Attaching Wood to Fiberglass - Watermaker Platform Questions

[SVAphrodite]

Hello there!


Long time stalker, first time poster.


I am working on my first large scale project, getting a watermaker on this boat.


We have selected the SeaWater Pro as our watermaker.



The engine bays on each side have TONS of empty space behind them.



It is 4' wide and goes about 30" deep past the rear mounts.


My intention is to do this on the PORT side. This is where the factory water maker would have been installed. As a result, the holes though the wall separating the engine compartment from the port aft cabin are already there.


The issue...this is my FIRST time doing fiberglass.


I want to walk through the plan and see what I am missing.


I plan to make a cardboard template today of that space. Next I will mark that line inside the hull and grind it down to bare fiberglass.


Next I will get the template much more perfect and then cut it out of 3/4" marine grade plywood.



I will sand down the edges of the plywood so it sits nice and snug along the curve of the hull. Then use West Six10 to glue it in.



After that hardens, I plan to use TotalBoat epoxy. Then I will tab it in with 4" strips. My plan is to probably do two layers.


The final for this is Pettit Protect and paint the board. Then I am ready to start installation.



Questions:
1) Does this make sense? What do you like/hate about my plan?
2) What is the best way to grind down the paint and coatings in the engine bay? I am pretty handy and have most tools on board.

3) Which TotalBoat would you use? This is my initial plan: https://a.co/d/aIolIY5
4) Which hardening speed would you do?
5) Pettit Protect is obnoxiously expensive. Anyone have a similiar product they trust just as much? I used a 2 part epoxy paint from Sherwin Williams when I was on land. My dad used to paint water towers. It isn't made for a BOAT so it was much cheaper. Thinking that might be sufficient for this project.




Thank you!

[coopec43]

Well you've certainly thought about the problem and no doubt your system will work. But I think you are over engineering the problem.

During construction of my yacht I have had to make mounting points for a number of pieces of equipment such as steering sheaves and hydraulic steering ram.

For a water-maker I will sand the inside of the hull where the unit is to be mounted while USING A FACE MASK! I will lay chopped strand matt (CSM) using polyester resin. Once cured I will heavily fiberglass two strips of SS angle iron (but cut away on the middle and ends) to allow it to be f/g to the hull.

I will then attach the unit to those mounting points.

(this method was recommended by the fiberglass supplier.and epoxy resin is not necessary)

[Jammer]

Originally Posted by SVAphrodite

Questions:
1) Does this make sense? What do you like/hate about my plan?

Sure it makes sense. I'm having trouble visualizing how large the plywood will be. I like to use G10 for stuff like that but it's expensive in larger sizes. Usually 1/4" is sufficient, since it's stronger than plywood. The advantage is that it doesn't rot.


https://www.jamestowndistributors.co...ct-detail/8758


If you're trying to tack it in place with the six10, use Devcon Plastic Welder. It's a methacrylate adhesive that sets up very quickly, bonds better than epoxy, and it's cheaper than six10. Ace hardware stores usually carry it or you can get it on Amazon. It will set up in 15 minutes and so you can get on with your project. It only comes in the double plunger syringes, just get several of them if you need to.

2) What is the best way to grind down the paint and coatings in the engine bay? I am pretty handy and have most tools on board.

Die grinder and a 3" sanding disk. The ceramic ones will last longer, Grainger has them if you can't find them anywhere else. Use a respirator.

3) Which TotalBoat would you use? This is my initial plan: https://a.co/d/aIolIY5

I've switched to Silvertip and use that now. It's a 2:1 non-blushing epoxy similar to the one you've linked to. The one in your link is OK if you're using totalboat.

4) Which hardening speed would you do?

Fast, unless it's going to be 75 F or warmer where you're working.

5) Pettit Protect is obnoxiously expensive. Anyone have a similiar product they trust just as much? I used a 2 part epoxy paint from Sherwin Williams when I was on land. My dad used to paint water towers. It isn't made for a BOAT so it was much cheaper. Thinking that might be sufficient for this project.

If you're following my advice and using G10, you don't have to paint it at all, and if you do it's just for color, so you can use any inexpensive paint.

[s/v Jedi]

Originally Posted by SVAphrodite

Hello there!

Long time stalker, first time poster.

I am working on my first large scale project, getting a watermaker on this boat.

We have selected the SeaWater Pro as our watermaker.

The engine bays on each side have TONS of empty space behind them.

It is 4' wide and goes about 30" deep past the rear mounts.

