Fiberglassing my newly cored deck.

[jgbrown]

Originally Posted by Chotu

Ok. Everything looks good to me! You did the best you could with the core bonding. Sorry to hear about the leaks in the inner layer of existing glass. But you got it done with screws.

I'm not sure I agree with the poster talking about not using just biax. I've used just boss all over the place as per the plans and not once has it pulled in any way drilling it or cutrying it.

Might be a polyester issue? Because it doesn't do that with epoxy.

No idea either, maybe thinking of screwing down wet? Makes no sense in poly either(which I would use in this case).


To the original poster: generally overlapping is better than a butt, also easier to line up when wet. However with the amount of glass you're putting on I wouldn't worry.
I'd be tempted to forgo one of the layers of 1708, and start with a fairly resin rich layer of 2x csm to start on the core, then wet out as normal above that. We often find dry patches when peeling decks. For the mats I wouldn't try to butt(top or bottom). Get feather edged 50", overlap approx 1-2".

One thing to avoid is "stacking" your 1708 seams. To avoid this and make your life easier, cut your first bow pieces narrower(and only the bow piece). E.g.: 50" 40" 30" 20". Then leave all the following pieces full width, and your seams will not be in the same place making for a stronger result in my opinion.

[coopec43]

Originally Posted by jgbrown

To the original poster: generally overlapping is better than a butt, also easier to line up when wet. However with the amount of glass you're putting on I wouldn't worry.

One thing to avoid is "stacking" your 1708 seams. To avoid this and make your life easier, cut your first bow pieces narrower(and only the bow piece). E.g.: 50" 40" 30" 20". Then leave all the following pieces full width, and your seams will not be in the same place making for a stronger result in my opinion.

I agree with ALL your comment but just homing in on one point in particular.

OVERLAPPING I had a tradesman fiber-glasser helping me with the initial lay-up and he absolutely insisted on overlapping. He said there wouldn't be a boat manufacturer in Australia that didn't overlap.

But of course they would all be working with female molds so the overlaps would not cause a slight "bump". (The "bumpiness" would be on the inside of the hull.)

As you say if the joins just happen to be in the one place the hull could be weak - perhaps dangerously.

We did start each lay-up with different widths "sheets" to stagger the joins.


Clive

[Benz]

Originally Posted by Wind River

According to Coosa Composites, the Bluewater 26 is about 30% lighter than plywood of the same thickness.

Bonus for lighter, stronger and waterproof!

I meant it's overkill in the foam-core world. There are far lighter coring products that would be suitable. Coosa is normally inserted only in areas that will have a fitting go through, where there will be high compression from the fasteners. So where there's a padeye designed in, you would cut a 6" circle out of the lighter foam core and insert a 6" circle of coosa.
This is also done to save money, as Coosa is pretty expensive vice Divinicell.
But again, nothing wrong with all Coosa, if the budget allows...

[Benz]

Originally Posted by Chotu

Ok. Everything looks good to me! You did the best you could with the core bonding. Sorry to hear about the leaks in the inner layer of existing glass. But you got it done with screws.

I'm not sure I agree with the poster talking about not using just biax. I've used just boss all over the place as per the plans and not once has it pulled in any way drilling it or cutrying it.

Might be a polyester issue? Because it doesn't do that with epoxy.

If you take a panel of fiberglass (or carbon) whose outside layer is plain biax, and drill through it from behind, usually the drill bit will "tear out" the hole a little as it emerges. Sometimes that tear out lifts a strand of the biax, which you can then easily pull right off the laminate. You are to be congratulated if it hasn't happened to you yet. Rest assured, if you do this for any length of time, it will.

It does it with 1708 as well, unless you put the side with csm facing out. The little strands of csm prevent that tear-out. That just requires planning your layup schedule correctly.

[Chotu]

Originally Posted by Benz

If you take a panel of fiberglass (or carbon) whose outside layer is plain biax, and drill through it from behind, usually the drill bit will "tear out" the hole a little as it emerges. Sometimes that tear out lifts a strand of the biax, which you can then easily pull right off the laminate. You are to be congratulated if it hasn't happened to you yet. Rest assured, if you do this for any length of time, it will.

