I mentioned this in another thread, so I glued some ecodeck together with thickened epoxy and tested it to destruction, the only prep was a wipe with metho. The material failed before the glue.
different manufacturers will have differing brews, this is the one from the big green shed

Thanks for the effort and information, woko

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woko said..
I mentioned this in another thread, so I glued some ecodeck together with thickened epoxy and tested it to destruction, the only prep was a wipe with metho. The material failed before the glue.
different manufacturers will have differing brews, this is the one from the big green shed

Interesting I would email this to Ekodeck including exact epoxy glue brand to get their comment. In the other post I have on-sent their advice to me that it is not Gluable or paintable. I pointed out to them a glue type used in HDPE pipes they said they would look into it their technical advice service is excellent. I am looking at the photos on a mobile screen only so a bit small but it appears that the glue has not failed or the Ekodeck has not failed rather the glue has simply not adhered to the Ekodeck at all. I may be missing something.

I must admit I was surprised. The ecodeck definitely failed, it took a fair hammering I even knocked it out of the vice, the damage is evident in the 3rd pic, in the end I used a piece of flat bar as a drift and it sort of sheared the composite off. The thin black layer on top of the white glue line is the remaining composite. The glue I used was nothing extraordinary a 5:1 fgi epoxy resin and a chopped cotton filler. The half I didn't destroy will spend some time on the dash board of the Ute to see how it goes with the heat as the composite expands

Ok great. Without making a meal of it if you can make up a piece of your planned toerail beam and put a 5:1 splice in it and load this in bending in the 2 directions - so ideally 2 samples- this could be instructive. Also a t joint sample loaded in lateral bending. These type joints maybe would be more generally representative than the lap joint in shear

Ok as suggested I've glued some more trials, the scarf is 3:1 as off cuts I have are limited & the T joint is on the sample for the same reason, the timber sample is for comparison, I glued these up yesterday morning & looks promising. The plan is to test the T joints then rip the composite scarf down the middle so I have two samples. I've also glued some composite to wood.
Any suggestions as to testing methods other than beat the crap out of it with a hammer ?

Sorry for Delayed response would not beat the tar out of them with a hammer as such an impact loading would not be normal. Suggest a 3 point bend set up as per numerous ASTM standards be done. Load applied gradually via car jack and deflection monitored with dial gauge if possible or calipers or 0.5mm steel rule. Try and get 5-10 points before failure so as to graph them load vertical axis deflection hoist axis. If you had a load cell to monitor load this would be ideal also but realise you don't have a test lab in your shed. Next post will give link to show what the astm 3 point bend test looks like. For the t samples guess just hold the top flange of the t In the vice and push sideways on the vertical lower web end. Turn the t shape upside down

Google 3 point bend test heaps of links will come up

All good, had a couple of sunny days onboard & even got a sail in. Now rainy day games.
The T joints required a lever to make them part, the wood sample put up bit more of a fight, it's dimensions being larger would have contributed





The composite to wood sheared off as in 1st test

The 3 point test was surprising. With the vice jaws open 200mm and the scarf centred and a centrally located clamp, 1 turn of the clamp screw gave a deflection of 5mm, 1.5 turns gave a 7mm deflection and 2 turns gave a 9mm deflection, it was as I was getting ready to take a photo at this point it exploded









So in conclusion it appears that the composite can be glued. Ordinarily something like a T joint would have a nice fillet and be reinforced with glass tape to add strength. The composite is brittle compared to wood and as such has limited uses and is more expensive than Merbu but it doesn't bleed like a wounded beast

Top job you have done right there thanks for the heads up. Think you nearly have a test lab in your shed. Yes test samples must be geometrically equivalent to be able to compare load and deflection results as you would be aware.

google the below for a good article - using a 4 point test method which is an alternative to the 3 point. Some good graphs.
the strength of scarf joints Wooden Boat Magazine

Most timber load test show the quick failure mode as per your results - as soon as a bit of plastic characteristic comes into the load deflection curve failure is imminent. Yes merbau and tanin bleeding I hope I got a good epoxy resin and primer cover on steps I made as in the other article - time will tell.

Woko,

Thanks for the testing. What thickened epoxy did you use?

