Strip building

[cs]

I ain't ready to start, but I can start thinking and planning. I've got the plans for a Roth Friendship sloop. It was designed as a carvel planked boat. Now don't try and change my mind, it is made up. What I plan on doing is converting the construction to strip planked instead of the carvel.

Now on to my question. All the strip planked stuff I've read talk about putting a layer of glass on the outside. After my recent expeirance glassing my canoe I've decided that I don't like glass. So I want to strip this boat and not glass it. Is that okay?

Chad

[cs]

MIke when I start to do this I will use the same plank thickness as designed for the carvel. Is the glass for strip neccesary? What are potential problems?

Chad

[cs]

So strip building does not require the glass to help with a tight hull. Carvel use the swelling of the planks to seal the hull and I was thinking that the strip used the glass, but are you saying that it is not needed to seal the hull?

Chad

[imported_Steven Bauer]

The 'glass isn't neccesary, but your planking thickness will need to be increased. You wouldn't spend years of your hard work and free time without having a Naval Architect or boat designer or someone really knowledgable help you with the new scantlings, would you?

Steven

[ 07-08-2004, 08:21 AM: Message edited by: Steven Bauer ]

[cs]

Steven, If I understand everything (which is highly unlikly) strip planking is stronger than carvel. If I leave the frames and plank thickness the same as designed for carvel, but do it in strips I should be making a stronger boat.

Chad

[Popeye]

Are you adverse to molding on (set in epoxy) a layer or two of veneer instead of cloth?

[Tonyr]

You might like to consider using an adhesive between the strips. For ease of handling (no mixing) and low cost, PL Premium construction glue is hard to beat, but most people seem to use epoxy anyway.

The big benefit here, I have found, is that much less precision and skill is needed if you use a gap filling glue, than if you rely on your perfect workmanship and the plank swelling.

These opinions may not be widely shared - we shall see!

Tony.

[cs]

Tony, If I do this without glass I will probably use some type of gap filling glue. More thn likely I'll use epoxy, but Weldwood is also an option.

Chad

[alteran]

What problem did you run into glassing the canoe?
I'll be starting another this fall and have also found this to be the most challenging part to get just right.

[cs]

I had wanted to finish my canoe clear, but the sloppy glass job I did did not allow me to do this. No excuses, just I'm not as skilled at that as I wish I was. Besides wood sands so much easier than wood coated epoxy.

Chad

[RodB]

I have been looking quite hard at building my next boat (30 foot sailboat) strip-planked (as Macnaughton puts it "sheathed-stripped" and I think you would be making a mistake not to sheath the hull. From my understanding the the fiberglass is a structural part of the hull and supplies the strength across the joints where the strip-planked hull needs it. As as matter of fact optimal stripped-planked hulls are sheathed on the interior of the hull with unidirectional glass. Other Fabrics like Xynole or Dynel would not be a good idea unless they overlaid fiberglass cloth because they are too flexable.

In other words, the strips themselves provide ample strength fore and aft , the fiberglass sheathing both outside and inside completes the structure and makes it the strongest structure for its weight that you can build in wood... a monocoque structure. THis is all summarized in Macnaughtons Scantling Rules for Sheathed -stripped Construction. Have a talk with Tom Macnaughton and see what he says about your proposed method of construction. I am sure he could offer some alternatives.

RB

[ 07-10-2004, 02:50 AM: Message edited by: RodB ]

[Tomcat]

I wouldn't do it. For an afternoon or so work, you would positively seal the fate of your boat if you glass it. You don't have to glass the inside, though it needs frames and an epoxy coating if you don't.

The biggest continuous glassing job I did was about 220 square feet, and it took half an afternoon. it made every subsequent step easier. It made every step leading up to the glassing easier. If you do it, you will have a boat which according to WB has the lowest maintenance cost and requirement of any type.

You don't have to sand the glass, and in fact shouldn't. Once the glass goes down, you can cut away the extra, and use filler to fair the hull.

I don't beleive it is practical to clear finish any boat that isn't stored inside, you can clear finish the insides of course. But the outside should be faired with 410, and then painted.

[Meerkat]

Jamie Hascall's "Victoria" is a 35 year old 30' strip plank build - "glued and nailed", no exterior sheathing (aside from fairing and paint). A dry boat.

I wouldn't use anything but epoxy to glue the strips - but nailing the strips together seems to be passe' these days with better, truly waterproof glues.

I suspect that by using glued strips, you're going to end up with a substantially heavier (and stronger) boat than if it was made with carvel.

[ 07-10-2004, 02:21 PM: Message edited by: Meerkat ]

[Jon Etheredge]

So I want to strip this boat and not glass it. Is that okay?
A few years ago I visited Dick Pulsifer at his shop where he has built a fair number of Hampton boats. As I recall, he uses cedar strips that are edge nailed with bronze ring nails and 5200 between the strips. He tapers and bevels the strips so they meet with square edges (instead of using a bead and cove for example). I believe that he has been building Hampton boats this way for more than 20 years and it is a very quick method for him.

He doesn't use glass sheathing or an epoxy coating (unless he has changed pretty recently).

This is a "traditional" method of building on parts of the Maine coast.

[Tonyr]

While a boat may well be strong enough without sheathing with epoxy/fibreglass, the main reasons I am going to sheath mine are (1) to keep water out of the soft and light cedar (to stop it getting double the weight by the end of the season); (2) to greatly improve abrasion resistance and (3) to cover and protect the fairing compound I use to make up for my inferior workmanship.

