Modifying carvel planked plans for strip-planked (sheathed-strip) and/or coldmolded [Archive]

JimD

08-10-2003, 11:19 PM

Rod, the way I heard it, in general, traditionally planked boats, whether carvel or clinker, are more heavily, or at least more frequently framed because the planks aren't attatched to each other so strong framing is necessary. For glued strip plank or cold mold the framing tends to be lighter or farther apart because the hull is essentially one solid monocoque structure and therefore the planking is hardly planking at all in the end and adds considerable strength overall. The table of offsets should indicate whether the measurements are to the outside of the planking or the inside. Designers usually loft to the outside dimensions but often not so with carvel because its obviously not easy to define the 'outside' when the planks overlap. Its easier to define the station molds that the planks go over, meaning the inside. That's what I've read in a few books on the subject, anyway. What boat is this? If you're talking about a ten or 12 foot daysailer you probably can't mess it up much anyway. If its a big blue water cruiser then ask a pro for a cost estimate.(Just my humble opinion smile.gif )

Aramas

08-10-2003, 11:23 PM

The way grey seal is built would work just as well with cold moulded or strip composite of similar thickness, with no other changes. Or use McNaughton's and do it right (McNaughton's scantlings produce very strong and presumably long lasting boats, albeit at the cost of weight)
Doing it in carvel or proper lapstrake would also be easy, since it's so standardised. Probably heavy though. You might have to take light beer when sailing on her smile.gif
Grey seal seems a nice enough boat, but to my apparently heretical eye the ends of the cabin and cockpit are butt-ugly. So shoot me smile.gif

RodB

08-11-2003, 12:28 AM

Ok, lets take Atkin's 30 foot "Benbow" (written about in much detail in "Of Yachts and Men") which was designed for carvell planked construction.. Most construction details would be for the traditional methods of the day. From "Fore and Aft" to "Benbow" to "Talley Ho" Mr. Atkin built them with very particular methods that resulted in a collection of "systems" that worked, and worked together.

There certainly has to be more to it than just adjusting the size of the molds taking the hull scantlings into consideration. In addition to needing less frames, I would think the keelson , stem, etc., would have to be changed to laminated construction as strip-planked or cold molded would not allow for movement. Wouldn't the deck and cabin structure be simpler with say plywood and laying Dynel for decking.? Would this "epoxy construction" also call for other changes from the traditional methodology?

I'm thinking the basic plan would need to be gone over by a knowledgable professional and basically modified throughout for the different type of construction?

Perhaps the experienced boatbuilders look at this as a fairly straight forward adaptation, Wouldn't most people need some detailed guidance?

I want to learn what is necessary for this type of adaptation, as many of the plans of serious beauty and interest are traditional plans. I'm not saying I wouldn't build traditional, but for my 30 foot cruiser, I will build to withstand the hot climate and to minimize maintenance.

[ 08-11-2003, 01:38 AM: Message edited by: RodB ]

Aramas

08-11-2003, 02:21 AM

If you use a scantling rule it gives you the minimum dimensions of all the major components, along with spacings for frames, floors, deckbeams, keelbolts etc. That in itself is enough. The rest is just building methodology. There are any number of books available that give blow by blow accounts of building methods. Most of them work. Some, however, are whacky methods suitable only for the author's designs. A book called something like 'The New Cold Moulded Construction' that is about building sharpies with tongue and groove flooring springs to mind.
Any composite design assumes that all the chunky bits are laminated. Thick bits of wood and epoxy don't like each other much. As a general rule of thumb, anything over 3/4" is too thick to use with epoxy. Some say less than that.
Figuring out a scantling rule is a bit of a hurdle, but once you get it the first time it's easy enough. My first attempt was for a fictitious 100 metre bulk carrier using DNV (at college), so little boats are a piece of piss for a trained digger (that one's for Shane - it means easy smile.gif )
Cold moulded construction produces wonderful hulls, and if I won the lottery and paid someone else to build, that's what I'd use. However, it's a lot more work than sheathed strip, and a lot more wasteful. Just building the mould is almost as much work as a strip plank hull, and then you have to spile and lay half a dozen to a dozen layers. Yuk. Even McNaughton's scantlings for cold moulded construction carries a warning about it being it being a particularly labour intensive building method.
Your best bet is to...wait for it.......buy some books! smile.gif
The Gougeon brother's book is of course the bible. Although by itself it's not particularly useful, it's an invaluable reference in conjunction with more structured books.
Something like Ian Nicholson's book on WRP building is a good start. There are also numerous booklets made by boatbuilding schools for their courses. I have one from Sydney Wooden Boat School that's very complete, down to earth and cheap. I'm sure other schools do much the same. Check out the WoodenBoat Store and read reviews of the appropriate books (use google to find reviews).
Lastly, I recommend buying the full set of McNaughton's scantling rules. I think they're about $30 or so, and well worth it.
Armed with the above or similar, it's actually fun to nut out how the little suckers go together. Well, mostly, anyway. At least you yanks won't have to convert them to metric. Cubits and spans, feet and inches etc. have a certain archaic charm, but they suck donkey scrota for anything involving mathematics.
Edit: I know that this is a horribly long post, but I thought that I should add that one of the advantages of getting a pro to redesign a classic hull, is that they can eliminate some of the pointless affectations that graced yachting fashion in the past, and significantly simplify building. Ditching hollow garboards and waterlines can make building far easier, and, if thoughtfuly done, improve performance ander most conditions.
In general, old designs had complex hullforms, low freeboard and rather basic accommodations. A modern design in a classic style can be faster, roomier and cheaper/easier to build.

[ 08-11-2003, 03:49 AM: Message edited by: Aramas ]

Bruce Hooke

08-11-2003, 09:45 AM

I think you've got it about right RobB. While various books will give you scantling rules for most of the basic components, it's a long way from there to a complete construction plan that could be relied upon to produce a safe and seaworthy 30' sailboat. Pretty much every structural member will need to be re-designed to some degree and the impact of those changes on things like the distribution of weight in the boat and the stability will need to be considered. Chances are there will be many other changes such as a more modern engine, that may have additional impacts. All of this calls for bringing in a professional yacht designer. I've been teaching myself yacht design for something like 20 years and I would not trust myself to make such a conversion on a 30' yacht without at least having a professional go over my plans.

