Frames – Building A Boat

Here, about half of the frames are erected.

There are 29 double-sawn frames, each a different shape. Most consist of 12 overlapping white oak futtochs held together with black locust trunnels. The futtochs for most frames are 2 1/4″ thick, giving a frame 4 1/2″ thick (the fore-and aft “sided” dimension). The inboard-to-outboard dimension (the “molded” dimension) is 4″. The middle 2 frames are larger, sided 5 1/2″ by 4″ molded.

The following slide show summarizes the one year period following keel laying in July 2012, including roughly the first half of frame construction (you might want to turn the sound off).

Each frame took almost 3 weeks to build. They were erected on the keel as they were completed, with the help of family, friends and an electric hoist. Due to space limitations, the frames were assembled on a platform built over the keel. Since the framing platform covered the keel in the middle of the boat, the middle 12 frames were assembled last and set aside until all frames were completed and the framing platform could come down.

The video below is a time-lapse over 6 weeks showing installation of the final 12 frames, as well as the keelson and step for the foremast.

Assembling the last 12 frames and keelson (Time lapse video)

Frame process description – If you really want to get into the nitty-gritty of my frame building process, this link will take you to a 10 page step-by-step description. I wrote this mostly for myself so I could remember what I did from one frame to the next. Otherwise, I recommend just looking at the pictures, which are captioned to explain a little about the process.

I should note the process described might not be appropriate for larger boats. We were able to cut the bevels on the inside and outside of the frames after assembling the rough shaped futtochs and then separating port and starboard sides, to cut each side separately. For frames larger than Lion‘s, the bevels may need to be cut on each individual futtock before assembly. This adds another level of complexity. The big, beautiful Gloucester schooners of the 19th and early 20th centuries were done that way. To learn that process, I recommend visiting Harold Burnham‘s yard in Essex, Massachusetts. He has built some larger, beautiful schooners fairly recently. You can also go for a ride on one of them! Before starting Lion, I did just that, and it was inspirational!

(NOTE: For latest work on the boat, check the Deck page.)

The photos that follow show some of the details of frame construction, which took almost 2 years.

Most photos are captioned to explain the process. Click on any photo to enlarge and scroll through the galleries:

Futtoch arrangement. It’s different near the ends of the boat where the deadwood rises up, but similar. (from “Fishing Boat Construction: 1 Building a sawn-frame fishing boat”, UN FAO Technical Paper 96 Rev. 1)

Box nails set on the Body Plan of the lofting floor

A piece of 1/4″ plywood will be placed on top and pressed into the nail heads, making a series of impressions in the plywood

Nails are then driven into each impression

A batten is then bent around the nails to duplicate the body plan shape for each frame

Cutting the patterns

One of these for each frame. Only the outer shape is pertinent. The inner shape is determined simply to preserve plywood and give enough width for pattern stiffness.

The grid lines and bevel angles are then transferred from the lofting floor onto each pattern. Photo by Jim Trish.

A platform on which to build the frames is constructed over the keel. There was no room to conveniently build the frames elsewhere.

Grid lines were drawn on the framing platform which duplicated those for the Body Plan on the lofting floor.

To position the frame pattern on the platform, the grid lines on the pattern are matched to the lines on the platform. This is then double-checked by measuring half breadths against the Table of Offsets. Photo by Tyson Trish.

The nominal frame width is 4 inches inboard to outboard, getting wider near the keel as necessary for strength. But, in addition, the rough futtochs have to be made wider to accommodate the bevel angles on the inner and outer faces. The amount of extra width is determined by the angle, and is calculated and tabulated for every half degree in this table. When drawing the inside shape of the frame on the platform, this extra amount is added to the nominal width.

After the frame shape is drawn and the futtoch joints are laid out on the platform, appropriate sized rough-sawn boards are brought in from the lumber stacks

One side of these rough-sawn boards will first be flattened on the jointer

Then they will be taken down to 2 1/4″ (for most of the frames) in the thickness planer. Photo by Jim Trish.

Defects (sapwood, knots, splits) are avoided by marking in red

Using 6 mil vapor barrier plastic sheet, a pattern for each futtoch is taken from the framing platform. The pattern is made about an inch over-sized to allow for inaccuracies and blade width. It is transferred to the board by marking through the pattern with an awl.

At this point, the rough futtochs are square-edged and about an inch over-sized in width. This extra inch is to allow for inaccuracies and blade width. It’s in addition to the extra width provided for the bevel angle.

A set of rough futtochs for one frame, along with the frame pattern

The scrap from one frame after cutting the rough futtochs. This will feed my small wood stove for about a week!

The futtochs are placed over the frame drawing on top of spacer blocks to allow room underneath for clamps, and also to prevent ruining the platform when drilling for trunnels

F-clamps hold the two layers of futtochs together, while 2×4’s are bolted and clamped down to hold the whole assembly in place over the drawing

Starting at the bottom, the futtochs are drilled and trunnels are driven. Bedding compound is applied between the futtochs. After the rough futtochs are assembled, a temporary cross brace and diagonal braces are added, the grid lines and bevel angles are transferred to the frame.

