Rocket-J

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My new project is to transform a 1/12th scale offshore, Mean Machine, to a 1/8th scale lake boat. The 24' to 30' Cats that frequent Lake Havasu and Northern California, not to mention Poker Runs all over the nation.
I would like to share this with who ever is interested but hasen't had the nerve to cut open a new hull.
I first set down with a photo of the new hull and a photo of the boat I want to simulate. It is very difficult to copy a hull with another unlike one, but you can create the image. In this case I brought the photos up to 1/2 model scale, overlay them, note the similar areas, draw in your modifications and make a plan.
For a "one off" model, I do not make a plug. I make individual pieces and cut and splice. For this model I bent thin aluminum into the shape of the deck and windshield, taped wax paper over the aluminum and layed two layers of thin cloth and resin over them. When dry, trim the new pieces to fit your plan and hull.
Then with a die gringer, I cut the new hull to accomodate the new pieces, removing only enough material to fit, so to maintain the integraty of your hull.
Here are todays photos. This is 4hrs work not counting the initial plan drawings. I will post regular updates as this project moves on.

Rocket-J

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Today I worked on the hard top. These lake Cats do not have tops, all open with an occational Bimini. For RC model purposes, I am putting a hard top on it.
Nothing has been attached to the hull yet. I started at the bow, made a new deck, windshield and now a top. Once this is finished and surfaced, it will be attached to the hull and canopy. Then I will cut the canopy from the deck. I also added some resin and matting in the front corners of the sponsons. I removed the squared off look. When I cut the sponsons round, I wanted some meat in their. Then I added cloth over the cut area.

dicko

Hey Rocket-J, looking good. I have a suggestion for you, after you have laid your glass out & worked the resin in, cover it with some peel ply, it's a very fine weave glass that absorbs excess resin and once the resin has set, you peel it off. it leaves you with a smooth finish that requires less filling and sanding to smooth out the surface. Once you've used it you'll wonder why you haven't used it before.

looking forward to seeing the finished product.

Cheers
Jason

Rocket-J

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Thanks Jason. I have never used it. I do use waxed paper on a finish application. Because I am using an unusual technique, I have to keep joining new pieces as I go. Every joint I make, I grind the edge surfaces to a paper thin edge so I can add cloth. It does get labor intence toward the end but I would rather do that than built a plug for one model. Plus, I like to sand it to a thinner surface to lighten it up. There seems to always be an excessive resin build up. Al

Rocket-J

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Jason,
Which resin do you use with your Peel Ply, moulding or laminating resin? I have worked professionally, with fiberglass, in automotive, boat and experimental aircraft and I have never seen Peel Ply, which doesn't mean too much, probably a lot of new things I haven't seen. Al

Dreamin Hemi

This website thread may answer some questions, although slightly off topic. I've heard of this before however never actually tried the stuff.

[link=http://www.boatdesign.net/forums/materials/peel-ply-14461.html]http://www.boatdesign.net/forums/materials/peel-ply-14461.html[/link]

I suspect it is similar to layering on a sheet of plastic over the wet resin or gelcoat to aid in curing, a technique that is required if non-waxed gelcoat is used on an exterior. Perhaps a new thread on the topic specifically? Wouldn't mind hearing users experiences with this.

By the way, I to have a Mean Machine...completely stock. This is going to be an interesting project thread. Keep it up!

-Scott

Dreamin Hemi

Pay particular attention to the link in post #12 in that thread. Probably the best description I've seen in a while. Amazing what results are achievable.

OK, here it is anyway....

[link=http://duckworksmagazine.com/03/r/articles/glass/bottom.htm]http://duckworksmagazine.com/03/r/articles/glass/bottom.htm[/link]

dicko

I use Boat Coat epoxy resin, a 24 hour resin.

I use the finer peel ply that goes around corners & bends quite well. Peel ply works similar to the film process in the link above, but absorbs excess resin into it instead of spreading the excess resin out. It works better around corners, the film works better on larger flatter surfaces.

Anyway, back to your build thread.

