Lofting- Applying the lessons of past Septembers.

Properly lofting the hull of any boat requires a level boat and a reference line- usually the centerline of the boat expressed a short distance from the keel. The reference line is a challenge in an upright boat because the keel blocking often obstructs the ability to express a true centerline.  I learned first hand from my classmates at IYRS last September that the alternative isn't so great. I sidesteped this challenge by making sure the blocking wouldn't interfere with a true center line.

The blocking allows me to tunnel a center line reference under the keel.

Leveling the boat requires a reference line- usually the water line. Two Septembers ago and then again in January I discovered that if the waterline is incomplete or doesn't represent the builder's original line you can have a boat that doesn't sit quite right. So in the case of a restoration it's useful to have that reference line correspond to those found on the construction drawings. For Marlin this presents two problems.

First was that the fire and previous restoration had obliterated a continuous set of scribed waterline marks. The garboards had previously been replaced and the transom refinished so start and end point were impossible determine with any certainty.

Compounding this problem is that the Herreshoff's drawings rely on a construction baseline that has no relation to the actual waterline (it's canted by 5-10 degrees).  This quirk is shared amongst the 12 1/2 family (12 1/2, Alerion, Fish, Marlin, 20 1/2 and Buzzards Bay c.f. Wooden Boat 218) and can lead to confusion when you have construction drawings (Herreshoff's and Mystic Seaport's) that key off of either line- as it did for my team's work on a 12 1/2 replica last year. 

The incomplete waterline data and a desire to level the boat to the construction drawings led me to seek some other visual clue that could establish a proper fore-and-aft level.  Examination of the floors at stations 11 and 14 revealed them to be the same height above baseline. This was true for the original drawing (presumably lifted directly from the Fish Class drawing, Hull #788) and two revised and expanded drawings that date from Marlin's construction.

The Construction Drawing. The water lines are the solid and dashed lines canted at about 5 degrees.  This drawing is not properly dated ("4/1937" penciled with with intials that suggest Bezonton as draftsman) and notes that the 788 Fish class molds are to be used (there was no offset book for the Fish, just a set of notations by NGH on the back of a 12 1/2 model). Addtionally the drawing doesn't indicate whether ASDH or NGH initiated the changes.

Engine and interior space drawing. Note the different construction details for the cabin sole- that's is what first clued me in. This drawing is dated 9/2/38. The date is interesting: it postdates the building of hulls 1420-22 (Marlin is believed to be 1421) furthermore it indicates that the Marlin class was a 'front burner' project when the Great Hurricane struck a week later.  The draftsman was Bezonton and, based on date, it doesn't reflect any input from the recently deceased NGH.

An inspection of floors 11 and 14 suggest they are not replacements from the aborted restoration and their heights correspond to the 1937 construction drawing specs. So I'm pretty confident that I can use them to establish fore and aft level.  I'll only know for certain when I get a chance to loft the long lines.

The faint scorch marks suggest original fabric

For the port and starboard level I've decided to use a camber mold set at station 13 as there aren't scribed waterlines on both sides of the boat amidships. The sheerstrakes are orginal and a subseqent check of scribed waterlines elsewhere on the boat had discrepancies of less than 1/16 of a inch, a fact that raises the confidence of my decision.

Now it was time to start taking lines and getting down to the brass tacks of actual lofting.