My intention is to do this on the PORT side. This is where the factory water maker would have been installed. As a result, the holes though the wall separating the engine compartment from the port aft cabin are already there.

The issue...this is my FIRST time doing fiberglass.

I want to walk through the plan and see what I am missing.

I plan to make a cardboard template today of that space. Next I will mark that line inside the hull and grind it down to bare fiberglass.

Next I will get the template much more perfect and then cut it out of 3/4" marine grade plywood.

I will sand down the edges of the plywood so it sits nice and snug along the curve of the hull. Then use West Six10 to glue it in.

After that hardens, I plan to use TotalBoat epoxy. Then I will tab it in with 4" strips. My plan is to probably do two layers.

The final for this is Pettit Protect and paint the board. Then I am ready to start installation.

Questions:
1) Does this make sense? What do you like/hate about my plan?
2) What is the best way to grind down the paint and coatings in the engine bay? I am pretty handy and have most tools on board.

3) Which TotalBoat would you use? This is my initial plan: https://a.co/d/aIolIY5
4) Which hardening speed would you do?
5) Pettit Protect is obnoxiously expensive. Anyone have a similiar product they trust just as much? I used a 2 part epoxy paint from Sherwin Williams when I was on land. My dad used to paint water towers. It isn't made for a BOAT so it was much cheaper. Thinking that might be sufficient for this project.

Thank you!

I recommend you use epoxy instead of polyester when the budget allows because it isn’t as nasty to work with.

First I recommend you start with a laser to draw the line. When the boat isn’t level, you can lock the laser and create fixed angles that are not level.

After that sand that line to remove the gelcoat incl. a couple inches each side of the line, say 2” above and 2” below.

Now switch the laser back on and use a hot glue gun to glue small blocks under the line to support the platform. Create the pattern using 2” wide strips of thin material and hot glue. When using tiny amounts of hot glue to attach to the support blocks, you can pry it off without breaking it.

Now for the platform go down in size material to 12mm 1/2” or even 10mm/3/8”. Cut a piece off at least an inch larger all around the pattern, sand that on every side and edge, the vacuum it, brush it and wipe with denatured alcohol. Now drape a light weight (6 ounce)fiberglass cloth over it, cutting it so it doesn’t overhang the edges more than 1/8”. Wet that out with epoxy resin with normal hardener. Use a plastic spreader, a brush and an aluminum fin roller to saturate it and work out any air bubbles. I often heat the plywood with a heat gun just before pouring the epoxy on which prevents most air bubbles.

It is best to add peel pky as second layer immediately and roll that too making sure it’s fully saturated as well. After curing you pull the peel ply off and have a surface ready for the next steps without the need for sanding.

Do the other size as well then after fully curing use the template to cut it to dimensions and make it fit in the boat. There will probably be an edge that isn’t glued to the hull and I like to round that at this time using a palm router. If this edge doesn’t get much touching/holding, you can simply brush it with epoxy, but I like to use the lightest weight fiberglass tape to cover it, like this one: https://www.amazon.com/Fiberglass-Cl.../dp/B01GKAQS1S
I use wide masking tape across the edge to keep it in place during curing and cover the whole edge that way.

After gluing it in place you can remove temporary supports including the hot glue blocks, make fillets and tab it into place first with the 2” wide tape, then with 4” wide tape. Now you need to decide if this is strong enough, add supports if needed, then paint it. I recommend using a barrier coat like TotalProtect to create a hard epoxy surface.

Look out when screwing into this surface as this allows moisture into the plywood. Normally using some sealant is good enough.

[SVAphrodite]

But on a Lagoon 42 there is tons of space behind the engine. like 30" x48". Adding a wood deck there would mean I can mount some milk crates and other things to store.



Also, I am doing the SeaWater Pro and it is not just two mounting points. I need about 14 mounting points.


THoughts?

Originally Posted by coopec43

Well you've certainly thought about the problem and no doubt your system will work. But I think you are over engineering the problem.

During construction of my yacht I have had to make mounting points for a number of pieces of equipment such as steering sheaves and hydraulic steering ram.

For a water-maker I will sand the inside of the hull where the unit is to be mounted while USING A FACE MASK! I will lay chopped strand matt (CSM) using polyester resin. Once cured I will heavily fiberglass two strips of SS angle iron (but cut away on the middle and ends) to allow it to be f/g to the hull.

I will then attach the unit to those mounting points.

