Build Log: RG65 Simpatico

I have started to build one of the original six simpatico kits. I have been following Kurt’s (M16) build log and thought I would document my experience as well. I will try and take pictures along the way and also update this log when able. Disclaimer: I have built several plane kits, mostly gliders, over the years and I have scratch built a Cobra Footy and Springer Pusher Tug from plans, so I am not a total novice when it comes to working with balsa and thin ply…but I am far from being a craftsman (as you will see from my mistakes which I will point out during the build). My other boat builds include several Victoria’s and a Soling 1M, but those were more of assembly projects rather than builds. Enough of the intro, let’s get started.

My box arrived with a good sized hole punched into the side…not a good sign. Several of the wood parts had been dislodged from their frames, but none of the critical pieces were damaged. The first two pictures show the contents of the box.

Since this is a pre-production kit the only reference document was the picture of the boat on the water, which was tacked to the outside of the box. I guess I will find out over the course of the build if everything was included.

More to follow…

The first step in the build is to put together a jig. The laser cutting is top notch and the needed pieces required very little effort to remove them from their holdings. I glued the jig pieces to a 1x6 piece of pine I had laying around the shop. I paid close attention to getting the jig as straight and level as possible because any deviance here would be magnified later on in the build. This picture shows the assembled jig.

The next step in the build was to install the bulkheads. As suggested by Kurt (M16) I ‘drilled’ a hole in bulkhead #4 in order to be able to route the sail servo wires to the receiver. I tack glued the bulkheads to the building board with low-temp hot glue.

I added the forward strong-back, the curved keel-son, and the aft keel-son next. For wood-to-wood joints I used medium and thin CA. It is at this point I made my first error. I positioned the forward strong-back on top of the jig instead of 3/16th of an inch above the jig. From some scrap balsa, I cut and sanded a piece to fill in the gap. Later, when I cut the hull from the jig, I will have to sand 3/16th of an inch from the opposite end so the deck fits properly. I had to shorten the aft keel-son about an 1/8th of inch in order for it to fit between frames #8 and #6 (this is known issue with the pre-production kits).

I then moved on to assembling the keel box and mast box. The keel box keys into frames #5 and #6; It is a tight, strong fit. The mast box assembly consists of six parts. It is built in layers and goes together quickly. Once again, I needed to remove some excess material to make the box fit between frames #4 and #5 (another known issue). Before enclosing the box with the last layer, I painted all of the interior surfaces with thin CA. This will waterproof the interior, in the event I cannot get to those surfaces later in the built. I glued the mast box in backwards. How do I know? Because there is a notch in one corner of the box, which is meant to key into a frame doubler later in the build. I will have to modify the doubler, but since the inside of the box is symmetric, no real harm was done. Well maybe to my ego. The next picture shows the assembly with keel and mast boxes installed.

Adding the stringers is the next part of the build. I made up a few clamps (thanks to Kurt for the idea in his build log pictures) and used clothes pins and T-pins to hold the stringers in place. I tack glues them with thin CA. As you can see from the picture there is a good bit of lumber hanging off the bow. I used a razor saw to the extra flush with bulkhead #1.

In the kit there were only four full length stingers. There are some shorter laser-cut pieces, but these are for the interior. There was probably enough scrap balsa from the holding frames to make the two additional long pieces, but the there was too much damage from shipping to make it worth cobbling something together. I purchased some 36 inch 1/4 x 1/18 balsa in order to finish the framing. In the picture you can see that the top two stingers required a good bit of shaping to fit between the mid-stringers and forward strong-back.

The assembly looks very clever, with a lot of engineering behind it. I can’t help thinking, though, that it seems like a lot of complexity (and extra weight?) for a chine hull. I’m interested in Kurt’s thinking on that.


The assembly IS very clever. All of the laser-cut pieces have keyed into each other without modification, which has made alignment and gluing true and easy. I think these early pictures are dominated by the building jig and oversized frames and it is hard to see the ‘true’ skeleton before skinning. Probably the only way to see that would be to cut the skeleton from the jig and then cutaway all of the extra frame material…for which there are cut lines already delineated.

In Kurt’s build log (Vision Sails " Simpatico" build log) Brian goes into some more detail on his design reasoning and weight. I have not put my boat on a scale yet, so I don’t know how it compares to others in its class. So far I have been judicious with the adhesives, but I suspect the balsa will absorb quite a bit of the waterproofing–I have not decided what I will use yet, possible polyurethane.


