Riotvan88

I've been building a smit Rotterdam kit and have painted my hull now onto the super structure. I used epoxy to seal the wood and get an even surface. Then used primer. The hull looked great until actual paint went on and I could see flaws everwhere. So sanded it back till it looked smooth paint again and still flaws. Sand paint sand paint....fast forward 5 cans later and I'm finally happy with the result. Here are my results Surely I've been missing some key tricks here? Is there a way to get a good finish without using a million cans and hours of sanding?

After some rumaging around I've found the empty tins of everything I've used. The complete schedule is Several coats of CPES 1X coat WS Gflex with water barrier additive 1X coat WS Gflex with fairing additive 2X full cans automotive high build primer 2X full cans plasticoat outdoor trade paint Black above waterline 2X full cans plasticoat red oxide below water line The boat looked smooth but each time I put paint on I'd spot flaws which is why I've used so many cans. Paint, sand paint, sand. Anyway I plan to add plimsol markins with decals and so will add a top coat to seal them in. Thus the top coat need be water proof to protect the decals. Hopfully the end result will be a matrix of layers that will keep her dry.

Still relevant. In Aerospace we still use isometric, 1st and 3rd angle projections. We don't draw them anymore we model parts/assemblies in a 3D program that then spits out whatever drawing is required. In fairness one must understand geometry to create the 3D model in the first place.

I've been using a 3D printer to produce detail parts in PLA. I guess of you want metal part then CNC is the way to go

I'm an Engineer when I was at uni in 2010 our teacher made us learn to draft on boards before we could go into CAD. I liked this approach as you actually use alot of the basic skills even in CAD especially true if using a parametric tool that uses sketches to create 3D objects. Contrary to popular belief CAD dosn't do it all for you it is simply a digital board that renders a 3D model from 2D infomation. A user still needs to be able to produce that 2D info properly for the system to generate a 3D visualization. You are correct however that drafting on a board is more of an art. At work I've occasionally though rarely had to work from drawings as some of our older products are pre CAD and still need modifying/upgrading. CAD certainly speeds up the design process as you can go through multiple iterations of a design rapidly on a CAD and detect clash easier. You can rapidly design multiple parts in assemblies and check fitment, tolerance, maintainabilty issues etc. From a user perspective as a tool to do a job CAD wins everytime. The 2D drawings produced from CAD programs do lack any artistic flair IMO and are bland. I occasionally design things for personal projects on my A0 Neolt drafting table using rotoring isograpgh pens and agree it is definitely satisfying to add line weights, stippling and little details to make the drawing really pop. Such things a CAD produced drawing lacks. But to be fair I end up using fusion 360 for 90% because it just makes the design process so much faster not to mention ability to 3D print mock ups and the like

That's a great idea, I have taken pictures along the way but I've not really recorded anything down. A bill of materials would be a good idea next time.

Good to hear I'm slightly concerned that I used WS epoxy without glass for a smit Rotterdam and now wish I'd glassed. Seems some have had sucess with epoxy only. Your boat has held up a decade and counting. Though I'll glass future builds

I know what you mean especially with varnish. I definatley didn't sand the epoxy off generally but it's possible certain spots might have been sanded though I can't really remember. I did lots of primer layers sanding between coats and occasionally sanded back to the epoxy layer in spots. I do remember mixing up small batches of epoxy to patch areas I suspected a sand though might have ocured but always a chance I missed one or two. That's the problem with an on/off project. Can't remember half of what I did to build it.

I see the problem with future expansion/contraction etc and I do wish I'd used glass now just for piece of mind. I'm semi tempted to strip paint and glass it but at same time I really really don't want to. That said the Gflex is used to seal full sized dinghys and day sailor boats. It has a much higher elasticity than polyester according to their website it's designed to create structural bonds in wooden constructions and does mention it's ability to accept flex and expansion. Didn't many older models simply use sanding sealer or varnish and do fine?

Cheers Bob I did two coats with Gflx one with water barrier additive and a final with fairing additive. The whole model was done in CPES as well as Gflex including decks and superstructure albiet only one coat of Gflex for those areas. Outdoor varnish was applied to all inside surfaces My concern is during all the priming, sanding, painting (done over months) I may have sanded through in some spots without realizing. Probably not but impossible to know now. I plan to give several coats of satin lacquer at the end which should also provide an additional waterproof barrier as well. I've made some small test hulls one with paint and topcoat only to simulate a potential sand through area and one with CPES, Gflex and paint to simulate the the hull generally. I'm going to place these in water 24/7 to see how long these coatings last.

