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Cantard
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Discussion Starter #1
I need to make a new engine cowl for the hydro. What is the best way to get the shape? Can I make some sort of mold and if so any pointers or tips you guys could give me? I have the front 3" and the rear 3" but need to make everything that goes between...somewhere in the neighborhood of 2ft in length is what I need to make.
 

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mo balls than $cents$
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11,734 Posts
built a lite frame work, cover with polyester tweed and resin that;) gives ya the basic shape to bondo too.
 

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You could make a positive mold out of foam, plywood, a combination,etc.

Lay plastic over the positive, put down the glass and resin, let cure. Then get it gelled.

At that point you can use the cover for a negative mold...gel first, then glass...
 

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Banne'd
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2,568 Posts
gosh, well you will need a plug o build a mold. And with the money you put into the plug alone you could buy a cowl.

Like the one chap said, you can use some form of tweed, cloth to get a little bit of the shape, wet it out with resin and it will harden to that shape, with a little sag here and there. Then cover it all with bondo and use a cheese board to cut it and shape it. And more bondo to fill in any pit's dips and inperfections. Sand it out smooth like 80 grit. Get some fairing compound and cover it. Sand the fairing compound down to 80 grit, primmer and sand that down to 180 grit. Then you are ready for the top coat. That should go on smooth enough to pull the mold off from it, it's sprayed on. Ya it's a bunch of elbo busting work, but it's the right way to do it.
 

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If you have the front and the rear,and just need to connect them (straight line), I would think you could use tightly stretched string for your framework. I dunno..just thinking outloud.
 

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Banne'd
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If you have the front and the rear,and just need to connect them (straight line), I would think you could use tightly stretched string for your framework. I dunno..just thinking outloud.

Yea thats it, you should be able to find a "strechy string" at a nice beach or sand bar, it might be around some hotties hipps, but that's ok.
 

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Cantard
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5,017 Posts
Discussion Starter #10
gosh, well you will need a plug o build a mold. And with the money you put into the plug alone you could buy a cowl.

Like the one chap said, you can use some form of tweed, cloth to get a little bit of the shape, wet it out with resin and it will harden to that shape, with a little sag here and there. Then cover it all with bondo and use a cheese board to cut it and shape it. And more bondo to fill in any pit's dips and inperfections. Sand it out smooth like 80 grit. Get some fairing compound and cover it. Sand the fairing compound down to 80 grit, primmer and sand that down to 180 grit. Then you are ready for the top coat. That should go on smooth enough to pull the mold off from it, it's sprayed on. Ya it's a bunch of elbo busting work, but it's the right way to do it.
I will give it a try. Thanks for the info. Any recommendations on cloth to buy?
 

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21 Daytona
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5,291 Posts
I like to use single layup glass, I wax a metal plate
layup a single layer of glass and resin let it cure
its easy to cut and bend to the shape I need
use masking tape to hold the shape then layup as many layers as needed for your project.
 

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Banne'd
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I will give it a try. Thanks for the info. Any recommendations on cloth to buy?
Anything that will absorb resin. If it's thin use several layers. Take the sheet off your bed, or use the wife/girlfiends best skirt. You ant the resin to stay in it, not drain out of it. If you have a fabric stor handy, stop by and look for some old material. I used some stuff that was about 1/8" thick, cost me $.50 for a yard, worked great.
 

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mo balls than $cents$
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speaker guys use fleece, it stretches and holds resin
that's how i learned to use the stuff:D if you can get ahold of some balsa , man it'd be easy to make a nice cover that's super lite(couldn't walk on it)
 

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I need to make a new engine cowl for the hydro. What is the best way to get the shape? Can I make some sort of mold and if so any pointers or tips you guys could give me? I have the front 3" and the rear 3" but need to make everything that goes between...somewhere in the neighborhood of 2ft in length is what I need to make.
What type hydroplane are you looking for an engine cowl for? There are several guys on this coast that have molds for inboard hydroplane cowls 5,6,7 liter etc. Conventional or cabover ?? Tim
 
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