PDA

View Full Version : keel replacement on 25' strip-planked amphibi-con



jcorlissf
10-20-2009, 05:06 PM
i'm looking for information regarding the replacement of the keel on the 25' strip-planked amphibi-con sailboat.
the keel was originally a built up keel containing mostly deadwood and a centerboard trunk (ctrboard is partiallially housed in iron ballast keel). i have removed the entire appendage in one piece and intend to simplify things by putting in a 1 1/2" plank keel with deadwood. the plank keel will be the cap for the centerboard trunk which will then be housed almost entirely in the iron ballast.

intending to laminate the keel in two 3/4" pieces under the boat i'm looking for some advice on the process. the situation at hand looks something like this. the framing on the amphibi-con is somewhat spare while the structure relies greatly upon the bulkheads for structure. there are light floors throughout the length of the the boat. the floors directly over the ballast keel are substantial and i have increased the size of some of the smaller looking floors.

the floors all seem to be pretty well rounded at the lowest point (not a good mating surface for flat keel plank). my thought is that i level a line up appx 1/8" for a flat mating surface for new keel plank. by taking the same 1/8 of bottom of each floor none of the actual rocker is lost is my sense and visually all will be satisfactory.

attaching the keel plank seems a bit of a puzzle to me. after the plank is attached i plan to walk down the boat replacing all the necessary floors and epoxying the whole business together. therefore i can.t attach the first 3/4 " keel lamination from below in order to hold the shape for the second lamination of the keel. e there is the idea of temporary floors sistered to the originals. fasten first plank from above to hold it in place. glue and screw the second lamination from below directly into the original floors.

many thanks for any thoughts.

Thad
10-21-2009, 07:51 AM
Those boats were resorcinol glued cedar strips. The bottom plank (keel) might have been mahogany and the deadwood and ballast hang on bolts through the heavy floors, with the keel being the cap for the trunk internal to the skeg/"keel" as you describe. The old iron bolts destroy that center structure. I would start by replacing floors. The hull with it's glued form is solid and you can shape the floors for the plank keel any way you can see to do it. I think using epoxy to glue in the plank keel is fine as the problems of fitting are extreme and thickened epoxy works. The only penetration of the plank keel is the pipe that carries the centerboard lanyard.

jcorlissf
10-21-2009, 03:10 PM
thank you very much for the thoughts thad.