I plan to screw a piece of plasteak to act as a drip edge above the port lights on my 1976 Oday 27. It will be a piece about 7/8" square and 9feet long. I plan to bed the screws in boat life. How is the coach roof made? Is it cored or solid fiberglass? Any suggestions?
- Status
O'Day decks were cored
the topsides were cored with end grain balsa. The proper way to do this would be drill the holes 3-4 sixes larger than needed, fill with epoxy. When cured, re-drill to correct screw size. You can use Boat Life or 3m marine silicone (that's what is used on to bed new gear on New boats....) Where in Kingston do you keep your boat??? There are a number of O'Days south of you in Chelsea. (CYC)
the topsides were cored with end grain balsa. The proper way to do this would be drill the holes 3-4 sixes larger than needed, fill with epoxy. When cured, re-drill to correct screw size. You can use Boat Life or 3m marine silicone (that's what is used on to bed new gear on New boats....) Where in Kingston do you keep your boat??? There are a number of O'Days south of you in Chelsea. (CYC)
Doesn't make much difference
Most coach roofs are cored to save weight and provide solid anchor points for grab rails, mast steps, etc. It doesn't make much difference for this type of low stress, new installation. You are going to drill new holes anyway, and bolt the material to the hull. A couple of things: you will want to cut holes in the interior liner pan so you can access the underside of the coach roof exterior. Buy the biggest pre-made plastic plugs you can find to cover them up when you are done. The bigger the hole, the easier it will be to fasten the nuts and to access the nuts for future maintenance. You could just drill your holes all the way through the interior liner from the outside coach roof, but that will leave you with exposed bolts in the cabin, as well as a nice pathway for rainwater to drip into the space between the liner pan and the hull. The only other thing you might want to do if the coach roof is cored in the area where the lip is being mounted is to remove the core around the new holes. Drill your holes and determine if you have drilled through solid plastic or if there is core material. If cored, overdrill the hole siginificantly larger than the size of your mounting screws. Fill the new large holes with epoxy (you will need to have access to the back of the holes to do this; see above) and let dry. Now, redrill the holes the correct, smaller size. If (actually, when) you get water intrusion, there will be no contact between the water and any core material, only the plastic.
Most coach roofs are cored to save weight and provide solid anchor points for grab rails, mast steps, etc. It doesn't make much difference for this type of low stress, new installation. You are going to drill new holes anyway, and bolt the material to the hull. A couple of things: you will want to cut holes in the interior liner pan so you can access the underside of the coach roof exterior. Buy the biggest pre-made plastic plugs you can find to cover them up when you are done. The bigger the hole, the easier it will be to fasten the nuts and to access the nuts for future maintenance. You could just drill your holes all the way through the interior liner from the outside coach roof, but that will leave you with exposed bolts in the cabin, as well as a nice pathway for rainwater to drip into the space between the liner pan and the hull. The only other thing you might want to do if the coach roof is cored in the area where the lip is being mounted is to remove the core around the new holes. Drill your holes and determine if you have drilled through solid plastic or if there is core material. If cored, overdrill the hole siginificantly larger than the size of your mounting screws. Fill the new large holes with epoxy (you will need to have access to the back of the holes to do this; see above) and let dry. Now, redrill the holes the correct, smaller size. If (actually, when) you get water intrusion, there will be no contact between the water and any core material, only the plastic.
Coach roof construction
My '78 O27 has a 3/8" balsa core & a total thickness of 3/4", plus an additional 3/16" for the cabin liner. Under the mast step where there is a high point loading, there is a pad of solid wood or plywood in place of the balsa. It's abt. 3/4" thick x 8" x 12". I suspect the cabin sides are solid glass as there would be less benefit from having a core at that point. The primary benefit of the balsa core is to increase stiffness while keeping weight down. It is very suceptable to rot wherever a hole is drilled for a fastening or cable etc and any such hole should be drilled oversixe & filled with thickened epoxy as mike c suggested in his post. This technique is called "potting" and it is described in detail in some of the West System manuals. Unfortunately the O'Days' were low cost production boats and the budget didn't allow for this, so anywhere hardware is fastened to or thru the deck or coachroof is a potential spot for water to get into the core & cause rot. That's why the decks get spongy around the chainplates.
My '78 O27 has a 3/8" balsa core & a total thickness of 3/4", plus an additional 3/16" for the cabin liner. Under the mast step where there is a high point loading, there is a pad of solid wood or plywood in place of the balsa. It's abt. 3/4" thick x 8" x 12". I suspect the cabin sides are solid glass as there would be less benefit from having a core at that point. The primary benefit of the balsa core is to increase stiffness while keeping weight down. It is very suceptable to rot wherever a hole is drilled for a fastening or cable etc and any such hole should be drilled oversixe & filled with thickened epoxy as mike c suggested in his post. This technique is called "potting" and it is described in detail in some of the West System manuals. Unfortunately the O'Days' were low cost production boats and the budget didn't allow for this, so anywhere hardware is fastened to or thru the deck or coachroof is a potential spot for water to get into the core & cause rot. That's why the decks get spongy around the chainplates.
- Status