oops!
Supreme Mariner
- Joined
- Oct 18, 2007
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A very common thing that we get asked on iboats ...is how to glass a deck and foam a hull.
I typed this answer for another thread, but decided it needed its own search easy thread for future reference.
When glassing a deck after it has been cut and fitted to the hull.
What you are looking to do is to encapsulate the plywood deck with glass.....on the bottom...and on the top, with more layers of glass on the top for wear.
The minimum you want on the top of your deck is 8oz. of glass. I use 2 layers of 1.5 csm, and a 6 oz woven. This gives me 9 oz on the deck with a smooth surface.
The tabbing is done with one 6-8 inch layer of 1708.
If you are adding a ski locker or any other under deck storage.....cut the holes out before you install the deck.
To properly do the deck......sand your wood (both sides).....and vacuum it off. Mix some unwaxed resin at 1.5 % mekp or even at 1% (70 deg) and wet out the underside of the deck and all edges.....wet it out good. .....wait till its tacky and starting to cure. Then mix some resin at the proper 2% cat rate and 4 % wax....and glass a layer of 1.5 oz. to the bottom of the deck.....let cure.
Dont worry about glassing the edges.
Thats the under side of the deck......done.....you can paint that if you wish, just for extra protection.....make sure you use a primer over the waxed resin. most people don't bother painting.
Now it is time to prep the hull for glassing.......grind (rough and scuff) the area where the hull will meet the deck, and about 9 inches higher.....all around the hull....(kinda like a bath tub ring) all you want to do here is grind off the top layer of resin on the hull to get to the surface glass. This can be done quick....and don't go very far into the glass at all....just the top layer of old resin.
Now vacuum the hull thoroughly......and clean with acetone.......don't just wipe it with a damp rag....but liberally wipe the area with lots of acetone.....your intent is to wash the area. !
Its time to screw your deck down.......mark the stringer and frame locations using a chalk line......this is where your screws will go.......lay down the deck....and pre drill the holes.....
fill the holes with a good amount of 3m 5200.,,,,,and screw down the deck. wipe off the excess 5200.
Now that your deck is all screwed down, its time to cut the fibreglass. don't worry about the deck hull gap right now....we will deal with that in a second.
cut your first layer of csm so it will cover the deck and go up the side of the hull 4 inches. and another one slightly larger so it will cover the same area but 6 inches up the hull.
then cut the exact same size of 6 oz woven roving.
For proper tabbing, use 1708 bi axe...cut several strips 8 inches wide....(you may also choose to use double tabbing by cutting another strip 12 inches wide and double tab the hull)
when you cut the 1708.....cut it going with the weave of the fabric. not across it......this will give you a frayed top edge that is just a real pain in the azz !
Cut enough strips to go all the way around the perimeter of the deck.
(usually you will have enough scraps from cutting the stringer glass to do this)
If you choose to go with double tabbing.....make sure that your second, larger layer of csm and the final 6 oz woven will cover the second larger 1708 tab.
Now that the glass and the tabbing is cut, lets deal with the gap around the edge of the deck and hull joint.
Some people use pl premium for this.....I don't like it because of the full 48 hour cure time before you can glass over it.....and I would rather have fibreglass between the hull and the deck....so I use peanut butter.
Mix up some peanut butter....and fill the gap, making sure that you don't have any sharp ridges, and that there are no dips in the gap.
If you get a dip......just wait till the peanut butter stiffens (starts to cure) and go over it again.
If the job is really rough.....wait till it cures, and grind it smooth.....You will have to vacuum and acetone the hull again.
If you wish.....you can leave small "gaps" at the transom area through to the bilge only.....This is so any deck water can drain to the bilge.....Do not leave gaps any where where you are going to foam.
This is the point where you foam the hull
Foaming the hull
If you wish to foam the hull using a totally water proof method.....so the foam will not ever get wet or water logged...read this link....
http://forums.iboats.com/showthread.php?t=234392 go to page 167....post 4158
This method covers usage of conventional pour in foam...
