I have recently caught the RC sailing bug and have begun the process of building a new boat. I chose to do a custom design rather than a class to get a little extra experience with some modelling software I have for school.
Now I’m into the build stage and am wondering what might be the best way to proceed.
I currently have a planked hull form done and have started the long process of sanding. I had originally intended on making this into a male mold for a female mold, and then using that female mold to make the final hull. But I’ve been thinking that is quite a bit of extra work for a one off hull.
Should I skip the female mold and make my hull from the male mold? I have a decent amount of carbon fiber/glass experience, and I am fortunate enough to have access to a vacuum equipment as well. I was originally intrigued by the better finished surface that a female mold would give me for the finished hull.
If you are only molding one or two hulls, the male mold idea works nice. Get it sanded to shape and put a layer of packing tape (tan or clear mylar) over the whole thing, overlapping each strip. Then your epoxy/glass laminate will not stick to it.
No way to easily do a vacuum bag layup, just squeegee the excess epoxy from the layup.
Great job with the planking! You could put a nice finish on the planked hull itself and show off those lovely planks. Of course you’d have to take out the heavy frames, so forget I said that…
More pics?
John Storrow
That is a beautiful boat. For a one off I’m with John. Show off that planking job!! Put a lay of light cloth(.75 oz) on it and pop out the frames. You’ll be surprized how light and strong it is. After all wood is Mother Natue’s composite.
Don
Thanks for the responses and the praise. I have thoroughly enjoyed every step of making this, and I would love to keep the planking if possible and it would save the trouble of the extra layups. I think I should be able to grind out the heavy frames relatively easily. Would one layer of carbon twill and just the planking be strong enough? provided I put in a few frames here and there?
Here are a few more pictures that I took as I went.
Sorry for the fogginess of the last pic, forgot to wipe the saw dusts from the camera lens…
A personal opinion: It appears from photos you used cedar wood - giving a nice looking strip-build finish. Looks like a few places there will be a need to fill between strips (at least from photos it looks that way). I would suggest that since you have spent (and will spend) a big bunch of time building the hull - you don’t skimp on the finish. If it were mine …
collect more sawdust if you can as you continue to fair the hull. Save and use as a filler to mix into your first coat of epoxy.
buy some good marine grade epoxy. I’m partial to WEST System - but System 3 and others are out there as well. A quart of resin and a pint of hardener should be more than enough - with left-overs for more building.
apply a single brush coat of pure epoxy/hardener to the entire outside of hull to (more or less) seal pores and fill small gaps between strips.
mix another batch epoxy resin and hardener according to instructions, then add in the sawdust to thicken up the mix and use a credit card and smear on this “paste” to fill any voids between strips.
sand down this second coat and if you scuffed trough the epoxy exposing raw wood, give another light coat of epoxy without thickener.
AT THE SAME TIME - apply a single layer of glass - anything from 3/4 oz. to 4 oz. maximum and apply epoxy to glass with stiff brush and stipple into weave.
repeat if necessary to assure all fabric weave is filled - and then sand with medium grit.
This should give you enough support to remove hull and coat inside as well - again using 3/4 oz. glass cloth. Don’t need to be fussy here, just keep epoxy amounts reasonable (not too thick). If you removed all templates, you can do one piece internal glass. While glass is till wet, you can add back in any template/stations needed. Once cured, you can apply thick epoxy as fillets where template edges meet inside of hull.
I’m not sure there is a need to use carbon (except for bragging reasons) and carbon sucks up a lot of epoxy which equals weight! Once cured (I would use slow setting hardener) you can flip back over and sand down the outside of hull - but not through the glass cloth. Use some good marine varnish and give two coats - allowing first to dry and lightly sand to remove any pimples, dust, bugs, etc.
This should provide you with a nice looking clear finished strip hull. From there - if the boat looks like you hoped and sails well, you can always follow “HEW’s” advice to cover with packaging tape and layup a heavy thick glass cover to use for a mold for additional hulls from glass (or carbon).
Just be sure the hull is finished well before coating with epoxy, as sanding gets harder with an epoxy coating. Good luck.
Great lines, and a superb planking job.
With a yacht that is quite flat such as this, you would benefit greatly from keeping the planking as flatter areas can deform once in the water.
You would use the planking as a core, and a sandwich construction gives the best stiffness to weight ratio.
As for your next move…
Sheath the outside with a light layer of glass, as previously suggested which would leave a transparent outer finish.
Place masking tape over the hull and use car filler to temporarily attach some carefully cut transverse frames on the outside. Ideally you would place them all at the same height to form a level top and mark the centreline from the building board.
Firstly, this will hold the hull in the correct shape whilst you then set about removing the building frames.
Secondly, When you turn her over, the outside frames will become the ‘cradle’ while you laminate the inside. If you want to use carbon, 1 layer on the inside would be perfect.
Thirdly, you can level the boat and you have a reference during the build which makes the fit out much easier.
If your cradle frames are nice and accurate, they can remain on the outside, only once the deck is installed would you release the outer frames.
Being placed on masking tape they will come off without too much persuasion and not leave a mark…
Dick, very good eye, I did use cedar and there are some sizable gaps in a few spots where the strips just wouldn’t quite bend enough. I love your advice on the saw dust, I was going to get the micro balloons that west has but this will be much cheaper.
You called me out again on using carbon purely for the bragging rights, but my wallet is screaming otherwise so i’m going to take your advice and find some lighter fiberglass cloth instead.
Jim, I like the idea of using the planking as the core and I intend on doing just that.