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Author Topic: D Class Boat build  (Read 15993 times)

Andyn

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D Class Boat build
« on: April 23, 2012, 08:31:03 PM »

I've been looking at the brand new RCMK K-30RZ for a while now, trying to decide what to put it in. Had quite a few ideas, such as a H&M cat, or a big rigger. Finally settled upon the HOR 50" mono, which looks to be a Delta Force copy underneath, with a rather nice looking top to it.

Both were ordered, the engine from GizmoMotors in Florida, and the hull coming from Hong Kong. After being stung for import duty on the engine I've finally got both here, and will start building shortly. All the running gear is already sorted, and I should be getting a more suitable radio box for it than the one I have this weekend. Due to space restraints and the pipe rules of the BMPRS, the fuel tanks will have to be the bladder type, and will be shoved up in the gunwhales out the way of the hot bit.

Toying with paint schemes currently, deck will be gloss black, exposed gel coat underneath with possibly a red hatch. Barry of Barry's model lettering will be supplying the decals for it. Also toying with the idea (on Scoop's recommendation) of getting the electronic CDI kit, I'll see how much room I've got left in the radio box. Either way, the boat's gonna go like stink %)

Andy.







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SallyB

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Re: D Class Boat build
« Reply #1 on: April 23, 2012, 09:09:30 PM »

In your hands, it could be fatal  {-) {-)

Agree with you there Danny!
Careful with black paint Andy, hard to see if you conk out and that lovely decor and hull could end up beaten up, perhaps a florescent stripe top and bottom? :)
Either way, pretty damn sexy.
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Andyn

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Re: D Class Boat build
« Reply #2 on: April 23, 2012, 09:15:47 PM »

It's getting some pretty large high vis Nyan Cat vinyls on it  %)
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craig dickson

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Re: D Class Boat build
« Reply #3 on: April 23, 2012, 10:30:00 PM »

That engine looks a beast and the hull a good quality moulding. :-))

What power output will this engine deliver (asking out of curiosity)?

Cheers
Craig
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Andyn

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Re: D Class Boat build
« Reply #4 on: April 23, 2012, 11:22:15 PM »

Supposedly they're 7.5hp out of the box, at up to 19,000rpm, though with the electronic CDI unit I suspect faster...
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craig dickson

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Re: D Class Boat build
« Reply #5 on: April 24, 2012, 06:54:42 PM »

Hi Andy

Out of interest I am in the build process of a Prestwich Thunder with a Zen7. Unfortunately it I believe can not qualify for BMPRS racing. I've just fitted the engine and prop tube.

I will be very interested to see further photos as your build progresses :-))

Cheers
Craig

Oh this is mine so far:

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Andyn

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Re: D Class Boat build
« Reply #6 on: April 24, 2012, 07:53:50 PM »

Today I've been rather busy, as I've had the day off work...

The engine mounts on the rear had to be re machined, as I need the engine as far forward on the rails as I can get it, this took quite a while to do. The end result is that the mounting rubbers now sit 3/4" further towards the engine, allowing the exhaust to actually sit inside the boat.

The rails were then marked up and slotted with the dremel, for both the engine and propshaft support. I've also filed out the air ducts on the deck, and fitted the rudder.

I then popped over to Bill to borrow a piston stopper and plug spanner, to set about trying to break my little finger attempting to undo the pullstarter dog on the back of the engine. I don't like pullstarts, they're an awful lot of effort for very little gain, especially when the engine is cold. This has been replaced by a pulley wheel to use a proper starter, and I've also fitted the coupling.

This is where we are now:

Andy :-)







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Subculture

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Re: D Class Boat build
« Reply #7 on: April 24, 2012, 07:59:44 PM »

'Ere, I've been bowdlerized?

Danny

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Re: D Class Boat build
« Reply #8 on: April 25, 2012, 11:12:38 AM »

Andy - don't forget to move your stuffing tube T-bar further forward.  Where its shown on the picture won't give enough support to the front of the tube.
Cheers
Danny

Andyn

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Re: D Class Boat build
« Reply #9 on: April 25, 2012, 07:19:12 PM »

Andy - don't forget to move your stuffing tube T-bar further forward.  Where its shown on the picture won't give enough support to the front of the tube.

Will do mate, it's got to be dropped a bit too...
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craig dickson

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Re: D Class Boat build
« Reply #10 on: April 26, 2012, 06:11:05 PM »

Hi Andy

Thanks for sharing the further images. I do like the layout of this engine for marine applications. I like the fact that unlike the Zenoah the exhaust is piped in a straight line with no need for bends in the manifold. Also I like the position of your starter pulley because it means that the belt does not have to stay in the boat risking snagging against the moving prop shaft etc.

Cheers
Craig
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Andyn

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Re: D Class Boat build
« Reply #11 on: April 30, 2012, 10:04:04 PM »

Done a little more work on it this evening.. Sanded out the stuffing tube hole in the radio box, sanded out the exhaust pipe opening in the rear of the hatch, and made a hole for the plug cap to sit in.

Space is very limited in this boat, hence the need for the plug cap hole (engine sits too high), the slot in the rear deck for the pipe (manifold doesn't go high enough), and the radio box slot, which will be reshaped when the stuffing tube is in the boat. There was only about 1/4" clearance between the bottom of the box and the hull, to be able to get a quarter scale servo in I'm having to use a deep V box.

