1/8 scale Smokin Joe

[Chris Migliaccio]

I am building an Mlboat works 1/8th scale Smokin Joe kit. Where is the center of gravity, and if I run a nitro engine, are there some basic measurements as to locate where the engine will mount, and will i need to build in a belly pan?

 

[Hydro Junkie]

The CG should fall roughly at the front of the turn fin. Normally, a turn fin is between 1 and 1.5" back from the sponson transom but, as those of us that build boats know, that's not set in stone. As far as where to locate the engine and belly pan, you want to place the engine, radio and fuel tank where they will help the boat balance in the approximate location desired, when the fuel tank is empty. Not all boats need belly pans either. Most times, a belly pan is used to drop the engine to provide clearance for a dummy engine covering the motor. Other times, it's used to lower the CG for better stability. Since you're doing a boat with the high air scoop, you may not need a belly pan at all, though that boat may have had one in full scale, meaning the kit should also have one.

 

[Steven Kinney]

I just Built the 1/6 scale ML boats Smokin Joes. I put the fuel tank in the nose of the and the motor just behind that. I had to do a belly pan but that was just so I could get the side exhaust under the deck. For a nitro boat you shouldn’t need to do one. You will have plenty of room under cowling to fit everything. I wouldn’t do a belly pan unless you have to it’s a lot if extra work for nothing in your your case. If you want I can post some pictures of my layout even though it’s gas scale might help you get a few ideas.

 

[Chris Migliaccio]

I just Built the 1/6 scale ML boats Smokin Joes. I put the fuel tank in the nose of the and the motor just behind that. I had to do a belly pan but that was just so I could get the side exhaust under the deck. For a nitro boat you shouldn’t need to do one. You will have plenty of room under cowling to fit everything. I wouldn’t do a belly pan unless you have to it’s a lot if extra work for nothing in your your case. If you want I can post some pictures of my layout even though it’s gas scale might help you get a few ideas.

That would be a great help! Thank you

 

[Steven Kinney]

 

[GraysonTaylor]

I'm working on a '93 Madison which is pretty close to Smoken Joe's. I spent a lot of hours thinking about the motor mount and location. At first I was thinking about rail mounts as far forward on the flat bottom as I could go. I think the boat is going to be rear heavy because of the turbin tube wings and stuff. Putting the center of the cylinder where the floor goes from flat to angled looks about right to me, (unqualified :-| ). I'm happy to see Steves gaser looks like the same location I guessed at. Moving the motor forward required a small motor well. Not that hard to do. Plus it may even help the boat get onto plane better. My well is 3/16 deep and is a continuation of the center slope. 1/4 spruce plus 1/16 sheet. It then goes flat for about 1/2 inch. About as wide as the motor.

Before going further, get a 6" or so piece of tubing and stick it in your collet to see where the shaft will exit the boat. Big help.

Since the boat starts to curve in right where the flat bottom angles upward, 5" rail mounting wasn't going to work for me. I saw a pic from Phil and cloned it. I set the Speedmaster mount at 4" and made new rails. Kind of a challenge because the floor isn't flat and I have two quarter x quarter sticks running across the joint. I also felt that a floor mount was going to be a pain because of not mounting it on a flat floor.

Samuel pointed out that that if you decide to offset your motor in the tub, be sure and test fit your cowl as it may not clear. I went center tub.

Pictures would have been better, but I'm out of space right now...

Hope this helps.

 

[Chris Migliaccio]

Thanks, for the great information, any pictures you can provide would be greatly appreciated. I like to see what others have done, because i tend to overthink things.

 

[GraysonTaylor]

Thanks, for the great information, any pictures you can provide would be greatly appreciated. I like to see what others have done, because i tend to overthink things.

I'm an expert at analysis paralysis….
Haste makes waist, make haste slowly!

PM me your email by I can send pictures that way.

 

[GraysonTaylor]

Signed up for pictures.....

 

[Chris Migliaccio]

I like your engine mounts

 

[Greg Wannamaker]

Signed up for pictures.....