It does it with 1708 as well, unless you put the side with csm facing out. The little strands of csm prevent that tear-out. That just requires planning your layup schedule correctly.

That's a drilling problem.

That means you're not letting the bit do its work. A slow push through with more rotations of the bit and less pressure solves this issue.

But I see the point of having a layer to help with this issue which would happen on biax, triax or uni.

[Cadence]

Originally Posted by Wind River

I have recently removed the teak decks and re-cored the side and foredeck on my Hudson Force 50 Center Cockpit ketch. I am getting ready to lay down new glass and started pre-cutting the pieces.

To duplicate the thickness of the original layup I will be putting down 5 layers of 1708 bi-ax topped with two layers of 1.5 oz. CSM. That will get me the average 1/4" thickness of the skin I removed.

I'm sure the best scenario is one giant piece of glass per layer with no butted seams in each layer. Obviously that is not possible so smaller pieces will need to be butted together. The glass I have is 50" wide and there is a spot on the foredeck where it could be laid down at full width, but the 10 foot by 50" fabric is a bit unwieldy. The narrow side decks can be done in two sections per layer and rolled out as I go, so there is not much of an issue there. The transition from the side to the foredeck is where there will need to be more joints.

My question is how big of a deal are butt joints within the layup if they are staggered between layers? Lets say 6" or more apart?

What about small areas where the larger pieces leave a void? Is a small patch there anything to be concerned with?

Should I avoid butt joint at the expense of a lot of wasted fiberglass?

Am I concerned about nothing?

Stagger the joints, I would by 6" per layer. Each layer is butted but over laps the previous layer by the 6".

[Nicholson58]

Consider finishing your top most layer with Veil. This is a very fine material that gives no strength to thickness but helps level the finish effectively hiding the weave below. This reduces finish grinding and fairing. It’s also very cheap.

[JOHNMARDALL]

You don't say whether you're planning to use Epoxy, Polyester or Vinylester resin, each of which has different kicking, curing and bonding characteristics. You also don't say if you're experienced in laminating work, which also makes a difference in how to approach a big job like this. Here are a few basic suggestions:


1. Before you start, apply preservation tape and sheeting to all adjacent surfaces - there will be a lot of resin seepage and dripping which will be incredibly difficult to get off without creating another major repair job.
2. Install an awing over the entire work area before you start, to keep the rain and sun off your work. The rain will have obvious effect on the fiberglass materials not yet wetted out with resin, but the sun will take you by surprise- even on a cool day, direct sunlight will cause the resin to kick (initial set) uncontrollably fast.
3. Unless you're already in a cold place, keep your resins in buckets or drums of ice water - the cooler the resin, the longer you'll have to wet out the fiberglass and roll out the bubbles

4. Especially with polyester and vinylester resin, work with small pieces of CSM and fabric until you really get the hang of it. If you try to use large sheets, you'll probably get a kicked edge halfway across and have to grind it down and make butt joint to get going again.
5. This project is going to take several days and there will be many occasions when you're going back on cured or semi-cured work. If you're using epoxy, you must water wash the cured face before adding more laminations, to remove the amine blush which will cause delamination after a year or two, depending on conditions. Before starting with additional layers, with any of the resins, give the surface a light sand and grind or sand off any big bumps- it's much easier and better to do it as you go than than at the end when the bumps have been magnified by additional laminations.
6. However many people are working on this, always have one person, with a buck of acetone and some chip brushes, who is cleaning the tools all the time.
7. Buy a large supply of high quality latex gloves that are big enough for you. I buy mine in automotive parts supply stores, not hardware stores. Pull on two or three gloves over each other - it saves time when all you have to do is peel off one layer rather than pulling on new gloves over wet hands. Oh, and keep a can of talcum power next to the glove box, because once your hands are soaked in sweat, even when you towel then dry, you still won't be able to get new gloves on without talc.
8. Stay with your plan to put a layer of CSM between each layer of cloth or roving - you'll get much better adhesion and fewer voids. Of course, if you're using a combination product, the CSM is already there, but it's a bit hard to wet out and de-bubble the double layer.
9. Machine the edges of the existing lamination where it meets the new work so that you get a geometric connection not just a bonded connection.



I hope this helps, please feel to come back with questions.
Good luck



John Mardall
Vetus Maxwell Boat Equipment.

