Someone laughed at the melamine one i built a few months ago so feel free to laugh at this one... its what comes out of the inside that counts, when i laminate the inside it should come out 1 inch smaller on all diameters than the plywood box on there now so it will look quiet a bit smaller than what u see
the step back is only 250mm or 10inch i realized with my width i had to add the lower engine mounting bolts width plus the thickness of laminate times 2 plus a little more width just so the nuts for the bolts sit on flat glass and not the radius in the corners this is what i came out with the lower corners will have to be trimmed to fit the hulls V
the outside lips of the mould has to be much larger to fit the vacuum hose and to tape down the vacuum bag around the radius of the mould so it looks huge but reassured it will be much smaller people will probably laugh before they read this last bit...
i made a booboo on the face plate of the mould cut it 100mm to low so had to remove 100mm and put in a small brace that is currently lifting it off the transom this will be removed when i glue the mould together the braes are there only temperately
Have to admit i have never vacuum infused before and i have only ever once wet hand layup than vacuum bagged which was very easy and successful, if i can afford it looking to order the MTi vacuum infusion hose it stops the resin at the hose from going back into the vacuum line instead of using the ordinary spiral hose and a catch pot much cheaper to use as a one off too and i am hopping it allows all the cloth to wet out evenly thoughout the mould
I just sacrificed a length of cloth in this rain i layered the brack/mini pod with the 630g woven roving i had to cut down each corner and over lap it sat really well in the side and back corners
I sat down and thought about vacuum infusing, hand layup, vinylester, epoxy, with adding a mask yo use the vinylester will bring the cost up close to epoxy
Also thinking of going chopped mat as first mould layer than cloth than mat 10 layers of each with the epoxy resin
Do u guys think i would bennifit using some 45 corner timber in the corners to soften the cloth wrapping around it and to get rid of that boxy look?
Any thoughts?
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Gazza, you must really like making things hard on yourself by even thinking about vacuum infusing, you are not building a high tech addition to your old boat, by the time you get the special resin, all the peel films and plastic covers, decent vac pump, plus fittings etc. and the setup time you could have finished this in 3 to 4 of days at half the cost and effort doing basic glasswork.
My suggestion, and this is the way I would and have done in the past, would be to get your self a sheet of MDF 16mm, and build yourself a female mold in the final shape out of it, so bottom, back, sides and transom. once you have that shape, before assembly, wax the MDF pieces several times. Assemble and get some curved corner timber strips (Bunnings) and fit inside to the two end sides and transom bottom, wax those as well, get some Plasticine and force it over the curved strips inside using a piece of plastic pipe, you can use a hair dryer to heat and make the Plasticine more pliable. You can use the release wax to also smooth out the plasticine. Give the whole inside a coat of PVC mold release and then you are good to go.
1) Give the inside 2 separate coats of Gelcoat, after each coat, put a air fan to blow air into the pod mold as the styrene coming out of the curing gelcoat will stop the curing evenly/properly.
2) Once gelcoat has hardened, coat it with resin add a layer of 450gsm CSM glass and more resin and laminate, do one layer first using unwaxed resin (use unwaxed resin for the entire build). Roll out the air bubbles, that will complete the first layer and if you roll it out properly you will have no egg shell voids later.
3) When that layer has hardened add three more layers CSM, W/R, CSM, (using unwaxed resin) (600GSM, 800GSM w/r. 600gsm CSM)
4) Cut up some ply sheet to fit inside the mold, make a resin bog and spread it on each piece at a time and clamp, lay up each sheet individually, 1 to 2 layers of CSM, once set laminate the ply in. Cut 2 more sheets for the transom.
5) Wet out and roll 2 layers CSM ( or 3 layers of CSM, W/R, CSM) on the transom, (wet one ply face, lightly clamp to the wet glass, repeat for the last piece. (Using 3 x 1/2" ply layers with the layers of glass will end up about 50mm thick.
6) Add another 3 layers of CSM, W/R, CSM over all the sides to tie it all in, you may need to repeat this step as well depending on what size motor you intend to put on the back. (If you do add the additional 3 layers of glass then do it before the ply)
7) Cut some more ply for bracing on the inside, laminate the "+" (cross)" outside the pod and then glass, when cured, fit it inside the pod (at 90 degrees not diagonally) and laminate it in with strips on the edges. There are lots of other ways for reinforcing the inside of the pod.
8) Make a top and laminate it in the top of the bracing, You could just get a sheet of glass, wax it, apply PVC release, Gelcoat it, laminate with about 8 to l0 layers ( in 2 goes so it doesn't over heat) peel it off cut out the hole/s for access hatch covers
9) Flowcoat the insides, you may need to tape off areas where you want to glass the top cover to. Saves sanding by doing it.
