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Building a Crackerbox step by step with lots of pics!

Old 08-08-2009, 05:37 AM
  #51  
Tidnab
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Default RE: Building a Crackerbox step by step with lots of pics!

Here's what dicko was refering to about chaffering the chine edge on the left side to form a non trip chine.It really helps and if used with a non trip trim tab with a 45 degree bend on the outer edge you can almost eliminate barrel rolls,but still have to let up on the throttle into the turn to drop the bow and then work the throttle around the turn.I used the method of the 3 pieces of 1/8"x1/4" to make my chine stringer so I went 3/8" on the chine angle,but you would have to stay at 1/4" on yours.I went up a little further on the chine.
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Old 08-08-2009, 05:54 AM
  #52  
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Default RE: Building a Crackerbox step by step with lots of pics!

Might be an idea to do it on both sides if hes wanting it to turn well both ways?.
Mart
Old 08-08-2009, 06:00 AM
  #53  
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Default RE: Building a Crackerbox step by step with lots of pics!

Good point mart and I wasn't thinking about which way they run their courses in Australia,clockwise or counter clock wise,if he was going to get into racing.
Old 08-08-2009, 08:26 AM
  #54  
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Default RE: Building a Crackerbox step by step with lots of pics!

I was wondering why you guys were saying only the left side!So its a counterclockwise racing thing is it. Kinda like nascar eh?
Nah i'm not thinking of getting into racing, except for with my brother possibly, but he's got a 50cc engine so we won't be able to go near the official races.
But i see what you're getting at with the stern chines: make them less "grippy" so the boat can successfully pivot arount the skeg, is that the idea?
Oh and i'm not liking the sound of dissolved fuel line clogging the carbs, i might go for tygon stuff after all. Its just that i paid $10 for 20cm of it at the local ripoff store!!!
Old 08-08-2009, 09:40 AM
  #55  
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Default RE: Building a Crackerbox step by step with lots of pics!

Its the same as how we do them on the t boats exept we have a much bigger one,we have a non trip side or sides so when the boat turns the water rides up the side instead of hitting it as it does if its flat and thus causing the boat to trip and maybe flip etc.Having the non trip makes them slide smoothly round so if i were you id add one each side seeing as you might like to turn both ways and not worry?.
Mart
Old 08-08-2009, 08:21 PM
  #56  
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Default RE: Building a Crackerbox step by step with lots of pics!


ORIGINAL: CrackerboxSydney

I was wondering why you guys were saying only the left side! So its a counterclockwise racing thing is it. Kinda like nascar eh?
Nah i'm not thinking of getting into racing, except for with my brother possibly, but he's got a 50cc engine so we won't be able to go near the official races.
But i see what you're getting at with the stern chines: make them less ''grippy'' so the boat can successfully pivot arount the skeg, is that the idea?
Oh and i'm not liking the sound of dissolved fuel line clogging the carbs, i might go for tygon stuff after all. Its just that i paid $10 for 20cm of it at the local ripoff store!!!
You did get ripped off, I pay a few dollars for a meter at Gasweld.

I only rounded the left side of my hull as I generally stick to right hand turns as if I were racing. My hull turns well both ways, but i hit the right hand turns harder than the left hand ones so I didn't see the point in doing both. The prop rotation generally helps keep the boat flat in lefties anyway as the boats favour turning right over left due to the diraction the prop rotates.

When you mount the skeg you want to mount the trailing edge about 1/4 to 1/2" in front of the CoG and about an inch to the right hand side of the hull. This will help the hull track straight & turn better also. There is a cracker thread on this forum with lots of good tips & pics that will help you. It's a bit old now so you will have to do a search to find it.

I have a lot of info writtten down in my test book for crackerboxes, once you get close to mounting & setup I can shoot some more info your way.

Cheers
Jason
Old 08-10-2009, 02:35 AM
  #57  
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Default RE: Building a Crackerbox step by step with lots of pics!

Gasweld - i'll have to check them out. I think there's one in the area.
Anyway, been working on the engine mounts, as you can see in the pics. The engine is flipped upside down in the picture so you can see how the mounts are bolted to it.
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Old 08-10-2009, 09:00 AM
  #58  
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Default RE: Building a Crackerbox step by step with lots of pics!

