Building an RS540

The Forum for RacingSparrow radio controlled yachts. Focussing on build your own scratch building, free plans for download and a comprehensive builders guide book.

Best wishes and happy sailing, Bryn Heveldt.

Building an RS540

BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

13 Jul 2016, 22:44 #1

Hello everyone, my first post here!

I have been wanting to build a sailboat for a while now, but I don't like the lack of flexibility in most kits. And most plans I found to be lacking in usable information. After weeks of searching, I finally stumbled across this site! I HAPPILY got the book after looking at the preview. MORE than enough information to get started. Although an advanced chapter on other rigging options would be nice. Or even just more info on that maybe. Anyways, off topic...

I printed out plans for the 750. They are a little too big for materials I have on hand, and my pond of choice. And the 375 is just a tad too small. I don't like the RG65 profile. And the footy is just a completely different boat... I LOVE the profile of the original. And since I am not building this for a specific class to sail in (being my first sailboat anyways), I decided to make my own size!

After some calculations and poking around, I discovered that I had to print the 750 plans at 68.9% to get the 500mm length. Not sure why the odd size, but whatever... Laying out on my table, and this looks like the perfect size to build! Large enough that nothing looks like it will be cramped, small enough to fit my needs and hopefully still sail well.

So the first question... What process and programs could I use to generate an edited and rescaled set of plans? I have a Macbook with tons of software. Adobe Pro, Photoshop CS5, and Open Office. (I also have PCs on hand with similar software.) If I can generate an editable set of plans that I can work with as I build this, I will HAPPILY give them back to this community!
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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

14 Jul 2016, 06:52 #2

So I have been working on this all evening with the help of the guys over in the RCGroups forum. I think I have the editing/scaling process down and posted up a possible final revision of the hull plan. Check it out!

Kevin, when you get a chance to read this, please post up or PM me any advice and suggestions. If you would like to add this to the plan download collection, let me know what file size/resolution I should send you. And if I have stepped on any tails, I can pull down the attachments...

EDIT: Not there yet, the printing size is wrong... Somewhere in the process, I messed up the scaling.
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racingSparrow
Site Admin
Joined: 06 Sep 2012, 03:27

01 Aug 2016, 02:10 #3

I just saw this post. I could potentially send you some original plans in illustrator format if that helps.
I may have to dig them out from some old computer and dust them off. Might be a valuable resource for people to have access to.
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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

01 Aug 2016, 05:24 #4

Thanks Bryn that would be cool!

So the build is progressing wonderfully! After a lot of pondering, we increased the size to 540mm from the original plan of 500mm. The idea was to fit it into a euro Micro 540 club class. Good thing too, it is a tight fit at 540 not only for electronics, but weight.

There is a very detailed build thread here over on RC Groups. I will post up a summary in pictures here shortly!
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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

06 Aug 2016, 06:52 #5

Disclaimer: Most of these pictures will have been posted first in my build thread on RCGroups. For the detailed build thread and discussions, head over there! This thread I am doing differently with mostly just pictures and commentary.

So the sailing bug bit me many years ago.... I was in Annapolis Maryland and found an awesome book, The Handbook of Sailing by Bob Bond. Not sure why at 15 or so I had to have it, but I did! And somehow I scraped together enough money to buy a Dumas Lightning Sailboat kit. It wasn't RC, but I had the book and I could figure it out! :lol:

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I figured out a lot for sure. I converted a Futaba Servo into a homemade sail winch. One I am sure would run and run... :shock: I don't remember doing much more to it than opening it up and filing some parts off... I spent weeks building that little boat, making it pretty. Lots of sanding and varnishing. It passed the float test. And it sailed nicely out to the middle of the pond! And then the wind picked up, capsized it, and it sank...

The boat was never seen again. Along with the radio gear I had borrowed from one of my Dad's airplanes... I was devastated. It took me years to realize what I did wrong, I hadn't weighted the keel, it was intended to be a static display boat... :oops:

During this time, I had also been carving a sailboat out of blue insulation foam. I finished that, waxed it. Somehow came up with fiberglass and resin, glassed it. Then I tried to melt the foam out. Not sure what went wrong. Vague memories of using gasoline and it not melting the foam evenly or something. It was an unstable mess. Two defeats. I was done. I think I actually threw the book out....