The reason for using the MDF is that it is flat and smooth (unlike most ply) so once you add the first 2 coats of gelcoat to the mold you should only need some minor sanding followed by a cut and buff to give you an excellent finish. Also the two coats will help prevent sanding down to glass, most of the problem areas will be in the corners with the plasticine.
It's sounds much harder than it actually is and what I haven't mentioned is allowing small areas cut out of the ply for the bungs and drainage, sealing all timber etc. angling the sides so it doesn't look like a box and also adding looks and strength to the design. Do not lay up more than 3 layers on the flat areas otherwise it can bow and build up heat.
Don't build up the overlaps too much as it can also lead to bowing on the flat areas and you will probably have to plane down the ply edges so it doesn't make an air void between the glass and the ply.
There are also various methods to attaching a pod to the boats transom, either glass directly to the transom, or else as a separate pod, that way you can take the assembled mold under cover to glass it, but then you need to attach it to the transom via bolts, glass/adhesive.
Unfortunately I can't write down and teach all the things that you need to know as that would take way too long but this could give you some ideas to work with. What works for me may not work for you as you don't have the experience that I have but it isn't as hard as it sounds and you will get a much better product. Just my 2 cents worth.
Thanks for the lengthy post Ed sounds really hard that way, i have built the female mould already from 12mm ply seems strong as its not deep i also bought some 30x30 cornering to round off the edges as u mentioned i was originally going to round off the edges by filletting the mould
Thanks for your laminating schedule i only have 600g WR on hand i was going to go 450 chopped mat powder bound and 600g WR with epoxy resin as i need to work in the back yard
The vaccum infusing was only to laminate 20mm's in one hit but it was going to cost about $500 to set up everything
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As I mentioned, might sound hard but it really is easy, I suppose once you know something next time round it is easy. As for doing a solid 20mm laminate in one hit, you will probably get thermal runaway in the resin, I don't know about Epoxy but the most layers I laminated in one hit was about 12 using ordinary resin and I had to use a water hose to keep the temperature down, had to dice it afterwards as the resin go so much heat it fractured and almost started to burn. Also not sure that even using vacuum infusing that the resin will work it's way through that many layers.
The resin they use for vacuum forming is pretty thin from what I gather, I have never used that method myself but did study up on it at one stage as I was thinking about doing a boat that way. Even got a pump and 300l reservoir to hold vacuum in case the power went down in the middle of a pour. But even then, from what I remember nobody did that thick a laminate in one go. Out of curiosity why would you want to do a 20mm laminate anyway?
Here are a couple of pics of one I built about 25 years ago, got a bare hull and fitted it out on a 23ft Scarab, and the other pic is of the completed boat sitting in the water at Tangalooma, I added wings on the sides to for use as a duckboard, made it so much easier to climb out of the water after a swim.
Regretted selling it but needed the cash for a house deposit.
did a beautiful job on that scarab , what a nice hull and so deep in the back ..
Thank you, with the 225 Evinrude on the back it used to do 43knots, I actually prefered it to the 26ft Scarab I did up a few years ago, I found another new bare hull about 6 months ago for $2500 on Gumtree, been sitting in a shed with just the floors put in and I was sorely tempted but as I am downsizing to get ready for doing laps around Oz in the next 18 months my missus would have my head if I took on another project, not to mention that I would have nowhere to store it after we sell our property and couldn't use it for several or more years whilst traveling, so probably for the best, it didn't last long in the for sale ads.Originally Posted by catshark
Just an odd shaped caravan...…..
That look like a really well build pod Ed
I was going a solid laminate for strength and no wood to ever rot, atm the cloth is really cheap i probably over built that test piece at 20mm the step back bracket/mini pod will likely be around 15mm or about 20 layers the cloth is .6mm the mat is .8mm per layer so it should be around the 14-15mm mark
I figured if i added fibreglass instead of the plywood it can only be stronger but i am hoping that theroy works not really worried about the extra weight over plywood it would probably be 10kg more
Just really worried about the plywood going unscene and rotting loosing the engine and at a criyical time off shore i cant swim and i dont wanna be eatin lol
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Why not treat the plywood with Evadure? As it is epoxy based it will be compatible with your resin system. Plywood is hard to beat for strength. It will be easier to add internal bracing to the pod as well. PS aren't you using wood in the transom anyway?