Tony.

[Dennis Marshall]

Speaking of strip planking, I was wondering how one determines the scantlings for it. I have plans for Bolger's Spartina. Construction specs call for 1/2" clinker ply planking. I've been contemplating the possibility of stripping it because I like the looks of a smooth hull, but the tedium of fairing, glassing and fairing does not seem so attractive.

Dennis

[Tomcat]

There shouldn't be any problem using 410 on any boat where the wood is designed to remain bone dry, and the surface being faired is glass fiber, not wood.

One puts the 410 on, or your choice there are meriad systems, Not to cover bad workmanship, in fact that probably won't work too brilliantly, but to fair cloth edges that naturaly occur when you wrap up any boat.

What I have never understood about edge nailing/gluing is how the boat survives the inevitable expansion if there isn't any gap between the planks. With 5200 I guess I could see it, though why anyone would want to use a truckload of that stuff in preferene to epoxy... I don't mean as a spcific product for a given use, but rather why one would want to adopt a method that requires swiming in an ocean of the stuff.

Just ask the designer what he thinks about planking it in strip, as to the scantlings. If the designer isn't around, and you are subbing for ply, I would just go with a similar thickness and pretty heavy glass, like 18-24 on the outside over half inch. That should cover the stringer effect where the laps are. Basicaly strip is real strong, so make up a sample and compare stiffness in two axis, 0 and 90, to your sample of ply. I don't see any reason for the strip to weigh more, so that should be taken into account, 1/2 with 18-24 would probably be heavier, which isn't likely necesary.

I think the gougeon's have some info on comparative laminations. The one I always liked was that 3/8 cedar with 5 ounces of uni carbon on each side at 90 deg is better than 1" D-Fir boat plywood. In hydromat testing the 3/8" can't just act as a core within the carbon bridge, so it shows how strong cedar can be on a comparative basis.

Just look at a bunch of boats and the materials they used, and you will eventualy come up with your answer. Every boat is designed a little different and the way certain loads are carried like for ballast can vary, so it isn't as simple as just substituting or copying, or following a formula. You have to look at the whole thing, and come up with a plan for the substitution. I always come up with a weight budget, and then try to figure the best way to spend it. If i am moving to a structuraly superior system, I know the new scantlings, for a given weight, won't be weaker, and I may not want to significantly lighten the boat, since that eventualy means redrawing everything. That kind of job isn't all that complex.

[ 07-11-2004, 03:00 AM: Message edited by: Tomcat ]

[cs]

It is mentioned to ask the designer about some of these questions. The boat was desinged by McKie W. Roth Jr. I'm not sure if he is even alive. Does anyone know? I bought the plans through the Maine Maritime Museum.

Chad

[Jack Heinlen]

Chad,

I don't know if Roth is still around. MMM should be able to tell you.

Re strip building. Just an aside really, as all the comments about gluing and sheathing etc are interesting, but one of the world's great proponents of strip planking, Alton Wallace(now deceased) built hundreds of his Westpoint skiffs out of pine and galvanized finish nails and nothing else. He also knew in his nerve cells how to bevel plank.

I think the sheathing is unecessary, but a gap filling glue would fit. If building with the same thickness planking you should have no problems. Do a search of Cyrus Hamlin and you'll turn up some information on the developement of the Controversy and Amphibicon, light displacement boats built glued-cedar-strip in the fifties and sixties, unsheated, and most still going strong.

[ 07-13-2004, 07:15 AM: Message edited by: Jack Heinlen ]

[Jon Etheredge]

The boat was desinged by McKie W. Roth Jr. I'm not sure if he is even alive. Does anyone know?
Yes, Roth is still around. He is selling house plans and such these days.

McKie Roth Design website (http://www.mckieroth.com/index.html)

[swanko]

I have a strip plank 34' atkins double ender. It was launched in 1966 after a ten year building program. the strips are 1-1/8 square honduras mahogany in double sawn oak ribs. The ribs are 2'-0 O.C.. The strips were bedded in white lead putty and toe nailed with 10d galv. finish nails.The planking is fastened to the hull with 3" Galv. screws. Painted with oil base paint.

Still going strong. In my opinion, after dealing with wood boats for over 35 years, strip planking is the strongest, longest lasting method of building a boat ever devised.

[cs]

Thanks for the link to Roth. I have sent him an e-mail so maybe I will hear back from him.

Chad

[cs]

Here is a reply back from Roth.

Dear Mr. Smith: Thanks for your interest in my design. The problem with strip-builts from my experience is in the hard bends, for instance just forward of the rudder post in the turn, and around the transom above the water. The strips must be narrow in these areas in order to make the turns ok as the planks go up from one to another. The one strip boat i did build (more than 40 years ago) i did by curving and hollowing the edges of each strip. The difficulty was edge-nailing the strips without breaking thru in addition to the problem i mentioned above. Many Scandanavian boats used to be built using tapered strips, like caravel planking but with narrower planks. I guess this is how i woudl go on the sloop, but of course this would be nearly as much work as caravel planking. Another possibilty would be laminating with, say, 2 layers 3/16" thick laid at opposite diagonals followed by the outer layer 1/4"+ thick laid as if they were caravel. Hope these ideas are helpful.
Sincerely, McKie RothChad