View attachment 280178

It’s an ok idea but you will almost certainly struggle to keep them in place, your engine vibrations will break them free. That’s why most either anchor their mounts to the actual engine well sides or through the hull bottom. Good to be creative but fear you’ll be disappointed in the end.

 

[Greg Wannamaker]

I'm working on a '93 Madison which is pretty close to Smoken Joe's. I spent a lot of hours thinking about the motor mount and location. At first I was thinking about rail mounts as far forward on the flat bottom as I could go. I think the boat is going to be rear heavy because of the turbin tube wings and stuff. Putting the center of the cylinder where the floor goes from flat to angled looks about right to me, (unqualified :-| ). I'm happy to see Steves gaser looks like the same location I guessed at. Moving the motor forward required a small motor well. Not that hard to do. Plus it may even help the boat get onto plane better. My well is 3/16 deep and is a continuation of the center slope. 1/4 spruce plus 1/16 sheet. It then goes flat for about 1/2 inch. About as wide as the motor.

Before going further, get a 6" or so piece of tubing and stick it in your collet to see where the shaft will exit the boat. Big help.

Since the boat starts to curve in right where the flat bottom angles upward, 5" rail mounting wasn't going to work for me. I saw a pic from Phil and cloned it. I set the Speedmaster mount at 4" and made new rails. Kind of a challenge because the floor isn't flat and I have two quarter x quarter sticks running across the joint. I also felt that a floor mount was going to be a pain because of not mounting it on a flat floor.

Samuel pointed out that that if you decide to offset your motor in the tub, be sure and test fit your cowl as it may not clear. I went center tub.

Pictures would have been better, but I'm out of space right now...

Hope this helps.

Your right to be mindful about the finished tail weight of your 93, there’s a lot going on back there, if I were to rebuild Frosty, that would be an area of focus in my build. Focus on building all things in the back as light as you possibly can, it really adds up. Wings and Verts, hollow and light,if you add foam floatation to them, go easy on the epoxy, it to adds unwanted weight. Good luck in your build and balance!

 

[GraysonTaylor]

It’s an ok idea but you will almost certainly struggle to keep them in place, your engine vibrations will break them free. That’s why most either anchor their mounts to the actual engine well sides or through the hull bottom. Good to be creative but fear you’ll be disappointed in the end.

The key to my madness is zero stress when bolting. A couple of pieces of tape on the mounts to simulate the thickness of the sealer and glue in place while bolted to the motor. After that, it will be easy to add blocking between the motor rails and the sides of the tub at the top. That leaves me with a rectangle of frame on the rails that I think will stay. Then agian, I've been wrong before and it will happen again

 

[Hydro Junkie]

Grayson, you were referring to an belly pan. The Madison had a full length belly pan from the bottom break to the cockpit. I have (or had at least) pictures showing the belly pan so, if I can find it, I'll post it. One other thing about the Madison. When it was "turbinized" prior to the 1991 season, it had hydroshoes added that extended 26" back from the transom at the deck. Most people won't add this change, installed by Mike Hanson, as it adds complexity to the build and doesn't follow Roger Newton's plans.

 

[Greg Wannamaker]

Thought you might like these, Frosty is in the hospital right now getting a new carbon fibre butt flap and many cosmetic fixes from the years of battle. Thought you would also like to see the engine belly pan as it’s meant to be.

 

[Greg Wannamaker]

Apologies for hi jacking your post Chris, lost site of your initial question, back to Joe’s talk.

 

[Wesleys Custom RC]

Thought you might like these, Frosty is in the hospital right getting a new carbon fibre butt flap and many cosmetic fixes from the years of battle. Thought you would also like to see the engine belly pan as it’s meant to be.

Is that a rc boat works hull? The old fritz mold? I have that boat as well.

 

[Greg Wannamaker]

No, it’s a wood scratch build.

 

[GraysonTaylor]

Thanks for posting Greg. I have the rear shoes on. Your pictures have been a great help. I need to figure out the winglets at some point.

 

[Hydro Junkie]

I knew I had a picture of the full sized 8806 Madison/Oberto someplace. Here's a shot from between seasons after the boat was reworked so that it could use a full moving canard rather than the fixed canard with flaps. It shows how accurate Greg's boat is as far as the bottom configuration.