Does my 1985 Classic Angler have a balsa or plywood floor, i did a search but was unable to determine whether it was plywood or balsa or a combination of the two. If needed, i might repair a small area where there were once some screw holes and was not sure if the floor was plywood or balsa.
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CockPit floor
- Thread starter Tug
- Start date
Tug":1b5l1tbr said:Does my 1985 Classic Angler have a balsa or plywood floor, i did a search but was unable to determine whether it was plywood or balsa or a combination of the two. If needed, i might repair a small area where there were once some screw holes and was not sure if the floor was plywood or balsa.
Tug-
Someone with one of the pre-1987 (1980-1986) Classic C-Dorys will be able to tell you the exact construction, but I remember that the floor of those flat-bottomed C-Dory Classics is made up of a sheet or sheets of marine grade plywood encapsulated by fiberglass on both sides (outer and inner).
I seem to remember that the wood layer is about one inch thick.
Since it is approximately 20 feet long and plywood comes in sizes of 4' x 8' and 5' x 12', there are probably several over layered sheets of 1/2" thick sheets layered so that the joints on the top and bottom layers don't coincide.
In either case, it's all still plywood.
I've never heard if it's fir, Phillipine mahogany, pine, or whatever.
Hope this helps!
Joe. :teeth :thup
Just as a discussion point, you can probably use a variety of things for coring. I say "probably" because I don't know how large the area is or exactly where it is located. But presuming it is small and more or less in the middle of the field (that is, not at some critical junction point or etc), you could use plywood or balsa or potentially foam coring. The core isn't totally unimportant (it needs to have a good bond with the upper and lower fiberglass/epoxy, for example), but it's mostly a spacer to hold the fiberglass skins both apart (distance) and together (epoxy, etc.). Depending on the size of the holes, you could also possibly fill with thickened epoxy (in stages if larger, so as to avoid excessive heat buildup).
Whether or not you want to glass over the top depends on the size of the hole in the top skin. If it's more than 1/2" or so and you only used epoxy (or other resin), without adding a new upper skin, then you could get outline cracking later.
If you are glassing over a slightly larger area, then you want a certain amount of overlap with the existing glass. In areas where flushness doesn't matter, it can be achieved by simple overlap. In areas where a final flush-with-the-original-material surface is desired, then you grind a taper into the existing glass. Around 12:1 ratio to the thickness of the glass skin of the area you are filling. So, for example, a 12" diameter hole in a 3/8" thick (solid fiberglass) hull would have a 4-1/2" taper.
When adding back the fiberglass you will generally use more than one layer, cut concentrically. In that case, I like to use the largest layer first, then taper to the smallest piece on top, especially when building to flush final surface. That way when you sand and fair, you won't cut through the largest, "best" layer as it will be safely on the bottom, with full adhesion. To get the shape of the glass pieces established, I lay down a piece of clear plastic and mark the outline of the patch shape in sharpie on the plastic, then cut it out to use as a pattern.
That may be more than you needed/wanted to know. Anyway, you may not need to exactly match the coring, material-for-material, depending on where the repair is to be made and how large it is. If larger, then you have similar stress characteristics and etc. to think about, but I'm guessing your repair may not be that large.
Whether or not you want to glass over the top depends on the size of the hole in the top skin. If it's more than 1/2" or so and you only used epoxy (or other resin), without adding a new upper skin, then you could get outline cracking later.
If you are glassing over a slightly larger area, then you want a certain amount of overlap with the existing glass. In areas where flushness doesn't matter, it can be achieved by simple overlap. In areas where a final flush-with-the-original-material surface is desired, then you grind a taper into the existing glass. Around 12:1 ratio to the thickness of the glass skin of the area you are filling. So, for example, a 12" diameter hole in a 3/8" thick (solid fiberglass) hull would have a 4-1/2" taper.
