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Jul 19, 2016, 02:33 AM
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Build Log

Racing Sparrow RS540, first time build!


The build will be a 540mm OAL Racing Sparrow scaled down from the RS750. I have been kicking around asking lots of questions, and getting some awesome help!

I know this is not the ideal size for most, but for me and my little pond, I hope to make it perfect. I went with 540mm to fit it into the Micro 540 class, that is likely only a club class. But whatever. I am for now building it to fit those rules.

As of now, still collecting inspiration and information. And hopefully parts. I have a snipe going out on the controller I want. And later this morning I am off to the local regatta club meeting! Should be fun!

An especially loud shout out to pwallace is in order! He is helping me tremendously getting my badly done version of the plans cleaned up and improved a TON!!!!

Okay first silly question for this thread... PVA glue. I went into Home Depot and got the "Say what?" look from the long-timer. We both googled it and found references to some bookbinding glue, and lots of pictures of Elmers Glue All. NOTHING there specifically said "PVA Glue" or Polyvinylacitate etc.

I got some Titebond III Ultimate. It says "passes ANSI/HPVA" blah blah. I also have some Elmers Wood Glue. Are either of these PVA, or good enough?

It will be a balsa planked hull.

EDIT: I have been updating my "Building an RS540" thread over in the Racing Sparrow forums! It is mostly just my pictures and commentary on them, so a much more condensed version of this thread.
Last edited by BiggsDarkLighter; Aug 26, 2016 at 11:32 PM.
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Jul 19, 2016, 12:36 PM
a.k.a. Bob Parks
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The Titebond Ultimate III would be my choice. It is waterproof. You will need lots of clamps / rubber bands to hold things together while it dries.

From Wikipedia "Poly(vinyl acetate) is an aliphatic rubbery synthetic polymer with the formula (C4H6O2)n. ... as wood glue PVAc is known as "white glue" and the yellow as "carpenter's glue" or PVA glue."

BP
Jul 19, 2016, 03:13 PM
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Dick L.'s Avatar
I guess my suggestion is use a good grade of marine epoxy. It is far better as a true waterproof glue, you can roll it on to seal the inside AND outside of the balsa sheets. Mix with a bit of silica or micro balloons and create fillets between bulkheads and hull panels, or reinforce and seal the keel trunk. Unlike Titebond, epoxy sands much better if needed. You can use it with some lightweight fiberglass (or carbon) to wrap the keel to strengthen and prevent twisting or bending.

NOTE epoxy from a hardware stays a bit flexible and is a "bear" to sand. It cannot be rolled or brushed to seal panels. I use and recommend WEST System which is a bit spendy, but after your time spent on redesign, and then on actual building, I sure wouldn't trust my efforts for a glue that ".might" not hold in a wet environment.

Just basing on number of boats I'v built.... you will have enough for other boat buildings if you so desire.

Ask yourself how many wood boats, canoes, kayaks have been built and sailed using Tightbond as opposed to marine epoxy. It only costs a bit more to go first class !
Jul 19, 2016, 04:26 PM
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I agree with you Dick L. Sadly I sux at building and can only get about 3 planks per side a night. I think a canoe can be nailed to place the boards and the epoxied. The sparrow stock finish is "paint class" so I am hoping BDL gets a little better build that can be finished in epoxy or maybe a layer of fiberglass instead of paint.
Jul 19, 2016, 04:39 PM
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CA glue to tack strips in place, then brush coat interior bulkhead, etc. Foam roll (3 inch roller) the exterior of hull. Brushing interior will help glue strips to each other and fill very small voids. Once sanded, epoxy takes primer, or direct paint very well, or if built with care, can be finished clear allowing a nice looking wooden hull.
Jul 19, 2016, 05:02 PM
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Quote:
Originally Posted by Dick L.
... Once sanded, epoxy takes primer, or direct paint very well, or if built with care, can be finished clear allowing a nice looking wooden hull.
Leaving the interior "visible" is defiantly my end goal.

Quote:
Originally Posted by pwallace
... The sparrow stock finish is "paint class" so I am hoping BDL gets a little better build that can be finished in epoxy or maybe a layer of fiberglass instead of paint.
I am defiantly wanting to leave visible top planking. The hull I want some color on. Maybe not the WHOLE thing, but I do like color! Either a bright orange, or a baby blue comes to mind. Baby blue is winning mostly...

I am really well versed at building using CA, but I also know it is not as friendly to my system. I suspected this glue (as recommended in Sparrow's building manual) would be safer and kinder to me and my workshop. Not the best ventilation.

With that in mind, my plan was to use the PVA (Titebond III, and it "claims" it is waterproof) for basic assembly. Then go with the Marine epoxy to brush and seal the inside and outside as needed. I would limit the CA to locations where that type of glue made more sense to use.