For years, I tried to figure out the name of that book... Recently I realized it was likely either renamed, or an original cover I had to look for. Well seems it was both. I found a few that looked possible, and ordered some used copies. I had finally found it!

Why a sailboat, again? Not really sure. Maybe it was a past project that haunted me for not having completed it. Maybe it is this area. Living by the beach, with a pond on every corner. I was mostly decided, and then went to one of my local regattas. I was HOOKED!

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But my pond I felt was too small for an awesome 1 meter Soling. And I wanted more build time and to really get my hands into the project. I spent weeks looking for free plans. Or any plans that jumped out at me. I found the Racing Sparrow.

The other plans were complicated for me, having no knowledge of boats. But I could scratch build airplanes all day long! So when I saw the Racing Sparrow, then looked at the plans, I knew it was the one. I downloaded the preview, and as soon as I realized how detailed, yet tailored and specific it was, I bought Bryn's book!

It is super detailed, but very specific to the Racing Sparrow. The only area I felt lacking in, was planking. So I studied up on that a lot more. I printed out plans on my little printer. Tiled the pages, cut, taped and laid them out. The RS725 was too big for my needs. I felt the RG65 lost the appeal that the RS725 had caught my eye with... I was a bit stuck...
Last edited by BiggsDarkLighter on 06 Aug 2016, 07:50, edited 1 time in total.
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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

06 Aug 2016, 07:48 #6

After staring at my printed out plans (I think I killed an almost brand new ink cartridge on my printer...) I decided I wanted to build an RS500 sized boat. The RS375 I could tell wouldn't fit radio gear very well. So I figured out the math, and called the plans to an "RS500" size. I even figured out how to edit the plans in Adobe to get my recalculated measurements. Never did sort getting it called correctly without loosing clarity. But just printing it at the calculated percentage did the trick.

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I spent some time trying to figure out the whole editing and scaling thing here: Finally, pwallace stepped up and offered to help me with this. And then some revisions!

And then the discussion in the thread turned to reasons why I shouldn't do a 500mm Racing Sparrow.

The first big one was, build whatever your local club sails. They ONLY sail Soilings. And I was under the impression (by what they themselves were telling me) that getting a Soiling would cost me over a grand! I also wanted to scratch build my first boat, not put together an ARF kit. I wanted to learn planking and plans scaling for another project I am dreaming of.

I was going to build my RS500! I am stubborn at times...

Then it was, well it won't sail. Too small. After hearing out these arguments, I partially took their advice on both accounts. I had found the interesting Micro 540 class. Micro Magic sized boats, except a development class. Suddenly, a class I could build for, register my boat, and maybe make a couple more even! So, I decided to go with a RS540.

Most importantly though, this was a size that would fit my pond, my back room, and my budget!

With this size though and the class restrictions, I needed to mock up the outline. So I did another print, and drew lines for the regulations box. I maxed the size to safetly fit in the box with a touch of breathing room. OAL was supposed to come to 550mm.

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Everything looked like it would fit, so pwallace and I started banging out ideas. We likely got carried away. When we were done, he had taken the 3d Sparrow plans and morphed them into something else. We had a set with a keel, some extra stringers, and in the end a VERY nice build! But, this is also adding on the weight...

The guys made some skin of the pants voodoo calculations, and came up with a magic target weight for me to hit. 430g.

BTW Bryn, ANY input into displacement, calculations, and how you decided on your target weights would be very helpful here! I am finding that 430g is likely an awesome number to make it super light and super fast, but perhaps not a realistic target to hit. I am QUICKLY gobbling up the weight allowance. But more on that in a later post...

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After a bunch more work on pwallace's part, I had gathered up enough materials, and was ready to start building.

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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

06 Aug 2016, 17:50 #7

The biggest addition pwallace made, was to add a keel.

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As I went, I made minor additional changes. The first "Keel Rear" split at the bulkhead F notch. So I thickened the area between E and F. Later in the build, it would split again right there, but the thicker section gave me enough to just glue it back together with CA.