When adding back the fiberglass you will generally use more than one layer, cut concentrically. In that case, I like to use the largest layer first, then taper to the smallest piece on top, especially when building to flush final surface. That way when you sand and fair, you won't cut through the largest, "best" layer as it will be safely on the bottom, with full adhesion. To get the shape of the glass pieces established, I lay down a piece of clear plastic and mark the outline of the patch shape in sharpie on the plastic, then cut it out to use as a pattern.
That may be more than you needed/wanted to know. Anyway, you may not need to exactly match the coring, material-for-material, depending on where the repair is to be made and how large it is. If larger, then you have similar stress characteristics and etc. to think about, but I'm guessing your repair may not be that large.
Sunbeam":1g8beosq said:Just as a discussion point, you can probably use a variety of things for coring. But presuming it is small and more or less in the middle of the field (that is, not at some critical junction point or etc), you could use plywood or balsa or potentially foam coring. The core isn't totally unimportant (it needs to have a good bond with the upper and lower fiberglass/epoxy, for example), but it's mostly a spacer to hold the fiberglass skins both apart (distance) and together (epoxy, etc.).
If you are glassing over a slightly larger area, then you want a certain amount of overlap with the existing glass. In areas where flushness doesn't matter, it can be achieved by simple overlap. In areas where a final flush-with-the-original-material surface is desired, then you grind a taper into the existing glass. Around 12:1 ratio to the thickness of the glass skin of the area you are filling. So, for example, a 12" diameter hole in a 3/8" thick (solid fiberglass) hull would have a 4-1/2" taper.
I have cut down this quote, but do want to comment on several issues. First core materials are important. If not, you could use a hollow cardboard box (which in fact was used in some of the early Taiwan boats). There is a certain amount of shear force that is extremely important in choosing the core, as well as the compression strength. Boat builders choose a specific core material for a very good and specific reason. Certainly nothing wrong with using a small repair of plywood, or solid laminate--many hulls are built that way, to take the load of a fitting, or where a thru hull hole will be bored.
The 12;1 taper applies to a repair in a hull of only laminated fiberglass, and generally to a full breach of the hull laminate. On the inside of the bottom of the C Dory, it would be advisable to do a little grinding, but nothing like the 12:1. Even doing a repair on blisters on the outside of a hull, it is very rare to do a 12:1 scared.
If I made it sound like the core was unimportant, bad me! Geez, I need to be careful about what I write. Funny thing is that typically I'm one to discourage people from using "easier/cheaper" materials, because I often find them to be inferior.
What I meant to convey that it may be possible for you to use, say, balsa coring, if you have some on hand (even though your hull core is plywood). Or foam coring (not just *any* foam, but foam coring material, such as Divinycell, etc.). I don't know what you have on hand, but sometimes it's nice to have a few options, as long as they are all good materials that will work properly. On a larger repair, or at a critical junction, you have to think (more) about creating stress risers, etc. -- more than say, on a 2" repair in the middle of the hull where you do not have the same level of concern.
And that's true on the taper ratio. I was focused on the fact that some people mistakenly think the 12:1 is for the *width* of the hole, and they end up with crazy-huge tapers, when it should be calculated on the thickness of the skin being patched (but as you say, 12:1 is likely overkill for a smaller hole, especially if it is a "machine-made" shape - then in many cases you are basically just keeping water out, not re-building the structure).
Thataway: Thanks for bringing up these points. I certainly don't want to encourage sub-standard (or ridiculous overkill) repairs.
What I meant to convey that it may be possible for you to use, say, balsa coring, if you have some on hand (even though your hull core is plywood). Or foam coring (not just *any* foam, but foam coring material, such as Divinycell, etc.). I don't know what you have on hand, but sometimes it's nice to have a few options, as long as they are all good materials that will work properly. On a larger repair, or at a critical junction, you have to think (more) about creating stress risers, etc. -- more than say, on a 2" repair in the middle of the hull where you do not have the same level of concern.
And that's true on the taper ratio. I was focused on the fact that some people mistakenly think the 12:1 is for the *width* of the hole, and they end up with crazy-huge tapers, when it should be calculated on the thickness of the skin being patched (but as you say, 12:1 is likely overkill for a smaller hole, especially if it is a "machine-made" shape - then in many cases you are basically just keeping water out, not re-building the structure).
