Strategies of Frame Repair
surveyor to go over the boat with you. Hard spots and open seams at the turn of the bilge on the outside of the hull are a sure sign of frame problems on the inside. Check the way the boat is supported. If the poppets are pushing up into the hull, there may be problems behind them. Find out what the fastenings are (nails, screws, or rivets), what material, what size (if screws), and whether they can still be withdrawn. Look for evidence of refastening. This information will help you decide what to do and may also give clues as to why the frames broke.

Go over the inside with a fine-tooth comb. If there’s a lot of joinerwork or ceilings remove all that you can and use every means available to inspect every possible inch of every possible frame. Use mirrors, flashlights, and fiber optics, whatever. The more you see now, the fewer surprises you’ll have later. Look especially for unfair spots on the inside of the planking. Hard spots may have been faired off on the outside, but they can’t be hidden on the inside. Open seams or unfairness’s on the inside usually indicate broken frames. Cracked frames may be hard to see in bad lighting, or where they are covered up by paint. Look for cracks along the side of the frame right where it contacts the plank. These cracks are almost always in line with the fastenings, which are, of course, near the edges of the planks (edges of the outer planking in double-planked hulls).

Check the heels of the frames for cracks, splits, and decay. Look at the floor-to-frame fastenings, and, while you’re looking, check the floor timbers themselves for splits (usually at the floor-to-frame bolts), decay, or crushed wood under the keel bolt nuts. Floor timbers should be considered a part of the frames a link in the chain, so to speak. It doesn’t make sense to put the frames in tiptop condition without having the floors in equally good shape.

Next, take a careful look under the bilge stringer for cracked frames; check the frame heads for decay as well as any place where the frame touches metal, such as chain plates or diagonal strapping. Check under the sheer clamp aft (where the bend is usually severe) for cracked frames.

Are there sister frames? If so, are they doing their job or are they too short or have they broken like the originals? Measure the size of the fastenings (if you are able to extract any) and compare them to the frame scantlings. Look to see how they were staggered and how close to the edge of the frames they came in places where the frames have broken. Check the radius of curvature of the concave face of broken or cracked frames, compare this to the molded dimension of the frames, and evaluate the severity of the bend. Measure the dimensions, length, and taper of the frames to get an idea of what materials you’ll need. Think about what joinerwork will have to be removed for access.

Keep going with this inspection and examine the rest of the boat in the same way. Look at the backbone: keel, horn timber, stem, deadwood, and transom; then at the planking; and finally at the deck. When you have digested all this information (you wrote all of it down, didn’t you?), decide what to do about the boat’s frame problems.
It doesn’t make sense to put one part of the boat in better condition than you plan to put the rest of the boat in, and it’s really foolish to cover over problem areas with new work. Don’t bother working on frames and floor timbers if the keel or horn timber is rotten; don’t waste time putting on a lot of new planks if the frames behind them are bad; and certainly don’t put a new deck on a boat if everything from the deck down isn’t in good shape. Thus, the logical sequence of repairs, whether you’re doing the work all at once or one item a year, is keel and backbone first, then floor timbers and frames, planking next, then deck, and, finally, joinerwork.

Frame repairs fall into two broad categories: out-and-out replacement and the installation of sister frames. Replacing damaged frames with new ones, if done properly, can restore a boat to its original strength and shape without adding extra weight. Reframing also preserves or increases a boat’s resale value, although the process can be involved and expensive in terms of labor.

By contrast, sister framing placing a new frame next to an existing cracked or broken frame is a stabilization measure that keeps a boat from falling apart any further. If the boat’s shape has been lost because of frame breakage, it is unlikely that it can be restored to normal by this method of repair. Sister framing adds weight and requires the drilling of more holes in the planking, tending to weaken it. Sister frames are rarely able to carry transverse loads as well as the original frames. However, sistering is usually a lot cheaper than frame replacement and can be accomplished more quickly and with fewer disturbances to the rest of the boat.

Replacing frames in a small, open boat is often just as easy as sistering, whereas in large boats, replacement is usually a lot more costly than sistering. The number and location of frames needing repair affect this decision, too. Frames carrying high transverse loads, such as those over ballast or near engines, centerboards, or maststeps, are not good candidates for sister framing, since it’s hard to tie in sister frames to the floor timbers and deck where these loads originate. Less highly stressed frames in the ends of boats may respond better to sistering.

From the structural point of view, reframing by replacement is always the best route, but when the condition of the rest of the boat or the conditions of the owner’s finances preclude this solution, sister framing may be the reasonable strategy.

But whichever method you choose, don’t make the same mistake the last person did. If you are reasonably sure that your boat’s frame problems are due to a design or construction deficiency, install the new or sister frames in such a way that frame breakage doesn’t reoccur.