Unfortunately I can't tell you how much this would be likely to cost, which I think is a large part of what you are asking. To some degree it will probably depend on the paricular design and how suitable it is for such a conversion, as well as how much detail you want in terms of construction plans...

On Vacation

08-11-2003, 09:52 AM

Maybe its time to sit down with a designer, one that you may have interest in, and give them a retainer to work with you on the right boat for your needs. I think you have contacted many, to feel them out, for a lot of information. In the end you will need to do this, to end up with a boat that will be properly engineered with you particular requirements.

John N

08-11-2003, 02:29 PM

RodB, I contacted Jay Benford a while back about getting his 27' Friendship sloop plan modified for carvel constr. from cold molded. He asked for a retainer of approx. $400.00( I lost the e-mail so I don't have the exact figure) then I guess there would of been a final charge when the work was complete.
I think most designers would work the same way, asking for a retainer then figuring out their hours when done.
btw, re. "looking for a 30' boat..." Have you checked out Benfords designs? There doesn't seem to be much interest in them on the forum for some reason, and not much on the web apart from a few people building his plywood sailing dorys. But I really like the look of them. He has a 30'boat you can build cold-moulded, carvel or even steel and he has drawn up over 20 different sail and cabin plans for it. Plus the Friendship really caught my eye.
http://www.benford.us/
John

RodB

08-11-2003, 09:50 PM

Thanks all for the comments. If I select an older design for my cruiser, that requires adaptation to a more modern method of construction, then I most assuredly will employ a professional to make sure all comes out properly.

My original thought for this posting was to see just how complicated it was to build many of the older designs in modern methods, for example Atkin's "Tern" or Alden's "Traveler". I do have MacNaughtons Scantling rules, now I just need to learn a lot more about boatbuilding.

Naturally, the more you study the many terrific designs from the past the more you are intrigued with many of them. I just have made it one of my goals to try to acquire the skills to make this conversion on any design I happen to like.

Additonally, the selection of a boat design to build is a pretty important decision and I do not take it lightly. Up to now I have been getting general information, on designs I am interested in within certain parameters. ie., simply just what is out their that already exists?, how good is it?, and what it costs for varying degrees of custom work. This continued research on boat designs from the past and present allows one to see the many solutions available to meet one's criteria. Once the basic parameters are sifted down, then pure aesthetics and perhaps some practical features such as ease of construction or handling features can help with the final decision. This process also allows for a good basic education on the building method choices and their pros and cons.

I am somewhere along that journey but not ready yet to box up my so called "parameters" as they are still changing somewhat. Sure, I have some leanings towards particular designs and have narrowed down my criteria quite a bit, but I don't have to make the decision yet and quite frankly don't want to. This is an enjoyable learning process and I feel you have to find out all that is possible before deciding exactly what you may want.

I am also one of those people who thinks that getting their is half the fun... at least thats the way its been on my present boat which is about 95% finished. I have enjoyed each and every part of the process from conceptualizing, to having a design done, to building , not to mention customizing the interior and deck layouts for simplistic functionality. I also designed a way cool console from scratch.

Anyway, I'm still looking at several designs and looking forward to considering a few more.

RB

[ 08-11-2003, 11:23 PM: Message edited by: RodB ]

Aramas

08-11-2003, 10:34 PM

The journey is most of the fun smile.gif

RodB

01-12-2005, 12:58 AM

Bump...Update: current thoughts...

I had pretty much decided to build a traditional design of my choosing strip-planked ("Sheathed Strip" ) epoxy composite construction ...sheathing the hull both inside and out... a monocoque structure...according to Macnaughtons Scantling Rules for Sheathed Strip construction. Since this posting began originally, I have learned a bit more about what would be involved to modify the construction of a traditional vessel.

It seems to me that converting a heavy displacement 28-32 foot cruising sailboat involves quite a bit more than others have suggested. A totally new construction drawing would have to be developed mainly to keep all the wonderful characteristics of the original design. Strip-planking a hull and sheathing it properly would result in an immovable structure that would have to be matched with an appropriate backbone, decks, etc...

I have come to the conclusion that to really capture the essence of a quality traditional design you definitely need a qualified NA to modify the existing design in quite a bit of detail or just have another similar design produced from scratch...

Obviously, the smaller the design the less important the construction (lesser scale) as you could just build the hull (outer shell) then complete the interior structures "strong enough"...and it would probably be ok. BUT, as the design got larger the engineering would become much more critical.

Take for example Hess's 30' "Bristol Channel Cutter" or Atkin's "Benbow" or Murry Peterson's Schooner "Susan"... these designs are great designs that have all the stresses from the ballast keel and rig computed into the design that has large beams in their construction... to convert them to a modern epoxy composite construction certainly would take a bit of doing to maintain the ESSENCE of the original designs in strenght, weight and weight distribution. The reason one would choose one of these designs is because of the compilation of qualities incorporated by the designer and keeping all those wonderful characteristics would be vital to my way of thinking.

Am I right or is it simpler than I think? I welcome input here as sometimes I do consider just choosing a modern design from the start...but boy I sure love several older designs.

RB

[ 01-12-2005, 02:44 AM: Message edited by: RodB ]

rbgarr

01-12-2005, 04:26 AM

For a wood boat in the tropics, I'd be tempted (but investigate it thoroughly) to build a selected design as drawn but with thinner carvel planking and then use the Vaitses method with cloth and epoxy to cover the hull and deck.

Billy Bones

01-12-2005, 06:32 AM

As one of the "seat of the pants" school I'd be inclined not to consult a naval architect but rather to study every aspect of the modern technique. If I read you correctly, you want to build a modern boat in a classic shape....

Boat plans seem to have two main parts: Structure (construction drawings and details, etc) and Shape (lines and offsets).

Once you're COMPLETELY familiar with the construction requirements of the modern technique, whatever it is, borrowing the shape from the classic is a matter of cutting and pasting. You can infer for yourself that floor timbers, for example, will be laminated in place instead of bolted to frames, the keel will probably shrink alarmingly in size(if not disappear althgether), a keelson will show up, frames will space themselves out more and be laminated instead of steamed or sawn, mast steps will likely grow, ring frames in way of partners, etc,etc,etc.

The weight of the hull may change (lighter) but you could figure that out easily enough and compensate ballast accordingly, keeping an eye on where you took the weight so you know where to add it back in, more or less.

