Southampton Solent Model Yacht Contest

willp14335

Member
408
98
Anacortes WA
Here's where the build starts to get exciting. Inspired by the design and build of Francis Lee which had an entirely modular structural insert that dropped into the hull, I extended this concept into my design. Using 3D design, I set up the structure arrangement and had all the parts 3D laser cut. I was then able to assemble all the parts together and pre-finish them before installing it all into the hull. This was good because I was able to make sure everything was aligned properly, bonded well and finished completely which made the interior structure a lot faster and easier to build while also being better finished and less likely to fail under loading.

The 3D design had the added benefit of ensuring everything would fit properly. This backfired slightly on me as when I placed my keel stiffeners inside of the integrated keel box to make sure they fit, it was so tight I had to hit the structural module with a hammer a bunch of times to get the keel free again. (it survived, luckily). After the structure was installed my light eggshell hull felt a lot stronger and more solid. All the parts are made 1mm birch faced ply.

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willp14335

Member
408
98
Anacortes WA
I'll drop in the keel too I guess, I'm kind of proud of that.

Both of the foils were 3D printed from ABS plastic. The keel was too long for the machine and had made in two separate pieces and glued together. Encapsulated inside of the keel are two full length 4mm diameter solid carbon fiber stiffening rods and one partial length 4mm rod holding it together. The keel has a filleted top that runs flush against the bottom of the hull and the stiffeners protrude from the top into the hull. This allowed me to make the hole as small as possible, 4mm by 12mm to reduce the chance of leakage. All three stiffeners go into the hull as this is where the max shearing forces are applied to the keel. The two stiffeners continue down into the two halves of the keel bulb which is epoxied on with lead spacers over the stiffeners and to the bottom fillet of the keel. I was very proud of the keel as it actually costed less than some of the carbon and laminated wood keels that other people used in their designs while keeping the designed NACA section preserved. In the 3D model you can see the designed fit of the keel stiffeners into the hull. The third one was added to reduce bending and help keep the two part keel fin together as I had originally intended it to be a single piece.

The rudder was a last minute addition to the hull to make the boat sail straight. I designed it in 10 minutes at one in the morning and had it 3D printed with next day shipping for it to arrive in time.

To figure out how to install it, I extruded a rudder stock through the hull in Rhino, measured it, and decided to cut holes in the same places at the hull and deck. Then I used a metal BBQ skewer for a rudder stock and epoxied the emergency rudder in place. Luckily the rudder ended up being straight and not leaking and it didn't fall off, much to my relief.

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Ed Lada

Super Anarchist
19,718
5,338
Poland
Very well done Will! Model boat building sure has come a long way since my young years when I loved to build model boats and balsa airplanes. Laser cut wood, ACAD, 3D printing, I used paper plans, a jewelers saw and an Exacto knife! I remember well putting tissue over balsa framed wings and then several coats of dope to make it look nice after wetting, gently stretching and blow drying the tissue to get it nice and tight.

Keep up the good work, I have a feeling we will hear more about you in the coming years.

 

willp14335

Member
408
98
Anacortes WA
Exacto knives were used to build this boat, but mostly to persuade the lightening holes to come out when the laser didn't cut all the way through the wood.

 

Jose Carumba

Super Anarchist
3,066
0
Pugetopolis
Will, I am so VERY impressed with your abilities. Keep driving hard and learning and stay curious. Oh, and definitely keep us posted from time to time!

 

SemiSalt

Super Anarchist
7,815
294
WLIS
In every generation, there is a certain amount of "what's the matter with kids today?" When you see a group like Will and his classmates, you have to answer "not much". I felt the same way about my kids and their friends.


 

Not My Real Name

Not Actually Me
43,112
2,855
In every generation, there is a certain amount of "what's the matter with kids today?" When you see a group like Will and his classmates, you have to answer "not much". I felt the same way about my kids and their friends.



I actually did that song in a duet in a high school play. I was dressed in a a t-shirt and waving a plunger around, my partner was in a housecoat getup.

 

Ed Lada

Super Anarchist
19,718
5,338
Poland
In every generation, there is a certain amount of "what's the matter with kids today?" When you see a group like Will and his classmates, you have to answer "not much". I felt the same way about my kids and their friends.

Meh. Pics or it din't happen!

 

DDW

Super Anarchist
6,700
1,229
The rudder was a last minute addition to the hull to make the boat sail straight.
No need to steer? I didn't see radio-control gear, so I'm assuming the racing consisted of "put it in the water and let it go"?


If upwind directional stability is an issue, you might try losing the jib and adding a small mizzen wing (if the rules allow). This is, after all, the reason airplanes have tails. You are looking for a change of CP with yaw disturbance tending to correct the disturbance. The jib provides this function but is inefficient at it: 1st because it is an inefficient airfoil, second, because its leverage is small. A small mizzen wing set at a slightly lower angle of attack, might eliminate the need for the jib and perhaps the rudder.

 
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Not My Real Name

Not Actually Me
43,112
2,855
In every generation, there is a certain amount of "what's the matter with kids today?" When you see a group like Will and his classmates, you have to answer "not much". I felt the same way about my kids and their friends.


This would have been around...1983? I don't think there are any surviving pictures. But back then I was a lot slimmer.

 

willp14335

Member
408
98
Anacortes WA
I'm going sailing today so I can't post any pictures. When I get back I'll post something about the float test and the hell that is silicone sealent.

 

Alcatraz5768

Super Anarchist
The bulb looks to have the maximum camber very close to the maximum camber of the fin. I was lead to believe that Tis was a no-no as the maximum compression of the water occurred at the same point causing a very high pressure point at the bulb fin join, leading to most modern bulbs having their maximum camber further back well behind that of the fin.

I may be very wrong in the theory but I haven't seen a bulb like yours on any modern yachts, but it might scale differently.

Your building skills are top notch and inventive, well done.

 

Ease the sheet.

ignoring stupid people is easy
20,349
2,342
The bulb looks to have the maximum camber very close to the maximum camber of the fin. I was lead to believe that Tis was a no-no as the maximum compression of the water occurred at the same point causing a very high pressure point at the bulb fin join, leading to most modern bulbs having their maximum camber further back well behind that of the fin.

I may be very wrong in the theory but I haven't seen a bulb like yours on any modern yachts, but it might scale differently.

Your building skills are top notch and inventive, well done.
Area rule?

 

Not My Real Name

Not Actually Me
43,112
2,855
The bulb looks to have the maximum camber very close to the maximum camber of the fin. I was lead to believe that Tis was a no-no as the maximum compression of the water occurred at the same point causing a very high pressure point at the bulb fin join, leading to most modern bulbs having their maximum camber further back well behind that of the fin.

I may be very wrong in the theory but I haven't seen a bulb like yours on any modern yachts, but it might scale differently.

Your building skills are top notch and inventive, well done.
Area rule?
Everyone in the class was given identical bulbs they were required to use. The addition of metal ballast to the keel was prohibited.

Take a look at the class gallery - they're all the same.

https://www.facebook.com/media/set/?set=a.10154195244155477.1073741949.212032765476&type=3&uploaded=102

 
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