(this method was recommended by the fiberglass supplier.and epoxy resin is not necessary)

[Madehn]

not familiar with that particular watermaker but in general:

i use west system epoxy in gallon cans as opposed to the 6-10- buy it and some filler and you will get tons more for your money-- buy some disposable mix cups ( you can reuse these several times) and some of the plastic stir sticks-- learn to make your own thickened epoxy- For your purposes i would not use FAST hardner, i would just use the regular stuff-- mix in 404 thickening bit by bit until you get the consistency of peanut butter- then you have enough time to mount your pieces firmly and neatly

once you get epoxy on clothes they are done for - the epoxy is so still that it will cut holes into the cloth adjacent to the dried stain- count on spilling some-- IMPORTANT- clean up while wet- i think i have used laquer thinner to wipe off spills and overun. I have heard of people using MEK and it works but that stuff is seriously toxic and i dont use it for anything anymore.

i have found that using marine plywood is worthwhile--

as far as painting- up to you- if you just want to waterproof it, brushing on two coats of epoxy will give it a good waterproof coating- pay special attention to the endgrain portion of the ply. you can always put the epoxy on and then paint it after- can even use spray on epoxy paint ( wash the blush off before you paint though)

i have mounted mini "decks" to the hull by mounting 2x2 wood to the hull with thickened epoxy using a fillet at both top and bottom, then securing my plywood decks to those 2x2 rails

as far as the watermaker- some models need to have oil changed in the pump- be sure you can get to it easily- maint that is easy to do gets done- if it is hard to do, it gets delayed. filters and prefilters likewise need to have easy access. my watermaker has two membranes that need to be replaced periodically-- they are about 4 feet long each and need a lot of room to slide in and out of their pressure vessels.

putting in my watermaker was a job that surprised me with how long it took me to make happen-i think i spent about 5 days getting all of mine situated and wire/plumbed in place-- nothing overly hard just took a lot of time- some fairly large wiring, some reasonably complicated plumbing with a lot of potential for leaks and wanting to make everything accessible all took some time.

to get paint and coatings off in order to mount you "deck"- i just use a wire wheel on a drill with a light touch-- fairly easy but messy- definitely wear a mask AND eye protection- fiberglass dust and paint dust are both nasty.

best of luck

[SVAphrodite]

Originally Posted by Jammer

Sure it makes sense. I'm having trouble visualizing how large the plywood will be. I like to use G10 for stuff like that but it's expensive in larger sizes. Usually 1/4" is sufficient, since it's stronger than plywood. The advantage is that it doesn't rot.

I would do G10, but this is on a Lagoon 42 and I want to fill up the engine rooms with flat spots so I can bold down some milk crates or whatever to hold spare oil and parts too. So much dead space in there.

I am not too worried about rotting because I would paint the marine grade plywood after.

Originally Posted by Jammer

If you're trying to tack it in place with the six10, use Devcon Plastic Welder. It's a methacrylate adhesive that sets up very quickly, bonds better than epoxy, and it's cheaper than six10. Ace hardware stores usually carry it or you can get it on Amazon. It will set up in 15 minutes and so you can get on with your project. It only comes in the double plunger syringes, just get several of them if you need to.

Any issues with using Devcon Plastic Welder for Wood to Fiberglass? Or is that if I was using the G10?

Originally Posted by Jammer

Die grinder and a 3" sanding disk. The ceramic ones will last longer, Grainger has them if you can't find them anywhere else. Use a respirator.

Got it! Thanks!

Originally Posted by Jammer

I've switched to Silvertip and use that now. It's a 2:1 non-blushing epoxy similar to the one you've linked to. The one in your link is OK if you're using totalboat.

Will look at it. Anywhere in particular you like to buy it from? Mind sharing why you choose that over TB? I am learning...

Originally Posted by Jammer

Fast, unless it's going to be 75 F or warmer where you're working.

Doing this on the boat in Miami. Some days it is hotter, but I can do it in the morning before it is over 75. Also it is about to get cold here.

[SVAphrodite]

Originally Posted by s/v Jedi

I recommend you use epoxy instead of polyester when the budget allows because it isn’t as nasty to work with.

I have never used either, but have a solid understanding of fiberglass. Will research polyester and see what I can learn!

Originally Posted by s/v Jedi

First I recommend you start with a laser to draw the line. When the boat isn’t level, you can lock the laser and create fixed angles that are not level.

After that sand that line to remove the gelcoat incl. a couple inches each side of the line, say 2” above and 2” below.