With a large hole saw......cut 2 rows of holes in each area that you wish to foam. (usually the area under the deck between the outer stringer and the upper gunwale). From back to front, the holes should be 10 inches apart. one row....near the side of the hull......the next row......4 inches away from the stringer.....keep all the cut out pieces.
Starting at the deepest part of the hull (usually the back).....pour in your foam through the hole near the side of the hull, let the foam run down and pool near the stringer and let expand.....then wait....give it 5 mins each time you pour it in...let it expand like it should. the holes near the stringer should have foam expanding out the top. pour in more foam into the same hole till it expands from the hole near the side of the boat..
repeat this process till your hull is foamed. both sides. Make sure the foam has properly expanded out the top of the holes, so there are no air voids under the deck (in the foamed areas).
After all the foam is poured in.....wait a full hour till the foam has properly expanded and cured.
Now we have to replace the wood in the cut out holes....
Take a utility knife and cut the top off the foam that has expanded out of the holes.
Take one of the cut out pieces of deck you kept..... re insert it back into the hole saw (with out the drill bit in the saw) and using 40 grit sticky back sand paper.....stick the sand paper to the wood in the hole saw, re insert it into the drill ....and sand the foam till you get to the depth of the deck. quickly check your work by placing a cut out back in the hole....a little too low is ok....high is not. make sure its flush with the deck. Do this to all the holes.
As before, mix up some resin at 1.5 % and liberally coat the edges of the cut outs....on the deck and the cut out parts. let cure till tacky.
While that is tacking........
Mix up some peanut butter.....catylize the resin first 1.5.....add your milled fibres, cabosil and glass bubbles...and mix that all together and coat the edges of the holes in your deck liberally with peanut butter....replace the cut outs and make sure the peanut butter squishes out the edges....If you have sanded the foam too far, and the insert too deep, just take a putty knife and add more peanut butter on top of the cut out till the deck is flat. repeat till all holes are filled to deck height.
At this time......I should mention, that you can do it another way......forgoing the top row of holes, and using the gap between the deck and hull to pour in your foam. this will save you the time of drilling the row of holes closes to the side of the hull, however it means that you must remove the excess foam between the gap so that you have proper contact to the hull and deck for the peanut butter......this can be done with a sawzall. But its time consuming to do properly.....You still need the row of expansion holes nearest the stringer....So its your call.
Time to glass the deck.
Now again,....using 1.5% unwaxed resin.
Wet out the whole top deck, front to back......saturate the wood....wet it out good, use lots of resin.......as before.....let it get almost cured...tacky, but not hard. (make sure you test the resin at the front part of the deck.....forget about the back part ...you started wetting out at the front...so that is where you will start glassing....the back will be semi cured by the time you get there).
If you are not going to gel-coat the deck....but just lay a carpet over raw glass. use waxed resin at the usual 2% cat rate, 4 % wax......if you are going to add another layer of anything over the raw glass...like gel-coat or dura deck.....ect....use unwaxed resin...
Again.......use waxed resin only if this is the last layer of glass that will contact the air (or carpet).
Everything else....use unwaxed. (if you change your mind later....and decide to gelcoat....the top layer of wax MUST be ground off).
Now....here is where it gets tricky.....Take a piece of plastic, big enough to move around on.....and lay it over the wet resin....but leave your area that you are working on first open and uncovered. This plastic is so your clothes don't stick to the deck when you are glassing and to lay the dry rolls of fibreglass in front of your knees when you are doing the deck.
Take the first layer of 1.5 oz csm. and glass only the area you can reach....you want to glass up the sides of the hull so wet it out over the tacky resin, and glass the deck and up the side of the hull minimum 4 inches. glass right over the tacky peanut butter you layed for the hull deck joint....if you did this properly...there will be no sharp edges or ridges to contend with.
this is your first layer and first bond......so get as much air out with your resin roller as you can.