The “floor timbers” (bottom futtochs which sit on the keel) are temporarily fastened with bolts, since it will be necessary to separate the frame here for cutting the bevel angles

Then the frame must be turned over to wedge and trim the bottom ends of the trunnels. Using the frame template and half-breadths from the Table of Offsets, the “cut-to” line marking the final shape of the outside of the frame is marked on this surface, about 3/8″ in from the edge of the rough-sawn futtochs.

The temporary braces are removed (seen hanging overhead), and the two frame halves are separated for sawing bevels on both the inner and outer faces. Photo by Jim Trish.

The angles are marked on masking tape. This shows the tape on the inner face, but the outer face (the plank side) was always cut first

On the loft floor, bevel angles were measured every 6 inches. In laying out the angles for cutting, they were interpolated between the measured angles to half degree increments. Photo by Jim Trish.

Josh getting a feel for moving the band saw table angle using the improvised handle. Photo by Jim Trish.

Blade movement pushed most of the dust right into Josh’s face. Photo by Tyson Trish.

It’s a 3 person job: one to push and guide along the cut line; one to move the table angle (which required matching the changing angle marked on the frame to the angle index on the saw)…… Photo by Tyson Trish.

…..And last, but not least, one to handle the weight and hold the moving frame flat on the moving table. Photo by Tyson Trish.

I got the easiest part. Photo by Tyson Trish.

Lofting was tough on the boots. Photo by Tyson Trish.

Frame Up!!

Building the boat directly over the lofting drawing, although done out of necessity for this boat, also has advantages. (Bigger shops of old often had a separate room for lofting – the “mold loft”.) But here, since the keel was positioned precisely over the Stations on the loft floor, the frame could be accurately positioned by plumbing down to the drawing. This simplifies the process boatbuilders call “horning in”, i.e.,getting all the frames plumb, level, square to the keel and equidistant from each other.

Piedmont was a little confused by the whole deal

But Bela knew exactly what she was doing! Photo by Tyson Trish.

Second frame pretty much the same as the first. Between frames, the drawing on the platform was erased and the next frame drawn in with a new template and half-breadths.

There will not be standing headroom in Lion. The height between the cabin sole and the deckbeams will vary between 4 and 5 feet. Photo by Jim Trish

Working aft, this is the first frame which doesn’t cross over the keel due to the deadwood rising up. It will be fastened to the sides of the keel/deadwood with trunnels and a through bolt. Here, it has a temporary 2×4 keeping the bottom ends stable until it is fastened in place.

Drilling for trunnels

After pounding the trunnels into the tight fitting holes, the frames would move around a bit, in spite of the 2×4 clamps. They would have to be re-positioned over the drawing before assembling more futtochs.

This frame toward the bow has bevel angles varying up to 29 1/2 degrees. In this and the following 5 photos, you may be able to see how the upper and lower layers of futtochs are offset by varying amounts, more bevel, more offset. The amount of offset was taken from the same table shown earlier for determining the futtoch widths.

With high angles, it was difficult to keep the frame from sliding downward, putting a lot of side pressure on the blade. If the frames had been much bigger, I’m not sure we could have handled them.

Ian has the most difficult job, holding most of the weight, responding to my sometimes frantic attempts to keep the saw on the line, all while making sure the frame sits flat on the moving table. The futtoch offsets are very obvious on the uncut side.

We measured angles in several spots on all frames after cutting the bevel. They were almost always within one degree, usually within 1/2 degree.

This great team cut most of the frame bevels. In fact, Josh adjusted the table angle for all the frames!

After the inner and outer bevels are cut, the frame is positioned directly on the drawing on the platform to: check the shape; transfer grid marks; and mark the cut lines for the fit against the keel/deadwood

Roller supports were used to help in cutting the fit against the keel/deadwood on the big bandsaw.

The inner faces of all frames receive the same bevel angle as the outer face, since this boat will also have planking on the inside. Inner planking is called “ceiling” on a boat. Lion’s will be 1 inch thick.

A good shot of the bevel angles.

Loose fitting dowels (under-sized trunnels) were used to align the frame halves while reassembling. Photo by Jim Trish.

The frames near the bow and stern get a “strongback” which ties the two frame halves together and to the deadwood

Another view of the strongbacks near the stern

The strongback can”t be added until after the frame bevels and keel joint are cut. To keep the bottom ends stable while turning and moving the frame, a temporary brace is used

After all cuts and reassembly are complete, a notch is cut through one futtoch…

Then the strongback is fitted, fastened and ends trimmed to match the outer bevel

Ready to go up

A view of the strongbacks in the aft end

Drift bolts ready to drive through the strongbacks into the deadwood

Celebrating the progress one year after keel laying

I think Weston has already gone fishin’

Assembling the aft-most frame

Aft-most frame going up

#1 Frame in the bow being assembled – only 3 futtochs per side vs 6 for the larger frames

Plumb bobs are hung to the floor to check frame position

Frame #1 gets no strongback. It’s just trunneled and through bolted to the stem

This frame and the next one forward get strongbacks which pass over the keelson. Since the keelson can’t be put in at this point, the strongback was fitted over a temporary piece with the same cross section as the keelson