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The notch not cut out here, is for the rudder post hole. I made up two of these to sandwich the post without the notch cut. When it was time to drill for the hole, it drilled nicely and DEAD center with the center cut out notch guiding the drill bit perfectly.

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The keelbox sides I made out of some random 1/16 plywood I had on hand. I think this actually came out of an automotive brake rotor box!!! Whatever the case, found and free materials!

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With these two Bulkheads, you can see how I setup the side stringers. I had trouble explaining this part to pwallace, so he had it slightly different.

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I wanted an open cockpit. And I wanted the sides to match the curve of the hull. I knew doing this later would be difficult, and how the side stringers were being done it was simpler to just cut out in advance.

I was thinking to put the rudder servo into the floor back there like on KIWINB's Green RG65. It has ended up under the front hatch instead though.

Lets backtrack a little though to methods and materials... These are the glues I have on hand to use. Building the hull and planking it has already burnt through two bottles of thin CA! Why still get the smallest bottle? Control! Much easier to use than the bigger bottle. CA was not the recommended glue of choice, the PVA. I found that it seems. Simple wood glue. But I don't have the patience to wait for it to setup.

But to procedures. The best way I have found (short of perfect plans and perfectly cut lazer parts) is to glue the templates down to the balsa, then cut out. The way to do this, is with some cheap gluesticks. It doesn't setup very hard, and once done it is easy to peel the templates back off. Usually, it doesn't even leave any residue behind.

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With the CA, I knew the next section would be possible. The whole point of a notched keel and bulkheads was about to show. With the notches, the bulkheads and keel assembled in a couple minutes!!! Once those were assembled, it was time to set the side stringers.

THIS WAS THE HARDEST SINGLE PART SO FAR!

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If you look closely, the backside is still only half done. I ran the top 1/4 x 1/8 light balsa stringers first. These took some fiddling. I did it on top of glass, with the top view hull outline below. I had to find the right spots to hold the balsa, zap with CA, move to next section. I think I ended up attaching at the front, skipping a bulkhead, glue, skip bulkhead, glue, then go back to the skipped ones. I wanted the natural curve and a section two down would change the curve on the previous ones. The ONLY way this could have been done this easily, was with CA. Even still, it wasn't easy.

After getting the top stringers in, I did the smaller one below. This gave me an edge L-shape. Or maybe more of a T-shape... The second stringer I had set in a bit closer and not flush so that once I started sanding in the hull side angle, I would loose the least amount of material on the lower stringer. I had to file most of the grooves a touch to fit this one perfectly. Again, I wicked in thin CA once it was done.

Here you can see another shot of this. Also the spruce "king-board" stringers. I ran this middle stringer from the mast step area up to the front. I used three laminated together so I could leave the center board out where it wasn't needed, but have an easy way to position it where it was.

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I don't know where the error occurred, but the keel notches were not perfectly aligned with the bulkhead positions on the plans... In the end, didn't seem to change anything and the hull profile worked out nicely. But either new plan views need to be come up with to account for this, or the Keel itself altered a tad. You can see this in the following shots. (These were not taken at perfect angle to show this, and exaggerate it a touch because of that.)

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Last edited by BiggsDarkLighter on 06 Aug 2016, 18:21, edited 1 time in total.
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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

06 Aug 2016, 18:14 #8

The transom seems to be a problem area... The normal method of fitting it after planking appears to come from the fiberglass plug method of building. Where it has to be fitted later. On a planked boat, it made more sense to me to fit it before. Now there are valid reasons for the other way too. Length. It is an easy place to adjust final OAL.

On my hull, I already know I had lost 3/8" due to the weirdness with the bulkheads and keel notches. I could have gained it back here, if I HAD to keep it above a certain length. Oddly, that loss put the OAL at exactly 540mm (once a front bumper is put on). So, I left it alone.

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I started by cutting the top stringers closer to the correct angle. Then I used the rear of the Keel as a guide for sanding. After that, I simply glued on a large enough scrap of 1/16, and then sanded the top angle in.

