View Full Version : Edge glued mahogany carvel planking

05-06-2017, 11:55 AM
In lieu of using white cedar planking I have considered using mahogany planking instead. I am too weary of the cedar swelling excessively once she is pulled out of the water. I have seen some edge glued cedar planking where the seams literally were pushed up slightly when the planking swelled. This left the builder to fair out the hull which created much thinner plankng upon completion. I THINK the mahogany would be more resistant to excessive moisture swelling and less apt to crack upon shrinkage. My boat will use wood?? planking over white oak frames.

Jay Greer
05-07-2017, 02:17 PM
Sounds as if the builder did not know how to fasten or caulk his cedar planked boat correctly. He may have used fastenings that were too small or not spaced correctly. Over caulking can result in planking that buckles when the boat takes up after launching as well. Facing the annular rings of the wood incorrectly in flat sawn stock also can result in unfair planking.
Mahogany can be used for tight seam planking. A Scandanavian method uses a special rolling tool to depress a portion of the center of each plank that is then planed down to the top of the depressed groove. Once the boat is launched, the portion of the wood that was compressed swells and seals the planking seams.

MN Dave
05-07-2017, 03:28 PM
The Scandinavian technique sounds interesting. I have to try it.

All wood swells. Have a look at http://www.wood-database.com

Atlantic White Cedar,
Shrinkage: Radial: 2.9%, Tangential: 5.4%, Volumetric: 8.8%, T/R Ratio: 1.9

Northern White Cedar
Shrinkage: Radial: 2.2%, Tangential: 4.9%, Volumetric: 7.2%, T/R Ratio: 2.2

Honduran Mahogany
Shrinkage: Radial: 2.9%, Tangential: 4.3%, Volumetric: 7.5%, T/R Ratio: 1.5

African Mahogany
Shrinkage: Radial: 4.2%, Tangential: 5.7%, Volumetric: 10.0%, T/R Ratio: 1.4

Gib Etheridge
05-07-2017, 04:33 PM
Western Red Cedar
Shrinkage: Radial: 2.4%, Tangential: 5.0%, Volumetric: 6.8%, T/R Ratio: 2.1

It might be easier to find enough vertical grain WRC.