Your lofting will look virtually identical no matter the building technique.

I've studied the classic study plans for years and years with much the same question in mind and noodled it out. My question now has become, given the wonderful possibilities allowed by the more modern construction techniques, what is the sense in dragging along so many of the constraints imposed by the classic form? Like, but not limited to, ridiculously small cockpits or even footwells? and so on. You really have to love the old boat.

If you plan to keep the hull shape and build out your own interior, scrapping the original plan altogether, the problem becomes a bit more tricky but, I think, still manageable.

Now I expect I'll get flamed by the NAs and engineers....

[ 01-12-2005, 07:42 AM: Message edited by: Billy Bones ]

TimothyB

01-12-2005, 07:57 AM

Honestly, I don't think that a carvel boat would be 'hurt' by her hull being stiff! Yes, it is 'made' to move, but in a heavily built boat, the less things move, the better. I'm sure an NA will tell me about moments of inertia and such, however after thoroughly reading Dave Gerr's book, the true differences between carvel and strip are:

(1) Carvel requires many frames, and ideally strapping, to prevent wracking. Strip doesn't require either
(2) Carvel planks are assumed to swell alot, strip planked hulls are not.

I can't find ANYTHING that says making a boat a stripper, that is to say using the strips AS the planks (not as a core for a fiberglass exterior) and following recommended practice would be a bad way to plank a carvel hull, all other things being equal.

If I wanted to convert a carvel boat to strip, I would leave the frame spacing, scantlings, etc all the same as carvel, and just strip it up. You'd have one hell of a strong boat. That way her shape and attributes are unaltered. You could even put in a traditionally caulked garboard if you wanted to feel salty. Or you could epoxy seal the whole shebang and cover it with Xynole or glass.

People would argue that you lose the advantages of strip construction, which are lightness and fewer frames, but I'd rather have strength than another 1/4 knot and a big redesign bill. The best thing about strip planking, I believe, is that you don't need to use amazing quality stock for the strips, and you can glue the strips to be full length planks throughout the boat.

Now if, on the other hand, you -want- to convert a classic design to laminates, plastic, and cloth so that you can gain cockpit room, make the boat less tender, have more interior room, etc.. well you pretty much have to talk to an NA. I wouldn't go near a project like that unless a designer or NA had signed off on the plans. There are many, many things to take into account and I wouldn't trust myself to find all of them.

But I still think Traditional strip planking is still a great way to build. ;)

[ 01-12-2005, 09:02 AM: Message edited by: TimothyB ]

mmd

01-12-2005, 10:59 AM

No flames, Mr. Bones, just a bit of warmth in a certain spot.... ;) :D

Be careful when you advocate reducing keel/backbone structures. Edge-fastened or glued strip construction will give you greater panel strength compared to carvel planking of equal thickness, but it adds little to the longetudinal strength of the hull. If you reduce the skin thickness and the backbone scantlings you will reduce the longetudinal strength of the hull, thereby making it less able to resist the stresses of hogging or sagging brought on by rig tension and seaway motion. This is particularly worrisome when an older hull form is fitted with a modern rig, as the tensioning on 1x19 stainless wire and braided polypropylene rope can be much greater than was the case with galvanized plow wire and manila cordage.

(Edit for a mis-spell)

[ 01-12-2005, 12:00 PM: Message edited by: mmd ]

Don Z.

01-12-2005, 12:05 PM

Originally posted by RodB:
Bump...Update: current thoughts...

Take for example Hess's 30' "Bristol Channel Cutter" or Atkin's "Benbow" or Murry Peterson's Schooner "Susan"... these designs are great designs that have all the stresses from the ballast keel and rig computed into the design that has large beams in their construction... to convert them to a modern epoxy composite construction certainly would take a bit of doing to maintain the ESSENCE of the original designs in strenght, weight and weight distribution. The reason one would choose one of these designs is because of the compilation of qualities incorporated by the designer and keeping all those wonderful characteristics would be vital to my way of thinking.
RBThis is interesting. I had thought hard about building Susan, I guess the biggest thing stopping me is that I think the SA/displacement ratio is a little low, which isn't so appealing. I'm looking for something a similar size, but with a little more canvas.

My point though (and I do have one) is that when I was thinking about it, I contacted Peterson's office, to ask about strip planking and cold molding, and if memory serves, I was told that best results would be strip planked, with fiberglass inside and out, and no changes to the total thickness of the plank. I was also told the use of glass was preferable to the use of veneers, though if memory serves that was more due to Mr. Peterson's (actually, his son, if I recall) personal feelings about cold molding in general.

I'm not saying you're incorrect, just repeating my experience with that specific design, and wondering aloud re: the discrepancies.

RodB

01-12-2005, 01:46 PM

Don Z,

To start off with, I simply love "Susan" and find her a great design aesthetically and according to my research she has a wonderful sea motion and handles fantastic under sail. She also is available now with a gaff/tops'l cutter rig.

I had the same conversation with Bill Peterson that you did, and I got the exact opposite recommendations (recently). He was against sheathing the hull at all, suggesting traditional strip-planking as a variation on carvell planking...as an easier method of construction for the uninitiated... He felt there were several areas where sheathing would fail simply due to the shape of the hull and it being hard to wrap glass in these areas and expect there to be no failure... He was negatively disposed towards building the decks Dynel sheathed in lieu of teak decks, which he felt were more appropriate for "Susan" and he felt the teak decks would hold up ok in the tropical environment.

He stressed the significant cost savings gained by taking advantage of all hardware molds that already existed not to mention the ballast keel. He also allowed you could laminate the backbone to coincide with the strip-planking... and mentioned that where to end the strip-planking was one problem to solve ..tying into the garboard area...

Bottom line he suggested if you wanted to build sheathed-strip construction per Macnaughton's Rules that "Susan" was probably not the right boat as she was quite a wonderful design as she is and its just not all that practical to just change the entire construction method and end up with the same boat...and he was not interested in redesigning her for same.

Mr Peterson has extensive experience building boats in several different methods. His recommendations here were made with the goal of keeping all the wonderful qualities of "Susan" intact.

I had been muddeling along under the misconception that you could pretty much duplicate a traditional design with modern methods in a fairly straight forward approach, however after talking to Mr. Peterson I have changed my mindset...also, I am beginning to see the advantages of just selecting a design that is designed from the start for modern epoxy composite construction.