Leave the rest of the glass rolled up in front of your knees ...so you can just unroll the glass like a carpet as you move farther down the hull.
One of the basics of glassing is to just use enough resin to fully saturate the glass, but not have so much that there is excess......With resin, remember...less is more
Since you are doing multiple layers at once.....you can use more resin in the second wet out stage....(after you have resin coated the wood till tack, and are wetting out for the first layer of csm).
After the section you are working on is glassed with csm, it is now time to tab the hull deck joint.
Take your pre cut 1708 8 inch wide strips and lay them half on the deck and half way up the wall of the hull.....glass them in.
If you chose to go with double tabbing....glass the larger pieces of 1708 now......go a little higher up the hull and lower on the deck.
Next.....take the larger second layer of csm, and lay that over the area.....and glass that in including over the tabbing...and higher up the wall....This is all done wet on wet.....so a good chemical bond is formed.
Now take the final layer of 6 oz woven roving....just lay it over everything. and using your resin roller....glass that in.....the 6 oz needs very little resin. to soak in...so it will usually drink any excess resin that was left over from the previous layers..
Now.....move your plastic back...and work on the next area you were just kneeling on...and repeat the process unrolling the fibreglass each time till you are all the way to the transom.
Watch out that you don't glass your self into a corner....and have the plan for glassing in your head before you start...
If you have left a hole for drainage in the peanut butter....just make sure that the hole is not glassed over.
if you have a ski locker, glass over the hole in the deck over the locker....but no need to resin coat the class that will be removed....just cut the glass after you have reached a full cure from the resin.
If you do have any major air bumps in the cured glass......the top can be quickly ground off after its cured......but don't grind down to the wood, or you will be glassing again....just grind off the bump.
That's it.......you are done. Beer time.
As you can see....this job will take a full day. it can be broken up into sections....after the deck is foamed...or after the peanut butter is added to the gap around the edges...I like to do it all at once, because of the good chemical bond you get.
cheers
oops
I typed this answer for another thread, but decided it needed its own search easy thread for future reference.
When glassing a deck after it has been cut and fitted to the hull.
What you are looking to do is to encapsulate the plywood deck with glass.....on the bottom...and on the top, with more layers of glass on the top for wear.
The minimum you want on the top of your deck is 8oz. of glass. I use 2 layers of 1.5 csm, and a 6 oz woven. This gives me 9 oz on the deck with a smooth surface.
The tabbing is done with one 6-8 inch layer of 1708.
If you are adding a ski locker or any other under deck storage.....cut the holes out before you install the deck.
To properly do the deck......sand your wood (both sides).....and vacuum it off. Mix some unwaxed resin at 1.5 % mekp or even at 1% (70 deg) and wet out the underside of the deck and all edges.....wet it out good. .....wait till its tacky and starting to cure. Then mix some resin at the proper 2% cat rate and 4 % wax....and glass a layer of 1.5 oz. to the bottom of the deck.....let cure.
Dont worry about glassing the edges.
Thats the under side of the deck......done.....you can paint that if you wish, just for extra protection.....make sure you use a primer over the waxed resin. most people don't bother painting.
Now it is time to prep the hull for glassing.......grind (rough and scuff) the area where the hull will meet the deck, and about 9 inches higher.....all around the hull....(kinda like a bath tub ring) all you want to do here is grind off the top layer of resin on the hull to get to the surface glass. This can be done quick....and don't go very far into the glass at all....just the top layer of old resin.
Now vacuum the hull thoroughly......and clean with acetone.......don't just wipe it with a damp rag....but liberally wipe the area with lots of acetone.....your intent is to wash the area. !
Its time to screw your deck down.......mark the stringer and frame locations using a chalk line......this is where your screws will go.......lay down the deck....and pre drill the holes.....
fill the holes with a good amount of 3m 5200.,,,,,and screw down the deck. wipe off the excess 5200.
