Should I reuse the top fiberglass skin

[jimjimmyjimjim]

Hi all! I'm sure this has been asked before but I got nothing when I did a search so . . . .

I'm replacing some water soaked core on my '71 Formosa. Actually, I'm replacing ALL of the core. Right now I'm on the last bit, ie. the side decks. On the fore deck I replaced everything above the bottom skin, that is, the plywood core and the top layers of fiberglass. I over built the heck outa the deck thinking that most of the stress is up there from the main mast, windless, Samson post, etc.

On the side decks I'm hoping to approach it a bit differently. I'm hoping to be able to reuse the top fiberglass skin and only replace the core. After removing the old wood I secure the core to the bottom skin with thicken epoxy, then secure the old top skin to the core with thickened epoxy and using fiberglass to reinforce the seams and tie the whole thing together. The side decks are about 20" wide and 15' long. I managed to remove the top skin in two long pieces without breaking or cracking them. The skin is a full 1/4" thick.

I've seen a bunch of videos and most reuse the old top skin, but every once in a while I come across someone who says to just lay down new laminate. The Boatworks guy reuses the top skin on his core replacements (from what I can tell) and the only objection I've heard from him to reusing the top skin seems to be that the top skin is usually going to break apart when you pry it up so you should assume you are going to have to re-laminate. If I can reuse the old skin it will save me a lot of time and some money - mostly time, but of course I don't want to compromise the strength.

I should add that the bottom skin is also very thick. It's almost strong enough to walk on by itself - although I try hard not to.

So, what do you guys think? Thanks for any help. Jim

[Spot]

I am interested in hearing what they tell you Jim^4.
So you 'gullied' your side decks? Did it hurt?

It seems likes there would be more materials saved but also more time spent to re-use the old glassing (beveling the seam and cleaning old core off the undersides).

I asked my fiberglass and resin vendor about some deck core repair this week My boat is such that it would be easier to do from the inside, no headliner and small boat with more obstacles on deck and a better looking outside than inside. He recommended using a heavy stitched biaxial+mat that would only take 2 layers to make the 1/8"(3.2mm) I need, polyester resin, and doing the repair in 2 stages. Core would go up first, then glassing, figuring out some sort of contraption to keep the materials up until bonded. We joked about flipping the boat over...

[jimjimmyjimjim]

Originally Posted by Spot

I am interested in hearing what they tell you Jim^4.
So you 'gullied' your side decks? Did it hurt? ..

Yes. I hope never to do that again.

[wingssail]

Originally Posted by jimjimmyjimjim

Hi all! I'm sure this has been asked before but I got nothing when I did a search so . . . .

I'm replacing some water soaked core on my '71 Formosa. Actually, I'm replacing ALL of the core. Right now I'm on the last bit, ie. the side decks. On the fore deck I replaced everything above the bottom skin, that is, the plywood core and the top layers of fiberglass. I over built the heck outa the deck thinking that most of the stress is up there from the main mast, windless, Samson post, etc.

On the side decks I'm hoping to approach it a bit differently. I'm hoping to be able to reuse the top fiberglass skin and only replace the core. After removing the old wood I secure the core to the bottom skin with thicken epoxy, then secure the old top skin to the core with thickened epoxy and using fiberglass to reinforce the seams and tie the whole thing together. The side decks are about 20" wide and 15' long. I managed to remove the top skin in two long pieces without breaking or cracking them. The skin is a full 1/4" thick.

I've seen a bunch of videos and most reuse the old top skin, but every once in a while I come across someone who says to just lay down new laminate. The Boatworks guy reuses the top skin on his core replacements (from what I can tell) and the only objection I've heard from him to reusing the top skin seems to be that the top skin is usually going to break apart when you pry it up so you should assume you are going to have to re-laminate. If I can reuse the old skin it will save me a lot of time and some money - mostly time, but of course I don't want to compromise the strength.

I should add that the bottom skin is also very thick. It's almost strong enough to walk on by itself - although I try hard not to.

So, what do you guys think? Thanks for any help. Jim

I have reused the top skin every time (I have recored several areas on my 43' boat). I think your approach is fine, with emphasis on using new glass on the seams.

