Building an Adirondack Guideboat-Backing out Revisited

As explained earlier, backing out was the old time guideboat builder’s term for hollowing out a plank so that it would fit over the turn of the bilge in the hull.  The turn of the bilge is the region where the hull makes a transition from being nearly horizontal to being nearly vertical.

Accommodating this rather abrupt change is daunting.  It is so daunting, at least for me, that I threw in the towel and went a different route.  Lewis Grant, who took over the guideboat shop his father founded in the 1880’s, put the difficulty of backing out thus, “To concave and convex the siding to 3/16 inch was a piece of work that one of the best house building carpenters in Boonville (where the Grant shop was located) could not learn to do right. He could work to a straight line but not to a true curve on this fine work.”

There are those who have a natural talent for doing such fine work.  Allison, the Adirondack Museum’s Boat Builder-in-Residence, can back out a plank using only her eyes to gauge how much to remove at any point along a plank.  Remember, when backing out a plank, the amount of material to be removed depends on the position at any point of the plank on the hull.  The greatest amount of removal is at the midships with the least amount (or none) as one approaches the stems.

This spring Dave Bloom finished a replica of the Queen Anne guideboat built by Caleb Chase in 1893 for the Pruyn family at Great Camp Santanoni.  He did so using my book “Tales of an Historic Adirondack Guideboat and How to Build one”.  It was gratifying to know that all my hard work climbing all over the original Queen Anne to get every possible measurement paid off.  I did get it right!

Now Dave was not to be dissuaded from backing out planks the old fashioned way.  In his email to me here is how he did it.  The first step was to make templates of the rib curvature at every 3rd rib station or so.  The second step was to mark the stations on the plank and shape the curvature from the template across the plank at each station using a sharp carving gouge.

Proper plank curvature at one station.  Template and gouge used to form the curvature are shown.

Proper plank curvature at one station. Template and gouge used to form the curvature are shown.

The next step was to connect the dots, so to speak, using an an inshave (a curved draw knife).

Using an inshave to back out a plank.

Using an inshave to back out a plank.

The inshave does the “heavy lifting” of backing out.  Dave finished the process using a plane with a curved sole, a shaped card scraper, and sandpaper wrapped around a heavy cardboard roll.

Plane with curved sole.

Plane with curved sole.

Scraper with shaped blade used in final smoothing of the backed out plank.

Scraper with shaped blade used in final smoothing of the backed out plank.

The other side of the hollowed out plank needs to have a convex curve applied to it that is parallel to the inside curve.  Dave marked the final thickness on the ends and edges of the plank and then removed the excess using a smooth or jack plane followed by sanding to the final shape.

Great work, Dave!

Next time we will see his finished guideboat during its visit to the Adirondacks.

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