Now that your deck is all screwed down, its time to cut the fibreglass. don't worry about the deck hull gap right now....we will deal with that in a second.
cut your first layer of csm so it will cover the deck and go up the side of the hull 4 inches. and another one slightly larger so it will cover the same area but 6 inches up the hull.
then cut the exact same size of 6 oz woven roving.
For proper tabbing, use 1708 bi axe...cut several strips 8 inches wide....(you may also choose to use double tabbing by cutting another strip 12 inches wide and double tab the hull)
when you cut the 1708.....cut it going with the weave of the fabric. not across it......this will give you a frayed top edge that is just a real pain in the azz !
Cut enough strips to go all the way around the perimeter of the deck.
(usually you will have enough scraps from cutting the stringer glass to do this)
If you choose to go with double tabbing.....make sure that your second, larger layer of csm and the final 6 oz woven will cover the second larger 1708 tab.
Now that the glass and the tabbing is cut, lets deal with the gap around the edge of the deck and hull joint.
Some people use pl premium for this.....I don't like it because of the full 48 hour cure time before you can glass over it.....and I would rather have fibreglass between the hull and the deck....so I use peanut butter.
Mix up some peanut butter....and fill the gap, making sure that you don't have any sharp ridges, and that there are no dips in the gap.
If you get a dip......just wait till the peanut butter stiffens (starts to cure) and go over it again.
If the job is really rough.....wait till it cures, and grind it smooth.....You will have to vacuum and acetone the hull again.
If you wish.....you can leave small "gaps" at the transom area through to the bilge only.....This is so any deck water can drain to the bilge.....Do not leave gaps any where where you are going to foam.
This is the point where you foam the hull
Foaming the hull
If you wish to foam the hull using a totally water proof method.....so the foam will not ever get wet or water logged...read this link....
http://forums.iboats.com/showthread.php?t=234392 go to page 167....post 4158
This method covers usage of conventional pour in foam...
With a large hole saw......cut 2 rows of holes in each area that you wish to foam. (usually the area under the deck between the outer stringer and the upper gunwale). From back to front, the holes should be 10 inches apart. one row....near the side of the hull......the next row......4 inches away from the stringer.....keep all the cut out pieces.
Starting at the deepest part of the hull (usually the back).....pour in your foam through the hole near the side of the hull, let the foam run down and pool near the stringer and let expand.....then wait....give it 5 mins each time you pour it in...let it expand like it should. the holes near the stringer should have foam expanding out the top. pour in more foam into the same hole till it expands from the hole near the side of the boat..
repeat this process till your hull is foamed. both sides. Make sure the foam has properly expanded out the top of the holes, so there are no air voids under the deck (in the foamed areas).
After all the foam is poured in.....wait a full hour till the foam has properly expanded and cured.
Now we have to replace the wood in the cut out holes....
Take a utility knife and cut the top off the foam that has expanded out of the holes.
Take one of the cut out pieces of deck you kept..... re insert it back into the hole saw (with out the drill bit in the saw) and using 40 grit sticky back sand paper.....stick the sand paper to the wood in the hole saw, re insert it into the drill ....and sand the foam till you get to the depth of the deck. quickly check your work by placing a cut out back in the hole....a little too low is ok....high is not. make sure its flush with the deck. Do this to all the holes.
As before, mix up some resin at 1.5 % and liberally coat the edges of the cut outs....on the deck and the cut out parts. let cure till tacky.
While that is tacking........
Mix up some peanut butter.....catylize the resin first 1.5.....add your milled fibres, cabosil and glass bubbles...and mix that all together and coat the edges of the holes in your deck liberally with peanut butter....replace the cut outs and make sure the peanut butter squishes out the edges....If you have sanded the foam too far, and the insert too deep, just take a putty knife and add more peanut butter on top of the cut out till the deck is flat. repeat till all holes are filled to deck height.
