by mihor » Tue Dec 05, 2017 23:28 pm
The original profile is (at least supposed to be) 65A010.
However, the cast iron shape is slightly thicker than this profile, so at least I needed to scale the profile a bit thicker to be able to fit it on the keel. Also, this profile is very sharp on the leading edge and as such, it is not very forgiving. Something with a bit rounder leading edge is likely much better. Either just rounding the original profile or looking for some other naca profile.
This is how I measured mine:
https://www.fe83.org/gallery/view_album ... 308&page=1
As for actually applying the filler on the keel, a very good approach is to apply two guide strips on the bottom and top part of the keel and then using metal tubes to “roll” the shape on to the surface between the guide fillings. This is, liberally apply the filler between the shape guides and then on top of the filler, place a perforated release film or peel ply and then squeeze out the excess filler with the tubes. Then simply let the filler harden and afterwards pull off the peel ply cloth or film. With this method you will be very close to the final shape after the first round of filling.
It is important to use a release film with holes in it (perforated release film) or use peel ply cloth to let the trapped air to escape while rolling the shape onto the keel, otherwise there will be a lot of tiny air pockets in the filling ,which after sanding will become pinholes that need additional filling. The method is described here (chapter 8.3):
http://www.westsysteminternational.com/ ... enance.pdf
I am not sure if glassing over the entire keel is necessary. Being an iron keel, it will at some point, start to rust again, regardless of what is on top of the surface. At that time, it might be easier to sand through an epoxy filler rather than a glass layer.
The original profile is (at least supposed to be) 65A010.
However, the cast iron shape is slightly thicker than this profile, so at least I needed to scale the profile a bit thicker to be able to fit it on the keel. Also, this profile is very sharp on the leading edge and as such, it is not very forgiving. Something with a bit rounder leading edge is likely much better. Either just rounding the original profile or looking for some other naca profile.
This is how I measured mine: https://www.fe83.org/gallery/view_album.php?set_albumName=album308&page=1
As for actually applying the filler on the keel, a very good approach is to apply two guide strips on the bottom and top part of the keel and then using metal tubes to “roll” the shape on to the surface between the guide fillings. This is, liberally apply the filler between the shape guides and then on top of the filler, place a perforated release film or peel ply and then squeeze out the excess filler with the tubes. Then simply let the filler harden and afterwards pull off the peel ply cloth or film. With this method you will be very close to the final shape after the first round of filling.
It is important to use a release film with holes in it (perforated release film) or use peel ply cloth to let the trapped air to escape while rolling the shape onto the keel, otherwise there will be a lot of tiny air pockets in the filling ,which after sanding will become pinholes that need additional filling. The method is described here (chapter 8.3): http://www.westsysteminternational.com/images/Fibreglass_boat_repair__maintenance.pdf
I am not sure if glassing over the entire keel is necessary. Being an iron keel, it will at some point, start to rust again, regardless of what is on top of the surface. At that time, it might be easier to sand through an epoxy filler rather than a glass layer.