There's going to be two problems with this boat, which I can do nothing at all about. Firstly, it's going to have quite a high center of gravity, owing to the fact the engine has the magneto pickup on the side of the engine. This is as low as it can go while the engine is still able to rock, but the engine is still quite far up. Second problem is quite obvious, it may have the center of gravity a bit too far forward. Nothing that can't be solved with a bit of lead as it's not out by far, but I'd rather not have to.

Other small issue is that I may have to have the radio box lid made out of aluminium, to stop it melting. There's a good half inch of clearance though, any thoughts? The pipe physically cannot go any higher...

I'm currently waiting on postie to bring me the throttle servo mount, throttle servo (Savox SC0252MG), twin 500ml fuel bags and the stuffing tube.

Shaft support will be moved a bit next, then I'll get the stinger on then it'll be time to paint

Andy :-)





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Danny

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Re: D Class Boat build
« Reply #12 on: April 30, 2012, 11:13:19 PM »

Hi Andy
Re. radio box and exhaust.  If you use aluminium (or carbon fibre) for the lid, be sure to use extensions on your rx aerial to bring it out of the box as 2.4 or 40 MHz won't pass through.  With half an inch clearance, you could try either the shiny aluminium tape on the top of the box as a heat reflector, or use a piece of plumbers heat diffusing pad (modern equivalent to asbestos) to absorb the heat.
Don't worry about the centre of gravity - it will give you a ready excuse when it barrels on the corners  ;D
Looking good though  :-))
Cheers
Danny

Andyn

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Re: D Class Boat build
« Reply #13 on: April 30, 2012, 11:22:46 PM »

I think I'll just use acrylic with an aluminium strip on the top of it, should do the job. A small strip of heatsink under the pipe might help matters, too.

Andy :-)
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gwa84the2nd

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Re: D Class Boat build
« Reply #14 on: May 01, 2012, 01:09:17 AM »

you could always wrap the pipe in car manifold wrap you can hold it with you and at full temp with that on  :-))
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craig dickson

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Re: D Class Boat build
« Reply #15 on: May 01, 2012, 06:22:14 PM »

Other small issue is that I may have to have the radio box lid made out of aluminium, to stop it melting. There's a good half inch of clearance though, any thoughts?

Hi Andy

Does your pipe have a water cooling jacket at the front? If so I suspect that half inch clearance should be sufficient (with the airflow via the front vents) to prevent problems to your acrylic radio lid.

In the photo below (for comparison), my Lynx has about 10mm between the 6mm perspex lid and the front cone of the pipe and it has given me zero problems:



Cheers
Craig
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Andyn

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Re: D Class Boat build
« Reply #16 on: May 01, 2012, 08:17:17 PM »

It does, needs resealing but will be used anyway.

Stuffing tube, battery, fuel bags and servo mount all arrived via postie today, so will be fitting in the not too distant future. It's like christmas round here at the moment... ;)
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Andyn

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Re: D Class Boat build
« Reply #17 on: May 01, 2012, 08:19:47 PM »

Oh, and if you're planning on racing that Lynx that pipe will need to be shielded.
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gwa84the2nd

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Re: D Class Boat build
« Reply #18 on: May 01, 2012, 08:31:31 PM »

i always wounderd on a pipe that extends beyond the limits what constitutes shealding the pipe then
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Andyn

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Re: D Class Boat build
« Reply #19 on: May 01, 2012, 08:48:45 PM »

Any pipe that protrudes more than 65mm beyond the transom needs sheilding, a bit of rolled ally around it will do the trick :-))
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scoop

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Re: D Class Boat build
« Reply #20 on: May 01, 2012, 09:13:02 PM »

i always wounderd on a pipe that extends beyond the limits what constitutes shealding the pipe then
Like Andyn says a bit of rolled ally with an air gap between the shield and the pipe, it's there to stop the rescue crew accidentally burning their hands on a hot pipe when they pick the boat up out of the water :-))

Cheers
Scoop
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gwa84the2nd

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Re: D Class Boat build
« Reply #21 on: May 02, 2012, 01:09:50 AM »

cool i will have to sea what i can do with mine then lol


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Andyn

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Re: D Class Boat build
« Reply #22 on: May 02, 2012, 11:08:17 AM »

That's gonna need a dustbin round it  :o
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martno1fan

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Re: D Class Boat build
« Reply #23 on: May 02, 2012, 02:58:10 PM »

cool i will have to sea what i can do with mine then lol




You need to get the motor further forward mate as i said before,i never had that much pipe out the back of mine,i used a bandless cone to cone pipe all that stuck out was the silencer on the end of the pipe.
Mart
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martno1fan

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Re: D Class Boat build
« Reply #24 on: May 02, 2012, 03:58:33 PM »

Forgot to mention James i used a deep vee header,i know some say they dont tune to the max but i never had any problems getting my boat to over 40 mph with a stock zen and it ran flawlessly.I know most guys use the 90% headers but you need to get the motor as far forward as she will go for those to work and also make sure you get the widest bend that will fit this makes the pipe a tad shorter too.Looking at your motor it can go forward a good 4 inches ?.
Mart
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