Some contradictions... I have certainly found several sources condeming the use of teak in hot environments as "drying out" and chasing leaks...and I had pretty much made up my mind that to get a boat that would stand up well in the hot, tropical environment that I should build a totally encapsulated hull and that the "Sheathed-stripped" method would be the easiest method for many reasons. As I am about to finish a 18 foot stitch and glue skiff, I have plenty of familiarity with epoxy and planned on going that route for my next project.

Another complication/too much information..., I have read Pardey's book "Details of Classic Boat Construction: The Hull in which epoxy is slammed as an adhesive that will last through wetting cycles and naturally mentions the Heat Defomation Temperature (HDT) ...which overall makes one stop and think about when to use Resourcinal and when to use epoxy as an adhesive. This "appendix" is definitely food for thought! There are some epoxy built boats that have had catastrophic failures...

All in all this entire subject is not so simple and there are many considerations. Mostly, for me, I have to consider whether I would want to deal with a traditionally constructed boat in the hot/tropical enviornment not to mention whether I want to build a boat that way, compared to building in the modern epoxy composite method. Also, how many times have I heard anecdotal nightmare stories on trying to maintain a traditonal boat in a hot/humid enviornment...chasing rot.

My understanding to date is that you need to properly redo/redesign a traditional design to build in the modern strip-planking method where you will sheath the entire hull, ending up with a monocoque structure. You would want to minimize the backbone thickness of solid wood, via webbing construction...or laminating to deal with this issue. Certainly weight distribution would be an area for an "expert" as maintaining the characteristics of the design would depend on this...also the keelson and through bolts holding the ballast keel would be vital...and how about the rig, what changes would be appropriate there. A completely different construction drawing would be required.

Would a lighter hull with increased ballast keep the same sea-motion and sailing characteristics of the original design? After all maintaining the characteristics of the original is the main point. With this lighter hull I assume the rig would change to maximize the advantages of the hull and increased ballast (larger sail plan, lighter masts). Finally, how much work would have to be done on this "redesign" of an existing design and how costly would it be?

I must honestly say that I must think hard before deciding on a traditonal boat as my choice... but converting one to modern construction, now thats the issue.

lots to consider,
RB

[ 01-12-2005, 02:57 PM: Message edited by: RodB ]

Don Z.

01-12-2005, 02:06 PM

OK, that makes sense to me... I may have misconstrued why he said not to cold mold... Though I do wonder, for your purposes (if I'm understanding them correctly) if "old" style strip planking (vice cold molding) may not be the way to go. Not 100% cold molded, but avoiding some of the issues you mention with traditional construction.

As Mr. Cleek frequently points out... methods and designs are a lot more closely aligned than one at first thinks!

So what you're saying is driving a lot of my decision making as well... with the added difference that I need something that will do well in light airs (and it takes some wind to move something with an SA/D ratio of <14, like Susan)... But a small schooner...

And to really confuse me... Metre boats and square metres do well cold molded, especially ones like Vortex based on glass designs... there is a significant weight savings in wood over glass, but a Swede 55, in glass is not that far from "traditional" looking. Depending on how you define "traditional". Perhaps length to beam figures in? Full keel as opposed to fin? If that's true would something like Fame do well cold molded?

I think I studied the wrong subject in college!

RonW

01-12-2005, 02:09 PM

I see some of these sheathed strip planked methods coming very close to being framelss, and I question the durability. Think MMD gave a very fair warning on loosing longitudial strength to a degree that in later years you may see the hull sagging or hogging.
I think Timothy B statements are right on target, couldn't agree more.
Here is what JOHN ATKIN says concerning strip planking in one of his articles.

-Strip-planking might well be the next, or another, practical method of building a round or a V-bottom hull. These have proven as strong as any hull, depending on design and materials used.

Conventionally, round bilge strip planked hulls are built on the station forms, with the frames steam bent and installed within the finished planking. Thus a "monocoque" hull is fashioned, much after the manner of a cold molded hull. Frames may be on far greater centers -- and ribbands, with strip planking, are not required as utilized in traditionally planked hulls. A V-bottom hull is strip planked directly to the sawn frames, as no station forms are usually used. Strip planking though more time consuming, provides all manner of methods in achieving the desired strength. -----

It is my understanding that the first traditional strip planked hull was in 1895, by a boatbuilder that just simply used all the scrap lumber up by cutting it into square planking and applying by using nails to fasten the planks to each other.The end result was a lot of readily available lumber at many times cheaper then the premium straight, clear vertical planks that where needed for carvel planking. Also the strip planked hull was a lot stronger then the carvel planked hull. But the draw back really wasn't time, since you have to figure the caulking and fairing in the carvel hull, But the real drawback and why the method didn't gain more popularity in the early 1900's is the cost of the nails.

Remeber We had not yet hit the industrial revolution where nails where spit out by a machine at a million or so a day.At this time the nails for this type of construction was considered just too dammed exspensive, yea quality lumber was cheaper.We where still running around in connestoga wagons. And not too many years earlier, people moving westward, where actually burning their houses down and then hanging around to sift through the ashes for the nails to take with them to reuse them in their next house.Lumber was CHEAP, NAILS WHERE NOT CHEAP.

I found a company that sells 316 stainless trim nails.At $7. a pound compare that to epoxy.
http://www.manasquanfasteners.com/
I see no reason why you couldn't take any of Atkin's plans and build as drawned, just plank with strip planking instead of carvel, should end up stronger. Just use proper size strips, and not thin strips and start ommiting the framing, trying to redsign the hull.

-- It seems that a lot of the discussion leads to building lighter boats. That may be another subject, rather then just replacing carvel with strip.

[ 01-12-2005, 03:13 PM: Message edited by: RonW ]

RonW

01-12-2005, 02:25 PM

RODB- Why don't you start another thread titled, Building a boat for tropical climates, pro and cons of different methods, what holds up and what doesn't. I think it might be a interesting subject.

RodB

01-12-2005, 02:58 PM

Susan may appear to need more sail area but remember she has a draft of 4 feet... that would be key in the parameters of "Susan". Also, she seems to perform well according to a couple of owners I have corresponded with.

