After much questioning and hand wringing over the past couple of months, it all came together. Thanks to all that fielded my questions! Below is what I did to salvage a rusted out keel, preserved for posterity. Hopefully you won't have to do this... but as these boats age, you'll probably eventually get there.
The procedure was to cut out the area of metal around the rotted-out keel pivot hole, hand-file it nice and tidy, then drill and tap it to install a replacement block. I kept things as close as possible on the galvanic scale without actually using iron bolts and blocks. The replacement block is 1.5" wide, fitting with a bit of room to spare in the keel trunk, while also being more snug than the original. This will help later as I try to eliminate THUNK THUNK noises.
I basically had to build a bunch of stuff to handle the keel. Dimensional lumber built a gantry, a cradle, and a keel-dolly. A $30 one-ton winch and cheap scissor jack from harbor freight provided the lifting power.
-Firstly, the replacement block was drilled out and had all edges rounded off. No sharp corners in the keel trunk.
-Once the keel was in the garage, it was hoisted up to the calculated height needed to fit under the drill press.
-The pre drilled block was clamped in place and an outline was traced.
-An angle grinder with cutoff wheel did the plunge cuts, and a reciprocating saw WITH BLADE SPECIFICALLY FOR IRON finished the cuts. Do not use blades for steel, you'll burn them up.
-Stock was left by the saws for me to hand file and fine-tune to fit the block snugly and squarely.
-It was easier to move the drill press to the keel, much much lighter. 4 pilot holes were drilled then hand tapped.
* Curveball! A bad inclusion was found under one hole, and I needed to load an endmill up to "spot face" down to good metal. Otherwise you'd risk the drill bit wandering and/or breaking.
A drill press is extremely important with this job. You could theoretically hand drill through the steel and into the iron at the same time to maintain concentricity, but I would probably break a lot of drills.
Hardware is grade 9 flange bolts, 3/8-16 with 1 full inch of thread interface with the iron. I tapped holes into the peice of iron that was cut out and performed thread yield testing, the grade 5 bolts snapped before the iron yielded. This honestly surprised me, but hey, that's why I have a full inch of tapped depth.
A single bolt can support twice the needed load, so I went with extra safety factor and spread the load over 4 bolts.
Finally assembly will come after a generous coating of POR-15, then the whole thing will get painted... bright "save-my-a$$" orange.
The procedure was to cut out the area of metal around the rotted-out keel pivot hole, hand-file it nice and tidy, then drill and tap it to install a replacement block. I kept things as close as possible on the galvanic scale without actually using iron bolts and blocks. The replacement block is 1.5" wide, fitting with a bit of room to spare in the keel trunk, while also being more snug than the original. This will help later as I try to eliminate THUNK THUNK noises.
I basically had to build a bunch of stuff to handle the keel. Dimensional lumber built a gantry, a cradle, and a keel-dolly. A $30 one-ton winch and cheap scissor jack from harbor freight provided the lifting power.
-Firstly, the replacement block was drilled out and had all edges rounded off. No sharp corners in the keel trunk.
-Once the keel was in the garage, it was hoisted up to the calculated height needed to fit under the drill press.
-The pre drilled block was clamped in place and an outline was traced.
-An angle grinder with cutoff wheel did the plunge cuts, and a reciprocating saw WITH BLADE SPECIFICALLY FOR IRON finished the cuts. Do not use blades for steel, you'll burn them up.
-Stock was left by the saws for me to hand file and fine-tune to fit the block snugly and squarely.
-It was easier to move the drill press to the keel, much much lighter. 4 pilot holes were drilled then hand tapped.
* Curveball! A bad inclusion was found under one hole, and I needed to load an endmill up to "spot face" down to good metal. Otherwise you'd risk the drill bit wandering and/or breaking.
A drill press is extremely important with this job. You could theoretically hand drill through the steel and into the iron at the same time to maintain concentricity, but I would probably break a lot of drills.
Hardware is grade 9 flange bolts, 3/8-16 with 1 full inch of thread interface with the iron. I tapped holes into the peice of iron that was cut out and performed thread yield testing, the grade 5 bolts snapped before the iron yielded. This honestly surprised me, but hey, that's why I have a full inch of tapped depth.
A single bolt can support twice the needed load, so I went with extra safety factor and spread the load over 4 bolts.
Finally assembly will come after a generous coating of POR-15, then the whole thing will get painted... bright "save-my-a$$" orange.