After all of the stringers were tacked in, I glued in the optional keel box braces. With the long keel of an RG65, this area is going to be subjected to a lot of stain, so I thought it was worth the extra weight. I used medium CA to secure all of the stringers to the frames. One area that is a challenge is the stern frame (#8). All of the stringers are butt-glued to a very small area and they can be easily knocked loose. CA wicks into the balsa and the bond is not strong. Once the panels are in place everything will be secure, just need to be careful while manipulating the entire assembly when trying to get glue into hard to reach places. Finally, in preparation for adding the side panels I sanded all of he frame and stringers flush.

I put the side panels on first, using tape and clothes pins as clamps. The bow and stern edges needed a good bit of trimming to lay even with the top edge of the second stringer. This is the joint where the side and mid panels meet…or in this case overlap.

The mid panels did not require any trimming on the top; they lined up nicely with the third stringer. I tacked the panels to the stringers and frames with thin CA. after I remove the assembly from the jig, I will use either medium CA or thin epoxy to secure the panel to panel joints from the inside. There is a good bit of overlap with the side panels; I will trim and sand them after the joints have been sealed.

Hello Scott,

Thanks for posting yet another build log. This only insures that I get all the bugs worked out, which I have taken care of all know issues and will be modified in boats kits #13 and on. I now have exact fit hull panels developed directly form the 3D model, I have adjusted and rearranged parts so that the kit will provide the proper amount of stringers, and have fixed any dimensioning problems as mentioned.

I am working on making a proper instruction manual. I do hope the files sent out to all kit owners has helped. They include several technical drawings and a partial assembly manual.

On the weight issue, I feel that I really couldn’t make the boat any lighter. Secondly, the designed displacement of this boat is over 1kg. This is not intended to be a 800gram build, as I feel that not all races will be in light air and the added stability of hull design and good engineering will make this a good all around boat to have. Just my opinion of course…

Again, I appreciate the support and keep the suggestions coming.


The top panels were the next items added. I really struggled with trying to get these two pieces to lay down properly: good contact with the frames, the strong-back and the keel-sons. The panels are very flat from the stern to just forward of the mast box and then take on a significant compound curve terminating to a point at the bow. In this picture the panels are taped down and have a good fit with the mid panels, but they were not in contact with the frame assembly.

It was known that these pieces were oversized and needed to be trimmed, but try as I might, I could not get it to work. I decided to cut the new panels, this time in three pieces. I cut a single piece for the relatively flat back-end. The 1/32nd thick ply easily took the shape. I then cut two pieces for the front. I used the original panels as a starting point and then shaped, fitted, sanded, fitted, sanded, fitted, and finally got to an acceptable (for me) point. This picture shows the three panels and the boat completely skinned.

After I cut the boat form the jig, I will put in some small balsa blocks at the three way joint since they all share a single frame as a gluing surface.


looks good scott…

I think I may have walter talked into a ranger hull from craig… which mean we’l lhave three 3 rgs, locally not counting craigs…

I am struggling with those top panels also.
It would be interesting to see how things would go together with non oversized planks.
The section were the six panels come together at the bow is a bugger.
I will post more information and pictures soon, but have been kind of busy working 6
day weeks and shoveling out from the last snow storm.
I did order one of those GWS 3 turn servos, and will report on how it functions when I
receive it.


When I divided the top panels into three pieces it was much easier. It still was a challenge getting the right shape to make the compound curve come together at the bow. These are the pre-production versions of the kits so we get to have all the fun working out the kinks. Brian has been very pro-active in resolving all of these discrepancies we are finding and I suspect that builders of the production kits will not have these challenges.
I also ordered the GWS 3T servo. Additionally, I ordered a digital servo for the rudder: the GWS Naro+D, and the programming card…I think this should more than meet the requirements.
I am in a hold for now, as I want to make a cradle to support the hull once it is cut from the jig. I need to get the supplies and the time. That work thing is taking up most of my time as well.

I received my servos today. I did a quick check of the S125 3T with a DX6i, a AR6110 receiver, and a 6volt battery. The servo made 2.5 rotations with 100% throttle throws. When I max the throws (via transmitter) to 125%, I get a full 3 rotations. Bottom line: I think this servo will work just fine. I have the digital programmer as well, and will probably set the endpoints to something less then 2.5 turns, but more than 1 turn. The final setting will come during or afar the install. Just thought I would pass on the info.

