Pakinto Build

I used to race Marbleheads back in the late 80’s and 90’s. Then the class pretty much died and our club switched exclusively to EC12s, and I had no interest in them. I got out of sailing all together, big boats and little ones when my son was born 18 years ago. Then last year I started looking at the RG65 class. I liked it because the rule is very open, like the Marbleheads, but the boats are much cheaper and easier to manage. When I found out that the National Championships were going to be in Reston Virginia, an hour and a half away, I decided that I had to do it. After not sailing an RC boat for 18 years and not having an RG65, and the race being less than 2 months away, I realized I had to get moving. I talked to Craig of Breaking Wind Boats to get a Round Ranger hull and Eric Rosenbaum for a set of sails. The round Ranger is based on one of my all time favorite boats, the Roar Edge Marblehead. The Roar Edge is very narrow with low wetted surface. It is very quick in light air and very well mannered as the wind comes up. A fantastic all around boat. And the Round Ranger RG65 proved to be no different. The hull and bulb both arrived very quickly and looked great. I had never built a plastic boat before, but it seemed to make a lot of sense for the small size of an RG65, and I rapidly got the boat together, about a week before the race. My boat was definitely fast. Unfortunately, I was still a little rusty. But the race was a lot of fun and I was (re)hooked.
So when Breaking Wind announced that they were coming out with a new boat, I immediately contacted Craig to get a hull from him. Since it is still somewhat in development, the only way I could get one now was to offer to do a build log. Well, Craig bit and here it is.
Now, a racing boat is like a tennis racquet. It is a piece of sporting equipment. It should be as simple as possible. Everything that goes into it should be necessary, nothing extra. It should be built strong and reliable, but not overbuilt. Don’t worry about aesthetics; if it is fast, it will look good. Try to fight the urge to put in a cool gadget or system. I have been down that road, and complicating a boat does not make it faster. It just makes it more complicated to sail and is another thing to break down. So, to sum it up, I am going to build this boat strong, simple and light. In other words, fast. OK, that may sound a little arrogant, but if you want a fast racing boat, that is what you do.

The hulls arrived to day from Craig. They are very nicely molded and I saw no flaws or imperfections. The boat is called the Pikanto and was designed by Maximo specifically for Breaking Wind Boats. It is noticeably based on the current crop of IOMs. I immediately got started. First, I carefully trimmed off the excess material around the shear with a pair of scissors. I left about 1/8 to 1/4 inch to form a flange around the shear. This gives you a surface to glue the deck to as well as the curve in the plastic gives strength. Next I went around the shear and bent the flange down some to be parallel with the deck. I also trimmed the extra material around the deck down to about ¼”.

Are you going to follow the design drawing for the keel and rudder? Personally I was never a fan of swept back leading edges.

Hey Don. First off, I am using a straight vertical LE fin, akin to what Eric is now producing. Second, I am actually doing 2 boats. This one will be conventionally rigged, the other one swing rigged.

The last time I ran simulations in XFlr, a straight vertical TE with a swept back LE fin performed better.

All I did, was use the same foils, dimensions, etc., but just changed the planform.

subscribed and watching! looks good so far! would I be correct in thinking that the round ranger hull i have (yet to start) is from the same guy?

Yes. The build will be very much the same.

I’m really looking forward to watching this build, hoping to learn some tricks from the pros. :cool:

Cutting the slot for the fin is one of the most critical steps in making a fast boat. You want excellent alignment of the fin. However, if you do manage to cut the opening off center, don’t worry, you can fix it by opening up the hole and aligning it when you put the trunk in. But if you get it right now it is easier and cleaner. First mark the leading and trailing edge locations of the fin on the bottom of the boat. The Pakinto fin leading edge is 345.5mm from the transom. Next I tape a piece of string down the center line of the hull. Make sure that you are in the center of the bow and stern and then you will have to eyeball it to make sure that the string runs straight down the center. Now draw a line down either side of the string from the fin leading edge location to the trailing edge location. Try not to touch the string or you will move it. Do the same for the rudder location. Remove the string. Now drill a hole at the fin leading edge location of about the same radius as the fin leading edge. Do the same at the trailing edge. Also drill the hole for the rudder shaft. Using a fresh X-Acto blade cut an approximate airfoil shape from the leading edge hole to the trailing edge hole. Test fit the fin, it should be to tight. Carefully sand the opening until the fin fits.