Today, I got a plank of Ecodeck (www.bunnings.com.au/137-x-23mm-5-4m-decking-greystone-composite-ekodeck-classic-grooved_p0121079) from the Big Green Shed, cut it into short lengths and made up a new floor for my engine bay. The only way to fix the floor is to glue or epoxy it to the inner face of the hull, hence the question. I will glue the floor up with epoxy and fix the actual beds to the floor.

As far as the material is concerned, I regard it as a softwood replacement, but without the tendency to rot. It is not as hard or stiff as hardwood, but drills, saws and planes much like pine, but with smoother edges and shavings. It drills something like HDPE drainage pipe. I imagine that it will deform plastically, meaning that if you fix it out of shape, it will adapt to that shape in time.

The photos below show the upper and lower sides of the floor. The lower side has been planed to fit the camber of the inside face of the boat hull.

As per his prior post Woko used;

The glue I used was nothing extraordinary a 5:1 fgi epoxy resin and a chopped cotton filler.

Sorry to say but I would not use this Ekodeck on a boat. My interpretation of Woko's posts is that he has concluded the same. Again I would suggest you ask Ekodeck. In the previous post which I brought this product up I mentioned Ekodeck's advice that it can't be painted or glued, but I found a HDPE pipe glue which could work - Ekodeck said they would assess this but I've not had any response since. Hope I am not the source of a great rush to use plastic "timber" products made from HDPE on boats.

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Achernar said..
Woko,

Thanks for the testing. What thickened epoxy did you use?

Today, I got a plank of Ecodeck (www.bunnings.com.au/137-x-23mm-5-4m-decking-greystone-composite-ekodeck-classic-grooved_p0121079) from the Big Green Shed, cut it into short lengths and made up a new floor for my engine bay. The only way to fix the floor is to glue or epoxy it to the inner face of the hull, hence the question. I will glue the floor up with epoxy and fix the actual beds to the floor.

As far as the material is concerned, I regard it as a softwood replacement, but without the tendency to rot. It is not as hard or stiff as hardwood, but drills, saws and planes much like pine, but with smoother edges and shavings. It drills something like HDPE drainage pipe. I imagine that it will deform plastically, meaning that if you fix it out of shape, it will adapt to that shape in time.

The photos below show the upper and lower sides of the floor. The lower side has been planed to fit the camber of the inside face of the boat hull.

Ach, I use a 2:1 fgi epoxy I previously posted 5:1 but I'm sure any epoxy will work as with most things advertising makes them better, milled fibre ( glass powder) makes an even sturdier glue than milled cotton. With the mechanical fixings you have there it would be over kill to go to milled fibre I think. As I found ecodeck is more brittle than wood. The percentage of wood/ bamboo fibre is I believe 60% + time will tell about its rot resistance prep I only wiped with metho. As it turned out I stumbled across a site that has done more extensive test than I did so I was merely repeating the results. Google wood plastic composite (wpc) epoxy.com ? they went into various prep including an interesting heat polymerisation of the glueing surface and are advocates for west system.
I think your biggest issue will be getting the hull substrate thoroughly clean of oil, you've made a good start, it's not the best place to be using hydrocarbon based degreasers ( get a good respirator ) but they run rings around alkali water base ones, thats from experience ive spent a lot of time in the last 6 months degreasing the bilge of a 60 year old workboat that has a DD power plant

My fishing vessel was 68 years old when I sold her. Hard wood frames and Oregon planks. All the engine room frame work for an auxillary engine and all the other bits were done in treated pine and left unpainted.

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r13 said..
As per his prior post Woko used;

The glue I used was nothing extraordinary a 5:1 fgi epoxy resin and a chopped cotton filler.

Sorry to say but I would not use this Ekodeck on a boat. My interpretation of Woko's posts is that he has concluded the same. Again I would suggest you ask Ekodeck. In the previous post which I brought this product up I mentioned Ekodeck's advice that it can't be painted or glued, but I found a HDPE pipe glue which could work - Ekodeck said they would assess this but I've not had any response since. Hope I am not the source of a great rush to use plastic "timber" products made from HDPE on boats.

r13,

OK, so what would you use? As you can see, I'm looking for a floor plate, with the dimensions of my Ekodeck floor, that can be glued or epoxied to the hull. I can then glue/screw/epoxy the beds onto the floor plate.

The floor plate does several things;
1 Provides a flat reference plane from which I can measure and manufacture the beds
2 Spreads the load from the beds to the hull, especially engine vibrations*
3 Provides something to glue/screw/epoxy the beds to, so that there is no need to screw or drill anything into the hull.

