Brian…
If you look closely at my pic. you can see that there is a cupped shape between the chines, do to the grain of the ply.
We call it “oil canning” in my trade.
In my experience building r.c. airplanes it is common to place the grain the other way, you lose some strength but
get a better result in the shape of things.
On such a small hull I don’t think strength matters much.
Try this, for the new panels.
Have your’e laser cutter guy do a test with some paper card stock. It’s a great way to test things out, and not burn
up allot of expensive plywood.
Kurt,
Nice clean lines on your panels. If you have not done so already, be real careful cutting the hull from the jig. The balsa frames are very tender.
Scott
Well it sure has been a long time sense I posted anything, so here are some pic’s.
The next thing to do is start thinking about the servo installation , I have read everything
on the other build log.
My thinking is to cut the front of the servo mount, making it a “C” shape rather than the
servo being completely surrounded by the mount. It might make it easier to fish it out
if you can slide it forward and out.
I can’t tell by looking at Scott’s pictures if he is using a closed loop (sorry I have never
used an actual drum winch servo before, so I don’t know the correct terminology) or if
both sides of the loop are passing thru the same opening in the bulkhead?
Hey Kurt,
Looks good…
Yes you will want to go with a closed loop setup. Use two exit tubes through the bulkhead. Refer to the diagram I sent along with the rest of reference materials…email me if you have any problems.
Brian
Got some work done over the weekend.
I made my own servo mount out of 1/8th balsa laminated with 1/32nd ply.
The servo rests on the keel. You can see I will have to drill a hole in
the winch drum to access the two mounting screws buried by it. That will
make it possible to remove the whole thing through the deck if needed.
If you turn the servo 180 degrees, it will move the drum off centre and you may be able to unscrew the drum and thereby gain access to the servo mount screws.
John
I guess I didn’t explain that too well, what I meant was a hole in the drum that a screwdriver could
pass thru to get to the mounting screws.
It turns out having the servo resting on the keel would put the rigging line exits rather
close to the bottom deck. I can put a shim on top of the keel, so that’s not much of a problem.
However, with the amount of room to work in and short distance to the bulkhead, I am
thinking it might be easier to run the lines to opposite side of the hull.
I could use some advise here, I have never dealt with anything but arm winch.
I’ll attach a picture The black sticks represent the rigging line and roughly how they
would pass thru the bulkhead.
Hi Kurt,
I don’t mean to be critical but I don’t much care for your proposed sheeting arrangement as outlined by those black sticks. I think you should be trying for as straight a run as possible off the sides of the drum.
Friction is the enemy of continuous loop sheeting systems. A proper continuous loop has a “feed” side and a tensioning side. The “feed” side is the one your sheet(s) is connected to, the tension side has some sort of spring in it to maintain tension so the loop stays on the winch drum and the pulley at the other end (I use a mail rubber band to bridge two bowlines and pull them together on the tension side). If there is too much friction in the loop then it both takes more power to pull in the sails (load + friction) and the tensioner can become over-stretched and a loop can be dropped from the drum or the line can jam in the pulley.
Is it possible to run the lines of the continuous loop from the winch drum on either side of the keel? Running the lines straight aft off the drum would be the most friction free solution and give you better performance with less chance of a dropped loop or a jam.
Niel…
Thanks for the advise. I could run the lines on both sides of the keel if I have to.
I was looking at Scotts pic’s and they are so small you can’t see how he did it.
Maybe he could post a close up shot 
Just as a test I taped on one side of the bow deck, and taped in the servo mount
(it’s not glued in yet) to see if the servo w/drum attached would be serviceable
thru the deck opening. It is, and NO I didn’t cheat
Hey Guys,
Kurt this is how you should run it…see attached pic. Install servo so the drum is offset to the starboard side. Then install two pieces of cut tubing one on top of he other directly in line with the drum grooves. Like others have stated, this will be your two sides of the closed loop system. In my experience, you will not need a tensioner for this size boat and or system. You can however, use a small o ring if you want. You will want to tie your sheets to the aft end, or pulling side of the loop so that fully sheeted in, pulls the towards the block in the stern.
Any questions, please email me.
Brian
One other question while I think of it. If you are more familiar with a swing arm winch then why are you using a drum winch in the first place? The drum and pulley in a continuous loop system weight more than a swing arm system and are more complicated to set up. Particularly if you are only using a 360 degree throw drum winch.
