Resealing Windows

[ccriders]

I have a 1976 Pearson 28 which has windows that seem to be ubiquitous for boats like it (catalina, o'day, pearson, etc). Infact I purchased a reseal kit from Catalina Direct that contained new rubber gaskets and sealants for these windows. The windows are made from an aluminum extrusion that consists of a flange that fits against the outside of the cabin top and three channels one for the glass, one for a trim piece, and one for attaching screws. This is a one piece extrusion that would look somewhat like "luu". On the inside there is another extrusion that clamps the window unit to the hull and hull liner. As recomemded by the Pearson 28 Yahoo group, I filled the space between the cabin sides and the hull liner to make a stiffer clamping surface. My question is about the sealants provided. One is Dow Corning 795 Silicone Building sealant which is directed to be used between the inside surface of the glass and the rubber gasket and then between the inside surface of the rubber gasket and the aluminum channel. The second sealant is 3M 4200 quickset which is directed to be used between the aluminum flange and the outside of the cabin sides.

What I find curious is the placement of the 795 on the inside surfaces of the glass and its rubber gasket. It seems to me that if the rubber gasket alone is insufficient to stop water intrusion this arrangement guaratees that water will be trapped in the glass chanel with no way to exit and given it will be salt water, this could cause serious problems. Am I wrong on this?

Also, based on discussions here about butyl tape for sealing deck hardware, it seems that butyl tape might be better than 4200. This might be expecially true here since there is only about 3/8 inch overlap between the cabin side and the window flange. Which would you use?

Thanks for your help,
John

[pdqaltair]

Originally Posted by ccriders

I have a 1976 Pearson 28 which has windows that seem to be ubiquitous for boats like it (catalina, o'day, pearson, etc). Infact I purchased a reseal kit from Catalina Direct that contained new rubber gaskets and sealants for these windows. The windows are made from an aluminum extrusion that consists of a flange that fits against the outside of the cabin top and three channels one for the glass, one for a trim piece, and one for attaching screws. This is a one piece extrusion that would look somewhat like "luu". On the inside there is another extrusion that clamps the window unit to the hull and hull liner. As recomemded by the Pearson 28 Yahoo group, I filled the space between the cabin sides and the hull liner to make a stiffer clamping surface. My question is about the sealants provided. One is Dow Corning 795 Silicone Building sealant which is directed to be used between the inside surface of the glass and the rubber gasket and then between the inside surface of the rubber gasket and the aluminum channel. The second sealant is 3M 4200 quickset which is directed to be used between the aluminum flange and the outside of the cabin sides.

What I find curious is the placement of the 795 on the inside surfaces of the glass and its rubber gasket. It seems to me that if the rubber gasket alone is insufficient to stop water intrusion this arrangement guaratees that water will be trapped in the glass chanel with no way to exit and given it will be salt water, this could cause serious problems. Am I wrong on this?

Also, based on discussions here about butyl tape for sealing deck hardware, it seems that butyl tape might be better than 4200. This might be expecially true here since there is only about 3/8 inch overlap between the cabin side and the window flange. Which would you use?

Thanks for your help,
John

I won't comment on the rubber/glass part; I'm not sure I understand and I have no expereince.

Bedding the frame to the side with RV butyl is perfect. I have done this. The factory did this with my boat. Zero leaks after 13 years and very easy to pull a port when needed (dropped an anchor on one, breaking the lens). Use extra and trim with a dull knife or sharp bit of plastic.

If it is cold now, warm the FRP and frame with a hair drier so that everything flows right. They only need to stay warm for 5 minutes.

[ccriders]

Thanks PDQ. I went with the butyl tape in lieu of the 4200. Looks like it will work well. Still curious about putting 795 on the inside surfaces of the rubber gasket.
John