A little knowledge is a dangerous...

[davebrown]

Salty Dogs: I am gradually trying to wean myself off of plywood and end up being able to build real wooden boats without glass.

I want to build a cosine wherry and ALTER THE DESIGNER'S PLANS, which proves that I am part fool and part dreamer.

I want to use either 1/2x3/4 spruce strips or, more work but easier to bend--1/2 x 1/2 strips, with epoxy in the seems and either no glass or a small glass rub strip on the very bottom of the hull.

The Cosine Wherry is designed to be a strip built boat--but with 1/4 canoe style stripping under several layers of glass.

I have two worries: first, will the boat be stiff enough if I strip it with little or no glass, at either size stripping?

Second, will the boat gain too much weight to be a reasonable build? If the hull stays at or under 200 lbs., that would be a good result...

[Ian McColgin]

You can build to this design lighter if you stay all wood-epoxy but you need to work out the scantlings correctly.

I recommend a consult with the designer. The original plan is the easiest to build to but there are options.

Additionally, you may want to learn about Cutts' method and even the possibility of three layer cold molding - two ashcroft and outer strip.

This was intentionally inspiring rather than detailed as I don't really know which will work best for you.

Glass really gives less abrasion resistance than many credit. Put a sacrifice pad or metal half-round under the skeg and keel and just below the turn of the bilge.

[Figment]

Abrasion resistance is one thing, but impact resistance would be my concern.

I'm not talking about ramming-speed impact, just the occasional bump into a dock, trailer, sawhorse, etc. These minor dings can add up over time, ya know? I think that outer layer of glass could serve to keep the hull looking better in the long run.

Ian's right... consult the designer. It certainly is a pretty boat!

[JimConlin]

The original design calls for 1/4" strip planking, glass structural skins and minimal interior framing. Estimated weight is 100 lbs.

With 1/2" strip planking and no skins, you will need a significant amount of transverse framing just to hold the boat together. You'll have no trouble topping 200 lbs.

Why?

[davebrown]

I want to learn how to use the heavier strips,and I want to minimize the fiberglass work on this boat. My next boat is an ocean pointer, and there are some design similarities but the big difference is the planking.

I use a trailer, thus a 200 lb boat is acceptable--a 400 lb boat is too unwieldy.

[Keith Wilson]

I’m very skeptical about building a light strip-planked boat without any frames or fiberglass. I think that the edge-glued planking won’t have enough cross-grain strength, and will tend to split as the hull flexes (and flex it will).

There were lots and lots of small strip-built boats made from around 1900 to the end of commercial wooden boatbuilding in the '50s and early '60s. It was the standard way of building a fishing boat in the Midwest, originally rowboats but later for outboard power. There were hundreds of small boatshops in Minnesota, Wisconsin, and Michigan that turned them out in large quantities; they were the early 20th century equivalent of the ubiquitous tin skiff of today. They used edge-nailed cedar planking that was quite thin, with no adhesive between the planks at all, and lots of small steam-bent frames, clench-nailed to the planking. They weren't all that heavy (at least in spring); I think you could keep the Cosine Wherry well under 200 lbs if you were careful. She wouldn't tolerate abuse as well as the glassed version, however.

You can download (as .pdf files) an article by Weston Farmer with an excellent description of the construction method, as well as plans for Dolly Varden, a lovely little outboard skiff here. (http://www.svensons.com/boat/?p=Utility/DollyVarden) Farmer BTW, is IMHO a very unjustly neglected designer. You might want to also read the section about strip-planking in his book, From My Old Boat Shop. This is a pretty good way of building a boat, and is the direct ancestor of today’s fiberglassed strip-planked designs.

The solution to "a little knowledge" is to get more. ;)

[ 03-07-2005, 05:50 PM: Message edited by: Keith Wilson ]

[davebrown]

Message received: this is exactly what I was inquiring about: strip building the cosine with heavier construction might be an interesting and successful way to do it, but it will require scantlings.

The designer, as so often happens, appears to ahve the most efficient way of doing it, in spite of my goal of using it to learn to build an ocean pointer.

[htom]

The immeadiate problem with the change from 100 pounds to 200 pounds is that the TOTAL displacement for the Cosine Wherry is supposed to be 300 to 400 pounds, including the hull.

[George Roberts]

Looks like a little more knowledge might be more dangerous.

[Figment]

George, you're slipping. I thought you'd be in the first five responses on this one for sure!

[DugT]

Kieth,

Thanks for posting the Dolly Varden link. That looks like the perfect boat to start learning traditional boatbuilding...makes me want to try the 13 foot version. Also, judging from the shape of the hull, it looks like you could build it lapstrake without too much trouble. I think it might cost a little more than $60.00 these days though.

Doug

[George Roberts]

davebrown ---

Perhaps you could find a similar sized boat built using the style you want to use. Then you could simply use those construction details in your boat.

Figment ---
smile.gif

[davebrown]

Know of any strip-built wherry style boats in the 16-17 foot range?

[htom]

Here's an edge-nailed Whitehall: http://www.glen-l.com/designs/canu-row/whitehall.html

[George Roberts]

That boat is 350 pounds. A bit more than you wanted. The wood strips are 1/2" thick about what you wanted.

I did not look at the details enough to see more than that.

[davebrown]

love it! great looking boat. i don't think the weight is prohibitive.

thnx.

[Keith Wilson]

FWIW, the Glen-L boat is fiberglass/epoxy sheathed just like the cosine wherry, although you could certainly build her in the old style with frames.

[ 03-14-2005, 04:46 PM: Message edited by: Keith Wilson ]

[DugT]

Wow...that Whitehall is a beauty...how would she perform as a sailboat?