I am not an expert here though. Does this sound like a good plan?

The PVA gives me time to work, fix mistakes, and hopefully get a decent planked hull built. And no, I already had NO plans to trust all my efforts to just basic wood glue LOL! I just was unsure what to use for the inside coating.

Oh boy I can use some of my crazy mechanics tools for this! I got several nice borescopes. Gotta make sure everything is properly coated right?!
Jul 19, 2016, 07:23 PM
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You should be able to use Titebond in the manner you propose. Just be carefull with runs and squeezeouts as that will be visible through the epoxy coating. Nothing strctural, just cosmetic.

Sounds like you are on track with ambitions for an A+ finish.

Good luck. Post questions if you run into something you are unsure of.

Dick
Jul 19, 2016, 08:50 PM
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I promise, some cool pictures are going up shortly!!! At the moment though, pwallace has the neatest pictures of what is happening LOL!

Quote:
Originally Posted by Dick L.
...

Good luck. Post questions if you run into something you are unsure of.

Dick
Thank you! I do, still got some servo questions! I am supposed to let Mr. Wallace know what servos I am going with, and I am still not completely sure. Elsewhere, this was partially answered...

Quote:
Originally Posted by Rusty Nail
...A Footy can use a slower geared 9gm sail servo for a balanced rig. The Una McCormack rig or the Stollery Swing rig qualify. Standard sloop rigs need quite a bit more torque unless you bare away briefly before winching in to unload the sail, so 12-15gm slow servo.
The Micro 2 MG BB (GWS micro 2BB MG) is a popular RG65 standard rig sail servo. Maximize throw on your transmitter limits. Rudder torque can be low so 9gm servo ok.
I am considering these servos on eBay:

Cost for any of the options seems reasonable for me. But first off for this boat, do I even need a sail winch, or just go with an arm setup? I would lean towards the winch as tuning the length I suspect will be tons easier. But even the lightest one weighs in at 45g. Is this too much for a baot likely to be a tad heavy? Or would the aluminum arm on a "standard" servo cost me almost as much anyways?

I would lean towards the 55g one with metal gears. But according to the specs, the 45g one should be enough.

I am thinking to go with the 6 turns. Again, my radio (whatever my final choice ends up being) should let me dial it in. Too much is better than too little I would think?

(While I am ordering from them, going to grab extras. Would the 61g programmable one give me anything over the 55g for a Soling 1 meter? I see one of these in my future! I would prefer the price on the 55g one... LOL!)

I am not finding the GWS servo mentioned yet. Will dig around more for that. Thinking to go with an emaxx MG 9g servo. I use those elsewhere anyways (no more on hand at the moment).

If I can happily just use the 9g servos for both sail and rudder... Would the weight savings be worth perhaps the less ideal throw???

I need to order a handful of 9g servos, and plan on ordering whatever I will use for the sail later tonight. Cost will determine if I am getting a new radio too.

I am going to try and post up a few of my choices shortly...
Last edited by BiggsDarkLighter; Jul 19, 2016 at 09:03 PM.
Jul 20, 2016, 08:57 AM
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Dick L.'s Avatar
As a reference, I have used the following servos for my RG65 builds. Up to now, I haven't seen a need for digital servos, so these are analog, and prices reflect that. I may switch to digital for my current build.

Also, I find I prefer the speed of an arm winch over a slower, drum winch.

I use:

Hitec HS-645MG for sail control
Hitec HS-322HD for rudder control

Also, don't overlook the purchase of the units used for the DF65 which you can buy via ("WindwardRC") as they are pretty inexpensive. The sail control is a drum, the rudder control is an arm. Check with him for current pricing and availability. I usually purchase my servos through SERVO CITY as they can add a servo extended for many of the servos for 180 degree rotation, and also are a great place for repairs. Very knowledgeable folks and technicians there .

Mine (Hitec) are probably overkill for a smaller boat, but I have zero defects or problems with them in the larger RG65 boats.
Jul 20, 2016, 09:16 AM
Boomer1
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Is this the boat under discussion?
Jul 20, 2016, 09:22 AM
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Dick L.'s Avatar
Yes - but in a scaled down (size)
Jul 20, 2016, 09:47 PM
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Sorry for the delays. Solidworks is infuriating!

Why solid works? This video show how scanned plans can be turned into a boat:
Using SolidWorks - Canoe hull loft using surfacing (8 min 23 sec)
(8 min)

The sparrow plans are simplified so you can print at home and cut out. Laser cutters are not really rare any more so I am adding notches and alignment points to aid in assembly with tools in solidworks. Simple things like a notch along the top edge of the deck for a stringer to hold things square and give the deck something to bite.

In scaling the servos are now the wrong size. I have to confront this at some point for my next build so why not learn here.