[Sailorman Ed]

why did they use small pieces of plywood in the first place? Heavy and small pieces are not very strong, also difficult to bond well. I also agree the comments from JohnMardall but I prefer nitrile gloves, more durable.
I think the Coosa is overkill and heavy. Divinicell would provide the same results for less money and less weight. The strength comes from the outer layers, not from the core.



I am sure you already know but overdrill and fill all screw holes and bed with butyl, countersinking the top of the hole. Time consuming but very effective.
Ed

[Wind River]

Thanks everyone for all the input.

It seem there is a consensus that butting the layers and overlapping without stacking these joints in the same area would be a good plan. That is the route I will take.

As far as the Coosa board, I chose it for several reasons. The original core was plywood and Coosa improves on that with similar strength, less weight and no water absorption issues. The original core was squares of 15mm and 18mm with no real rhyme or reason for the difference in thickness. I had to work within these limits and Coosa was available in 5/8" which is right between the two. I did not see any other suitable material that was available in this thickness. Seeing that Wind River's beam is 14-1/2" feet I felt that a solid stiff core was in order. I don't see it as overkill, but if it is, I would rather err in that direction. "Nothing overbuilt has ever failed."

JOHNMARDALL - Thank you for your input once again. You had given your time and expertise on my bottom peel post a while back.

"You don't say whether you're planning to use Epoxy, Polyester or Vinylester resin, each of which has different kicking, curing and bonding characteristics. You also don't say if you're experienced in laminating work, which also makes a difference in how to approach a big job like this."

I had planned to use polyester for the laminating of the deck but have recently been reconsidering using epoxy. In another deck re-core thread, I believe it was Nicholson58 that suggested using U.S. Composites 635 Thin epoxy. With their slow hardener there is no amine blush. In Southern California, I should be able to stay within their minimum temperature range of 70 - 80 degrees in the shrink wrapped enclosure my boat is in. If the temps do drop below this, their literature states that the cure may take 2-3 days. As long as there is still a full cure, having that kind of time to work may be just what I need.

Usually there is a significant difference in the cost of polyester and epoxy resin. The 635 Thin epoxy in the quantity I will need can be had close to the same cost as the poly if I purchase in the 53 gallon drum with 27 gallons of hardener. Remember, I still have a large cabin top and a large aft deck to re-core and a bottom to do also. Currently, I have little experience laminating this thickness of glass but I suppose when I am done I should be well acquainted with the process.

Any thoughts on this?

"Machine the edges of the existing lamination where it meets the new work so that you get a geometric connection not just a bonded connection."


I have tapered the edges of the margins down towards the core. Is that what you mean by this?

Thanks again for all the input

[Wind River]

Originally Posted by Sailorman Ed

why did they use small pieces of plywood in the first place? Heavy and small pieces are not very strong, also difficult to bond well. I also agree the comments from JohnMardall but I prefer nitrile gloves, more durable.
I think the Coosa is overkill and heavy. Divinicell would provide the same results for less money and less weight. The strength comes from the outer layers, not from the core.



I am sure you already know but overdrill and fill all screw holes and bed with butyl, countersinking the top of the hole. Time consuming but very effective.
Ed

I assume the squares of plywood were used in the same way that the squares of balsa and Divinycell are used when they are on the flexible sheets. I don't agree that the strength comes from the outer layers. I understood the way a cored deck works, was the inner and outer skins, when bonded together, forms a kind of I beam which gives the deck laminate even more stiffness and strength.

I have removed all the stanchion bases that bolt though the deck and will re-attach them to the gunwale instead. This remove 64 potential leaks in the new deck. Only two cleats and two padeyes will penetrate through this deck now.

[coopec43]

[IQUOTE ]Currently, I have little experience laminating this thickness of glass but I suppose when I am done I should be well acquainted with the process.

Any thoughts on this?[/I]

I helped others build their boats before I attempted mine so I knew the basic techniques. But as a precaution I hired a tradesman fiber- glasser just for about 6 hours. I felt I had the confidence then to do a good job.

If you can cajole some of your mates into coming around to give a hand that would be good as sometimes laying the glass can be a bit time critical when the resin starts to go "off".