Clamp the file in a vice and make sure that it is vertical. Slide the hull and fin over the trunk and line the hull up on its waterline and laterally. Tack glue the trunk into the hull with a couple of drops of CA. DO NOT USE MORE THAN A COUPLE OF DROPS! Any more and you risk melting the hull and gluing the fin in permanently. Remove the hull and trunk from the fin. Scuff up the inside of the hull around the trunk and anywhere else that you will use epoxy. Epoxy has a hard time sticking to the smooth plastic. Mix a very thick paste of epoxy and micro balloons and build a fillet around the fin. Also, put a thick coat of epoxy/microballoons in the nose and then press a piece of balsa up in there. Set the hull aside to cure overnight.

Forgive the newbie questions, but are you using a pre-fabricated keel, or did you make that one, and what are microballons?

Funny you should ask. The keel is from Eric ( I was just talking to him about this. It is a very nice carbon fiber foam keel from a CNC mold. Pop Eric an email and he can send you one. He also makes trunks and rudders. And microballoons are small hallow glass spheres that look like a powder. If you mix them with epoxy resin they make a very nice paste that is strong, light and easy to sand. They are usually available from hobby or marine supply stores.

This morning I installed the mast tube, the jib attachments and the mast seat. The mast tube is simply glues to the front of the keel trunk. The jib attachments simply screw into blocks under the deck. The mast seat was a little more complicated. It would have been simple had I installed the keel another ¼” back. As it turns out, the mast is on the vertical rise to the foredeck. I ended up gluing a piece of ¼” balsa to the inside of the vertical and sanding a groove in it to fit the mast. I am using a Micro Magic gooseneck, so the gooseneck actually fits into a plate on the deck. Since my mast was seated in a corner, I simply put the plate under the deck. The gooseneck now goes through the deck and seats in the plate underneath.

For the rudder, the post will go through the bottom of the hull into the stuffing box. The stuffing box then protrudes onto the deck. I will use a deck mounted servo. The stuffing box comes up about ¼” above the deck to allow the attachment of the winch turn around. Next I arranged the deck layout. I will put the winch on deck with a continuous loop. The throw on the GWS 1 turn winch that I am using is 5 inches, which means that the sheet guide will be 4” from the mast. With all of the equipment laid out I built the sub deck infrastructure. This is mostly 1/16” plywood cross members and ¼” hardwood blocks for attachments. This is the part that people tend to over build. Notice how little structure there is in there. The cross members will be epoxied to the deck, so while 1/16” ply may seem light, it will be plenty. I included attachment points for shrouds, but I am not planning on using them. The hull and deck are ready for joining.

To join the hull and deck I mixed a very thick paste of epoxy and microballoons as shown in the picture. It is about the texture of peanut butter. Then I spread some around the base of the stuffing box. Next I spread it all around the shear, cross beams and attachment blocks. Also, I spread a bunch around where the keel trunk meets the deck on the underside of the deck. Then put the deck on the hull and tape it down. Set it aside upside down so that the epoxy flows down onto the underside of the deck. I also glued the two keel bulb halves together and taped them. Then I set everything aside to dry overnight.

Note - After curing, I am not completely happy with the hull-deck joint. Next time I will put a small bead around the inside lip of the deck as well.

I got the electronics in and the sheet lines strung up. I just need to float it to locate the bulb, mount it on the fin and build the rig. Then it will be ready to sail.

Nice job Gregg. You are tearing right along.


He’s not the only one !
ready to glue the deck on with MEK over here.
I went a little different way putting in the servo mounts.
my keel box is plastic but the shape is straight off the keel PDF posted.

Thanks Eric. The keels and rudders are beautiful!

There has been a little discussion about the change in Center of Lateral Resistance on the boat due to the straight leading edge of the fin versus the designed raked fin. TTypically I put a fixed lead from the leading edge to the mast. For an RG65 it is 33mm for a swing rig and 0 for a conventional rig.

Next was the test float. I floated the hull in the bathtub without the fin. I placed the bulb on the deck and moved it until the boat floated on the waterline. I then marked the position on the deck. Then back to the shop. I remounted the fin and leveled it up in the vice. Then I dropped a perpendicular from the mark and marked the fin position on the bulb. Next I drilled out a slot in the top of the bulb for the fin tab to fit in. I inserted the tab and leveled the bulb. Then I wicked in thin ca to fix the bulb on the fin. After the CA dried I drilled a small hole into the bulb and through the bottom of the fin. Then I inserted a small piece of metal rod to pin it in. I then drilled a small hole through the deck and into the top of the fin. I tapped it for a 6-32 bolt to hold the fin on.