Im waiting for the shops to open to get some prices on products going to try polyester multi laminating resin but i cant work out how it works, i am reading u can only do up to 3mm laminate at a time but if u need a wax layer on top of that 3mm than how do u put on further layers?
if i were to laminate 15mm using the multi laminating resin than put on the final wax layer to cure it all would it actually cure thru 15mm? i understand the heat may be excessive its only a small job i can pick up a fridge box or washing machine box and take my vertical window air conditioner out the back and stick it on the side of the box set to 19c im thinking that could be a plan but unsure... have only ever used polyester for one tiny trailer roller mount hole in a hull
also from my understanding polyester without styrene or wax it shouldn't stink much? worried about my neighbours and pets and stuff if it is the wax/styrene that smells i can cope with it for one final layer
Don't try to over complicate things, just make a pod the same as your transom, ply and glass, you might be able to make a mould to get the outside nice and smooth, but constructing, strengthening will be so much easier, and easier for possible modification later, that said, I still think leaving the transom as is will be the best long term outcome, even if you have to cut a "notch" out of it.
Gazza, the way that wax and styrene work is that if you use a waxed resin, the wax seeps out of the wet resin and sits on top blocking moisture by making a thin barrier and stops the surface from going sticky, in other words if you know that you will have to sand the laminate down then that is what you have to use otherwise the sanding paper will clog up within seconds. If however you need to go over it and add more laminate then do not use waxed resin as all the wax on the surface has to be removed by sanding cause it will stop the next layer from binding to the previous surface. (bit like painting over an oily surface).
Using acetone to try to remove that wax can help but it generally only smears it around more than removes it. Sanding is the way to go as it also keys the surface to physically bond to the new laminate, without the wax the new resin binds to the surface chemically and physically bonding to it providing there is not too much time between laminates ie: 12 hours or so depending on weather conditions otherwise you will need to rough it up.
The styrene in resin is used to dilute the resin to make it thinner and able to penetrate the fibreglass mats and also make it easier to work with, as it cures a portion of it evaporates out of the resin into the atmosphere hence the smell. To stop the smell you need to cover it up with plastic on top of the laminate directly, OK in small repairs but unpractical on large areas unless you are doing an infusion process laminate. You can also buy a small tin of wax in styrene solution to add to unwaxed resin or add to gel coat to turn it into flow coat, I think that is about 5ml per liter of resin or gel coat but you would have to check with the shop, so you don't need much. Atmospheric styrene will also stop the resin or gelcoat from surface curing properly hence the reason I suggested using a fan to blow it out from a female mold, you don't need to do this on a male mold.
Putting an air con over a thick laminate over the size that you are suggesting won't work, resins need a certain temp to cure properly, it contains a promotor such as cobalt which reacts with the MEKP and generates heat for the resin to cross link the polymers and form the bonds, (not sure if the promotor also contributes the the cross linking), anyway the colder the climate the more promotor the manufacturers put into the resin but the MEKP ratio to set the resin stays the same, that is why they make summer and winter resin mixes, to keep the reaction temp more constant.
Getting back to the aircon, whilst the cold air may reduce the top part of the laminates temp causing those layers to not cure properly, the internal layers will continue to build up the heat as the glass will act as an insulator and the resin will probably self destruct and fracture massively on the bottom to middle layers. I am sure by now you have left a small pot of excess unused resin lying around and it stated to crack and maybe even start to smoke. Same thing but between the glass layers. Resin needs to cross link within a narrow temp range for it to work properly. I have no experience using epoxy to make thick laminates so it may be different.
As for not using plywood in between laminates, if you seal the plywood off properly you will not have any problems, I have worked on very old boats 40-60 years old and the plywood is still as good as the day it was built.
Where problems arise is if the laminator didn't do a good job building something and the laminate developed a crack that let water seep into and reach the plywood or else drilled into it and didn't seal the hole with epoxy. Also there are differences in the wood that is used to make plywood, ie; hardwood vs pine. Do things right and it will outlive you. By the way silicone adhesive is not a good sealant, moisture does penetrate it over time.
Thanks guys i appreciate the help i just went and picked up some supplies spent more than i wanted and came home with double of what i needed the shop didnt have the exact sizes i needed but theystill had what i needed
i bought 20L of wax free poly, 1L of blue mold release, 10m of 450 csm i had a good conversation with old mate at the shop and he answered a lot of my questions about the laminate and process he said to only laminate 3 layers no more or it will crack as u mentioned Ed and it will get too hot he also said not to glass in the sun and to only use 12mls of mekp for 1L of resin in this weather, i couldn't afford the gelcoat for the mould so i either have to wait untill this week and order a litre or paint the job after it comes out of the mold, which of these would u guys chose paint before or after?
i am going to keep it simple first layer of chopped mat than a layer of WR let it cool off an repeat sounds quiet easy and much more favorable over the epoxy, with the epoxy while i was doing the transom i noticed if i sanded it after 24 hours the sander would clog so it needed 48 hours minimum between layers
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