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View Full Version : Batten-seam construction revisited.



Gray-Sea
08-08-2014, 10:37 AM
I've read every thread here that the search feature can reveal, and you guys are so outstanding in your knowledge that much of it is way over my head!

What I'm trying to accomplish is to get an educated understanding of the history of this type of constitution in motor yachts; advantages, disadvantages, how and why it came to be, and it's relation (if any) to plank-on-frame and cold-molded boat construction.

Any references to books, magazines, websites, or past issues of Wooden Boat would be greatly appreciated.

Thank you kindly for any direction and information!

J.Madison
08-08-2014, 10:40 AM
Batten seam has the advantage of allowing rather wide planking stock to be used. It also requires less framing than carvel and gives a smooth skin unlike lapstrake. Thinner planking thickness can also be used when compared to carvel.

Thats just a start...

nedL
08-08-2014, 10:47 AM
It allows for overall lighter weight, less wood, lower cost construction. The construction method easilly goes back to the '19-teens'.

Peerie Maa
08-08-2014, 01:08 PM
In the UK it was common on smaller light weight yachts like the Humber Yawls, derived from canoes. They needed to be light weight, as they were often moved to new cruising grounds by train or steamer.

Dunno about bigger motor boats though.

Gray-Sea
08-09-2014, 01:51 PM
Thanks, fellas, I appreciate you insight.

Peter Malcolm Jardine
08-09-2014, 04:35 PM
All of the above, but no one has mentioned a major contribution: strength. Batten construction is very strong, even with light builds. Here is a construction picture of Slo-Mo-Shun, one of the fastest wooden hydroplanes ever constructed. You can see the use of battens throughout the structure. Some of the battens used in Hydro's are small laminations, carefully put together for maximum strength and stiffness. It would be very unfortunate to have a precision three step hydro design start to flex at around 250 miles per hour. For some reference, Slo Mo Shun was 28 feet long, 11 foot beam, and weighed about 4700 pounds. The Allison engine in the boat weighed about 1500 pounds 'dry' and probably closer to 1900 at operational weight.

http://www.slomoshun.com/images/slo4buil-topRibs.gif


Battened hulls are also extremely stable. They don't move around in the same way as a carvel boat, because they are heavily fastener or adhesive reliant. Chris Craft used batten construction for many of their hulls, and their largest hulls in wood were built upside down, then turned over for finishing and the install of the cabin and interior structure. With two layers of planking and the use of battens and full length stringers, this made for a very stiff, relatively light and ultimately faster boat, which was a real consumer desire in the 50's and 60's Lots of other builders in the powerboat field used battens... Rybovich was another builder who wanted high strength and speed... so light was right.

Want to see the use of fasteners on a batten seamed hull? Here is a larger Chris Craft Constellation hull from the 60's..... Take a close look at how many bronze frearson screws are used on this boat! The bottom was fir plywood, with mahogany plank over top. In between the frames were stiffening battens running parallell to the frames, and topsides was edge to edge with a small routed channel filled with putty, and the battens behind the plank seams were notched into the frames. They were 1X3, and planking was typically 8 inches wide. The key here was strength, and stability. These boats, when in good shape, are a breeze to finish, and they are such beautifully fair hulls, and they stay that way..... until rot starts to set in. The other part of their strength to consider is it is in-the-water strength. A lot of batten hulls have been badly damaged by improper blocking of the hull on haulout, particularly on a bigger boat.

http://www.seabuddy.net/photos/d/12598-1/4+yz+475d200.jpg


The downside is different than most planked hulls.... it's an integrity issue. If any of the parts are in question, the whole boat is in question. Fastener corrosion, rot, chine bolts breaking, and even cabin and deck degradation weaken the entire structure. You only have to see an old rotten Chris in slings to see how nasty this can be. You dare not patch, you need to look at the overall hull integrity in order to repair the boat properly.

There are a lot of hulls that use the same design concept..... consider a lapstrake hull. Its planking overlap provides immense strength even with light planking stock. In power boats, hull weight is an important factor in gas consumption and performance.... battens work very well.


Last photo is my own CC which had a small repair on the port side. It's a bad idea to short plank these boats, so we had to go back far enough to plank properly, and it gave an opportunity to check other parts of the structure.

http://img.photobucket.com/albums/v378/nanzep/002-11.jpg

Gray-Sea
08-09-2014, 05:26 PM
That's so much, sir!
Immensely helpful and insightful.