Epoxy Resin Advice

[Steve509926]

One of Rednecks "keel boards" has cracked and needs to be replaced (more of which to follow over the next few weeks as I have a few design ideas I want to try)

I've never used epoxy resin to seal plywood and I thought I'd give it a try, but which one? Advice please

Stumbled across this one

https://www.epodex.com/en/product/eco-system/

anyone tried it?

[whiskylee]

West systems has been around for a long time, it's not the cheapest but lots of tutorial videos out there

https://youtu.be/_yQnQzwRtcM

Sent from my moto g(8) power using RIB Net mobile app

[Orwell boy]

I have used East Coast fibreglass ,pretty fast service and some good project guides
https://www.ecfibreglasssupplies.co.uk/topic/projects

[GuyC]

I tend to use SP Systems, which is the same as Gurit.

If you are using the epoxy as a varnish, you can get UV stable resins.

East Coast Fibreglass Supplies has some good info on its site.

[Waterman1]

I would suggest West System if you can find it. Small company, still family-owned. Research and technical advice is without comparison. All marine epoxy products are not created equal. The Gougeon Brothers (manufacturers of West System epoxy) in my world are the experts and I have never been steered wrong using their products on my boat. The technical advisors are all university-trained engineers. They are available by phone and wonderful to work with. I don't work for them nor do I receive any income from this endorsement!

[jeffstevens763@g]

Originally Posted by Orwell boy

I have used East Coast fibreglass ,pretty fast service and some good project guides
https://www.ecfibreglasssupplies.co.uk/topic/projects

+1 I use these on all my projects, prime the ply first then glass up finish with flowcoat the stuff I used is on my console build.

[Steve509926]

Originally Posted by jeffstevens763@g

+1 I use these on all my projects, prime the ply first then glass up finish with flowcoat the stuff I used is on my console build.

Because the airdeck keel board won't be visible and I'll be putting on at least 3 or 4 coats of epoxy, do I need to finish with a flowcoat?

[jeffstevens763@g]

Originally Posted by Steve509926

Because the airdeck keel board won't be visible and I'll be putting on at least 3 or 4 coats of epoxy, do I need to finish with a flowcoat?

You don’t need flow coat Steve but I would prime it because it soaks into the wood if it’s just to give it a waterproof coating. If you want strength I would prime first, glass it, then flow coat.

[Limecc]

Originally Posted by Steve509926

Because the airdeck keel board won't be visible and I'll be putting on at least 3 or 4 coats of epoxy, do I need to finish with a flowcoat?

Flowcoat is based on Polyester, they say epoxy can go on poly but not the other way, not that it matters much in this instance.

3 or 4 coats is overkill, you're adding a lot of unnecessary weight. All that's needed is to close the grain off, two generous layers is plenty.

I'd consider using thinner ply as a core and using a layer of chopped strand to make up the correct thickness, flat it back with an orbital to finish. You'll need a router to prepare the edges. 600g CSM laid up is 1mm thick. Don't paint/prime it beforehand if you glass it, you want the Poly or Epoxy to saturate the grain to get a better bond.

Here's something I viewed recently that you might find helpful around 13 mins in. It's a great series actually. Enjoy.

https://www.youtube.com/watch?v=2gQvnH9CWjE

[Steve509926]

Originally Posted by Limecc

Flowcoat is based on Polyester, they say epoxy can go on poly but not the other way, not that it matters much in this instance.

3 or 4 coats is overkill, you're adding a lot of unnecessary weight. All that's needed is to close the grain off, two generous layers is plenty.

I'd consider using thinner ply and using a layer of chopped strand to make up the correct thickness, flat it back with an orbital to finish. You'll need a router to prepare the edges. 600g CSM laid up is 1mm thick. Don't paint/prime it beforehand if you glass it, you want the Poly or Epoxy to saturate the grain to get a better bond.

Hindsight is a wonderful thing

I've already cut the new Airdeck Keel board out of 18mm ply as I had a sheet in the workshop, and it will be too thick if I glass it, so I will continue down the epoxy only route.

If the design works, I'll run with this Airdeck Keel board for this year and probably make a new one out of glassed 12mm ply for next year.

[Limecc]

Originally Posted by Steve509926

Hindsight is a wonderful thing

I've already cut the new Airdeck Keel board out of 18mm ply as I had a sheet in the workshop, and it will be too thick if I glass it, so I will continue down the epoxy only route.

If the design works, I'll run with this Airdeck Keel board for this year and probably make a new one out of glassed 12mm ply for next year.

