I have a 1995 Seapro WA. There is a panel beneath the dash/steering area that encloses the cuddy that rotted out. It's to the right of the cuddy door. The panel is made of 3/4" plywood and has some sort of laminate on the side that faces out that color matches the fiberglass of the rest of the boat. The interior side has carpeting glued on matching the rest of the cuddy. It's approximately 3' x3' and screws in. I could use the old panel as a template to cut out a new panel. I was thinking of using a treated exterior plywood but I wanted to know if there is something better to use and what I can use for the exterior? The fiberglass color is white-ish, it has a slight cream tint.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Replacing Rotted Panel
- Thread starter seachunk2
- Start date
Hiya seachunk2,
I'm pretty sure FG or some paints won't stick to pressure treated so if you were planning to FG any part of the exterior that now has, as you describe, "some sort of laminate" it won't work. I would use marine grade ply and cover all sides, edges and the inside of any hole you drill with a few coats of epoxy resin and go from there.
I'm pretty sure FG or some paints won't stick to pressure treated so if you were planning to FG any part of the exterior that now has, as you describe, "some sort of laminate" it won't work. I would use marine grade ply and cover all sides, edges and the inside of any hole you drill with a few coats of epoxy resin and go from there.
- Joined
- Jan 1, 2000
- RO Number
- 3238
- Messages
- 4,831
"I'm pretty sure FG or some paints won't stick to pressure treated"
Checking the references on the Glen-L DIY boat site, pressure treated plywood has no issues with epoxy. The biggest issue is moisture content, which applies whether or not the (ply)wood is pressure treated.
For non-hull use, regular exterior plywood should work. The only difference between "marine" and "exterior" grades is that "voids" are allowed in exterior grade, and they are not in marine grade ( allows water to run through interior cracks in interior layers ) Properly edge sealed, you should have no issues. Both grades use the same glue.
Note that there are several different types of plywood once you get away from the "exterior grade plywood" found at the big box stores. Some of these marine grades are excellent, and offer fine performance for the $$, event though they are pressure treated ( and "Lloyd's approved" )
All that said, if the hatch is in a normally protected area, and not usually heavily rinsed with water, an edge sealed piece of exterior grade should serve you well ( it is also very likely what was used OEM )
Checking the references on the Glen-L DIY boat site, pressure treated plywood has no issues with epoxy. The biggest issue is moisture content, which applies whether or not the (ply)wood is pressure treated.
For non-hull use, regular exterior plywood should work. The only difference between "marine" and "exterior" grades is that "voids" are allowed in exterior grade, and they are not in marine grade ( allows water to run through interior cracks in interior layers ) Properly edge sealed, you should have no issues. Both grades use the same glue.
Note that there are several different types of plywood once you get away from the "exterior grade plywood" found at the big box stores. Some of these marine grades are excellent, and offer fine performance for the $$, event though they are pressure treated ( and "Lloyd's approved" )
All that said, if the hatch is in a normally protected area, and not usually heavily rinsed with water, an edge sealed piece of exterior grade should serve you well ( it is also very likely what was used OEM )
Thanks for the replies. The rotten panel did have contact with water during wash down. This is a 1995 boat so it lasted 17 years. The OEM panel does look like ordinary plywood but I didn't notice that any sealing was applied at the edges or elsewhere. There appears to be a thin film laminate of the exterior side whereas the interior (the side facing into the cuddy) had carpeting material glued on. My guess was that the water was absorbed from the bottom and drawn up into the panel over the years. If there wasn't any sealant on the plywood, the bottom edge acted as a sponge every time I'd wash down the boat. Eventually the plywood panel separated as it did. If I could find an off white solid plastic panel that's at least 1/2" thick, it would last a really long time. The exterior side would match the boats gel coat color and I really don't need the carpeting on the interior wall. I just don't know where to get such a panel.
- Joined
- Jan 1, 2000
- RO Number
- 3238
- Messages
- 4,831
0.5 inch ( 12 mm ) Starboard should be available at that "marine store on every cormner", or from Piedmont Plastics ( or other plastics supplier ). You might call King Starboard to get the vender most appropriate for you.
Note that Starboard, which might bve available in a good color for this project, is HDPE, ans as such has a few characteristics you should know about. In spite of this it is often being used in what I might call a structural usage, the material is not designed for structural usage. It also has a very high coefficient of thermal expansion, which means that a) it expands and contracts at a rate different from fiberglass, and b) if the sun shines on it unevenly, it can warp ( at least, temporarily ). But it might be a good product for this. Note that it is virtually impossible to glue anything to it, or paint it. Graphite ( ie: pencil marks ) are essentially permanent.
