HMCo. Tolerances

[Adam]

Somewhere I saw a list of acceptable HMCo. building tolerances - IE - board length, thickness, etc...Where might I have seen this and can someone point the way?

[Steve]

Sounds like the Herreshoff scantlings, published as "Herreshoff's Rules For Wooden Yachts".  Try Skene's.

[Adam]

Yep thats the one....thank you, sir...

[Erick Singleman]

Funny you mention this.  As I rebuild my 12 1/2, I am not very impressed with the accuracy of build construction by HMC.  I will confirm some of my suspicion when I view the original plans this Friday but here are a few examples:

The frame spacing is supposed to be 7 1/2 inches.  Most of them are 7 1/2, but some distances are 7 1/4, 7 3/4, and two of them are 8.0.  Yes these frames have been replaced, sistered, etc, but I am taking the measurements based on the holes in the keel plank for the floor timbers.  Since the keel plank has never been replaced I can figure out where th eoriginal frames were.

Additionally, I have two keel bolts going through the dead wood that are not drilled straight to the center of the keel plank, but are an inch and a half from the centerline. Holes drilled in the floor timers are not always centered either, the port side hole may be forward a bit while the starboard one is aft a little bit (not sure if this was on purpose, but it is not consistent, some FTs have al the holes on the centerline.

[Adam]

Erick - you actually touched on why I wanted it as well... I'm trying to recognize certain building methods that are "Herreshoff" so I can actually identify one built by HMCo. – Also the fact that I have read much in the changes over time of building (esp. the 12 1/2), that I was curious as to the amount of leeway there is in the 12 ½.

Of course my real plan is to convince Adam L. to spend his time using the NGH machine on the original Model….

[Steve]

This is turning into an interesting thread.  After 1936, HMCo made a few changes to the 12 they called "improvements", not to be confused with the "Improved Model" with a flush after-deck.  Among the changes were a one-piece mast partner and plywood rather than laid cedar bulkheads and decks.  I am convinced that these changes were made due to expense pressures, as the Company was suffering financially by that time.  It is not a stretch to believe they used other cost-cutting measures that may have impacted the quality of the product.  George Zachorne, Jr. has done a lot of work on 12's, including some of the last ones built.  He observed that the build quality of the last ones was often sub-standard, noting that in some cases it looked like they used whatever scraps of lumber were left in the stacks.

Erick's boat is one of the later ones, so this restoration project may very well leave the boat in better shape than when it left the factory.

I would also suggest that staggered screw holes don't necessarily indicate sloppy construction.  When I was taking boat-building classes, my instructor was highly skilled and beyond meticulous.  He had us purposely stagger screws and rivets in many situations so as to mitigate the risk of splitting.  I'm not sure if this could be the case here.

-Steve

[Erick Singleman]

Thanks for your insight Steve.  BTW, do you know what the perceived benefit of the single piece mast partner is?  My boat does indeed have the single piece version, however my though is that the two piece would make it easier to step the mast, and might be the more desired one to have.  Not that I would change mine, I am trying to keep my boat as original as possible in it's configuration.  Although I am going to put bronze drifts in the transom, not steel like the ones that totally corroded in mine.
 

[Steve]

I think the advantage of the one-piece mast partner was that is was less expensive to manufacture.  The original configuration makes stepping / unstepping the mast easier.