Also, do not get it confused, when I say strip-planking I mean "Sheathed strip" construction as Macnaughton's scantling rules describe, where the fiberglass sheath both inside and out is structural and makes for an extremely strong and stiff hull...plus the lightest hull for any construction...NOT traditional strip-planked construction which us just a variation on carvel planked traditional construction since the rest of the boat would be the same as the original. You certainly can design a boat from the start as a heavy displacement cruiser, just make the strips and sheathing thick enough to achieve the weight required. Its the changing the traditioal method over to the modern composite method that is up for discussion.

Here she is "Susan"
http://www.imagestation.com/picture/sraid154/pff94d6e0ac9a807ecf2a88f9d4bf0670/f57ee3cb.jpg
http://www.imagestation.com/picture/sraid154/p5bf66c007e4ef35211a33a667347d24d/f57ee3d2.jpg As a Gaff cutter
http://www.imagestation.com/picture/sraid154/p90008a93c4a99ddec7992ea4e88847de/f57ee3d4.jpg Gaff cutter planked...

[ 01-12-2005, 04:30 PM: Message edited by: RodB ]

mmd

01-12-2005, 04:20 PM

Edge-fastened, strip-planked commercial lobster and net-fishing hulls were common in the Northumberland Strait area from western Cape Breton through to northern New Brunswick until the advent of fibreglass took over the industry. The hulls were not long-lived, but that was primarily a function of low-quality materials (for economy) and hard use.

If interested check out this web page (http://www.civilization.ca/hist/lifelines/linsg01e.html) by David Walker, Curator Emeritus of the Maritime Museum of the Atlantic.

http://www.civilization.ca/hist/lifelines/images/linsm15a.jpg

RodB

01-12-2005, 04:24 PM

Mlke,

I was under the impression that traditonally strip-planked boats have a great reputation overall for withstanding lots of use and standing up over time. Didn't one guy on a recent thread tell of his boat lasting 40 years and still going strong and his hull was strip-planked, with frames and white lead between the strips...all mechanically fastened.

I checked out the post above just now, I didn't see it when I started this reply. . . very interesting....we can all build a reasonably priced boats with that method.

RB

[ 01-12-2005, 05:41 PM: Message edited by: RodB ]

RonW

01-12-2005, 04:36 PM

We mentioned this on another thread as well, that the longevity was due to the boats being built out of Spruce. Economy was a high priority.

Looks like they built some real boats, for real men. http://www.civilization.ca/hist/lifelines/images/linsm18a.jpg

RonW

01-12-2005, 04:39 PM

RodB -here it is. check out swanko...

http://media5.hypernet.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=010819

mmd

01-12-2005, 04:40 PM

I don't recall the conversation, but I don't doubt the facts. Most wooden Strait boats lasted only 12-15 years, but good materials, detailed construction, and proper maintenance could extend the life of the boat by two or three times that figure.

Commonly, there was no bedding between planks and some rather cheesy wood could be put to use. The boats were launched in mid-April and fished hard until October, when they were hauled for the winter. Storage often consisted of parking them in the potato field beside the house and shoring it upright with four pieces of cord wood. Tarping was optional. The end result was that the hull had little maintenence, poor storage, went through vicious freeze-thaw cycles, and often had quantities of fresh water in the bilges. A lot of the derelict boats I've seen have been abandoned because the bilges go soft and deform, and the stern beyond the sternpost/prop apeture droops. These are common structural problems in boats of this type, but the symptoms are exacerbated by the common poor storage methods of the day.

RodB

01-12-2005, 05:06 PM

I add this from the other post on strip-planking for discussions sake:
swanko
.
Member # 5436
posted 01-10-2005 05:30 PM *** ** ** ** * * **
------------------------------------------------------------------------
I have a strip planked Atkins double ender. 1-1/4 x 1-1/4 mahogany, nailed 12" oc with 10d galvanized finish nails (toenailed). Minimal double sawn oak ribs; seams bedded with white lead. 39 years old, stiff and solid, doesn't leak a drop. she has been as far as venezuela (sp?) and was even driven ashore at Ocean City Maryland during a gale.
strip planking has impressive strength and durability.
----------------------------------------------------------------------------------------
Pretty impressive.... we can live without epoxy.

One note, mahogany was used for the planks, and that is much better stability wise than the softer woods used on modern strip-planking...that certainly would be a factor of major importance conerning the success of a tratitionally strip-planked hull.

Still, if you just substitute traditional strip-planking for carvel planking you still have the expense of the lumber to build the rest of the boat traditionally and also the problems of maintenance and rot that goes along with traditional boats in hot climates...so you have built with a simpler and stronger method than carvell planking but have still stayed with traditional construction. I do not think traditional strip-planking is much different than carvel, and we are talking about the advantages of encapsulated hulls and decks (modern sheathed-strip) and how to convert the traditional design to that method of construction while still maintaining all the great characteristics of the traditional design.

RB

Don Z.

01-12-2005, 08:06 PM

Originally posted by RodB:
Susan may appear to need more sail area but remember she has a draft of 4 feet... that would be key in the parameters of "Susan". Also, she seems to perform well according to a couple of owners I have corresponded with.
Not sure how to take that... Yes, she draws only four feet, but as I recall, she weighs quite a bit... my specs are lost in the pile of stuff still in storage from when I was mobilized... I do remember thinking she'd be hard to push along in light airs, such as we might find on the Chesapeake late summer. I remember thinking at the time that saving a bit longer for a Bluenose Jr (Roue) or Tyhee (Alden) might be a better idea.

I'm very interested to hear if those you've corresponded with have mentioned anything about light airs. I know she'd love a blow...

RodB

01-12-2005, 08:39 PM

Susan's displacement is around 13000 lbs..
I asked one lady who built "Susan" around 10 years ago and she said she had no complaints...but we covered a bit of ground quickly and that was the only comment on that subject. I asked more about how she did in open water, handling, etc.

You should e-mail Bill Peterson.

RB

RodB

01-14-2005, 01:52 AM

Mlke,

I assume your first choice, strip-planked, is the modern sheathed-stripped per Macnaughton's Scantling Rules.

The tropical building post is focused on best building technique to withstand the hot/humid tropical environment, not diagnosing deterioration causes.

