Strip Planking

[EKE]

I'm reviewing the study plans and scantlings for Romilly SPV by Nigel Irens. He calls for western red cedar strips, of either "concave/convex" of "speed strip T&G" configuration.

Having never built using sheathed strip planking, these terms are somewhat mysterious. I assume that the "speed strip" is some sort of toungue and grouve milling that keeps adjacent strips aligned between molds. Is "speedstrip" a special milled shape?

"Concave/convex"....hmmmm....does this refer to an alternating edge bevel to serve the same purpose?

Gougeon Bros. recommend no bevel at all for sheathed strip planking, provided the curvature of the hull is not too severe. They recommend using wood dowels occasionally laterally between planks to keep them flush.

Can anyone offer any guidance on this?

-Erik

[JimM]

Hi Erik
Speed-strip is a trademarked name. You can see a picture of speed strip at this web site. Speed-strip (http://www.maritimewoodproducts.com/hull.asp)

Here is a web sit about Bead and Cove Strips (Concave/Convex). Bead and Cove Strips (http://www.guillemot-kayaks.com/Building/StripBuilt/CoveNBead/Strips.html)

You can buy either type of strip and have them sent to you or make you own bead and cove strips with a router. If you don't want to use these types of strips, just make your own stock on a table or band saw. Its your choice who you want to build.

Jim McGee

[ 02-05-2005, 01:54 PM: Message edited by: JimM ]

[paladin]

you can make your own 'Speed Strip" on a table saw.....and either way is easy for one person to build using proper clamps.

[JimConlin]

The benefits of applying an edge treatment in strip planking include:
The strips support one another between mold stations. If there's a wobble in a strip, its neighbors will show it the error of its ways. If you butt-joint strips, the neighbors offer guidance. T&G is probably better than cove&bead in this. Maybe you can get away with wider mold spacing.
If using cove & bead, the gaps between strips are minimised. This reduces the quantity and weight of the inter-strip adhesive, whatever it is. If the boat is to be finished bright, less filler will be needed. In either case, less print-through of variations in the density of the core.

[TimothyB]

Speed strip is really just to avoid having to bevel the strips as you go around the curve of the hull. They then also put in a slight T&G to help the strips lock together when you lay them up so you don't have to use so many clamps, and in theory provide a larger gluing surface. So, the $$ you pay gets you pre routed and T&G strips that you can just layup right away. A real time saver.

I like clamps, especially the quick jobbies made from 1" ply, and I like nails so I'm not concerned about glue. In -my- case, speed strip isn't important, and in fact would probably hurt me because I definitely like really beefy scantlings. Also, I like cheapness so although I won't skimp on materials, neither will I pay more for them than I have to, so I would rout my own B&C if I wanted them.

It's all up to you and what you are comfortable with.

One more thing:

There are basicaly two types of strip construction. One in which the wood of the strips is the structural member, and one in which the wood is a rigid core for a fiberglass layup and is NOT the structural member.

The first type has been being called 'Traditional Strip' and you can glue or not glue the strips. You can even toss a layer of glass over it, as long as its the wood that makes the hull strong.

The second type is the G. Brother's method which uses FG for the structural hull, and the wood is esentially a plug that stays behind as core. This is often referred to as 'Conventional Strip'

I would be hard pressed to tell you what you should call a Traditionaly Stripped boat that had many layers of FG over it. I suppose an FG sheathed old Stripper. ;)

[ 02-05-2005, 10:35 PM: Message edited by: TimothyB ]

[JimConlin]

For the method where there are glass skins on both sides of the strips and the skins supply most 'thwartship strength, I prefer the term 'strip composite'.

[RodB]

Macnaughton calls your 'strip composite ' ..."sheathed strip" construction and the fiberglass cloth is structural...see "Macnaughton's Scantling Rules for Sheathed Strip Construction". The scantling rules on this method have been based on some very good studies but it seems many folks do not build this way alone, they modify the method somewhat for increased safety margin...although Macnaughton says this is a waste of time and not necessary if one builds exactly as his scantlings rules dictate...ie., proper thickness of strips and proper sheathing thickness both inside and outside of the hull. Unidirectional glass is recommended for the interior of the hull.

I would be interested in how much more you would spend by either using the speed strip or
concave/convex strip over the standard square strips....You sure see some great jobs on strip-planking using only square strips.

RB

[ 02-06-2005, 01:12 AM: Message edited by: RodB ]

[EKE]

Thanks a lot for all of the informative responses! I really appreciate the quick support.

Irens calls for 19 mm thick cedar strips for Romilly (22' LOA, 3300 lbs dspl). That's 3/4". His outline spec calls for "external glass sheathing to help prevent damage to the planking and ensure the structure remains sealed."

When I build her I'll probably use some form of T & G.

[EKE]

What are you trying to say, Mike? :confused:

[ 02-06-2005, 11:26 AM: Message edited by: EKE ]

[RonW]

Eke - you can not use tongue and groove, tongue and groove will not go together in a curve such as the outside of a boat hull. Period...
Read this and be informed, also do a search on the building and design forums.

http://www.sredmond.com/strip_plank.htm

This is concave ......and this is convex..
..........(...............(............
A curve in and a curve out on the edges of the strips.

[ 02-06-2005, 01:12 PM: Message edited by: RonW ]

[TimothyB]

I think folks aren't picturing the speed strip planks right..

http://www.maritimewoodproducts.com/hull.asp

There you go. That should make it clearer when you say 'T&G' with regard to speed strip.

