Removing Three Inches of Twist

[Bob Smalser]

http://pic3.picturetrail.com/VOL12/1104763/8408305/113106749.jpg

Fella brings me a little Merriman Pram to save that he and his late father built from a kit some time ago. The boat was never finished and sat for at least a decade upside down on uneven ground.

http://pic3.picturetrail.com/VOL12/1104763/8408305/113106757.jpg

The rot around the sheer was straightforward enough…removing the three inches of twist in the hull would be the hard part.

http://pic3.picturetrail.com/VOL12/1104763/8408305/113221962.jpg

While I thought about it, I made new laminated knees to replace the stock ones made of quarter-inch plywood, lamming them in place for speed rather than building forms:

http://pic3.picturetrail.com/VOL12/1104763/8408305/113221960.jpg

http://pic3.picturetrail.com/VOL12/1104763/8408305/113344753.jpg

http://pic3.picturetrail.com/VOL12/1104763/8408305/113344752.jpg



I also replaced the tops of the transoms…

http://pic3.picturetrail.com/VOL12/1104763/8408305/113344747.jpg

http://pic3.picturetrail.com/VOL12/1104763/8408305/113600037.jpg

Continued….

[Bob Smalser]

http://pic3.picturetrail.com/VOL12/1104763/8408305/113600129.jpg

…and scarfed in new sheer plank sections as required.


http://pic3.picturetrail.com/VOL12/1104763/8408305/113600027.jpg

I broke out the bumboard (fore-and-aft forward seat) and made standing knees for bow and stern transoms, which the boat originally lacked.

http://pic3.picturetrail.com/VOL12/1104763/8408305/113944400.jpg

Then having decided how to remove the twist, I measured the boat, both in diagonals and from keel to sheer at several places to determine if I’d have to break any of the planking joints to bring the boat into true. As it was less than a half inch off, I decided I would only have to remake the boat’s interior joints, so I broke out all the knee, seat, board trunk and support joints.

Making a strongback to hold the boat, I simply used spalls and clamps to bring the boat back into true, and remade all the joints and installed the new knees while the boat was in the clamps.

http://pic3.picturetrail.com/VOL12/1104763/8408305/114210681.jpg

I also added a framing member beneath the light (half-inch) center thwart that ran from seat riser to seat riser (longitudinal members that hold the seat up), and forward beneath the bumboard far enough to tie into the standing knees I made for additional support to the twisted bow transom. I could have made these hanging knees beneath the bumboard instead of on top, but that would have been additional work for less support, and I like the look of exposed joinery.

http://pic3.picturetrail.com/VOL12/1104763/8408305/115208293.jpg

I left the boat in the clamps for a week for the epoxy to reach full strength and the wood to achieve some “memory”. Most joints were fastened with bronze screws as well as glued, but most were done using fillets of thickened epoxy. The deteriorated plywood was sanded sufficiently with 60 grit to remove the mold, treated with Smith’s CPES penetrating epoxy sealer, and immediately hotcoated with a high-build marine epoxy primer. The thick primer allows for fairing rough surfaces prior to topcoating. Tight, interior areas that couldn’t take primer like the daggerboard trunk were treated with red lead primer.

http://pic3.picturetrail.com/VOL12/1104763/8408305/116470956.jpg

The final result is close enough to please the eye, helped by the additional camber I added to the transom profiles. The canvas bumper saved time in eliminating detailed and time-consuming treatment of the sheer…

http://pic3.picturetrail.com/VOL12/1104763/8408305/115575873.jpg

…and allowed construction of oars, rudder, daggerboard and spars within the allotted time of 60 hours.

http://pic3.picturetrail.com/VOL12/1104763/8408305/116470959.jpg

[Tom Hamilton]

Amazing. Yes, the final result is close enough to please the eye. In under 60 hours no less. Your customer must be delighted.

Your posts are wonderfully instructive. Thanks for sharing this one.

How's the new house coming? (hint, hint)

Best regards, Tom

[Vaughn McMillan]

60 hours? :eek: Do you sleep, Bob? Great job as always, and very informative narrative with the pictures. You've done this before, huh? :D Thanks for posting.