Rocket-J

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I don't consider this "off topic". If we are sharing information on custom fiberglass fab or remodel work, then this is all pertinent.
I use a stiff plastic cover on Gel Coat repairs or where I need a near finished product. I do nearly no mold work, but if I do, I use PVA (release agent), Gel Coat, then my glass for a nice finish. What I am doing here is bass ackward. I have made many car parts, including full fenders, using the start at the inside and work out. I don't want a smooth finish until I get to the end. The big problem with these models is the thickness of your final work. The Mean Machine hull is only .020" to .030" thick. That is only 2 layers of my fine cloth and resin. Any seam ends up too thick and needs its final sanding. There are no large, flat surfaces here to work with so it is not a major problem to surface everything when you are done fabbing. I use tiny air tools with cutting dics, sanding dics and polishing pads, when I need them.
No work on the boat today, it rained and my glass work is done outside. Keep sharing the ideas. Al

Rocket-J

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Today I made a simple jig to help bring the top, windshield and side scoops together. Taking photos in the middle of a project is like taking picture of your appendectomy, in progress. Just wanted to show the step by step. Like I said, I am not real concerned about the surface at this time. It is important to get the shape and be symetrical. When the fiberglass work is done and surfaced, I will be spraying white Gel Coat on it. Bad weather is slowing the progres.

Rocket-J

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I put the front deck/cowling assembley back in the jig to finish off the sides and air scoops, where they will attach to the boat. The jig keeps everything symetric. This piece , that runs from the front to rear, is ready for surfacing now. I already started surfacing a little. When that is finished, I will attach it to the hull and exsisting cowl. Then with a die grinder, cut the cowl section from the deck section.

Rocket-J

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I put two vertical pieces and a horizontal support for the new deck. There was a gap between the top of the sponsons and where the new deck will be. I used wedges and blocks to hold the resin and cloth in place under the top of the sponsons. I forgot to take photos of the blocks before, so I took some afterward. They have the blue painters tape on them, to keep the resin from sticking. I also used the aluminum mold I use to make the new deck. This gives a perfect fit to laminate the new deck too.

Rocket-J

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Okay, the new deck and canopy has been laminated to the hull. Then, with a die grinder, I cut the line accross the front deck and canopy/hatch. I removed the hatch, cut the inside of it apart, this was the part of the old hatch that will not be used. I left it together to maintain the intergity. I also put in a "firewall" type divider to support the deck when the hatch it on. I surfaced both the deck and the hatch, and I am ready now for filler and Gel Coat.

Rocket-J

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One step closer now to the new look and room for the big motor. This canopy gives me an extra 1/2" above and an 1" forward for the new 7.5 engine. Next is just a lot of sanding on the hull and prep for the new paint. No big deal. After that I will remove the fiberglass moulded motor mount and fab a new mount and fuel tank area.

Rocket-J

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I got my New 30year old K&B 7.5 ducted fan motor today. Rated at 2.3hp at 23k RPM and a Perry carb and fuel pump. There were several of them on Ebay for $60 to $100, new in the box, and you can still buy some parts. I purchased a marine head and flywheel from Mecoa. I don't run enough to wear it out.
This entire project is on a budget. I know a Miss Vegas is about $200 NIB, but building a boat is more fun than running it, in my opinion. This is one of Aeromarine flood boats ( $90 with hardware) and $125 for a new, coverted to marine, 7.5, made in USA engine. Mostly, I am having fun, shopping and building, and thats what a Hobby if for. Support your local Hobby Shop.
The 7.5 engine is just slightly bigger than the .25 (made in Tiwan-sp) engine I was going to use. Hull now is 2 lbs and motor is 1 lb.

Rocket-J

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With the hull and canopy remodeled, I have removed the old motor mount and servo box, cleaned the inside of the hull and started the layout for the new engine. Started fabbing a new motormount and planning the location of the engine for proper balance.

3ns

Hi Al.

It looks really nice. Just curious, how much can you tilt an engine towards the bottom?
I can see that yours has a very large tilt. Does this put stress on the rubber isolaters?