RB

TimothyB

01-14-2005, 08:51 AM

I don't think anyone intended to make this thread a "Strip Planking is Great!" Thread, although I do agree with that sentiment ;)

Honestly RodB, Based on your musings and the various bits I am seeing here as to what you really desire, you want a go fast, light displacement medium range cruiser that looks like a classic. Am I off target?

Given that I am ON target, I would highly suggest that you employ the services of a firm to do the deaign, or, failing that, Talk to a firm that has already done what you are looking for, like Brooklin Boat Yard (http://www.brooklinboatyard.com/), operated by Joel White's son, Steve. I was up there looking at a boat and got the full tour of the boat yard and the design loft.. very nice! They know exactly what it takes to design such a vessel, as they have already done so, built them, and even berth a few of them at their mooring field.

Plus, the Brooklin Inn is great, and they have -fantastic- food. :) I'd go again just to hang out on the docks for a weekend and take in the Maine coast.

RodB

01-14-2005, 01:30 PM

The boats that I am intrigued by tend to be heavier displacement...Peterson's "Susan", Atkin's "Tern" and "Eric", Alden's Malabar Jr cb/version, Winslow's modified Friendship Sloop (gaff headed/spoon bow)...but I am trying to come up with an appealing design on the lower end of draft...that is not any bigger than I need and offers a great package...ie., a design by a talented experienced NA that obviously came out great and just "worked".

Perhaps aesthetics is one of the main driving factors here but history and positive commentary about the wonderful characteristics is certainly a part of it.

I am comfortable with the epoxy composite building method simply because of my experience with epoxy in my first boat (an 18 foot stitch and glue flyfishing skiff) . Modern sheathed-strip construction seems a perfect match up...the next step in a continuation in technical difficulty for one with my background to proceed to another level of project in size and scope.

I am comfortable with it and honestly not very comfortable with taking on a 30 foot traditionlly built boat simply due to zero experience in this type of construction (I may end up doing this anyway).. It just seems an easier task to build a strip-planked sheathed strip boat with sheathed Dynel decks ...an encapsulated boat... and I have confidence in the longevity and durability of such a craft and my ability to build it well.

Having a boat designed from scratch is quite an expensive proposition and I feel there is a way to achieve what I desire without that major cost. I just happen to find immense appeal in the older traditional designs...

I just thought having an existing design gone over by a professional would result in reasonable cost, and quality modified plans that would take advantage of the many wonderful characteristics of the original design although different construction...ie., the same weight distribution even with lighter structures with modern epoxy construction.

RB

Ray Weber

01-15-2005, 01:05 PM

Does anyone know where I might fined other pic and drawings/specs on the schooner "SUSAN"? Or her sisters? I thought this might be quicker than going through all the back issues of WOODEN BOAT...Thanks.

RodB

01-16-2005, 03:09 AM

Hey Ray,

First and foremost contact Bill Peterson with any questions etc :
peterson@lincoln.midcoast.com

There is a great writeup on "Susan" in two of Roger Taylor's "Good Boats" series, namely"

"Still More Good Boats"
" Thirty Classic Boat Designs"

"Still More Good Boats" has a complete chapter on "Susan" (reprinted in "Thirty Classic Boat Designs) with good history and lots of good detail and descriptive comments by Taylor. If you cannot get a hold of this, (I think Bill Peterson may have some copies) I have both books and could make you a copy).

There is a current article in the November/December 2004 issue of
"Ocean Navigator" issue No. 142
this article is on a cutter version recently launched with a few photos, etc...

I have a few photos and drawings of some details received from Bill Peterson...see below:

http://www.imagestation.com/picture/sraid104/p7b9da222fb81a52041d0e90be8bc23bc/f990300f.jpg
http://www.imagestation.com/picture/sraid154/p6476cf96802350d130b8df019a7dcedb/f5748928.jpg

Murry Peterson sailing... http://www.imagestation.com/picture/sraid154/pf2efa8c0d57d0ab1e0a6b94b6fe768af/f574893b.jpg
http://www.imagestation.com/picture/sraid154/p0cb0fed767a544670a5d12de4a957127/f574892d.jpg
Recently launched gaff/cutter version ... http://www.imagestation.com/picture/sraid154/p05c400994722d3c1abd3a6f0650e036a/f574891d.jpg

The deck of the schooner: http://www.imagestation.com/picture/sraid154/p0692c13b06434d2e19e2535fd0a69a05/f5748916.jpg

Hope these help,

RB

[ 01-16-2005, 04:16 AM: Message edited by: RodB ]

Ray Weber

01-16-2005, 09:33 AM

Thanks RodB that is perfect..I love Schooners

RodB

01-16-2005, 01:10 PM

I recently had some reasonable suggestions on converting a traditional heavy displacement design to modern composite construction... and suggesting not even worrying about consulting an NA for anything...

It goes like this:
Laminate the backbone including stem and post as one large piece via overlapping layers with seams staggered... ie., using profile of backbone...just fabricate it laying on its side, layer after layer pieced together with staggered seams of layers... (you could laminate in pieces and bolt together also).

Laminate the frames and leave none out...just as original plans show... (perhaps make them a bit thinner to decrease weight some but maintain plenty of strength).

strip-plank the hull (sheathed strip) to proper scantlings and sheath both interior and exterior with proper thickness of glass...

Laminate/cold-mold cabin tops, construct decks with ply... and sheath the decks with Dynel. laminate bulwarks/sheath all....

She ends up a little heavier than original because of the heavier frames but overall the boat ends up built pretty much to the plans and is a heavy displacement structure heavily built.

Besides the obvious "lots of cutting and gluing...lots of labor" Are there any negatives with this scenario? The backbone would obviously take plenty of time to glue all the layers together but would you need to recalculate any scantlings for anything?

Sounds reasonable...

RB

[ 01-16-2005, 03:03 PM: Message edited by: RodB ]

01-16-2005, 03:36 PM

Rod,

Laminate the backbone including stem and post as one large piece via overlapping layers with seams staggered... ie., using profile of backbone...just fabricate it laying on its side, layer after layer pieced together with staggered seams of layers... (you could laminate in pieces and bolt together also).
This is good, laminations should be 3/4" thick maximum. No butt joints, minimum 8:1 scarfs, 12:1 is better.