Thataway: Thanks for bringing up these points. I certainly don't want to encourage sub-standard (or ridiculous overkill) repairs.
I went over the floor today inch by inch and found 3 probable soft spots , ( each about 3x3 inch in diameter ).one in the cabin and 2 in the cockpit. These will probably be larger after I cut back to dry material, I am reluctant to start the repair because repair materials are not easily obtained here and I don't want to be sitting here with holes in the floor and no way to fix them properly. I want to use the boat this summer. I think I can wait until the Fall to investigate and start the repairs, that way I can cut out the wet plywood and see what is to be done and what materials I will need. I will than be able to order what I need in the Fall to complete the repairs and even do them in the Spring if need be. It seems like something I can do although I imagine the hardest part will be to redo/replace the non-slip gel coat floor coating to a decent looking condition. Tug
I agree that sounds like a reasonable plan. Sounds like now you would feel rushed, whereas you'd have plenty of time in fall/winter. And once you open it up, you will no doubt find you need to order this or that (no matter how well you plan) and then you won't end up having to pay for rush shipping or etc. (like you might now) because you are losing precious summer days. You'll have time to open up, assess, think and plan, and then go to it.
Just about everything you need should be available to order, so as long as you have the time and inclination, it's okay to not be able to get things locally.
These things don't move that quickly, so what you have now shouldn't double in size or anything dramatic over the summer. You might try to to not have water sitting (between trips) in those areas, if you can avoid it.
In a perverse way, I find it can be kind of fun to cut the old/bad out, and then make it better than new (as long as you are not stressing over missing prime season).
Sunbeam
Just about everything you need should be available to order, so as long as you have the time and inclination, it's okay to not be able to get things locally.
These things don't move that quickly, so what you have now shouldn't double in size or anything dramatic over the summer. You might try to to not have water sitting (between trips) in those areas, if you can avoid it.
In a perverse way, I find it can be kind of fun to cut the old/bad out, and then make it better than new (as long as you are not stressing over missing prime season).
Sunbeam
shellndanm
New member
I had good luck with nida core. I would bet the area you need to repair is larger than you think. I have a link to the supplier I used in my photo album(Bob actually found the place for me). I used a circular saw the cut out the rotten area. A grinder was too messy and too imprecise. I would drill pilot holes to determine the extent of the rot in the immediate area of the sot spots
If I need to replace a larger section of the cockpit, does anyone know exactly what the original floors dimensions were on a 1985...like was it one inch of plywood sandwiched between 1/4 inch ?? of fiberglass cloth. I probably will not be able to determine any dimensions by taking a small piece out because I am sure everything has sunken down over time . I will probably use marine plywood , I called and there is a place locally. Tug
The glass layup will be very close to what I sent you in the PM's. There will be layers of mat and heavy roving on the bottom. The thickness of this outside or bottom glass is going to be the same as originally laid up. The plywood should also be the same dimension. The layer nearest you--or where you walk will most likely be a couple of layers of cloth and mat each-there might be one layer of roving, but I doubt it. When you make the cuts, and chisel out the old wood, you will be able to see the thickness of cloth on the top.
You will probably be replacing it with more modern materials, but cloth and mat will also work IF you go with polyester. If you use epoxy (recommended), you will probably use cloth--either bi-axial or triaxial.
A lot will depend on how many and what type of "patches" you have to make. But it may be easier and cosmetically better to use something like "KiwiGrip" to do the entire floor, than to try and replicate the gelcoat on the floor….but again it will depend on what you find...
You will probably be replacing it with more modern materials, but cloth and mat will also work IF you go with polyester. If you use epoxy (recommended), you will probably use cloth--either bi-axial or triaxial.
A lot will depend on how many and what type of "patches" you have to make. But it may be easier and cosmetically better to use something like "KiwiGrip" to do the entire floor, than to try and replicate the gelcoat on the floor….but again it will depend on what you find...