Now switch the laser back on and use a hot glue gun to glue small blocks under the line to support the platform. Create the pattern using 2” wide strips of thin material and hot glue. When using tiny amounts of hot glue to attach to the support blocks, you can pry it off without breaking it.

Got it! No laser level on board, but I am good with careful measurements. I like the blocks idea. No hot glue gun, but I think I can source that!

Originally Posted by s/v Jedi

Now for the platform go down in size material to 12mm 1/2” or even 10mm/3/8”. Cut a piece off at least an inch larger all around the pattern, sand that on every side and edge, the vacuum it, brush it and wipe with denatured alcohol. Now drape a light weight (6 ounce)fiberglass cloth over it, cutting it so it doesn’t overhang the edges more than 1/8”. Wet that out with epoxy resin with normal hardener. Use a plastic spreader, a brush and an aluminum fin roller to saturate it and work out any air bubbles. I often heat the plywood with a heat gun just before pouring the epoxy on which prevents most air bubbles.

Why down a size? It is a 30"x48" platform. I also already bought and had the wood cut at the store to size so I could get it to the boat on teh dinghy. thoughts here?

You are saying to lay fiberglass to the wood I am putting in first? Not just glue it in with the six10?

Originally Posted by s/v Jedi

It is best to add peel pky as second layer immediately and roll that too making sure it’s fully saturated as well. After curing you pull the peel ply off and have a surface ready for the next steps without the need for sanding.

Never heard of or used peel ply...this guy seem accurate?

https://www.youtube.com/watch?v=T-TXRqejb3I

Originally Posted by s/v Jedi

Do the other size as well then after fully curing use the template to cut it to dimensions and make it fit in the boat. There will probably be an edge that isn’t glued to the hull and I like to round that at this time using a palm router. If this edge doesn’t get much touching/holding, you can simply brush it with epoxy, but I like to use the lightest weight fiberglass tape to cover it, like this one: https://www.amazon.com/Fiberglass-Cl.../dp/B01GKAQS1S
I use wide masking tape across the edge to keep it in place during curing and cover the whole edge that way.

Good idea for making the edge beefier!

Originally Posted by s/v Jedi

After gluing it in place you can remove temporary supports including the hot glue blocks, make fillets and tab it into place first with the 2” wide tape, then with 4” wide tape. Now you need to decide if this is strong enough, add supports if needed, then paint it. I recommend using a barrier coat like TotalProtect to create a hard epoxy surface.

Look out when screwing into this surface as this allows moisture into the plywood. Normally using some sealant is good enough.

Got it! Makes sense for keeping moisture out of the holes.

More importantly, what is your cost to come to Miami to help me with this? You seem to really know!

[SVAphrodite]

Originally Posted by Madehn

not familiar with that particular watermaker but in general:

i use west system epoxy in gallon cans as opposed to the 6-10- buy it and some filler and you will get tons more for your money-- buy some disposable mix cups ( you can reuse these several times) and some of the plastic stir sticks-- learn to make your own thickened epoxy- For your purposes i would not use FAST hardner, i would just use the regular stuff-- mix in 404 thickening bit by bit until you get the consistency of peanut butter- then you have enough time to mount your pieces firmly and neatly

404 is the filler? I am already overloaded...I would love to save the money here, but if I do that wrong, I am nervous I have an even bigger battle to fight. I don't think I woudl need more then 2-3 tubes of six10 so for this project I am okay with that. I want to learn this though. Any good videos or advise here?

Originally Posted by Madehn

once you get epoxy on clothes they are done for - the epoxy is so still that it will cut holes into the cloth adjacent to the dried stain- count on spilling some-- IMPORTANT- clean up while wet- i think i have used laquer thinner to wipe off spills and overun. I have heard of people using MEK and it works but that stuff is seriously toxic and i dont use it for anything anymore.

Made plenty of epoxy tables in my day...i am ready for that! lol

Originally Posted by Madehn

i have found that using marine plywood is worthwhile--

seems good! Got the wood bought and cut!

Originally Posted by Madehn

as far as painting- up to you- if you just want to waterproof it, brushing on two coats of epoxy will give it a good waterproof coating- pay special attention to the endgrain portion of the ply. you can always put the epoxy on and then paint it after- can even use spray on epoxy paint ( wash the blush off before you paint though)

Good call. What do you mean "wash the blush off"?