I guess my main beef with the “Simpatico” is the adherence to the appearance of the IOM. An RG has nothing in common with the IOM. The IOM has a weight restriction for the hull so building a dingy deck is a flourish that there is room for under the IOM’s minimum weight limit (BTW, there is no crew to sit in the cockpit). RGs have no weight restrictions so building them light is a priority, even heavy displacement ones benefit from light weight construction techniques as it increases righting moment and lets your boat carry its top suit into higher winds. While the “IOM look” might be attractive to some, adding the build weight above the waterline doesn’t make sense on RGs. In addition it drives the builder to mount the r/c gear in a similar orientation to an IOM, with the drawback of having tighter spaces to do so in, in these much smaller boats.
I would approach the build by foregoing the aft section of the dingy style deck, the raised fore deck is okay. I would go with a flat deck in the back, probably 21st Century Cloth, and mount my radio flanking the keel box or just aft of it as a removable unit. The sheeting would be more straight forward and there would be more room to work with. Sheet or sheets would exit at or near the stern through “U” shaped teflon tubing. A simple and light weight, double sheeted swing arm system for the sails and the weight savings would go in the bulb for improved righting moment.
I’d also go with a swing rig, but thats just me.
Here is a removable r/c unit from one of my Footies. The RG ones are the same size but instead of the whipstaff tiller arm shown I use a drum and cable system for rudder control. I’ll try to get a photo of the RG set up soon.
Niel…
I can’t argue any points you have made about the design, from a purely competitive viewpoint you are probably correct. I am building because I like the looks of it
and will probably never race it as there are few RG’s in my area.
Brian…
That pdf file confuses me, it shows both sides of the loop on the same side of the drum. My servo is positioned almost exactly as in the drawing, just changed the
servo plate so it fits the servo snug and has no front.
Kurt
Hey Kurt,
Corrected the drawing…sorry.
Brian
New file attached…
Kurt,
Shoot me an email so we can get you back on track…I can’t seam to find your email in my address book. B
Kurt,
Sorry, I don’t have a close-up picture of how I ran the lines on the winch, but I will try and explain. I have both lines coming off the same side of the drum. If you look at the drum, you will see a small hole between the upper track and the center of the drum and between the lower track and the center of the drum. I put a knot in one end of the line, then threaded the unknotted end from the center of the drum to the upper track, I wound the line around the upper track one full time. I then threaded the line through the top hole in the bulkhead. I ran the line down to the block, around the block, and then returned to the bulkhead, where I threaded the line through the bottom hole in the bulkhead. I then wound the line one time around the lower track of the drum, in the OPPOSITE DIRECTION of the upper track. I then threaded the line through the hole in the lower track of the drum to the center of the drum. I tied a knot in the line to terminate it. In summary, the line starts and ends at the center of the drum. In operation, I have the winch set to make two full rotations. The set-up I described is for the stick in the center. when you move the stick up from center line will spool off one track and spool onto the other track and vice versa. FYI: When I put the real line in, I will put more then a knot to keep it in place at the center of the drum.
This is only half of the solution. Next, put the stick in the fully closed position and mark the line near the block. Now move the stick to the fully open position. The mark should travel up to, but not through the bulkhead. If you don’t get the full travel or too much travel, you can adjust the end points on the drum to rotate more or rotate less as needed. You can then tie line(s) that go to the main and the jib anywhere near the mark on the running line. If you want or need to keep tension on the running line you can replace a small amount of it with a spring or with elastic material.
Hope this helps,
Scott
Scott,
Thanks for the explanation, I was a little confused by Brian’s original pdf drawing.
I have got the hull to the point that its time to start thinking of what sort of paint
to use. The interior was sealed with polyurethane as well as the undersides of all
the upper deck pieces. (At this point the hull is 8 oz.)
I will probably seal the exterior with Z-poxy finishing resin before paint.
The angle of the rudder on my boat came out kind of steep (see picture) and does
not match angle at the top of the cut plywood parts. I can still change this if
needed, the rudder tube is not glued in yet.
Kurt
Kurt,
It looks like we are on the same build schedule…slow and steady. Your boat is looking good; great attention to detail. I will be putting the rudder and keel together next, so it will be interesting to see how my rudder lines up.
Scott
Thanks Scott,
I am putting this kit together as close to how Brian originally designed it as possible. Now there were some problems with a couple panels.
After talking to Brian I was able to get these resolved with allot of work on my end(remember my kit was a prototype).
The only major change is the sail servo mount. I think that Neil needn’t worry about my boat as far as accessibility goes, so it would be
nice to put this argument to bed.
I am trying to make this thread about the boat, not my building skills. If anyone wants to know how I did something just ask.
Here is the modifications made to the kit so far, not many!
sail servo mount.
Replaced four pieces of deck material with two longer pieces so there was no seam.
Put a small piece of 1/64th ply on the backside of former #4
Added a strip of 1/64th ply on the top of the foredeck stringer
And thats it, no re-engenering (other than the servo mount)
Kurt