Function. The keel is epoxied in place with the stock boat. Because the mast is keel stepped and the keel is fixed you loose a lot of the flexibility of deck stepping to adjust for winds. Also the side stays are WAY inboard.

Play. The sparrow has a flat deck. Why not give it a little curve and make the hatch pretty?
Jul 20, 2016, 10:05 PM
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The plans has an arm servo for sails and the rudder post below the deck under two hatches. Looking to keep this configuration.

It would be possible to make an open transom too like the green boat on the sparrow website (the rudder servo would live in the hatch)

http://www.racingsparrow.co.nz/index.php
Jul 20, 2016, 11:32 PM
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Thread OP
Quote:
Originally Posted by pwallace
Sorry for the delays. Solidworks is infuriating!
I got through enough of that video to feel bad for you! I couldn't do it lol... I have plenty of patient to sit here while you do that voodoo! Maybe I will go buy some more wood for haul planking. I guess I could even start cutting planking strips.

Quote:
Originally Posted by pwallace
The sparrow plans are simplified so you can print at home and cut out. Laser cutters are not really rare any more so I am adding notches and alignment points to aid in assembly with tools in solidworks. Simple things like a notch along the top edge of the deck for a stringer to hold things square and give the deck something to bite.
All very awesome additions!

Quote:
Originally Posted by pwallace
In scaling the servos are now the wrong size. I have to confront this at some point for my next build so why not learn here.
Okay, still trying to sort that out... With the amount of effort that is going into this, I am hesitant to just use "any old servo." But I am also very concerned about weight. Seems weight is an achellies heel on a boat this small.

Currently, I am taping up a few more plan cut outs. I need visuals. These at least give me a good idea of final size. And also I can measure and "fit" in things like the servos.

Quote:
Originally Posted by pwallace
Function. The keel is epoxied in place with the stock boat. Because the mast is keel stepped and the keel is fixed you loose a lot of the flexibility of deck stepping to adjust for winds. Also the side stays are WAY inboard.
Your loosing me on some of this, remember newbie! Mast is "keel stepped"? "Deck stepping"?

We (pwallace and I) are making keel removable. Mostly so the whole deal can be changed out. It is logical to assume, that this will not sail perfectly the first time out. I am making friends at the local model yacht club. When it comes time for its first sail, I suspect I will get plenty of tuning help! As long as it is built with that flexibility.

Does the keel box need to be made a little longer so a change of keel could relocate it forward or backward?

Is this for "deck stepping"? That was the smallest one I found... If that is what is needed, might have to make one. I saw some "chain stays" too. I think that would be used to move location of the side stays? Bear with me, still waiting for my sailing books to arrive.

And in interests of not going to crazy on the costs, can a simpler row of brass hardware store eyelets be used for adjustment on the side stays? I saw an on deck video (and I believe it was a Racing Sparrow too) where you could see how one side goes limp while sailing, the off-wind side. (I really need to learn all the proper terms, give me a few weeks...)

Quote:
Originally Posted by pwallace
Play. The sparrow has a flat deck. Why not give it a little curve and make the hatch pretty?
I am all for this! I love the way that green RG65 Sparrow is done up. But all these adjustments come with one consideration and a concern. Weight costs. We are already possibly building it on the heavy side with the interior bulkheads...

Lets give this some tuning flexibility if possible. But hopefully not at too much weight cost. I am going to try and save weight with the servos and radio gear. My receiver will only weigh 5.8g. I think I can get battery voltage telemetry without using heavy sensors, and at worst case a simple voltage divider setup. Servos, that I am sorting out here briefly I hope.

But the end boat is going to be small. And as such, I am hoping for a quick boat, but don't expect it to be racing against the local 1 meter Soling bunch either. And it will be mostly sailed on the smaller "holding ponds" that are EVERYWHERE in Florida, than on the big ponds/lakes that are also found all over. For those, I will build more lol!

And Mr. pwallace remember my input comes from the concept, if it looks good it will (hopefully) sail good. I do not have the experience here to make, or understand, most of the design tweaks. So I will leave final say of these changes up to you.

If you design it, I will build it!

And on that note, I have more plans to tape together! I am going to have to go buy more ink before I get a chance to print out the final build sets!

I will be back shortly!
Jul 20, 2016, 11:37 PM
Registered User
Thread OP
Quote:
Originally Posted by pwallace
The plans has an arm servo for sails and the rudder post below the deck under two hatches. Looking to keep this configuration.

It would be possible to make an open transom too like the green boat on the sparrow website (the rudder servo would live in the hatch)

http://www.racingsparrow.co.nz/index.php
Hold on, are you saying the rudder servo would be completely UNDER the rear deck, and still get the nice "cockpit" area?? I was thinking to try this idea out once I decide on servos and have measurements...


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