Here's an image from their site:
http://www.maritimewoodproducts.com/images/hull1side_new.jpg

Now, personally, I would not go this deep, and I would do a 'slight' T&G but ALSO with Bead and Cove, again 'slight' You have to finish the edges anyway so you can finish them curved instead of straight.

BUT they claim that you can get 7 degrees of twist out of a strip. And many boats have been built with this method. If N. Irens is recommending this method, then it should be fine. If you really have questions or concerns about it, the fella is right: Talk to the designer. You own a set of plans and presumably the right to bug the designer with questions ;)

[RonW]

Tongue and groove and cove and bead strips will work much better on a 40 ft. sail boat, that has a deep keel resulting in a long gradual slope. As compared to a 20 foot boat that has some hard curvature to the smaller hull.

To get a 7degree twist on a strip, simply means a sloppy fit with room to twist. And that means epoxy to take up the slack. What none of these diagrams show is as you go around a curvature,with either tongue and groove or cove and bead the inside of the strips hit, and you open up the outside of the joint, another place to use epoxy to fill in the gap.

Who designs these joinery methods? EPOXY MANUFATCURERES.....

Another thing about these per cut strips that are half again wide as they are thick fail to mention, is grain orientation.They would almost have to use vertical grain lumber to end up with the grain on the strips running from in to out on the hull as they should.Which they don't.

I think anyone considering building a strip planked boat, would compare the price of precuts to stripping their own, as well as using square strips that you can orientate the grain and have a much better fits then filling in with epoxy, would be surprised at the cost savings as well as labor.

A simple and solid construction method that has worked very sucessfully for over a 100 years, is being modernized to the point that it has to rely on epoxy to fill the cracks. I fail to see the improvement.

[RonW]

with one caveat is that the use of simple strips have actually created new and improved many traditional designs for the average guy

That statement should also be 100% true, BUT.
Anything that is not plywood, carvel or lapstrake is being deemed as strip planking. With variations and deviations growing daily.
Then everyone wants to mix and match a little of method B along with some of method D and a touch of method F to create a new and improved version called method Q. Then problems crop up.

I am convinced that many designers have not studied the method-and variations of- well enough and add to the confusion.

Variations all seem to be driven by,
A- lack of reasonable joinery fitting, resulting in, get it close and fill in the gap with epoxy.
B- let's see how many frames we can leave out, resulting in less framing labor and a lighter boat, till they fail.
C- eliminate nailing the strips together,save labor, again relying on epoxy.

What should be a simple and cheap method that can result in reviving traditional round designs for the homebuilder, is being overly complicated, and exspensive due to excessive use of epoxy.

This is not a knock epoxy thread, but so many methods seem to be redsigned as to create ways to use epoxy. All right everyone that has stock in epoxy companies raise your hand.

[EKE]

ASK THE DESIGNER WHY HE SPECIFIES THIS METHOD, AND NOT A FORUM.
I'll make sure to exhaust all other sources of information before I dare to come to the steps of the oracle again, Mike. ;)

I don't recall asking anyone in this forum why a particular method was specified by the designer. I simply wasn't familiar with the term "speed-strip".

When I said I'd use T&G, I was using the term generically, to refer to one of the sections specified by the designer.....rather that straight square strips.

To those who kindly offered the information I was seeking, I'm grateful.

EKE

[EKE]

If a person is not aware of the issues that come with this method, then alerting the person to the potential downfalls is not in anyway a putdown either, my new found friend. I know that, Mike! smile.gif I'm grateful for any and all assistance you and the other knowledgeable persons can send my way. That's why I asked!

My reaction had more to do with your suggestion that my question might send you to the other room to beat your head against the wall. tongue.gif Wouldn't want you to hurt yourself.

No offence taken, my friend. Thanks for the help.

[RonW]

Eke - the whole discussion or debate was over the techniques and variations on the strip planked method. No one was trying to be rude to you. Check over on the design board under = converting carvel to strip planking = Think you will see that opinions can be varied and that is a good thing.
We all become more informed and actually have to think about it. Stick around and learn how to build a wooden boat, or how NOT to build a wooden boat.

[TimothyB]

I think that there is a romantic attachment to Carvel, as it is beautiful and functional, and long lasting.

But Traditional strip planked boats have been around for a very long time, and deserve the name "Traditional".

The thing that separates the various methods, I believe, is not glue but -sheathing-. Once you go that route, you are irreversibly modern in method. You can build a stripper with no metal in it.. just use thick strips and (strong) wooden dowels. The Pinisi have been doing that for many, many years.

If you build a strip plank boat that doesn't need sheathing, it should be thought of as a traditional wooden boat. The idea that carvel is the end-all-be-all of wooden boat construction is a bit dated, I think! Strip planked vessels have been plying the oceans for a very long time and are inherently stronger, stiffer, and require less of an investment in materials. A complete win in my opinion.

There are those who would argue "a carvel boat can be completely refitted in 'the outback' with only hand tools and wood"; and they would be right. But you could easily put a patch on a strip plank boat in timbuktu until you could GET some nails and glue, once you made it to civilization.

I believe it is worth the trade of greater stiffness and strength, fewer/lighter frames, lower materials cost and lower skill level needed to build for complete repairability in remote areas.