Btw, how's the vertex doing? Do you find any issues with it?


cheers.

3ns

Rocket-J

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Hello 3ns.
Did you get you boat running again.
I gave up on the CY .25 engine. I bought an old K&B 7.5 ducted fan engine, New in Box. I also bought a marine head, heavy duty connecting rod and built a water cooled header.
I don't use isolators. I build most of my own hardware, as much as I can. My mount works like a thremos bottle plug. I have a rubber conical shaped plug with a 10/32 screw through it. The motor mount has a stainless steel sleeve in it. The tighter I tighten the screw the more firm the motor mount gets. I am having a problem with the engine location. I could not get a cone shaped flywheel, so I had to turn and balance this one. Then I have put a slight bow in the bottom of the tunnel, to get the engine as low as possible. I am still working on the best location.

3ns

Hi Al.

Looking good. Like your mounts. Wish I could do that.
Any reason why you gave up on the Vertex?

Btw, have not run my boat yet. Took your advise and
epoxied a aluminuim plate on the transom and glassed it.
Repainting it as i was not happy with the earlier paint.

Pls keep those pictures coming. Waiting to see how she'll
finaly look like.

3ns

Rocket-J

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Hello 3ns.
I am a horse power guy. Everything I own is big HP and torque. I just decided that I wanted some go-power. The .25 engine is rated at more hp and more rpm but I think the 7.5 will have more overall power. Horse Power is a function of Torque and Rpm. I think the only way the .25 gets that high of HP rating is buy spinning it at 40k rpm. Propably better for the racer than what I want. I haven't had any experience with either one of these engines so I don't know. I couldn't afford a CRB (big dollar) engine. It looks like the K&B 7.5 is more similar to the Enya .60 I use to race. I might have better luck tunning it. Maybe someone will chime in here. I also need to know what size fuel tank are most people running with a 7.5 engine.

Rocket-J

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Finally got more parts. This is the point of the rebuild that takes more time and thought.
In the photos below, you will see that I have put an OS 180 degree, water cooled header and an OS flywheel on my K&B. These are NOT direct bolt up items. I rotated and redrilled the header flange to suit my application. Be careful not to drill into the water passage. The flywheel takes a bit more thought. It has a long collar that comes back over the nose of an OS engine. There is no room on the old K&B DF engine. I used the DF spacer and collet then put the OS flywheel and collet in front of that. The I.D. of the OS collect is larger than the K&B DF bolt so I had to make a sleeve and spacer for all of that to fit. It will take a large paragraph to show that entire operation, so lets just say it is possible with enough time and thought. Just be sure and check the run-out with a dial indicator before you run the engine. This is one place that close enough is not good enough.
I built my own muffler that simulates dual exhaust headers. I did this with an RC Unlimited Hydro that worked very well. Just make sure that anything after the stinger on your pipe, is a larger diameter than the stinger. I also have a directional baffle inside the muffler. All my stainless will be polished when I am completed.
I am using dual 6oz. fuel tanks. This K&B 7.5 DF has a fuel pump that I will connect to the last tank and pressurize the first from the exhaust pipe.
Right now I am moving everything back and fourth to get my CG in the ball park. My total weight with all parts stacked in the boat is 4.7 lbs. No fuel, of course.

Rocket-J

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I need advise.
I have never run a flex shaft. I know, I just came back from the dark ages.lol
Question; How large of a gap can I run between the drive shaft tube and the engine? I have a 1.25" gap now. Will that work? Thanks.

TCHedOff

ROCKETJ: I read in another thread a guy asking the same question.... ideally, the smaller the gap the better.... like just enough gap to get your starter belt on & off; 1.5 inches seems ALOT! The other guy was asking about a smaller gap (1"?) and the concensus was that even this was on the high side.

Rocket-J

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Thanks TCHedOff. I will get a new tube and flex shaft. If I had seen that thread I could have saved you the typing.

wave waker

wow! goin strong!! i like the muffer[8D]