As I said before your boat isn't being built,fastened down to a building board and if the boat has any twists in the hull ,you may have one of the most uncontrolable crackers ever made.It should have been on a board till the bottom and side skins were all on, then taken off and the decks applied.I see in the pics you have some kind of engine mounts that are not in the Dunlap plans.Your engine rails should be stood upright and at 5" in between and made of 1/4" ply.I go a little heavier on my rails at 3/8".Even better is to extend them all the way to the transom,for more strength and it gives you a nice place to attach your radio box.Those blocks may not hold in a hard pull.I wouldn't worry about mounting the engine before you get the boat to an almost completed stage.Sort of like we say here."Putting the cart before the horse"
Old 08-11-2009, 03:09 AM
  #59  
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Default RE: Building a Crackerbox step by step with lots of pics!

ORIGINAL: Tidnab
you may have one of the most uncontrolable crackers ever made
That sounds awesome!!!

We'll just have to see how i go. Maybe i'll have to build another one next year: what a lovely excuse that'll be.
As for the rails, i got out a measuring tape and couldn't see how 5" rails would fit around my engine. Anyway, you'd be absolutely horrified at my brothers boat in this case! hehehe.

Ok i've test-mounted the engine. Looks alright. Sounds like next on the agenda is skinning the bottom and sides!

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Old 08-11-2009, 04:06 AM
  #60  
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Default RE: Building a Crackerbox step by step with lots of pics!

All my 28 cc weedy powered boats have 5" rails they fit just fine you just have to use some imagination to figure it out.Heres a few pics of my mounts before i trimmed them back a bit to remove some weight etc.Notice i removed the clutch and i used a cmb .90 collet with m 8 thread to fit the output shaft.
Mart
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Old 08-11-2009, 04:17 AM
  #61  
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Default RE: Building a Crackerbox step by step with lots of pics!

I hope you've got the means to move the motor forward or most likely back to adjust the CoG. To me it looks like the engine will be mounted too far forward, especially for a weedy. Remember, when you have it finished you want the CoG to be about 30% from the transom with an empty tank of gas.
Old 08-11-2009, 04:45 AM
  #62  
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Default RE: Building a Crackerbox step by step with lots of pics!

ORIGINAL: martno1fan

All my 28 cc weedy powered boats have 5" rails they fit just fine you just have to use some imagination to figure it out.Heres a few pics of my mounts before i trimmed them back a bit to remove some weight etc.Notice i removed the clutch and i used a cmb .90 collet with m 8 thread to fit the output shaft.
Mart
That looks quite neat the way you've done your mounts - very impressive!Maybe i'll have to have a re-think of mine.

ORIGINAL: dicko

I hope you've got the means to move the motor forward or most likely back to adjust the CoG. To me it looks like the engine will be mounted too far forward, especially for a weedy. Remember, when you have it finished you want the CoG to be about 30% from the transom with an empty tank of gas.
Oh really?I thought that the idea was to place the engine at the COG of the boat, that's why i placed it there. Hmm, it should be easy to move it back. Realistically, how much improvement will this make for someone just looking to have fun (eg no racing) ?

Old 08-11-2009, 04:51 AM
  #63  
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Default RE: Building a Crackerbox step by step with lots of pics!

The motor should allways be the last thing mounted into a boat,best way to ballance things is when the hulls finnished mount your hardware on the back, fill the radio box with all your gear and set it in the boat then add the tank half full with fuel and sit the motor with mounts and pipe if your using one in the hull and move it arround till the boat ballances at arround 30%.Then you can mark the rails for mounting .I strongly advise installing some rails,you can slot the bulkheads for and aft of the compartment to accept them this will help make them strong then glass them after to the skin and frames .
Mart
Old 08-11-2009, 07:01 PM
  #64  
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Default RE: Building a Crackerbox step by step with lots of pics!

Most people I know balance the boat with an empty tank at 30%, you rarely have the CoG much further back than that, but often have it further forward ( up to 34%) which the fuel can account for, if not lead weight can be added to the front of the boat. Not saying having fuel in the tank is wrong, just showing a different way of doing things.

Having the weight too far forward will make the boat ride wet (nose down too far giving a lot lore wetted area - more power required to push it along) which is slow and also give it a tendancy to spin out in turns.
Old 08-11-2009, 07:06 PM
  #65  
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Default RE: Building a Crackerbox step by step with lots of pics!