---
I would use exterior plywood, "paint" it with an undercoat of epoxy, sealing the panel as well as edges, then paint and/or carpet as desired. Mount it or re-design it so that it does not stand in water. Done as I describe, it will be fine. It will be "casually waterproof" and not suffer from the periodic washdown, as long as it does dry out after a few hours, and is normally dry. My design will not last long term, standing in water continuously...
---
The panel you describe is almost certainly plywood ( maybe exterior, maybe not ) with one side coated in Melamine. This is a moderately common practice. It is fine as long as immersions are brief, and the panel is normally dry. It will fail ( as occurred ) when the panel does not dry out after these brief immersions.
Most of the plywood in boats ( at least those of recent manufacture ) use "interior grade" or equivalent for anything above the waterline, or not constantly in water contact. It saves weight, and $$$. Personally, I do not care for the practice, but as far as I can tell, the practice is nearly universal in all but "premium" grade boats ( and even then such materials are used in "dry spaces".
My preference is for all materials and structures on a boat to be at least "water resistant/tolerant". But that does cost more and usually also weighs more.
Note that Starboard, which might bve available in a good color for this project, is HDPE, ans as such has a few characteristics you should know about. In spite of this it is often being used in what I might call a structural usage, the material is not designed for structural usage. It also has a very high coefficient of thermal expansion, which means that a) it expands and contracts at a rate different from fiberglass, and b) if the sun shines on it unevenly, it can warp ( at least, temporarily ). But it might be a good product for this. Note that it is virtually impossible to glue anything to it, or paint it. Graphite ( ie: pencil marks ) are essentially permanent.
---
I would use exterior plywood, "paint" it with an undercoat of epoxy, sealing the panel as well as edges, then paint and/or carpet as desired. Mount it or re-design it so that it does not stand in water. Done as I describe, it will be fine. It will be "casually waterproof" and not suffer from the periodic washdown, as long as it does dry out after a few hours, and is normally dry. My design will not last long term, standing in water continuously...
---
The panel you describe is almost certainly plywood ( maybe exterior, maybe not ) with one side coated in Melamine. This is a moderately common practice. It is fine as long as immersions are brief, and the panel is normally dry. It will fail ( as occurred ) when the panel does not dry out after these brief immersions.
Most of the plywood in boats ( at least those of recent manufacture ) use "interior grade" or equivalent for anything above the waterline, or not constantly in water contact. It saves weight, and $$$. Personally, I do not care for the practice, but as far as I can tell, the practice is nearly universal in all but "premium" grade boats ( and even then such materials are used in "dry spaces".
My preference is for all materials and structures on a boat to be at least "water resistant/tolerant". But that does cost more and usually also weighs more.
quote:
Originally posted by jtybt15
Just curious, 3/4" ply is structural thickness but I wouldn't use screws on any structural member.
...and you really don't need marine grade ply on anything not in contact with water.
The builder used screws. Why would you not? Apparently it is a good thing that he did or the replacement would be more difficult.
This panel is obviously in contact with water or it would not have rotted in the first place.
George
Thanks again. The panel is covered in a melamine type material. I was surprised to read in Radioactive's post that this material is commonly used. I would think that it's just too fragile for use on a boat. The panel is washed down whenever I rinse down the boat but what I think doomed it was the 3" trim that's screwed on as a base trim on the bottom. Water has probably been getting behind the trim and over the years enough water was absorbed by the (probably) unsealed plywood that it eventually swelled up and delaminated itself. However, since it provided 17 years of use I guess I'll put another one up with some improvements (i.e. seal the edges) and I'll probably get another 20 out of it.
George,
Re-read. I said I wouldn't use screws on ANY STRUCTUAL member.
...and continuing what Bill said. I would shy away from using starboard or any HDPE because of it excessive rate/amount of expansion. If you do use it, Overdrill the holes in the HDPE to allow for movement and don't tighten the screws too much. Otherwise,the warping can and will eventually pull the screws out.
Re-read. I said I wouldn't use screws on ANY STRUCTUAL member.
...and continuing what Bill said. I would shy away from using starboard or any HDPE because of it excessive rate/amount of expansion. If you do use it, Overdrill the holes in the HDPE to allow for movement and don't tighten the screws too much. Otherwise,the warping can and will eventually pull the screws out.