Now that Mahdee has been launched and is still afloat, I have a little more authority–ignoring the time factor–on what makes for a good boat hull. I still believe, counter to intuition, that holes make the hulls good. I have posted an occasional description of some the holes that make up the Mahdee. While the memory is still sort of fresh, and before it is completely befuddled by the rigors of voyaging on Mahdee, I have compiled a “Hole of Fame” to document the extremes and notables among the seemingly non-ending string of holes.
–Longest: The seven foot long 7/8 inch diameter hole that opened up the wire chase at the top of the mast. Challenge: Keeping the drill centered in the mast and not losing the bit at any of the extension joints. Unfortunately Milwaukee doesn’t make anymore the 7/16 inch hex extensions needed for a deep of hole of this diameter. I drilled the last 18 inches with an Irwin extension that didn’t hold as well; it was really stressful.
–Largest diameter: 6 1/4 inch diameter holes for the portals that go through the 7 inch thickness of planking and oak blocking along the hull. Challenge: Holding the drill while standing on the scaffold and bracing so that when the bit jammed, I wasn’t tossed by the recoil.
–Toughest hole: the 2 1/4 inch counterbore in the lead keel for the keelbolt nut that also included drilling through a rod of old keel bolt that couldn’t be removed. Challenge: drilling these counterbores in lead required that the bit never stopped from the moment the drilling started to the the point where the drill was clear of the lead. The heat of drilling would soften the lead and if the bit stopped in the lead, the lead would re-solidify and the bit would become part of the cast leak keel. This one hole, however, had the additional challenge of an embedded rod of bronze at one side of the hole. It took two of us to hold the drill and as the auger blades hit the harder bronze, the drill would kick hard and we needed to be holding on really tight. Just as we got the hole to the minimum depth needed, the gear box in the drill disintegrated. Fortunately, the drill was less than a week old and Milwaukee repaired it under warrantee–but the technicians did admonish me to take it easier on my drill.
–Most tedious holes: The 300 3/8 inch diameter holes for the bolts attaching the frames to the floors. Challenge: Very tight clearances. I started with a Milwaukee close quarters drill, but it was threatening to melt down so I switched to an air-drill. These holes usually required 3-4 drill bits of different lengths. Each bit would add about two inches in depth, the drill was disconnected from the bit, a vice grips was used to twist the last bit out of the hole. The next larger bit was pounded into the hole to make clearance for the drill to be fit in and on the bit and the chuck was tightened–two more inches were drilled, etc. Then, a counter bore bit was used to make the entry and exit points perpendicular to the hole direction so that the bolt head and nut would sit flat against the wood. Repeat 299 more times.
–Most screw holes: The holes for the 10,000 (yes, ten thousand) planking screws. Challenge: Four different diameters needed (tip, threads, shank, counterbore…thank goodness for Fuller bits), then the 10,000 bungs that needed to be drilled out to fill the counterbore at the top of each screw. This probably would qualify as most tedious, except that we hired someone to make and set bungs. Actually 2 or 3 “someones” as they kept quitting.
–Most bolt holes: 3/8 inch diameter. Lots and lots of these. I have broken more 3/8 inch diameter bits that most people own in total drill bits. Challenge: Not breaking them by doing something stupid–i.e. don’t stand on an electrical or air hose while standing on a plank and pushing on the drill. Those cords roll and can take your feet right out from under you. It took me a couple of broken bits to figure that one out. Many more were broken by nicking something metal inside the wood (e.g. an old steel fastener).
–Most Critical: The approx. 3″ diameter 32 inch long stern/prop tube hole. Challenge: this one had to be spot on, because a small angular error would have huge consequences on the engine placement. The cutlass bearing near the propeller had zero play and the stuffing box, 3 feet further forward had a babbitt bearing which made the propeller shaft a rigid object that continued on through the transmission and engine (connected to the prop shaft with less than 4/1000 inch error) to a point 10 feet further forward. Lots of stress while drilling this hole. A close second was the rudder shaft hole through the countertimber which really needed to be aligned with the gudgeon bearing at the base of the keel over 6 feet away. The rudder shaft, however, just had a bearing at the top of the rudder tube, so it was a tad easier.
–Most challenging: The 4 foot long 3/4 inch diameter holes that hold the tailfeather to the keel. Challenge: With the 1000 lb tailfeather timber in place, the existing holes from under the keel needed to be drilled up and through the tail feather. There was about 12 inches between the bottom of the keel and the asphalt underneath. The drill head took up 6 inches. Sort of like drilling for oil, the bit was inserted into the hole and drilled up a few inches, then the next extension was attached and the drill went further up. The Irwin Speedbore bits, however, had barely a single turn of flutes, so after each turn of two of the bit, the bit had to be extracted so the chips wouldn’t jam the bit. The first 3 feet was really just clearing the hole of old lead putty and stuff. Then it was solid purple heart. An inch forward, max, and then retract the whole assemble of extensions to clear the chips and then back in. A couple moments of impatience lead to exploded couplings and hours of trying to fish out the remaining bit pieces.
–Most logistically challenging: The holes for the 3/4 inch diameter 4 foot long deck blocking and mast partner bolts. Challenge: The deck beams needed continuous blocking from the mast partners forward to the breast hook and stem totaling 14 feet. This required figuring out which holes to drill first, where to put pockets for nuts, how to sequence the assembly so that the offset bolts held all the blocking together. And, oh yeah, make sure the blocking bolts wouldn’t cause problems when the windlass, bowsprit and other critical deck hardware that was attached months later (we saw when we bought Mahdee, the original naval pipes from the windlass cut into these bolts, so the original configuration was less than desirable).
I will probably think of some more really notable holes, but this is it for now.
