Ed:
the steel scrap from washer fabrication was imbedded in polyester
Mixed and poured into the keel around the centerboard trunk.
water intrusion due to slow permeability of polyester
No. From cracks someplace: around where the bottom of the trunk is bonded to the keel (example of this repair on MSOGphotosite.com or MSOG.org ... I can't remember which), impact damage, and/or around the rotation pin if there is incorrect layup or damage.
resulting also in pinching of drop board ( is it ballasted too? Also rusts and expands?)
The M15 (and 17 post-mid-80s) board is weighted with about 45#. Those filled with steel that have damage can rust and expand and get stuck. The 17s with cast iron boards can experience rusting and the scale, resulting in a wider board, that get stuck. Servicing a cast iron board (sand blasting, sealing, fearing (optional) and applying anti-fouling paint (if boat wet stored)) is done as needed. I serviced my M17 just before selling. The steel ballast if gets wet pinches the centerboard trunk and this sticks the board. Unfair keel shape, aka the port and starboard sides, can also be seen as bulges and/or cracks with weeping rust. A boat with steel can get a sticky board from the the centerboard and/or the keel.
some (smallish) owners somehow worked from inside to remove and replace ballast, others removed keel sides, reglassed and faired.
Yes (IMO easier to make access holes on the sides of the keel than ripping apart the interior).
repairs are a labor of love, as boatyard fees would be more than the boat is worth
Excluding servicing a M17's cast iron board yes.
Do freshwater boats experience this? ( more slowly?
Yes. Speed of rusting depends on how large the cracks/damage are = volume of water entering the steel. Wet ballast is wet ballast. Folks selling any boat (Mboat or not) as 'only used on fresh water' as being better than saltwater are just 'up marketing'. I'll add that M17 named 'ol44' had ballast way way way rusted and had expanded to such an extent it burst out of the keel resulting in catastrophic delamination. The boat had been ignored for a long long long time and it showed. :: Dave Scobie :: M6'8" #650 :: SV SWALLOW - sv-swallow.com :: former owner M17 #375 SWEET PEA - m17-375.com :: former owner M15 #288 SCRED - m15namedscred.wordpress.com <<-- new site! On Mon, Jul 5, 2021, 12:41 PM Edward Epifani <edepifani@hotmail.com> wrote:
Thanks guys. So if I understand correctly 1 ) the steel scrap from washer fabrication was imbedded in polyester resin in the well of the molded keel 2) water intrusion due to slow permeability of polyester resin)resulted in expansion due to oxidation( rust takes up space) 3) resulting in fiberglass failure ( cracks perhaps?) 4) resulting also in pinching of drop board ( is it ballasted too? Also rusts and expands?) 5) some (smallish) owners somehow worked from inside to remove and replace ballast, others removed keel sides, reglassed and faired. 6) repairs are a labor of love, as boatyard fees would be more than the boat is worth
Correct? Do freshwater boats experience this? ( more slowly?) Thanks, Ed