At this time......I should mention, that you can do it another way......forgoing the top row of holes, and using the gap between the deck and hull to pour in your foam. this will save you the time of drilling the row of holes closes to the side of the hull, however it means that you must remove the excess foam between the gap so that you have proper contact to the hull and deck for the peanut butter......this can be done with a sawzall. But its time consuming to do properly.....You still need the row of expansion holes nearest the stringer....So its your call.
Time to glass the deck.
Now again,....using 1.5% unwaxed resin.
Wet out the whole top deck, front to back......saturate the wood....wet it out good, use lots of resin.......as before.....let it get almost cured...tacky, but not hard. (make sure you test the resin at the front part of the deck.....forget about the back part ...you started wetting out at the front...so that is where you will start glassing....the back will be semi cured by the time you get there).
If you are not going to gel-coat the deck....but just lay a carpet over raw glass. use waxed resin at the usual 2% cat rate, 4 % wax......if you are going to add another layer of anything over the raw glass...like gel-coat or dura deck.....ect....use unwaxed resin...
Again.......use waxed resin only if this is the last layer of glass that will contact the air (or carpet).
Everything else....use unwaxed. (if you change your mind later....and decide to gelcoat....the top layer of wax MUST be ground off).
Now....here is where it gets tricky.....Take a piece of plastic, big enough to move around on.....and lay it over the wet resin....but leave your area that you are working on first open and uncovered. This plastic is so your clothes don't stick to the deck when you are glassing and to lay the dry rolls of fibreglass in front of your knees when you are doing the deck.
Take the first layer of 1.5 oz csm. and glass only the area you can reach....you want to glass up the sides of the hull so wet it out over the tacky resin, and glass the deck and up the side of the hull minimum 4 inches. glass right over the tacky peanut butter you layed for the hull deck joint....if you did this properly...there will be no sharp edges or ridges to contend with.
this is your first layer and first bond......so get as much air out with your resin roller as you can.
Leave the rest of the glass rolled up in front of your knees ...so you can just unroll the glass like a carpet as you move farther down the hull.
One of the basics of glassing is to just use enough resin to fully saturate the glass, but not have so much that there is excess......With resin, remember...less is more
Since you are doing multiple layers at once.....you can use more resin in the second wet out stage....(after you have resin coated the wood till tack, and are wetting out for the first layer of csm).
After the section you are working on is glassed with csm, it is now time to tab the hull deck joint.
Take your pre cut 1708 8 inch wide strips and lay them half on the deck and half way up the wall of the hull.....glass them in.
If you chose to go with double tabbing....glass the larger pieces of 1708 now......go a little higher up the hull and lower on the deck.
Next.....take the larger second layer of csm, and lay that over the area.....and glass that in including over the tabbing...and higher up the wall....This is all done wet on wet.....so a good chemical bond is formed.
Now take the final layer of 6 oz woven roving....just lay it over everything. and using your resin roller....glass that in.....the 6 oz needs very little resin. to soak in...so it will usually drink any excess resin that was left over from the previous layers..
Now.....move your plastic back...and work on the next area you were just kneeling on...and repeat the process unrolling the fibreglass each time till you are all the way to the transom.
Watch out that you don't glass your self into a corner....and have the plan for glassing in your head before you start...
If you have left a hole for drainage in the peanut butter....just make sure that the hole is not glassed over.
if you have a ski locker, glass over the hole in the deck over the locker....but no need to resin coat the class that will be removed....just cut the glass after you have reached a full cure from the resin.
If you do have any major air bumps in the cured glass......the top can be quickly ground off after its cured......but don't grind down to the wood, or you will be glassing again....just grind off the bump.
That's it.......you are done. Beer time.
As you can see....this job will take a full day. it can be broken up into sections....after the deck is foamed...or after the peanut butter is added to the gap around the edges...I like to do it all at once, because of the good chemical bond you get.
cheers
oops
between wax resin and non wax? I am not sure what exactly to purchase and how to mix. Would standard polyester "Boaters Resin" get me started? I do have some basics in aviation composites but its been a while.