Ive allways used half a tank that way the ballance doesnt change as much wether the tanks full or empty so they dont get too flighty when the tanks empty and they dont run too wet when its full.Makes sense to me anyways .
Mart
Old 08-13-2009, 04:53 AM
  #66  
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Default RE: Building a Crackerbox step by step with lots of pics!

Hey all,
Some good tips on balancing it all there. Good stuff! Iespecially like the news that it'll make it faster with the COG towards the transom.
However, i'm back at work now, so updates won't be as often.So bear with me.
Actually, if you could all come up with tips and suggestions as to how to do the 'skinning' of the bottom and sides, that'd be awesome, because that'll be what i'll be doing this weekend.
Cheers
Old 08-27-2009, 08:06 AM
  #67  
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Default RE: Building a Crackerbox step by step with lots of pics!

Hi all Sorry for late reply but i broken my hand and now just getting back .here the link for the steamer but it the 1200 watt model http://www.fingerhut.com/ProductGrou...pxid=73658.And for the picture CrackerboxSydney i can send them to you if you send me email
Old 08-27-2009, 04:08 PM
  #68  
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Default RE: Building a Crackerbox step by step with lots of pics!

Personally i would never of used that motor. I had one in a 44in mono. Its so heavy that my boat only sat an inch out the water at the most. Also it the same weight as 2.5 zenoahs manly because the flywheel and the clutch but really the flywheel and its no where near the power. And mine would never run good once it hit the water always shut off or came untuned. But if you insist on using it i would throw the wheel wheel out and get a electronics ignition.
Old 08-29-2009, 03:02 AM
  #69  
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Default RE: Building a Crackerbox step by step with lots of pics!

Okay been busy on skinning the bottom of the boat. It's looking awesome!
What we did was put the boat on a piece of ply, trace around it, and cut the shape out (plus 2 inches outside for extra).
Then we cut a groove for the front 1/3rd of the boat so that the ply would wrap near the bow (or is that the poop deck?) properly.
Placed the boat in position, clamped it all down and painted it all with the resin. In an hour we'll take all the clamps off and hopefully it'll hold.
Cheers all.
And hmm i really hope this floats more than an inch from the water. But we'll see.
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Old 08-30-2009, 06:34 AM
  #70  
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Default RE: Building a Crackerbox step by step with lots of pics!

Been busy trimming the excess off from the bottom skin, as when i initially glued it on, i only used a rough shape. I tried using an angle grinder like my brother was using, didnt work too well, so the jigsaw was all good in the end:
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Old 08-30-2009, 06:36 AM
  #71  
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Default RE: Building a Crackerbox step by step with lots of pics!

Glued one of the sides on. Raided the missus' clothes pegs
Also you can see how the groove in the base allowed it to bend at the bow in the third pic.
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Old 08-31-2009, 01:21 AM
  #72  
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Default RE: Building a Crackerbox step by step with lots of pics!

I only rounded the left side of my hull as I generally stick to right hand turns as if I were racing.
Becareful, in both US clubs it would make your hull illegal to race!
Even though we don't have any rules YET they will probably resemble the US ones to a point.
Old 09-11-2009, 12:52 PM
  #73  
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Default RE: Building a Crackerbox step by step with lots of pics!

Hi all here some up date on my Zipp kit cracker box it now house an Kawasaki Marine 50CC engine here some picture i also looking for som info on the engine # TD048D-131340
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Old 09-27-2009, 03:41 AM
  #74  
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Default RE: Building a Crackerbox step by step with lots of pics!

Ok its been a while but found time this weekend for more progress.
As you can see i've been working on the second side now (right side i think, can't remember)
Instead of mucking around with clamps and straps to hold it on, simply drilled a whole lot of holes for cable ties to go through. Ithink when it all gets puttied up and painted at the end they won't be visible. It was a lot easier this way.

What should we do about the top deck? My main concern is to leave a serviceable hatch/hole so i can get at the engine and fuel tank and electrics.
Also, where's a good place in sydney to go and buy the bits eg stuffing box, driveline, skeg, rudder, etc etc.
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Old 09-27-2009, 08:06 AM
  #75  
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Default RE: Building a Crackerbox step by step with lots of pics!

Hi all . CrackerboxSydney And you can get all boat part from here .The boat looking good

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