(* The vibrations will be damped by the polyflex bearings. I also intend to make the beds from the densest, heaviest hardwood I can find. The mass of the beds will damp the vibrations further, before they are transmitted to the floor).

Would an alternative be dense hardwood, painted or coated with epoxy or paint to keep the moisture out?

An older publication by the DPI for Timber in Boatbuilding includes a list of timbers for use in engine beds, see www.dpi.nsw.gov.au/__data/assets/pdf_file/0005/390299/Timber-in-Boatbuilding.pdf

If I don't use the Ekodeck, it only cost about $20 (the plank had a couple of chips and was sold as shop-soiled) and a morning's cutting and planing. The experience was informative.

That DPI is a very good article I had it in hardcopy a long while ago.

Numerous hardwoods would be suitable except merbau and some others due to the tannin / oil content as in prior text above. See last link below for other difficult to glue woods.

Red mahogany T+G as per here should be ok? Seems cost effective. Epoxy glue it after sanding and solvent (acetone or IPA) wiping the T+G lengths - see the technical data sheet of your epoxy to use the correct solvent. Sand joints smooth and 2 coats epoxy resin on the lot to finish off then glue it in, glue / screw the bends on ensuring the screw holes are well filled with epoxy glue to avoid water ingress, finish whatever paint you want suggest Norglass Shipshape.

narangbatimbers.com.au/product/flooring-red-mahogany-tg-sb/?attribute_size-mm=130x19&utm_source=Google%20Shopping&utm_campaign=Google%20Merchant%20Feed&utm_medium=cpc&utm_term=24724&gclid=EAIaIQobChMI2Pr4s4Kc9QIVlDY4Ch1ClQcUEAYYASABEgJjK_D_BwE

Good comments here re ensuring moisture content is low, sanding, solvent cleaning etc.

www.woodworkforums.com/f11/gluing-australian-red-mahogany-euc-resinfora-188685

www.wood-database.com/gluing-oily-tropical-hardwoods/

I always thought Aussie red mahogany is such a misleading name the red is the only thing in common. Out of the coastal hardwoods that are available I would be looking for bloodwood, tallow wood or greygum these are the preferred timber for fence post.
but how about pouring an epoxy glass floor ? Form work could be WPC, you could get real flash and set in some stainless threads for the engine beds. Epoxy gets cheaper the more you buy and off-cuts of heavy glass mat can always be found

Great thanks Woko I am probably missing things about 2 issues appreciate clarification;

1 Aussie red mahogany is as per here - the grade data etc is in the DPI article as per Achernar's post as well as at this link

www.woodsolutions.com.au/wood-species/hardwood/mahogany-red

Grey Gum is as per here and would be perfectly ok as you say - the reason I mentioned red mahogany was that it comes in the T+G decking so making an easy glue joint - grey gum could be available in T+G also.

www.woodsolutions.com.au/wood-species/hardwood/gum-grey

All hardwood is as per here;

www.woodsolutions.com.au/wood-species/hardwood

So as far as I can interprete Aussie red mahogany and grey gum is very equivalent - the modulus of rupture is probably the best property to compare. Did you mean Aussie red cedar which has a MOR of about 1/2 red mahogany and would justify your comment?

2 For WPC did you mean WRC - western red cedar.

www.woodsolutions.com.au/wood-species/softwood/cedar-western-red

Gee stainless thread inserts seems like a bridge way too far for this job.

That's the red mahogany I mentioned like all our hardwoods it's hard but not particularly rot resistant, the bloodwood & grey gum are prized for their longevity in the ground because of rot & insect resistant, tallow wood is also good and has a yellow waxy appearance similar to but not on the same class as the Australian teak ( flindersia ). Terpentine was traditionally used for wharf pilings of course spotty gum was used to build the trawler fleet but it's no use in the ground because of its lack of rot & insect resistance, horses for courses

WPC wood plastic composite

stainless threads I was thinking of was a length of threaded rod protruding from the epoxy glass moulded pour, overkill for a little motor? Probability

Spotted gum is not much use in trawlers. I eventually replaced the rotting spotted gum sections with treated pine. The trouble with spotted gum is shrinkage. I bought mine straight from the mill and was green and you could not always get the correct sections.
If I was to do the job on the engine mounts I would use treated pine. The same grade that is used for wharf piles. A few layups with epoxy and fibreglass cloth. Add some carbon fibre if you feel like wasting money.

