The first goal we had after buying Mahdee in August 2006 was to determine if we could afford to get her back into shape. The first months were a roller coaster with moments of discovery that the boat was in better condition than expected, and moments where we realized things were worse than expected.
On the positive side, the previous owner had removed so much of the interior that we had easy viewing access to most of the hull. Some of the frames (ribs) looked pretty bad, but many others appeared solid. During my first days aboard Mahdee while she was still afloat, I monitored the water in the bilge and it was constant with no bilge pumping. Thus, she wasn’t taking on water. During the tow across San Diego bay, the boat hit large wakes from the spirited piloting of nearby Navy and Coast Guard boats. I had insisted that the tow company place powered bilge pumps on Mahdee (Mahdee had no engine or electrical system onboard with which to dewater). Upon arrival at the haul-out point, the bilge water was still unchanged (which I am sure convinced the tow operators that I was overly conservative).
The boat movers put Mahdee on a truck trailer and transported her to her new home in the boatyard. The hull was solid and tight which gave me further confidence that much of her structure was solid. Pulling the garboard planks (bottom planks) was difficult due to the number of bronze screws and fully intact nails. We used a hole saw to drill out around the nails (thereby destroying the planks which we expected to replace anyway).
Up to this point, all the evidence was much better than expected. We had a solid boat which didn’t leak. We though we might get her back into the water in half the time alloted. Removing the planks above the garboards was too easy. A couple hits with a hammer and a 30+ foot plank would peel off the boat bottom unassisted. The nail fasteners on these planks were rusted down to thin wires at the plank-frame interface. Under the bungs, the nail heads were often in great shape, but the rest of the fastener was gone. This made me really worry about other iron fastened boats we had been on where the owner insisted that the nail heads were in great shape, and thus the rest of the nail was too. I suspect that those boats are in much less seaworthy condition than their owners realize.
Many of the frame heels were known to be bad from our original pre-purchase assessment. We expected to scarf in new heels to frames (where they attach to the floors) that were otherwise good. Some of the floors (floor beams that tie together the frames and the keel) where also known to be bad.
Following the example of what the yard had done with previous boats, we rented a pressure washer/steam cleaner to get the gunge out of the boat. With the garboards off, the gunge could be washed right out the bottom of Mahdee. When the steam cleared, I was surprised at how little was left of the forward frames. It seemed that the painted frames’ strongest component had been the paint. We had planned to replace most of the forward frames, but now there was no question. In fact, the structural integrity of the forward section of the boat was in question. We had to install station molds to stabilize Mahdee.
The degradation of the forward frames could be attributed to the design of the forward deck bulwark stanchions (where frames extended through the deck) which allowed water to leak down and rot the frames. It could also be attributed to electrolysis from the time when that part of Mahdee housed the gas-electric generators and battery banks. It could also be due to the lack of ceiling in the forward area (which creates a chimney effect to ventilate and evaporate moisture). It could also be due to the paint which holds moisture in the frames. The degradation could also be due to the pounding physical abuse the bow takes in heavy weather, or most probably a combination of all of the above.
We decided to address all of those points. The repair design will have the frames end below the deck and have separate bulwark stanchions which don’t penetrate the deck. There will be no generators in this part of Mahdee. We will install a ceiling on unpainted frames. And, we decided to use both double sawn and laminated frames. The forward most frames are double sawn, then every other frame is laminated. Double sawn frames are known for their strength. Even the laminated mahogany frames will be much stronger than the original steam bent oak.
Frames are analogous to the studs in the wall of a house only a lot more complicated. There are very, very few right angles on a boat. The frames should be at right angles to the keel in the horizontal plane — as seen in a birds-eye view. The actual intersection angle with the keel, however, is almost never a right angle since the hull has some vee shape to it. The outside edge of the frame has to match the angle of the curved hull planks which is a constantly changing angle that can be very large near the bow of the boat. Likewise, the inside edge of the frame has to be parallel to the outside so that clamps and stringers will sit flat against the frames. The cross-sections of a frame are parallelograms with different angles at every point along the frame. Double sawn frames require these angles to be cut and planed onto solid pieces of wood. For laminated frames to lie correctly, the top and bottom laminate must be a wedge-shaped piece for all but the amidships frames. Thus making frames is not easy.
Amidships and aft, the frames were mostly unpainted and seemed solid. As work progressed on the forward section frames, we decided to take a close look at the amidships frames. All of the planks on Mahdee had been refastened so that each plank/frame intersection had at least 4 bungs covering iron/nail fasteners. First we drilled out some of the iron fasteners. They were mostly gone and for at least two fastener locations per plank, the drill would go through easily with only iron oxide coming out around the drill bit. Our plan was to leave the more solid iron fasteners in and put 3″ #18 silicon-bronze screws in the remaining 2-3 fastener points.
We could get the new bronze screws to be tight, but that required virtually no drilling — the screw was able to self tap in the frame. The yard shipwright thought that the screws were tight enough to hold about 5 years. Then the frame would be shot and need replacement. We didn’t plan on spending the time and effort to redo Mahdee and her interior just to have to rip it out in 5 years for reframing. To test his opinion, I cut a section of one of the nicest frames and took cross-sections. The blackening of the wood and puddy-like substance on the new screws I took back out showed significant degradation of the wood. I now have to agree that the strength of those nice looking frames is only a fraction of what they were when new.
In our original assessment of the boat, we decided that the rebuilding would be within budget even if we had to replace all of the frames. We knew there would never be an easier time to do it (interior removed). So, we might as well plan on re-framing the entire boat and sleep easier. In retrospect, the reason Mahdee seemed to be in so much better shape than she actually was, was because she was originally so over-built. The frames are over 2.75″ square on 12″ centers. Most of the heels are embedded in pockets in the keel. To relieve stress on the garboard planks, Mahdee has 11 intermediate frames which span bilge stringer to bilge stringer and bolt to the other side of the floors from the regular frames. The upshot is that amidships, there are areas with very little plank showing on the inside of the hull. The yard shipwright wryly noted that we could add a few more frames and then have no need for planks.
As of today, we have 24 new frames pairs installed– 10 double sawn and 14 laminated. By the New Year, we will be ready to laminate 7 more frame pairs, have one more double sawn installed and be ready to laminate 9 of 11 intermediate frames. I think we are past the halfway point in framing and for the first time since August, I feel the boat is becoming more solid.
David