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This is a MAJOR advantage to using tempered glass as a work surface. It is flat. You can glue stuff down to it, and simple scrape the glue orr later. You can cut on it (dulls blades super fast though), and all sorts of other things. Like working right above plans, while keeping the plans protected.

After getting the top angle, it took some careful "fairing" of the bones to get the transom edges to follow.

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The final outcome was well worth the effort though! I had some issues of deck twist because of a warp introduced at Bulkhead C. It was taken care of by popping it free from the stringers, adding in some small scrap braces, then regluing. I think I had simply cut the keel notch too deeply. If all is perfect, this is something having the parts lazer cut would have prevented.

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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

06 Aug 2016, 18:42 #9

Weight... Weight can be the death blow. As mentioned above, we have a dark magic calculated target weight of 430g to hit. In reality, I think I have a tad bit more room... KIWINB's 500mm RS came to 690g.

But I want a boat capable of nice sailing in a gentle wind. My pond is sheltered on all sides by houses. I think KIWINB's RS500 tends to like a heavier breeze. This is something I will be able to play with, I have a nice little anemometer to do a bit of "more scientific" testing on this. I got it for my quadcopters, and then wondered what use it was later. But for sailboats, it is MUCH more helpful!

Currently, I have an almost finished hull. Leaving in the bulkheads, and adding in keel and side stringers has slowly piled the weight on. At the same time, they have also contributed to a planked hull that was very easy for me, as a first timer, to build.

I am not sure I would do anything differently (structure wise) on the next build of this boat... But then it is still too early to tell.

I ended up making all the bulkheads 1/8" thick. I think I could have gotten away with 1/16, but with a catch. On bulkheads E and F, I laminated two sheets of 1/16" to give a cross grain. With a 1/16 final thickness, I would have had to also do the same with Bulkhead D. Bulkhead C2, we eliminated.

Also I think any cutouts you know your going to make, really have to be done before assembly. It took way too much effort doing these later on, especially after planking...

I am still under the 430g weight, but I am going to be coming in VERY VERY close, and not sure I will be able to keep it below that.
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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

06 Aug 2016, 19:24 #10

I stared long and hard at many pictures and methods of doing the planking. I wanted a hull worthy of a simple clear coat. The method shown in the Racing Sparrow Build book, didn't look quite right for this to me. So, stubbornly, I did it my own way. I came across mentions of simply starting at the top and working down a bunch of times. Seemed the only real problem, was twist and warp on the last handful of boards.

I laid down a center keel plank, then the top sides, and went to work. The side stringers and the shaped transom, gave me secure places to glue.

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I think I could have done a little better with keeping the planks flush, but it worked out okay once I was done. I used thin CA for all the planking. I would take each board and mark the backside with a sharpie (will use pencil next time, this caused bleed through in a spot or two when the finish epoxy went on later). Then I would sand a slight angle to the edges by sitting the plane edge down on my glass and using the glass as a rest for the sanding block.

I would follow the curve of the prior planks and tack the plank to the last bulkhead first, then usually skip a bulkhead going to the next one. Going back to the skipped bulkhead after. After each section was tacked down, I would carefully clamp the boards close with my fingers so they butted up nicely, check curves, and wick in some glue.

This worked perfectly with zero issues or mistakes almost right up to the end. Maybe the last 25% of the planks saw some problems. On a couple occasions, the bottom warp introduced low spots and I had to carefully re-slice the boards apart along the seam to fix this. One of the very last boards got messed up badly enough, I had to cut it out and redo it completely. Only that one board on the whole job was unstable though.

Once I got to the back transom and started going up the keel, I had to use a couple thicker boards, and thinner ones to keep them even. You can't tell on the finished planking.

As I got closer to the end, I also had to add in small 1/16 scraps next to the keel to have something to glue planks to.

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The final result turned out better than "just okay!"

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After many many hours of sanding, I had managed to sand off 17g!!!

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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

06 Aug 2016, 20:03 #11

I don't think you could tell from the pictures above, but there were a bunch of less than perfect spots. Some low points. And a few very thin spots. Next, I had to correct these.