[jimjimmyjimjim]

Originally Posted by Spot

It seems likes there would be more materials saved but also more time spent to re-use the old glassing (beveling the seam and cleaning old core off the undersides).

I asked my fiberglass and resin vendor about some deck core repair this week My boat is such that it would be easier to do from the inside, no headliner and small boat with more obstacles on deck and a better looking outside than inside. He recommended using a heavy stitched biaxial+mat that would only take 2 layers to make the 1/8"(3.2mm) I need, polyester resin, and doing the repair in 2 stages. Core would go up first, then glassing, figuring out some sort of contraption to keep the materials up until bonded. We joked about flipping the boat over...

The time spent on cleaning and beveling the old skin is probably less than wetting out two or three layers of biax and then fairing it out. I will need to bevel the deck where the repair meets the existing deck anyway I go. An extra 2 inches on the old skin doesn't seem like that much more. But it's a consideration.

Repairing from underneath seems like it would be a lot harder. Keeping the biax from sagging, fairing upside down, resin dripping all over, getting all the air bubbles out - just seems more trouble than it's worth. If the repairs are relatively small it might make sense but otherwise, I dunno. Also, the reason you need to do the repairs might be because of leaks around the deck hardware. In that case you have to remove the hardware anyway. There are a few areas in my boat where it looks like they worked from underneath. It's very noticeable - the fairing was not very good.

The last time I laid up fiberglass I used 17oz biax and vinylester. It was difficult to wet out right-side-up. I can't imagine what it would be like upside down.

However, I'd like to hear how it goes and good luck.

[Spot]

Originally Posted by wingssail

I have reused the top skin every time (I have recored several areas on my 43' boat). I think your approach is fine, with emphasis on using new glass on the seams.

Thanks for that Wingsail!

Originally Posted by jimjimmyjimjim

The time spent on cleaning and beveling the old skin is probably less than wetting out two or three layers of biax and then fairing it out. I will need to bevel the deck where the repair meets the existing deck anyway I go. An extra 2 inches on the old skin doesn't seem like that much more. But it's a consideration.
Repairing from underneath seems like it would be a lot harder. Keeping the biax from sagging, fairing upside down, resin dripping all over, getting all the air bubbles out - just seems more trouble than it's worth. If the repairs are relatively small it might make sense but otherwise, I dunno. Also, the reason you need to do the repairs might be because of leaks around the deck hardware. In that case you have to remove the hardware anyway. There are a few areas in my boat where it looks like they worked from underneath. It's very noticeable - the fairing was not very good.
The last time I laid up fiberglass I used 17oz biax and vinylester. It was difficult to wet out right-side-up. I can't imagine what it would be like upside down.

However, I'd like to hear how it goes and good luck.

Thanks Jim^4!
Yes, for sure much harder from the underside. The boat has a molded toe rail that also surrounds the companionway as a riser for the wood that allows the ceiling hatch to slide on top and a sort of messy industrial chopper gun finish on the inside. All of the hardware will still have to come off. I imagine the coaching towards polyester resin was to help deal with wetting out the heavier stitched and mat fabric and having it set up faster than regular epoxy. I think the overhead work would be pre-coat ceiling, wet out new materials, then place overhead and clamp into place until set.

Thanks for letting me stir the pot a bit. I am hoping more people will come back to your specific questions. I like your username (Aye, alot) and your can-do attitude!

[jooa]

In April of 2018, I removed about 3/4 of the surface glass in my cockpit to repair rotten coring. Was able to remove the surface glass in 3 reusable pieces. Did pretty much the same repair and technique as what you described. Filled in imperfections with epoxy filler, sanded, and covered everything with KiwiGrip. The KiwiGrip was fabulous for covering pretty much all the flaws in my work. Haven't had a single problem since then and many sailors friends have commented that they simply cannot tell a repair was ever made. I was quite pleased with the whole repair and was able to go from start to finish in about 30 hrs of work.

[Boatyarddog]

Originally Posted by jimjimmyjimjim

Hi all! I'm sure this has been asked before but I got nothing when I did a search so . . . .

I'm replacing some water soaked core on my '71 Formosa. Actually, I'm replacing ALL of the core. Right now I'm on the last bit, ie. the side decks. On the fore deck I replaced everything above the bottom skin, that is, the plywood core and the top layers of fiberglass. I over built the heck outa the deck thinking that most of the stress is up there from the main mast, windless, Samson post, etc.