I assume the reason for using spotty gum for trawlers was the supply of good logs. Interestingly it's hard to tell spotty from grey gum in the bush except for the time of year that they shed bark, grey gum has an orange colour new bark

The local mill used to cut spotted gum for the local mines and this kept them busy. If you wanted spotted gum for boat stuff then you would book a day and they would cut it and load on to your truck. The timber was dripping wet but bent easy and was especially cheap.

Just thought you may want to check out Accoya from Britton timbers. I'ts treated but not with chemicals. A process called Acetylation. It was used on the Noosa Heads suspended walk way. It has a 50yr above ground and 25yr in ground warranty.
Its one of many new timbers that don't use nasty chemicals.

That accoya looks like interesting stuff, pickled pine. Will try to get hold of some when the country returns to normal what ever that is. Thanks

Stop press ! I was just putting the cutting list together for the delayed gunwale rail cap and came across a heap of inter web inputs that strongly suggest that the composite woods are prone to rot if it's not capped ie sealed, the wood flour within takes up moisture and the rot sets in. PVC decking boards would be excellent for my intention but alas they appear to be interlocking hollow sections and totally useless in my application. Back to looking for brown merbau or perhaps do the topsides in red and work with the tannin bleed instead of fighting it

Cripes that's a blast from the past thread.............thanks Woko for the update............

Hi Archernar,
If I was going to make a plate to glue to the inside surface of a fibreglass hull I'd look at using marine ply. If you only need a half sheet you can get AA grade marine ply from Bunnings 18mm thick and laminate it to about what you have made in the wood composite. It will be as easily shaped as the composite and can be epoxy glued down and then glassed over and onto the hull. You wont be 'experimenting' with anything new as far as products go either. I've only fitted two diesels into boats but I've been in the construction industry since 1976 so I would endorse what Ramona has said about using a treated structural grade pine for the longitudinals for your beds. You wont have shrinkage problems that you could get with hardwood. I know epoxy glues timber well but I have had to rectify/replace a previous builders attempts to make laminated structural hardwood beams used under a house that had entirely delaminated. They were glued up using epoxy.
I'd think about getting the bed timbers to what I thought was the correct and fix with 316ss screws and epoxy from the underside of the ply before I glued and glassed the ply to the boat.
Feel free to PM me if you'd like to have a look at what I did.

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woko said..
Stop press ! I was just putting the cutting list together for the delayed gunwale rail cap and came across a heap of inter web inputs that strongly suggest that the composite woods are prone to rot if it's not capped ie sealed, the wood flour within takes up moisture and the rot sets in. PVC decking boards would be excellent for my intention but alas they appear to be interlocking hollow sections and totally useless in my application. Back to looking for brown merbau or perhaps do the topsides in red and work with the tannin bleed instead of fighting it

Hey woko, what did you end up doing with your rail cap? I'm in a similar merbau/ekodeck loop. I just pulled a rub rail off my boat- some kind of Australian hardwood. Filled with rot. After 30 odd years, every bit of external timber that wasn't teak had rotted away. The teak, which thankfully there's plenty of, was as good as new after a light sand. Incredible stuff.

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bendeac said..

woko said..
Stop press ! I was just putting the cutting list together for the delayed gunwale rail cap and came across a heap of inter web inputs that strongly suggest that the composite woods are prone to rot if it's not capped ie sealed, the wood flour within takes up moisture and the rot sets in. PVC decking boards would be excellent for my intention but alas they appear to be interlocking hollow sections and totally useless in my application. Back to looking for brown merbau or perhaps do the topsides in red and work with the tannin bleed instead of fighting it

Hey woko, what did you end up doing with your rail cap? I'm in a similar merbau/ekodeck loop. I just pulled a rub rail off my boat- some kind of Australian hardwood. Filled with rot. After 30 odd years, every bit of external timber that wasn't teak had rotted away. The teak, which thankfully there's plenty of, was as good as new after a light sand. Incredible stuff.

Went with merbau in the end, there's some pics in what did you do thread. I discovered after a bit of experimenting that bleach not only removes the bleeding stain but also if you brush some bleach on it after shaping ( an unbelievable amount of stain runs out ) wash it off and you short cut the bleeding process. Unfortunately I didn't figure that out until the end of the project and was using the scrapes for some other job

Nice job woko! And a complex one, by the look of it.