Before I cut the boat off the jig, I needed to make a cradle in order to support the hull in its upright position. I cut some 1x10 pine for the cradle. I made a template from the negative of the #3 an #7 frames and made the uprights from an 8x10 piece of the pine. I marked the base, then drilled holes for dowels to connect the arms to the base. Yes, I know what you are thinking…the uprights are too short for the keel :confused:. This is true, but it is easier to work on the interior and deck at this height on the workbench. Later, when I am ready to add the keel, I will cut inserts (connected by dowels) to raise the hull so that the keel bulb will rest on the base. Also, the forward upright will be about 1/2-inch taller in order to for the boat to rest as the proper angle.

As you can see, I have cut the hull from the jig. I have rough sanded the panel overhang, but I have not leveled the sheer line yet. I left the excess on the stern frame to protect the small and fragile piece of balsa from being knocked loose. After a little more finish work I will take pictures and post the progress.


nice cradle I’ll give you specs for my soling and you can make me a cradle.

Once I get the specs I will write you up a quote and then we will see if you still want me to make you a cradle:devil3:

I finished up the rough sanding and added the cockpit stringers. My bow is not as nice as Kurt’s, but I think it will work just fine. I trial fit the ply cockpit pieces and they look like they will glue down and line up really well. One suggestion for the production kit is to see if the inside vertical piece of ply could be cut as a single piece–one less joint to worry about when finishing. In the overhead pictures, the shine is from epoxy I used to put in a few small strips of balsa to give some more gluing surface for the bottom panel. There is not much surface area for the bottom panels to adhere to and line-up with the side panels. I did not take a close-up picture of the doubler, but I had to put it in as two separate pieces, similar to what Kurt did. In may case, if you remember, I put the mast box in backwards so I did not have a slot to key in the doubler and therefore I needed to cut the doubler anyway to fit into my configuration. I did fill in the slot with a piece of scrap so the mast box is complete. One area of frustration has been the strong-back. When I first glued it in, I laid it even with the jig and therefore it was about 3/16th of an inch too tall. The wood is very soft balsa and it broke away with little pressure. I glued it back in place, but while sanding I snapped it off two more times. I think this piece needs to either be denser balsa, or it could be replaced with a keyed in part much like the keel-son. I have not glued in the keel-son; I want to install the servo tray first and maybe even install the servo without having to work around the keel-son. It does not need to be secured until it is time to put the deck panels on anyway. Overall the hull has some really nice lines. And, as you can see in the pictures there is not an overabundance of wood inside the hull, which is the impression you get when the hull is in the jig with all the extra balsa for support.

The next steps are to fit in the servo trays, cut the keel slot through the bottom panel, drill the rudder post hole, and then seal the interior with some light coats of polyurethane.

Hey Guys,

My unsolicited opinion is that the Simpatico as depicted in these photos is way overbuilt.

I can see including a frame to brace the keel and one for the mast trunk or tubes, but well designed panels should fit together to define the rest of the boat. Also, the IOM/dingy aft deck is an affectation in a class that is as weight conscious as the RG. It is not like you’re accommodating a crew! The fancy structure adds weight that would be better utilized in the bulb. A deck of “21st Century Cloth” over a few straight deck beams is the lightest way to close in a boat.

A boat this short with hard chines shouldn’t need a building board either. Now I understand that the Simpatico is being offered as a kit but a heavy hull and a complicated build do not give the buyer their money’s worth. I would hope that the Simpatico is blazingly fast because it seems that there are new designs popping up every few weeks. The time it takes to build a boat like the one that is featured in this thread may well mean that it is obsolete as soon as it hits the water.

Sorry, but I call them as I see them.

you have to remember Neil, that for some… myself included. that building is part of the pleasure… Ive seen boast that are 10% over min weight still win races…

Just a few words in response to Neil’s post…

While I appreciate your comments, this boat was never intended to be “the lightest” boat in the class…far from it actually at a sailing weight of 1.1kg. Since the trend seems to be going the way of the Marblehead…“light and skinny”…while fast, this is not always the way some people like to build. In order to get a boat into the 800gram range you have to build with composites. I myself prefer a nice wooden boat any day. But that is just my opinion.

While the kit does utilize a lot of wood for the build, it was intended for the builder that doesn’t want to spend a lot of time aligning and measuring for placement of critical parts. Yes the deck is an aesthetic feature but if we can’t enjoy our boats in every sense of the word, then whats the point? This isn’t an arms race…

I believe the intention of this thread was a build log, not a bashing session…

Again, just my opinion. To each there own…