - only I'm thinking it for the keel).

Now, the swift solo is all good, but I prefer something I can camp in, and more importantly, something I consider seaworthy. In my eyes, the one I'm about to build, and the bigger couta boats seems like two of the most seaworthy "open"/half deckers I can find, and that looks nice.

Am I worried that it can be done? Not at all, I'm quite sure the down-scaling wont matter much, although sails-wise I'm a bit worried. But then again, I'm going to have a pro on that matter, And if I decide that I will indeed make it higher peaked, I'm going have the same pro that will make the sails in the end calculate how much I will need to move my mast and take that into account.

Rudder-wise, I'm not worried either. I won't be making it true to the original, have you seen those rudders!? It really is a skimming board, so I will let myself be inspired by the coutas, and if it doesn't work as I intend it to, I will make another, and/or make the necessary trimmings. In my book, it's all part of the process, and I know I will learn a lot, but I have no intention or need as I see it to know all the math involved when I'm basically using a true and tried, long-tested working hull. Although I do realise I will be using math quite a bit though.

Of course I'm hoping it will go fast - for that kind of boat - but I still want it to be safe "cruiser", something "seaworthy", yet fun.

All of this is of course just preliminary thoughts from a soon-to-be small-boat builder, but I just wanted to give my thoughts upon it, thinking that if I do, I might actually get corrected if I was way too far off in my thinking. I'm very sorry if sounds like a rant, it's just that it is also nice to put my thoughts down in a (somewhat) coherent manner.

Btw, I'm thinking, that if it does indeed become too light, I won't bother changing the design, (i.e. making the keel heavier or something), I will propably choose to make lead ingots instead, thereby not making it too stiff, yet heavy enough (for it's size) to more like the original. Another thing is, the freeboard will be a plank higher than the design. The reason for this is that the original working boat was very low on freeboard because they needed to pull nets over the side, I don't.


This is a modern sandbagger from the board of Sparkman and Stephens I built some years ago . Mahogany bead and cove strips over laminated ribs .
Marco http://www.classicboat.it/writable/upload/photogallery/immagini/20/DSC_5173_web.JPG

That really sounds interesting, Casa - Do you have any more pictures? I'm especially thinking of the laminated ribs etc? Again, it's a little too modern, but laminated ribs sounds even more true to form than the ply plywood. Do you have watertight bulkheads in that too?


Sorry about the length of this post, and my idiotic opinions that propably doesn't hold much water (no pun intended), it's just that I'm for once really into doing something and I apparently get way too eager :(

Anyways, I hope it's all right to you.

Sincerely,

Andre

[Raggi_Thor]

It's an interesting project.
I was wondering if you would have movable ballast as in the racing sandbaggers...

[DanishBagger]

Hehe, more like "removable" if I get ingots. I'm afraid it will shift when I want it least to do that, if I went for movable. :)

[DanishBagger]

You can use 6mm okume [ ... ]


About the okume - I have found one (1!) place [ ... ] that makes marine-plywood, and they make it teak, ,mahogany, Oregon Pine, and gaboon. Should I go for one of those, or perhaps even try getting some okume from abroad?


:idea:

LOL, How stupid am I!! Turns out that gaboon is just another word for Okoume. Same wood I'm told! So Gaboon/Okoume it is! :cool:

[casavecchia]

http://www.classicboat.it/collection/index.php?idCategoria=7
Some more phographs.
Two watertight bulkheads, no ballast.
When trading messages back and forth with S&S I proposed building the boat in clinker plywood. They didn't agree but I am still convinced that this would be a better choice than strip planking, still in keeping with the New York Bay sloops tradition and may be with the Danish tradition too!
Marco.

[DanishBagger]

Wow, Casa - it really is nice!

Although it does look very modern, perhaps it's the very low freeboards (and the carbon, hehe).

I have no knowledge of any danish tradition with regards to "old" racing workboats, to be frank. But you're right if it's the clinker-build you're thinking of.

There's no ballast? Not even a dagger board with a little weight? Excuse me for asking a stupid question, but that seems a bit too much "racing" for my taste.

The "coating" on that bagger - is that epoxy with varnish on top, or something else? It looks awesome, and right now I'm torn between the yachty look of that, and matt-white since that seems more in keeping with the one I intend to build. But then again, it's for show, I'm making it nice to look at :D

[DanishBagger]

Ah, I was so focused on the pictures, I forgot to read properly.

