Budget Wild Thing

**stablgr** · 10-18-2009, 03:10 PM

Thanks Ace and Cornel.

I think I'm going to stick with the speed 700 motor for now. The chief designer (8 yr old son!) has insisted that it must have reverse (for now).

Progress over the next few days will be slow. Blame the cure time of the glue and the fact I'm trying to move house in the next 2 weeks.

I have a couple of questions with regard to the hardware and motor location:

1. I've read that the motor should be positioned at the cog (30% from transom). Is this correct and if so does that mean the cog of the motor should be located at the cog of the hull?

2. How far should the stinger extend beyond the end of the transom based on a hull length of 32"

3. What length of rudder blade should I be looking for and where should it be positioned in relation to the trailing edge of the prop. I'm assuming it should be placed as close to the centre line of the hull as possible to reduce the difference in left and right turns.

4. What dimensions of trim tabs and turn fins should I be looking at?

So many questions and SO much to learn.

**stablgr** · 10-19-2009, 11:54 AM

Some more photos

Attached Files

**CornelP** · 10-19-2009, 04:31 PM

1. I've read that the motor should be positioned at the cog (30% from transom). Is this correct and if so does that mean the cog of the motor should be located at the cog of the hull?
-Actually the COG of the complete boat (including batteries and hardware) should be at 30%. You can place the motor pretty much anywhere it is convenient. I was limited by the length of the Graupner flex...

2. How far should the stinger extend beyond the end of the transom based on a hull length of 32"
-Rule of thumb is stinger should be 10-13% of boat length

3. What length of rudder blade should I be looking for and where should it be positioned in relation to the trailing edge of the prop. I'm assuming it should be placed as close to the centre line of the hull as possible to reduce the difference in left and right turns.
-Not really, you want it on the right of the prop, to counteract it. The blade should extend about one prop diameter under the prop and placed about aligned with it.

4. What dimensions of trim tabs and turn fins should I be looking at?
-I did not install any of these and it was pretty smooth after being correctly setup. You can go for about 1 1/2"- 2" tabs and any medium turn fins.

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IMG_1229.jpg (74.1 KB, 28 views)

**stablgr** · 10-20-2009, 07:49 AM

Some more progress......

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**ace028** · 10-20-2009, 10:54 AM

Wow, it looks very clean and straight, keep up the great work!

**stablgr** · 10-20-2009, 04:18 PM

Thanks Ace. Not too shabby with just a craft knife, junior hacksaw, sanding block, some duct tape and glue! Mind you I did cheat a little and get the parts laser cut.

**stablgr** · 10-25-2009, 07:19 AM

A little more progress...

I've managed to get a little more done in the last few days.

As you can see I've cut away the stringers a bit to give me access to the outer compartments when the deck is in place. Additional strength has been added to the bottom of the hull with glass fibre mat. Sorry, I know CF looks cool but the glass mat was free!

I was also a little concerned at how fragile the bow was looking, especially bearing in mind my youngest son will be driving. So I've gone a little overboard and basically potted the bow with resin!

Once all that is fully cured I'll coat all of the interior with thinned down resin to make sure it's fully waterproof.

Also got the hatch cut out of the deck.

Any thoughts on adding buoyancy to the hull?

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**ace028** · 10-25-2009, 09:22 AM

I think it would be good to add some styrofoam to the bow, then sand it to shape because it will act as flotation and support the top skin of the bow from flexing in the middle.

Looks great man!!!

**stablgr** · 10-27-2009, 07:41 AM

This hull is going to be powered by a Speed 700BB brushed motor (the 8.4 volt version) running on 3S lipo cells. I was thinking of using an Octura 0.150" flex shaft with a 3/16" propshaft but have no idea where to start with prop choice. Also would appreciate knowing what sort of amp draw to expect with a suitably sized prop.

**stablgr** · 10-31-2009, 07:31 PM

OK. While I'm debating the motor etc to use I decided to play around with the superstructure of the hull. I don't know what to finally build this out of but had a play around with some card to see what I could come up with. Comments welcome....

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**CornelP** · 11-01-2009, 01:43 AM

If you add a recessed window, it will be perfect! Very nice...

**stablgr** · 11-24-2009, 05:37 PM

After a rather quiet spell I've made a little progress, but as you'll see not a whole lot...

Here I've added some expanding foam to the front sections for buoyancy and added strength/support for the deck. (Thanks for the tip CornelP)

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**stablgr** · 11-24-2009, 05:40 PM

A few more shots of the canopy. It's built out of card and now needs to be covered in glass fibre cloth and resin.

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**stablgr** · 11-24-2009, 05:45 PM

And finally the deck goes on after sealing on the inside.

All I need to do now is get my finger out and buy some hardware

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**ace028** · 11-24-2009, 06:00 PM

Looks awesome man!!! Great job, can't wait for more!!!