- Vaughn

[Richard Wolf]

I think you better get that watch battery checked. Seem no mortal could do all that in 60 hrs. Very nice though.

Richard

[Tyler Howell]

Just what I needed! Another lesson from BBB (Boat Builder Bob).
Think I'll try something new in the shop:D

Thanks

[Mark Singer]

Bob,
Now we are getting some woodworking! Great thread...wood has a mind of its own sometimes..

[Dan Forman]

Bob---You never cease to amaze me. I don't know a standing knee from a bumboard, but it is fascinating to watch the transition in these boats that you restore. Thanks for sharing.

Dan

[Kelly C. Hanna]

60 hours? Woulda taken me that long to figure out how to save it....:D

Beautiful work!!

[Gail O'Rourke]

Bob that is an amazing amount of work. The final result is gorgeous. Thanks for sharing the project.... you are brave to take on a project like that. Did you ever think along the way that it couldn't be done?

[John Bailey]

...and I like the look of exposed joinery.



Bob,

As always, very informative. As far as the above quote, only those that can make accurate joinery can make that statement. Having built an 8' dingy for my sailboat, I know that fitting those knees are not easy.

John

[tod evans]

nice job bob!

[Jerry Clark]

Thanks for sharing -- Bob-the Boat Builder:) !

[lou sansone]

wow... such skill... I am impressed. interesting enough bob, my nextdoor neighbor is named bob and is probably about your age. he is restoring the 1780 house next to mine with the same types of hard learned skills that you have. all I do is watch and learn and then do the same with my 1730 home, but not as good as bob next door does. thanks for sharing it.

lou

[David LaRue]

Bob,

Simply amazing! You, your customer, and his late father (looking from above)I bet they are very proud. Let's hope it gets better treatment this day forward.

[Frank Pellow]

I think you better get that watch battery checked. Seem no mortal could do all that in 60 hrs. Very nice though.

Richard
I am as amazed as Richard is. You did all that in 60 hours? Great job, as always, Bob.

[Bob Smalser]

No big deal. Simple boats. You can build one from scratch in 80 if you have patterns, and 100 if you have to loft.

What the photo sequence doesn't show is work on oars and other doodads began on Day One waiting for the glue to cure....it's just a mater of efficient management.

[Dave Richards]

Bob, thanks for posting this here. I read it and admired the work there as well.

I hope the owner of the boat has many years of enjoyment from the boat and your work. ;)

[Frank Pellow]

No big deal. Simple boats. You can build one from scratch in 80 if you have patterns, and 100 if you have to loft.

What the photo sequence doesn't show is work on oars and other doodads began on Day One waiting for the glue to cure....it's just a mater of efficient management.
Bob, first of all what does "if you have to loft" mean? It sounds like a nautical term for building by "winging it".

I guess I can believe 80 hours to build such a boat with plans. For me, at least, I think it would be easier to build the boat than to repair it the way that you have done.

[Bob Smalser]

Bob, first of all what does "if you have to loft" mean? It sounds like a nautical term for building by "winging it".



Before computers, boat lines were originally obtained with a carved wooden model of the hull then measuring it to obtain a "Table of Offsets" like the one below:

http://pic3.picturetrail.com/VOL12/1104763/2595357/96672158.jpg

The offsets are just heights from a baseline along the sequential "stations" or framing members of a hull. They are also breadths from a centerline (halfbreadths) to get the widths and diagonals.

"Lofting" is to draw the boat full size on a white-painted floor or plywood sheets to make the molds and patterns for the various parts.

Sounds tricky but it's really straightforward, and one can solve a lot of shape and dimension problems simply by extending some lines and lofting out the part to make a pattern.

From no more than that table above and the scantling sizes, the Dion Punt below was lofted and built in 80 hours:

http://pic3.picturetrail.com/VOL12/1104763/2595357/29566094.jpg

http://pic3.picturetrail.com/VOL12/1104763/2595357/29569137.jpg

[Glenn Clabo]

Moving to Boat Building Forum...