Once you drill the holes, you need to seal these back up with epoxy, not some silicone or 5200, if you use the boat before you do the work. I suspected that you will not really know what you are into unlit you do some cuts. Be careful with the drill--and don't go too deep. However, if you use a drill, you have to have a large enough hole to get a good sample--1/8" is probably not large enough--1/4" is better. Have you sounded out the floor with a phenolic hammer, or a plastic handle of a screw driver yet? Has a moisture meter been used?
I brought my boat home from the marina early this morning a drilled 9 core samples with a 3/8" drill about 3/8 of an inch deep.
I may add that these pictures are not the best.
http://i1201.photobucket.com/albums/bb3 ... 0_1932.jpg
http://i1201.photobucket.com/albums/bb3 ... 0_1930.jpg
http://i1201.photobucket.com/albums/bb3 ... 0_1928.jpg
I checked the wood shavings from every hole, all were dry and a yellowish white. They felt and looked good. Today was very hot and I wasn't wearing my hiking boots, I was in my bare feet and really couldn't feel the soft spots like I had felt them before. I did feel some flex in the hull when I shifted my weight up and down but I think that was the trailer bunks flexing on their own. All looks good and thanks everyone for the great responses and information . Tug
I may add that these pictures are not the best.
http://i1201.photobucket.com/albums/bb3 ... 0_1932.jpg
http://i1201.photobucket.com/albums/bb3 ... 0_1930.jpg
http://i1201.photobucket.com/albums/bb3 ... 0_1928.jpg
I checked the wood shavings from every hole, all were dry and a yellowish white. They felt and looked good. Today was very hot and I wasn't wearing my hiking boots, I was in my bare feet and really couldn't feel the soft spots like I had felt them before. I did feel some flex in the hull when I shifted my weight up and down but I think that was the trailer bunks flexing on their own. All looks good and thanks everyone for the great responses and information . Tug
Well that looks like good news! I have noticed that I oftentimes feel "false soft spots" if I walk on decks with something like tennis shoes on, as opposed to bare or stocking feet which don't cause that.
Well at least now you know for sure. Hard to beat a core sample.
I'm thinking about whether I would want to put a small piece of cloth over those holes or if just thickened epoxy would be enough. I guess that as I think about it, I normally end up covering those holes up - either with a fitting or a backing plate, or etc. Probably 3/8" is okay with just a plug of epoxy, but.... what does anyone else think?
The other factor I'm thinking of is that you don't have any undercut to "lock" the epoxy in place from cracking (around the perimeter of the hole). I guess I would have to consult my handy-dandy free WEST Systems guide to see what it said. Perhaps with a machined hole it is not a problem at all.
What I would do for sure would be to wet out the hole with neat (unfilled) epoxy first, then fill it the rest of the way with thickened epoxy.
Glad you have a nice, dry core!
Sunbeam
Well at least now you know for sure. Hard to beat a core sample.
I'm thinking about whether I would want to put a small piece of cloth over those holes or if just thickened epoxy would be enough. I guess that as I think about it, I normally end up covering those holes up - either with a fitting or a backing plate, or etc. Probably 3/8" is okay with just a plug of epoxy, but.... what does anyone else think?
The other factor I'm thinking of is that you don't have any undercut to "lock" the epoxy in place from cracking (around the perimeter of the hole). I guess I would have to consult my handy-dandy free WEST Systems guide to see what it said. Perhaps with a machined hole it is not a problem at all.
What I would do for sure would be to wet out the hole with neat (unfilled) epoxy first, then fill it the rest of the way with thickened epoxy.
Glad you have a nice, dry core!
Sunbeam
3/8 probably OK with just thickened epoxy--it sticks pretty well to wood! I would also sound the floor out with a phenolic hammer or the back of a screw driver handle. That is probably better than your subjective feel with hiking boots. However, if a place feels soft, it is certainly a good idea to investigate it.