Is the planks covered with some see-through cloth, or? And is the planks themselves mahogany, or how did you get that awesome hull finish? I mean, I even like the tacks or screws is visible.

[Raggi_Thor]

I agree, it's a very good looking boat!
Glass cloth, woven, 160-200g/m2 is "invisible".

[DanishBagger]

Nice, Raggi - could be something to consider, or perhaps a black?

As it is, right now I'm looking at pictures of the sandbagger "Annie"

http://www.mysticseaport.org/research/ru-annie2.cfm?mid=130

and this

http://www.mysticseaport.org/research/ru-annie2.cfm?mid=132

[Raggi_Thor]

Annie is also good looking.
Remember black can be very hot, and epoxy starts getting soft at 60-70(?) degrees.

[DanishBagger]

oh, yeah, I forgot that :(

Although ... I'm living in denmark .. hell, I should be more worried about the cold, he he.

Nah, you're right, that could be a problem.

I'm contemplating my plans. Thinking if I should make the finish a bit more yachtie as the one Marco build, as oppose to make it more of a fast fishing vessel, so to speak.

Dammit, Marco!! ;)

Btw, marco, am I right in thinking that those sausages are what gives it flotation, and not the watertight bulkheads?

How does it sail? Is it a very wet ride?

(the reason I ask is because I'm contemplating foregoing the extra plank I had imagined I would make, and that wave-breaker looks like it's necessary).

[DanishBagger]

Hm, come to think of it, maybe one could use some thin, flexible mahogany plywood to get that sort of finish?

Man, so many questions, sorry about that.

[casavecchia]

Andre,
the boat I have built is totally unballasted. It's exceptionally well mannered and stable but still a high performance centerboarder. If you search the Woodenboat Magazine Index you may find an article about the first boat built in USA, search for STEALTH DINGHY.
The hull is Honduras Mahogany, there is no glass , only epoxy and two pack polyurethane varnish.
There are two watertight plywood bulkheads, one at the aft end of the cockpit and one 50 cm. aft the mast. gate.
Planking a wide boat like a sandbagger is very difficult because the planks have to take a lot of twist in the forefoot region.
That's why I was suggesting the glued lapstrake method as plywood takes twist more easily.
My hull is 10 mm. thick, is immensely strong ( unnecessarily strong ) but I needed the thickness because the strips are blind nailed into the ribs so the nails dont show.
With glued plywood lapstrake you can get along with 8 or even 6 mm. mahogany plywood: the resulting hull will be much lighter.
Of course I am referring to this particular S&S design.
Marco

[DanishBagger]

Thanks for your answer (on the mail as well), Marco.

I have just ordered the issue from woodenboat. Also number 130-something, which seems to have something about bagger.

I have another question, though, I hope you can answer:

You say you used no cloth, but did you then use "old-style" planking, only narrower, but the traditional way where there narrower in the middle, and wider at the ends, etc?
Of course, I hope that some of this info will be in the magazine, but I'm thinking you might have had the planks themselves done the traditional way, yet with bead and cove as well, to make them tight?

[casavecchia]

The hull is strip planked but the strips are not constant in section. Instead they are all equally tapered fore and aft, i.e. wider in the middle and narrower at bow and stern.
Marco.

[DanishBagger]

Oh, like that. Very cool. I assume you made a bead and cove then? Or maybe, as I've read in a book about canoe strip planking, they're just "corrected" with a plane (angle-wise)?

Sorry to ask so many questions, I wish I could buy you a beer, and we could talk while having that - that way it might not seem like the inquisition. :(

Sincerely,

Andre

[casavecchia]

yes, bead and cove were routed after tapering the strips.
The Stealth Dinghy featured in the article on Woodenboat Magazine was built in glass/durakore strips.
Marco.

[DanishBagger]

The happy village-idjit I am, I just wanted to tell that I have finally found a place to build.

It's a small place, and weirdly enough I have to do the lofting etc. in the basement of this place. Then when I have made the frames etc. I need to carry the lot up, and set it up for the planking and so on. It's not perfect but at least it's a place. :)

[Raggi_Thor]

Gratulerer :-) og Lykke til :-)