I used DAP Lightweight Spackle for this. As described, it felt like the can was empty. It took two coats and three days to do. After each coat, I let it sit for 24hrs, then went and sanded it gently. This stuff is SOFT! I used 100 grit paper as a "file" to knock it down, then 320 grit soon as I got close to the hull so as to be gentler on the balsa. When I got down to the hull, I switched over to 400.

After two coats, it looked pretty good!

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I was slightly disappointed though. The back looks bang on, but you can see the filler elsewhere, and clearing this hull is unlikely to be the final outcome. But after all that, I had only added a slight amount of weight to it.

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Much debate had gone on in my build thread about what method to use to strengthen and waterproof the hull. To save weight, I decided not to glass it. After much more debate, I decided to use PT40 Z-Poxy Finishing Resin. Biggest deciding factor here was cost and ready availability, I could walk in there and pick it up. Budget is startinng to run out and using something like West Systems Epoxy was out of that range.

Then came perhaps the first big mistake... I didn't thin it. Maybe I should have used something else too, I don't know. I am likely to try a poly-acrylic sealer next time. To brush it on, I simply used disposable "chip" brushes. I had to work a few bristles out of the resin, but in the end ended up fine.

But done is done, and it DOES look awesome!

Image

Image

My workshop/garage can be buggy. I had the presence of mind to make up a cover before I brushed on the resin. Once finished, I covered it and let it sit for a day. Then came the disappointment...

Image

Again, my work surface shines! I didn't worry the slightest about the resin drips. Once it all dried, I simply scraped it off. This time I did have to actually get and use a razor scraper. The utility blade was painfully ineffective... :?

After another 2-3hrs of sanding, I managed to drop the hull weight down 3g to 85g. Still, a LOT of weight in that resin. I don't know that glass would have added enough on top of that to save me any worthwhile amount by not using it. I really think I can do this lighter next round with a different material...

I am not sure I would want to save this weight by cutting out bulkheads and stringers. I REALLY feel they made a huge difference in the final outcome. And with a boat that didn't get glassed, I think it added back in more strength than it cost me in weight.

This hull is strong enough that even with a step up to the RG65 size, I think it would be fine without the added weight of fiberglass. Still, I do think the bulkheads could be 1/16 instead of 1/8. Laminating 1/32 sheets together for bulkheads D, E, and F.

But is it the resin that made it rock hard and strong? Or would a poly-acrylic type finish work just as well? Won't know, unless I build another...
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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

06 Aug 2016, 21:01 #12

I deliberately have left a dull finish. As soon as I hit it with something like a 2500grit paper, the finish quickly starts to shine. If I liked the look of this, I could easily polish in a wet, glassy looking finish. The filler just detracts from that look too much...

I don't know what I could do to eliminate the need for filler on the next build. Maybe I could use 3/32 balsa and have just that little bit more room to sand. Or even 1/8, but I would have to sand off a LOT there and would worry a tad more about curving the planks.

The keel slot and rudder post hole were PERFECTLY located. I cut those out after the resin coat.

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At this point, I still need to epoxy in the rudder shaft, and seal the keelbox up. With the keelbox, We went for a longer design to give a touch more flexibility in keel fin placement. Anything we can do to add in a little tune-ability, might go a long way.

I cut some holes in bulkheads to rout things, and get room for the radio gear. This was a PAIN! I will do this before on the next build. But the BIG opening in Bulkhead D, might have to wait until the hull is planked...

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I may add in some more lengthwise bracing for the servo tray. I am also planning to make it removable. The hardware only costs me 3g, and here I think it is a price well paid. If the servo choices need to be changed, I need to NOT destroy the hull removing the tray. The keelbox is covered with a thin plywood strip, then the balsa squares for servo mounting. Then the servo tray on top. Keel fin will bolt on through the two holes. Likley only one will be actually attached to the aluminum fin spar. But that gives me enough spacing to mount it back further too. Keel fin will be removable, and also the keel bulb. I think just 3-4 more screws will happily secure the tray the rest of the way. The 4 would add in the 3g. I got a nice selection of stainless hardware to use for these!

The receiver will loose its case. It costs me 5g. And then I will add some right back on with waterproofing it. I think I will do a simple conformal coating using an acrylic clear coat. It will be a thick coating though! I might disassemble the servos and do the same to their circuit boards...