Originally Posted by Madehn

i have mounted mini "decks" to the hull by mounting 2x2 wood to the hull with thickened epoxy using a fillet at both top and bottom, then securing my plywood decks to those 2x2 rails

The issue is the angle that I am at in this rear engine room on the Lagoon 42. I think it might be more difficult to do that honestly.

Originally Posted by Madehn

as far as the watermaker- some models need to have oil changed in the pump- be sure you can get to it easily- maint that is easy to do gets done- if it is hard to do, it gets delayed. filters and prefilters likewise need to have easy access. my watermaker has two membranes that need to be replaced periodically-- they are about 4 feet long each and need a lot of room to slide in and out of their pressure vessels.

Good call! I have a pretty solid plan for that. I am all about maintenance and it being easy! Thank you!

Originally Posted by Madehn

putting in my watermaker was a job that surprised me with how long it took me to make happen-i think i spent about 5 days getting all of mine situated and wire/plumbed in place-- nothing overly hard just took a lot of time- some fairly large wiring, some reasonably complicated plumbing with a lot of potential for leaks and wanting to make everything accessible all took some time.

Yea, this is the part I am most excited for. Been thinking about it for about 2 weeks!

Originally Posted by Madehn

to get paint and coatings off in order to mount you "deck"- i just use a wire wheel on a drill with a light touch-- fairly easy but messy- definitely wear a mask AND eye protection- fiberglass dust and paint dust are both nasty.

You mean to get the gel coat off the fiberglass I am mounting too? I have a great full face mask and tyvek suit...all about safety when I play with fiberglass

Originally Posted by Madehn

best of luck

Thank you!

[shimari]

Originally Posted by SVAphrodite

404 is the filler?

Yes - 404 is a West Systems filler. It allows you to make your own thickened epoxy basically.

Originally Posted by SVAphrodite

Good call. What do you mean "wash the blush off"?

Amine blush is a by product of epoxy curing. You need to remove it before starting a second coat.

Originally Posted by SVAphrodite

You mean to get the gel coat off the fiberglass I am mounting too?

Yes - you need to remove the gelcoat from the mounting area to ensure you get a good bond directly with the fiberglass.

[Jammer]

Originally Posted by SVAphrodite

Any issues with using Devcon Plastic Welder for Wood to Fiberglass? Or is that if I was using the G10?

It will work fine for that too. It's useful for small bonds that you want to set up quickly where you need a gel-like consistency.

Will look at it <<Silvertip epoxy>>. Anywhere in particular you like to buy it from?

I get it from Fisheries Supply but lots of places carry it.

Mind sharing why you choose that over TB? I am learning...

TotalBoat is an economy brand that started out as the Jamestown Distributors house brand. I used their 5:1 epoxy at a time when their pricing reflected a considerable savings over the Gougeon Brothers WEST system epoxy that is the market leader in 5:1 formulations. Over time the cost savings became less significant and I switched back to WEST system.


Subsequently I came to the conclusion that the practical advantages of a 2:1 mix and no-blush formulation were more important that the slight advantage in ultimate strength that WEST and other 5:1 formulations offer.


None of these places own chemical plants that make epoxy. So the questions are: where are they getting their epoxy, and how careful are they about quality and consistency?


I came to the conclusion that the relatively small cost advantage of using TB products was outweighed by the years/decades long reputation for quality and consistency enjoyed by the better known brands. TB does not (or at least did not at the time I looked) publish as detailed test results as other brands do.

Doing this on the boat in Miami. Some days it is hotter, but I can do it in the morning before it is over 75. Also it is about to get cold here.

Probably either speed will work out OK for what you're doing. Slow is sometimes an inconvenience. Fast can be a serious problem if you get caught with the epoxy lighting off before you're ready on larger projects.

[Madehn]

had to leave for a bit but i think everyone else answered the questions connected to my answer-- Thickened epoxy using the west system is pretty simple to make and experiment with - once you start with it you will find a lot of uses- it is good for sealing/waterproofing anywhere that you do not need flexibility and that is not exposed to UV. i thnk a gallon can of the resin is about $100 bucks and the hardner is less. You use two different hand pumps one for hardner and one for resin that are made for the west system cans- that makes mixing them in the right portion pretty idiot proof-- one pump of hardener then one pump of resin then repeat- once you have the sesired quatntity stir very well- then add in the 404 a bit at a time and stir more - keep adding 404 and stirring it in until you have the desired consistency- i like mine to be like a stiff peanut butter when i am attaching to the hull- keeps fillets in place whie drying-- for coating for waterproofing you dont use any 404 just straight epoxy brushed on with a paintbrush- i use a cheap chip brush and throw it away each time. The plastic mixing cups can be reused- just flex them enough to pop the old hardened epoxy out and mix a new batch. tip - take the cap from the resin/hardener container and leave it upside down on the top of the container in a clear space- when done dispensing, turn the spout of the pump so that any drips land in the upside down cap - make for a cleaner working area. mix small batches at a time- too much at once will tend to cook off and harden before you can use it. There are a lot of U-tube videos out there on how to use-- jamestown dist i think had some good ones as well. if you get into it and run into problems send me a PM and i can give you a call and try to help you out. Later if you actually start to do fiberglass work, i have less expertise but have managed some decent projects