Laminate the frames and leave none out...just as original plans show... (perhaps make them a bit thinner to decrease weight some but maintain plenty of strength).

strip-plank the hull (sheathed strip) to proper scantlings and sheath both interior and exterior with proper thickness of glass...
Sheathing the inside of a traditionaly framed hull is incredibly painful and tedious. All those right-angle corners over each frame must be radiused to get the glass to stick. To do this with glass of any weight will be a glass cutters nightmare. Also you did not mention the floors and bulkheads, or clamp?

Fiberglass is heavy, on the order of three times the weight of Fir or mahogany, sheathing anything with glass and epoxy will add lots of weight.

I would suggest if you want to build a traditional hull using sheathed strips just glass the outside. Laminate your internals (frames, floors, clamps) with epoxy, then coat everything inside three times. Or leave the frames out and build over temp. molds, pull the completed hull off these, and glass the clean inside. A wood core hull.

All the best, Tad

RodB

01-17-2005, 02:15 PM

Great suggestions...they make lots of sense.

I guess the main concern would be building too heavy... so you would have to keep an eye on the weight factor...

I especially like the idea of scarfing the laminates for the backbone rather than just butting pieces together and staggering joints.

RB

George.

01-17-2005, 03:09 PM

My two cents... having built a strip-planked schooner from a traditional design, seat-of-the-pants, with no NA involved.

Unless you want to do serious racing, use traditional scantlings for frames, then strip-plank with traditional-thickness strips over them. You'll end up with a very strong and leak-proof boat.

If you want to save some weight, look up scantling tables for carvel planking. You'll find that many of them have scantlings for "light," "medium," and "heavy" or "blue water" construction. Use the "blue water" scantlings for planking, stringers, and backbone members, and the "light" ones for frames - you'll still end up with a hull stronger than a traditionally-built "blue water" hull.

And remember, frames in a strip-planked hull are there mainly for stifness, not to hold the strips together (as they hold the planks together in a traditional hull). You can get even more stiffness from structural bulkheads. Make your bulkheads structural, and you can skip the frames in their way. Add some serious hanging knees by the chainplates, and that will be stiff indeed!

Now, if what you want is an as-light-as-I-can-make-it racing hull, then get a naval architect - and also forget about traditional designs, they are too heavy by nature.

McB

01-17-2005, 03:59 PM

George, What did you build? Any pictures? Was it discussed in past threads?

I am looking very seriously at Crowninshield's FAME. Have been talking with Micheal aka-mmd about doing NA work for me.

RodB

01-18-2005, 02:53 PM

------------------------------------------------------------------------------------------
I would suggest if you want to build a traditional hull using sheathed strips just glass the outside. Laminate your internals (frames, floors, clamps) with epoxy, then coat everything inside three times. Or leave the frames out and build over temp. molds, pull the completed hull off these, and glass the clean inside. A wood core hull.

---------------------------------------------------------------------------------------

Tad,

Frames and floors I would assume you laminate as everything else unless you decided to go with bronze floors, like Pardey. What would you suggest?

If you build a "wood core hull" wouldn't you need to do some re-engineering for keelson, bolting on the ballast keel, etc. I think the suggestions I reinterated above were to simplify the process of building a traditional design within close proximity of the original boats weight and weight distribution, etc plus make the entire process simple and avoiding the need for an NA. It sure would involve a lot of cutting wood into small pieces and gluing up large pieces...

RB

George.

01-19-2005, 01:07 PM

McB, I built a 57' foot schooner based on the plans of two 1903 Gloucester fishing schooners. I modified the plans some, and strip-planked. Since it took me seven years I had plenty of time to double-check all calculations, and the nice thing about old designs for bigger boats is, when in doubt, overbuild - she needs the ballast anyway! ;) :D

Here is a picture. http://www.imagestation.com/picture/sraid136/p8442005d4d2b49c94f460087b5cb1296/f74ca329.jpg

I don't know FAME, but I'll be glad to provide any information or encouragement re: my experience with Dalia that you might find useful. Just let me know, and best of luck with your project. smile.gif

RodB

01-19-2005, 01:15 PM

WOW, A BEAUTIFUL SCHOONER....

RB

RonW

01-20-2005, 12:23 AM

George- I give you a thumbs up, great looking boat.And a lot of good solid info as well. I couldn't imagine taking on a job that would last for 7 years.So tell us more.
How many man hours in this job, you did have help didn't you?
How did you nail your strips together and did you use anything between the strips?
Did you use square strips, and what size where the strips?
Think I saw other pictures that you posted where you stripped from the keel up, with the boat sitting upright, is this so, and how did it work?
What native south american woods did you use?

Always like hearing and finding out as much info as possible on traditional strip planking.Thanks.

George.

01-20-2005, 06:02 AM

When I started, I figured on 3-4 years. Seven years and counting - interior still not finished!

I used square strips, 5cm by 5cm, made of ipe. They were edge-nailed with 10cm copper nails every 20cm, and the epoxy was thickened - first brush thin epoxy on both strips, then lay on thickened epoxy. BTW, ipe is very oily, so I wiped each strip with acetone, and then burned off the residue.

I took some time off work and did the backbone, frames and about 30% of the hull with a local carpenter assisting me, and once I figured he got the idea I hired another guy to help him finish. Still participated in my spare time, though. Then I took a few more months of working part-time to do the rigging and install the systems (steering, electrical, engine, etc.)

Building upright was the only way, as I did it outdoors on a derelict lot and had no way to turn it over. It sucked at times, though. The bottom was particularly nasty - at one point I actually had to shave my head to get rid of the epoxy drippings!

RodB

01-20-2005, 01:52 PM

How about some more photos???

George.

01-22-2005, 07:13 AM

Year 0
http://www.imagestation.com/picture/sraid155/pd26dd588347c199c4c540c7444c8b4c3/f561c3fe.jpg
Year 1
http://www.imagestation.com/picture/sraid155/p4ad6add23bd08ce55a8732e491809a12/f561c3d1.jpg

Year 2
http://www.imagestation.com/picture/sraid139/pd427d84d46321161a1886a69c1c3cf6b/f70d30e5.jpg

Year 3 and a half
http://www.imagestation.com/picture/sraid146/p4b9864089fb845afd3dd952216162286/f643d9c5.jpg
Year 6
http://www.imagestation.com/picture/sraid136/pd1495845c243431e3dfecb9c8bc856c2/f75c2f5c.jpg

RodB

01-22-2005, 06:09 PM

George, she looks fantastic... lots of folks can get a vicarious thrill from your project.