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This is a trial fitting of the rest of the gear. I am thinking the batteries will end up opposite the servos, likely on some sort of shelf. They weigh almost the same. Those two packs weigh in at 35g. I can leave them split to help with weight distribution, or combine them. I will end up with a 2S lipo pack.

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I built a little BEC to power up servos and receiver off the lipo pack. It is adjustable (until I seal it with epoxy) and I think rated for 3amps. I am adjusting the voltage here before powering the system up with it. Using a 3S in this picture. This guy gives me lots of flexibility in battery choices. I want the 6.5v for the extra kick that gives the servos.

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Servos! I selected Hitec for this, seems they are the favorite choice for sailboats. For the sail, I am using a HS-85MG. For the rudder, a HS-5055MG. Programmable is overkill on the rudder, but was the best and least expensive option on hand. My radio will be able to handle endpoint adjustment easily anyways.

For the radio, I choose the FlySky/Turnigy FS-T6S. It is intended for quadcopter use and trims are not "apparently" available. But after a firmware update and a couple menu settings changes, they are. You push a button on the back, opposite side of the stick you want to trim. It beeps, you blip the stick direction you want to trim. This would NOT work well on a quadcopter setup, but for sailing it should be perfect!

When I saw the case, I know I wanted to make this radio work! The white, I can dye to match the hull color. And the aluminum looking silver faceplate is removable, and gives enough depth to make a planked faceplate possible. But for now, we will leave it alone. The boat will get finished first, then fun with case modding I am sure will happen next.

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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

07 Aug 2016, 07:57 #13

I don't think you could tell from the pictures above, but there were a bunch of less than perfect spots. Some low points. And a few very thin spots. Next, I had to correct these.

I used DAP Lightweight Spackle for this. As described, it felt like the can was empty. It took two coats and three days to do. After each coat, I let it sit for 24hrs, then went and sanded it gently. This stuff is SOFT! I used 100 grit paper as a "file" to knock it down, then 320 grit soon as I got close to the hull so as to be gentler on the balsa. When I got down to the hull, I switched over to 400.

After two coats, it looked pretty good!

Image

Image

I was slightly disappointed though. The back looks bang on, but you can see the filler elsewhere, and clearing this hull is unlikely to be the final outcome. But after all that, I had only added a slight amount of weight to it.

Image

Much debate had gone on in my build thread about what method to use to strengthen and waterproof the hull. To save weight, I decided not to glass it. After much more debate, I decided to use PT40 Z-Poxy Finishing Resin. Biggest deciding factor here was cost and ready availability, I could walk in there and pick it up. Budget is startinng to run out and using something like West Systems Epoxy was out of that range.

Then came perhaps the first big mistake... I didn't thin it. Maybe I should have used something else too, I don't know. I am likely to try a poly-acrylic sealer next time. To brush it on, I simply used disposable "chip" brushes. I had to work a few bristles out of the resin, but in the end ended up fine.

But done is done, and it DOES look awesome!

Image

Image

My workshop/garage can be buggy. I had the presence of mind to make up a cover before I brushed on the resin. Once finished, I covered it and let it sit for a day. Then came the disappointment...

Image

Again, my work surface shines! I didn't worry the slightest about the resin drips. Once it all dried, I simply scraped it off. This time I did have to actually get and use a razor scraper. The utility blade was painfully ineffective... :?

After another 2-3hrs of sanding, I managed to drop the hull weight down 3g to 85g. Still, a LOT of weight in that resin. I don't know that glass would have added enough on top of that to save me any worthwhile amount by not using it. I really think I can do this lighter next round with a different material...

I am not sure I would want to save this weight by cutting out bulkheads and stringers. I REALLY feel they made a huge difference in the final outcome. And with a boat that didn't get glassed, I think it added back in more strength than it cost me in weight.

This hull is strong enough that even with a step up to the RG65 size, I think it would be fine without the added weight of fiberglass. Still, I do think the bulkheads could be 1/16 instead of 1/8. Laminating 1/32 sheets together for bulkheads D, E, and F.