[SVAphrodite]

Originally Posted by shimari

Yes - 404 is a West Systems filler. It allows you to make your own thickened epoxy basically.

Gotcha! Will research how this works!

Originally Posted by shimari

Amine blush is a by product of epoxy curing. You need to remove it before starting a second coat.

Got it! I have much to learn here! Do you like the peel ply to prevent this?

Originally Posted by shimari

Yes - you need to remove the gelcoat from the mounting area to ensure you get a good bond directly with the fiberglass.

Yea, I got that part, but wasn't sure if you were talking about something else...I wouldn't have thought a wire bit on a drill lightly would remove enough of the gel coat. Any tricks for knowing when to stop when removing the gel coat?

[SVAphrodite]

All makes sense!


So much to learn here! Thanks man!

Originally Posted by Jammer

It will work fine for that too. It's useful for small bonds that you want to set up quickly where you need a gel-like consistency.





I get it from Fisheries Supply but lots of places carry it.





TotalBoat is an economy brand that started out as the Jamestown Distributors house brand. I used their 5:1 epoxy at a time when their pricing reflected a considerable savings over the Gougeon Brothers WEST system epoxy that is the market leader in 5:1 formulations. Over time the cost savings became less significant and I switched back to WEST system.


Subsequently I came to the conclusion that the practical advantages of a 2:1 mix and no-blush formulation were more important that the slight advantage in ultimate strength that WEST and other 5:1 formulations offer.


None of these places own chemical plants that make epoxy. So the questions are: where are they getting their epoxy, and how careful are they about quality and consistency?


I came to the conclusion that the relatively small cost advantage of using TB products was outweighed by the years/decades long reputation for quality and consistency enjoyed by the better known brands. TB does not (or at least did not at the time I looked) publish as detailed test results as other brands do.







Probably either speed will work out OK for what you're doing. Slow is sometimes an inconvenience. Fast can be a serious problem if you get caught with the epoxy lighting off before you're ready on larger projects.

[SVAphrodite]

All makes sense!


Good trick with the lid and spout! Also wouldn't have thought that I could remove the epoxy from the buckets.


Thanks for the offer! I will reach out when I get into it!

Originally Posted by Madehn

had to leave for a bit but i think everyone else answered the questions connected to my answer-- Thickened epoxy using the west system is pretty simple to make and experiment with - once you start with it you will find a lot of uses- it is good for sealing/waterproofing anywhere that you do not need flexibility and that is not exposed to UV. i thnk a gallon can of the resin is about $100 bucks and the hardner is less. You use two different hand pumps one for hardner and one for resin that are made for the west system cans- that makes mixing them in the right portion pretty idiot proof-- one pump of hardener then one pump of resin then repeat- once you have the sesired quatntity stir very well- then add in the 404 a bit at a time and stir more - keep adding 404 and stirring it in until you have the desired consistency- i like mine to be like a stiff peanut butter when i am attaching to the hull- keeps fillets in place whie drying-- for coating for waterproofing you dont use any 404 just straight epoxy brushed on with a paintbrush- i use a cheap chip brush and throw it away each time. The plastic mixing cups can be reused- just flex them enough to pop the old hardened epoxy out and mix a new batch. tip - take the cap from the resin/hardener container and leave it upside down on the top of the container in a clear space- when done dispensing, turn the spout of the pump so that any drips land in the upside down cap - make for a cleaner working area. mix small batches at a time- too much at once will tend to cook off and harden before you can use it. There are a lot of U-tube videos out there on how to use-- jamestown dist i think had some good ones as well. if you get into it and run into problems send me a PM and i can give you a call and try to help you out. Later if you actually start to do fiberglass work, i have less expertise but have managed some decent projects