Congrats....

What wood did you use for frames, backbone, etc. Were your decks sheathed in Dynel or traditionally built with teak or fir...

I assume you did not sheath the hull. Nothing is as pretty as a schooner like yours.

RB

[ 01-22-2005, 07:16 PM: Message edited by: RodB ]

Ross M

01-22-2005, 07:46 PM

Damned Good Show, George!

Ross

PS: Maybe I am all wrong about this, but I applaud your decision to edge nail. It is my understanding that this helps greatly in the aftermath of a significant collision or, God forbid, she ever gets caught in the rocks. (I like to think about what happens after the big one).

George.

01-23-2005, 07:24 AM

Rod, the hull and frames and backbone are ipe. The deck, house, and spars are freijo (fray-JAW), a very light and flexible wood that glues very well - they used to make airplanes from it. The deck is laid over plywood and epoxied glass.

Ross, believe it or not, she dropped nearly three meters to the ground on launch day when a crane fitting broke. And sustained no damage, has not leaked a drop to this day (3 years)! One of the reasons I am a strip-planking advocate.

RodB

01-23-2005, 09:30 PM

George,

Did you sheath the hull? Was any part of the backbone laminated or all traditional construction?

You seem to have a blend of the two methods, old and new..

RB

PaulBal

01-25-2005, 10:34 PM

This has been a very informative thread. I have been dreaming about building the schooner Samanthe by R.H. Baker. I am going back and forth between traditional construction and strip planking. The boat would sail Lake Michigan and spend winters out of the water. Does fresh water and months on land change anyones opinion about traditional / epoxy construction? Has anyone here built her? Her description can be found on the Baker Boat Works site. I found it by linking through designers on by-the-sea.com.

PeterSibley

01-26-2005, 02:11 AM

Beautiful boat George!! Very interesting that you were able to get a good bond on your hardwood with epoxy....I've always been advised that at least with our Australian hardwoods,a good bond was difficult to achieve ,at least where strip planking was concerned .I'll reread the above.....your timber sounds worse to glue than ours.

I particularly like her stern.........very pretty smile.gif

RodB

01-26-2005, 01:18 PM

PaulBal,

Are you talking about traditional strip-planking (variation on carvel, edge nailed strips) but otherwise all traditional techniques and no sheathing....or a modern epoxy sheathed strip, where you not only epoxy the strips but also sheath the exterior (and interior in most cases) to achieve a monocoque structure.... ?

I think the modern method would result in a much better hull for sitting on the dry dock for a large part of the year.

RB

PaulBal

01-26-2005, 03:13 PM

Thanks for the reply RodB. I am thinking modern sheathed strip construction. Fiberglass cloth or other such material on the exterior, and at least epoxy on the interior. The project is in the dream stage, although I do have the prints.

RodB

01-27-2005, 06:49 PM

A few comments on building sheathed-strip...
Remember if you sheath her both on the interior and exterior per Macnaughton's rules then you can eliminate frames...The transverse strength across the joints of the strip planks is key to the strength and rigidness of the structure. You do hear negative comments on sheathing the interior mainly because of the labor involved in fairing the hull surface again on the interior.

Even with just a few frames and structural bulkheads one could apply unidirectional glass between the frames and triple coat everything...resulting in what the scantling rules calls for plus a bit more interior structure...still a monocoque structure with a bit more materials on the interior of the hull.

Macnaughton prefers sheathing the interior and exterior per his scantling rules to applying layers of veneer on the exterior. The veneers are just not necessary if one sheaths the hull properly. I think it comes down to just selecting a method to build by and doing it right...just as the method calls for. It seems many folks mix and match methodology usually resulting in overkill and heavier hulls than necessary. One of the great advantages of using modern methods is achieving a lighter hull which allows for an increase in the ballast keel which in turn results in an increase in ultimate stability and stability overall (righting moment etc). Also, modern building results in more room belowdecks etc simply because the hull is achieved with less materials.

RB

George.

01-28-2005, 06:52 AM

Rod, I did sheath the hull with one layer of thin glass and epoxy - more for smoothness and a good moisture barrier than for structure. None of the backbone is laminated - all traditional scarfed joints. The keel, however, is not traditional at all. It is basically an I-beam welded from scrap naval steel from a nearby shipyard, with about 7 tons of additional scrap welded on, and faired with cement. I drilled holes in it for floors and for the garboard, which is epoxied and bolted to this steel keel with 3mm bolts spaced 10cm. Reasoning behind it - lead and big timbers would have cost ten times more!

Peter - I was told ipe would not bond no matter what. I tested this before starting - epoxied several pieces, let them sit in the weather for a few months, and then tried to take them apart. Invariably what finally gave was the wood, not the bond. When you consider the strength of ipe that is some bond! When I cut ou the holes for portholes I did the same with the cutouts, and again no bond failure, so I am pretty satisfied.

The trick was to scratch the surfaces to be bonded, wipe them with lots of acetone, burn off the acetone residue with a torch, and then soak them with thin resin before laying on the thick stuff. When you apply acetone the runoff is dark brown and very oily, and you have to glue right away, before more oil from within the wood can work its way to the surface. Since it is hot down here I usually mixed the resin in glass trays (stolen from the kithchen!) over ice to keep it thin.

RodB

01-28-2005, 01:31 PM

George

Checking Macnaughton's rules for sheathed strip construction a rough calculation on the desired sheath thickness for a 30 footer (disp 14,000 lbs) would be approx 2 layers of 10 oz fiberglass cloth. That is substantial sheathing and really stabilizes the structure...but of course his scantling rules call for sheathing the interior also (not quite as thick)...and with this system sometimes creep shows up if the topsides are in the sun....This is where per Macnaughton, slow building may avoid this or if it happens to some extent, the first time your fair and repaint the hull, the problem goes away...since the creep (print through) is just a few thousanths....

I think today that it is common in heavier displacement hulls built along these lines that the builders choose to add two to three layers of 1/8 inch veneer for increased peace of mind over just sheathing with fiberglass. The following sheathing on top of the veneers is much less than that recommended by Macnaughton's scantling rules in this method.

They definitely end up with a bullet proof hull, even though lots of extra work. I can understand why one would make this choice considering the large investment in time and money...and if cost was not really an issue.

RB