Ah ok thanks for the reply. Did you use cloth on this hull or just west systems epoxy? I ask because I've built a model and used only west systems epoxy. I will glass future builds but I am interested to know how other models held up that like mine only used epoxy.

I have built two small test hulls each the size of a matchbox one with the paint system only and one with the epoxy coating only. Will build a third with epoxy + paint to be truly representative of my hull. I'm going to float these in a bowl to see how long the coatings last.

Thanks for the reply. I coated the whole hull in epoxy atond payed special attention to all hull penetrations. Then several coats of automotive primer and costs of paint. Inside has been varnished but could add epoxy to it as well. Boat will be on water 6-12 times a year summer only.

Hi thanks for the reply. I think you may have not understood the problem. I did not use any glass at all. I treated the wood with a penetrating epoxy then 2 coats of marine epoxy only no glass. I did this based on some recommendations (seems others have done it also) My worry now is that without glass the model is only suitable for display. Interested to see what others think.

What happened to the model? How did it leak? Was this built using WS gflex epoxy? I believe you commented on my thread about fiberglassing a hull. Did it leak due to using epoxy only with no glass cloth? I've done the same on my model. Bit concerned now.

Hi all seeking some advice I have built a smit Rotterdam kit. Intention was always to make it RC. Here is current progress However I am now deeply concerned I have made a huge error. When looking for advise on glassing the hull I was advised I could use epoxy resin only (no cloth) with additives 422 Barrier Coat...see thread below This was recommended by a couple of people so I went down this route and ended up painting the hull with Smiths penetrating epoxy sealer then did two coats of west systems Gflex epoxy with 422 barrier coat additive added. I'm now worried this was wrong and now the boat is unsuitable to be RC. This epoxy is what they on full size yachts and dinghys. (Used it myself to fill damage on an Enterprise dinghy) Any thoughts? perhaps I'm worried over nothing? would appreciate any wisdom on this. Future builds I'll definitely use glass. I just hope I haven't limited this to a static build.

Do you mean the fender? What's wrong with it? I've seen plenty of real yachts with a bow fender like that

Picked up this RC model sail boat second hand. Seller didn't know anything about it. I really liked the look of it and bought it. Its a fiber glass Hull with wood mast, decks and superstructure etc. The Hull looks exactly like a Revell Inga IV but the superstructure is totally different as well as the rig. It also looks like it either had 2 masts at one point or possibly the kit had the option to fit two masts. Perhaps its a custom design using an Inga Hull or modified Inga. Can anyone identify it?

Hi Jan. No this kit is the old version so the interior is very basic. I have made my own interior based on photos I found online. It is made in a CAD program and 3D printed into pannels that I painted and will assemble into the bridge. I've added fiber optic wire to the main consoles as I'm going to light the control panels. I've tested this with everything lose fit and it seems to work quite nicely.

Sorry for the late reply. I went for an industrial outdoor matt spray paint in the end. Here are some pictures of my build so far. The bridge interior pieces are just loose fit as I'm waiting to finish all the paint before gluing it into position.

*UPDATE* Managed to sand the epoxy smooth and is now in primer. 3M aluminium oxide sanding paper 80 grit and then 120 followed by 400 did the trick. Ready for paint now

Update* Thanks for all the advice in the end I used 3M sandpaper as someone else suggested previously. This sandpaper on a wooden block has knocked back the lumps and high spots in about 2 minutes of sanding. I didn't apply the epoxy thick, I used a credit card to try to squeegee it thinly onto the Hull rather than slather it on with a brush. I intend this to be a radio control model which is why I used epoxy. Now that the 3m paper is sanding it very easily I think the issue is exactly what someone suggested poor abrasive products. The surface is already smooth after a few minutes with 80 grit so I'll keep going with it. Perhaps worth mentioning is the sanding blocks I used previously were infi model sponge pads as pictured (I used 220g not 800g)

Thanks for the advice, I'll try to sand this with different abrasives as has been suggested. The epoxy is actually designed to be sanded so I do not believe this is beyond salvage with a better choice of abrasives. This is a kit and a re purchase is simply not an option. The choice of epoxy was actually a recomendation from this site.

I'm going to try your suggestion with some 3m sandpaper. The blocks have been ok for balsa,milliput and the like but don't seem to touch this epoxy

Thanks for the advice, I'm using sanding block by infi model. The model is getting smoother but at this rate it will take weeks of sanding. I'm going to try with some m3 sanding blocks. See if that madrs a difference.