On the side decks I'm hoping to approach it a bit differently. I'm hoping to be able to reuse the top fiberglass skin and only replace the core. After removing the old wood I secure the core to the bottom skin with thicken epoxy, then secure the old top skin to the core with thickened epoxy and using fiberglass to reinforce the seams and tie the whole thing together. The side decks are about 20" wide and 15' long. I managed to remove the top skin in two long pieces without breaking or cracking them. The skin is a full 1/4" thick.

I've seen a bunch of videos and most reuse the old top skin, but every once in a while I come across someone who says to just lay down new laminate. The Boatworks guy reuses the top skin on his core replacements (from what I can tell) and the only objection I've heard from him to reusing the top skin seems to be that the top skin is usually going to break apart when you pry it up so you should assume you are going to have to re-laminate. If I can reuse the old skin it will save me a lot of time and some money - mostly time, but of course I don't want to compromise the strength.

I should add that the bottom skin is also very thick. It's almost strong enough to walk on by itself - although I try hard not to.

So, what do you guys think? Thanks for any help. Jim

I did the very same thing to a Ericson33.
As I'm pulling up the old skin I drew a crowd of lookers, up came a big sheet of old deck along with the coring under it, dust and wood chips, and all.
Having the old tread pattern on it was invaluable upon replacing the upper sections.
It's very hard if possible at all to match this tread, and it lines right up to other pieces.
Seams were all hidden in the flat areas on each side of the upper sections and were very easy to fair and repaint.
It's the way to go if you dare.
SV Cloud Duster

[sailor_ed]

When it was done to my boat, after removal of core, a layer of mat was put down with the edges of the mat sticking up around the edge. (in the saw kerf). Then core thinner than original was laid in the wet mat. Then another layer of mat with the edges again sticking up in the kerf. The old deck skin was then placed on top and weighted with sand bags. After going off the mat in the kerf was ground flat. To hide the seam the kerf was masked by about 3/4 inch on each side and the area given several coats of gel coat, smoothed and polished. It just looks like a seam between sections of original non-skid. On the other side of the deck (where there was no repair) a similar line of gel coat was laid down so that it was symmetric and the whole looked like it was originally designed that way.



After 25 years of cruising a few hair line cracks are beginning to show at some of the seams but so far no sign of moisture intrusion and they are easily sealed.



The work was done at the yard where they built Bristol Yachts.

[44'cruisingcat]

If you have a moulded in non skid pattern in gelcoat on the decks it might be worth reusing the skins, just to keep the looks uniform.

If it's a painted on non skid like kiwigrip or glass beads, I'd reglass. You're guaranteed a good skin to core bond with no voids that way.

[Boatguy30]

if the side decks are 1/4" thick you need a 4" wide glass joint for a proper beveled glass joint. So 8" total. Decks are 15" wide? that's a lot of patch

[Boatyarddog]

Originally Posted by Boatguy30

if the side decks are 1/4" thick you need a 4" wide glass joint for a proper beveled glass joint. So 8" total. Decks are 15" wide? that's a lot of patch

Very low load area, and supported underneath.
Not like a hole patch.
IMHO, 2" wide is good here.
SV Cloud Duster

[h2ojunke]

My only concern with this would be air pockets trapped under the top skin. If I were doing this I would drill a #40 hole Every square foot or so to allow for even squeeze out and air escape. Put masking tape down first to reduce clean up time.

[Spot]

Thinking about trapped air is good thinking. Maybe try wetting out both surfaces and bending in the loose pieces gradually the long way rather than flopping them in all at once the short way.

[jimjimmyjimjim]

Originally Posted by h2ojunke

My only concern with this would be air pockets trapped under the top skin. If I were doing this I would drill a #40 hole Every square foot or so to allow for even squeeze out and air escape. Put masking tape down first to reduce clean up time.

Yes, that is a concern. I thought I'd deal with it by buttering the underside of the top skin and laying it down in such a way as to squeeze out the air and then weighting it from the midline out. The skin is about 12 -15 inches at its widest so I think I can handle it without drilling holes. But it might be safer to just go ahead and drill some.