Best wishes

Clive

[Wind River]

Originally Posted by coopec43

[IQUOTE ]Currently, I have little experience laminating this thickness of glass but I suppose when I am done I should be well acquainted with the process.

Any thoughts on this?[/I]

I helped others build their boats before I attempted mine so I knew the basic techniques. But as a precaution I hired a tradesman fiber- glasser just for about 6 hours. I felt I had the confidence then to do a good job.

If you can cajole some of your mates into coming around to give a hand that would be good as sometimes laying the glass can be a bit time critical when the resin starts to go "off".

Best wishes

Clive

Thanks Clive. I appreciate you taking the time to share your experience.

[coopec43]

In Australia everyone seems to use 2 liter ice-cream containers to mix their resin batches. Do you guys use them also?

Of course don't get any catalyst in your eyes because I've been told you have 15 seconds to wash it out otherwise you will have permanent eye damage. I take their word for it.

Clive

[Benz]

Originally Posted by Wind River

Thanks everyone for all the input.

It seem there is a consensus that butting the layers and overlapping without stacking these joints in the same area would be a good plan. That is the route I will take.

As far as the Coosa board, I chose it for several reasons. The original core was plywood and Coosa improves on that with similar strength, less weight and no water absorption issues. The original core was squares of 15mm and 18mm with no real rhyme or reason for the difference in thickness. I had to work within these limits and Coosa was available in 5/8" which is right between the two. I did not see any other suitable material that was available in this thickness. Seeing that Wind River's beam is 14-1/2" feet I felt that a solid stiff core was in order. I don't see it as overkill, but if it is, I would rather err in that direction. "Nothing overbuilt has ever failed."

JOHNMARDALL - Thank you for your input once again. You had given your time and expertise on my bottom peel post a while back.

"You don't say whether you're planning to use Epoxy, Polyester or Vinylester resin, each of which has different kicking, curing and bonding characteristics. You also don't say if you're experienced in laminating work, which also makes a difference in how to approach a big job like this."

I had planned to use polyester for the laminating of the deck but have recently been reconsidering using epoxy. In another deck re-core thread, I believe it was Nicholson58 that suggested using U.S. Composites 635 Thin epoxy. With their slow hardener there is no amine blush. In Southern California, I should be able to stay within their minimum temperature range of 70 - 80 degrees in the shrink wrapped enclosure my boat is in. If the temps do drop below this, their literature states that the cure may take 2-3 days. As long as there is still a full cure, having that kind of time to work may be just what I need.

Usually there is a significant difference in the cost of polyester and epoxy resin. The 635 Thin epoxy in the quantity I will need can be had close to the same cost as the poly if I purchase in the 53 gallon drum with 27 gallons of hardener. Remember, I still have a large cabin top and a large aft deck to re-core and a bottom to do also. Currently, I have little experience laminating this thickness of glass but I suppose when I am done I should be well acquainted with the process.

Any thoughts on this?

"Machine the edges of the existing lamination where it meets the new work so that you get a geometric connection not just a bonded connection."


I have tapered the edges of the margins down towards the core. Is that what you mean by this?

Thanks again for all the input

My vote would be for vinylester--works the same as polyester, but has better properties. If you use epoxy, you'll have to use epoxy products for fairing afterwards, which are also a bit expensive. The glory of poly/vinyl based products is that cure time is short, so you can smear on some Polyfair fairing compound and be sanding it 1/2 hour later. Not so with epoxy fairing.

If you use epoxy with slow-cure hardener, you'll be able to lay up large areas without having it kick suddenly. That's always nice. But if you use polyester or vinylester, you can lay down one layer at at time, work all the way to wherever you want, and then return to start and begin on layer 2 without sanding--even if it's begun to set, the layers will bond. (With epoxy, once it starts to kick, you pretty much have to stop and wait till later). Done this way, you can without hurry apply as many layers a day as time allows, and you can stop at convenient places to have lunch or leave and return later.
If the surface has tacked off enough, when you return, scrape it over quickly with a piece of 36-grit just to get off any sticking-up fibers that will cause lumps in your next layer.
I like vinylester not only because of the price, but because wet-out is easier, cleanup is easier (you'll go a week with one chip brush), and mixing is easier. The smell is worse. Also, there are more options for CSM, which you can't use easily with Epoxy.