Worth getting lightweight ply, the strength is in the glass. Boat hulls use balsa.

https://www.youtube.com/watch?v=uLKiDa2dqq8

[Steve509926]

Originally Posted by Limecc

Worth getting lightweight ply, the strength is in the glass. Boat hulls use balsa.

I actually don't mind the little bit of extra weight. It's low down and forward of where I sit, so it should help trim Redneck a little better when I'm solo.

[Limecc]

For waterproofing I've tried a few epoxies. All were successful. The low temperature stuff is thicker so can't help using more of it, I prefer the thinner stuff as it's more penetrating with additional coats if needed.
https://www.ebay.co.uk/itm/254627679885?

White vinegar works well as a brush cleaner.

[GuyC]

Whilst you are not planning to glass this time, a general comment is that if you do choose to use CSM with epoxy, you should choose a powder bound mat rather than an emulsion bound mat (which is what most of them are). The powder / emulsion is what binds all the fibres together in it's 'dry' state. Once you start brushing on the resin, it dissolves the binder and allows the mat to form to the shape. Epoxy won't dissolve the binder in emulsion bound mat. Some details below.

https://www.ecfibreglasssupplies.co....strand-matting

I know you've already cut the floor but it is worth using the albeit astronomically expensive marine ply unless you treat the deck as a consumable. WBP and the 'bargain' marine ply will start to delaminate pretty quickly almost regardless of how much encapsulation you do.

I use acetone for brush / general cleaning plus I wipe down the thing I'm epoxying beforehand to remove grease etc. and who doesn't like the smell of pear drops in the morning. The acetone dries quickly and doesn't contaminate what you are epoxying.

I tend to use 'disposable' brushes bought from Ebay. It depends on how frivolous you are as to how many times you clean the disposable brush.

[mikehhogg]

epoxy resins and others like polyester \vinylester etc are not waterproof on their own ,they must be topcoated with either flowcoat or gelcoat. Because you are using a piece of ply that you already had the cheapest option is coat with polyester resin maybe twice letting the first coat seal the edges and soak in .then coat with polyester topcoat .the only advantages of using epoxies are basically strength in the laminates but you are not laminating .

[Steve509926]

Thanks all, I now have a much clearer idea of what I'm I'm doing now and how I'll improve it in the future.

A couple of things which I don't follow:-

GuyC - why will good quality extetior ply "delaminate pretty quickly almost regardless of how much encapsulation you do"

mikehhog - I've searched t'internet and every site specifically states the excellent waterproofing qualities of epoxy resin. Can you give a bit more info as to why it isn't waterproof.

[mikehhogg]

Above the waterline it would have a good waterproofing quality. for underwater use the water will permeate eventually.The gel coat or top coat is usually considered the waterproofing coat. on the subject of ply there is only one true MARINE GRADE and that can be identified not by the BS stamp but will have a LLYODS Stamp. Most commercial boat builders use polyester resins as epoxy is just too expensive.

[jeffstevens763@g]

Have you thought of using this Steve

https://www.cladcodecking.co.uk/35-w...MaAv8UEALw_wcB

[Steve509926]

Originally Posted by jeffstevens763@g

Have you thought of using this Steve

https://www.cladcodecking.co.uk/35-w...MaAv8UEALw_wcB

Hi Jeff

If I was just doing a straight forward Airdeck/Keel Board replacement I would definitely look towards a composite board.
However, I am attempting to redesigning the front and back keel boards so that they work together and, hopefully, work more efficiently.
I'll post a couple of vids tomorrow which I think will give an understanding of what I'm trying to achieve.

[Steve509926]

Originally Posted by mikehhogg

Above the waterline it would have a good waterproofing quality. for underwater use the water will permeate eventually.The gel coat or top coat is usually considered the waterproofing coat. on the subject of ply there is only one true MARINE GRADE and that can be identified not by the BS stamp but will have a LLYODS Stamp. Most commercial boat builders use polyester resins as epoxy is just too expensive.

Hi Mike, completely appreciate where you're coming from, but we are talking SIB. The Airdeck/Keel Board will only spend 5% / 10% of its life in water. Max of a couple of weeks being wet before being stripped down, dried out and packed up.
I think exterior ply and a few coats of epoxy for this experiment will surfice. If it turns out to be a success, I will definitely go down the route of epoxy, glass and gel/flow coat.

I'll post a link to a new thread tomorrow re: Airdeck /Keel Board Redesign.