But is it the resin that made it rock hard and strong? Or would a poly-acrylic type finish work just as well? Won't know, unless I build another...
Reply

BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

07 Aug 2016, 07:58 #14

I deliberately have left a dull finish. As soon as I hit it with something like a 2500grit paper, the finish quickly starts to shine. If I liked the look of this, I could easily polish in a wet, glassy looking finish. The filler just detracts from that look too much...

I don't know what I could do to eliminate the need for filler on the next build. Maybe I could use 3/32 balsa and have just that little bit more room to sand. Or even 1/8, but I would have to sand off a LOT there and would worry a tad more about curving the planks.

The keel slot and rudder post hole were PERFECTLY located. I cut those out after the resin coat.

Image

At this point, I still need to epoxy in the rudder shaft, and seal the keelbox up. With the keelbox, We went for a longer design to give a touch more flexibility in keel fin placement. Anything we can do to add in a little tune-ability, might go a long way.

I cut some holes in bulkheads to rout things, and get room for the radio gear. This was a PAIN! I will do this before on the next build. But the BIG opening in Bulkhead D, might have to wait until the hull is planked...

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I may add in some more lengthwise bracing for the servo tray. I am also planning to make it removable. The hardware only costs me 3g, and here I think it is a price well paid. If the servo choices need to be changed, I need to NOT destroy the hull removing the tray. The keelbox is covered with a thin plywood strip, then the balsa squares for servo mounting. Then the servo tray on top. Keel fin will bolt on through the two holes. Likley only one will be actually attached to the aluminum fin spar. But that gives me enough spacing to mount it back further too. Keel fin will be removable, and also the keel bulb. I think just 3-4 more screws will happily secure the tray the rest of the way. The 4 would add in the 3g. I got a nice selection of stainless hardware to use for these!

The receiver will loose its case. It costs me 5g. And then I will add some right back on with waterproofing it. I think I will do a simple conformal coating using an acrylic clear coat. It will be a thick coating though! I might disassemble the servos and do the same to their circuit boards...

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This is a trial fitting of the rest of the gear. I am thinking the batteries will end up opposite the servos, likely on some sort of shelf. They weigh almost the same. Those two packs weigh in at 35g. I can leave them split to help with weight distribution, or combine them. I will end up with a 2S lipo pack.

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I built a little BEC to power up servos and receiver off the lipo pack. It is adjustable (until I seal it with epoxy) and I think rated for 3amps. I am adjusting the voltage here before powering the system up with it. Using a 3S in this picture. This guy gives me lots of flexibility in battery choices. I want the 6.5v for the extra kick that gives the servos.

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Servos! I selected Hitec for this, seems they are the favorite choice for sailboats. For the sail, I am using a HS-85MG. For the rudder, a HS-5055MG. Programmable is overkill on the rudder, but was the best and least expensive option on hand. My radio will be able to handle endpoint adjustment easily anyways.

For the radio, I choose the FlySky/Turnigy FS-T6S. It is intended for quadcopter use and trims are not "apparently" available. But after a firmware update and a couple menu settings changes, they are. You push a button on the back, opposite side of the stick you want to trim. It beeps, you blip the stick direction you want to trim. This would NOT work well on a quadcopter setup, but for sailing it should be perfect!

When I saw the case, I know I wanted to make this radio work! The white, I can dye to match the hull color. And the aluminum looking silver faceplate is removable, and gives enough depth to make a planked faceplate possible. But for now, we will leave it alone. The boat will get finished first, then fun with case modding I am sure will happen next.

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nabberuk
Joined: 18 Feb 2013, 21:56

07 Aug 2016, 08:48 #15

If weight is an issue why don't you build a plug and then you can should be able to get a pure fibreglass hull or even carbon fibre if you have the pennies
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BiggsDarkLighter
Joined: 13 Jul 2016, 20:20

08 Aug 2016, 03:11 #16

Weight is an issue on a boat this small for sure! But, we floated it last night and got a clear displacement target weight of 450g.

It is going to be close, but I am still aiming for the 430g target, and still on track to do it. The deck is going to be a tad weight costly, but I have other places still where I can get it back. I think we will be okay!
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