Roberta's Torpedo

Designs for inboard or outboard power

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bob smith
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Re: Roberta's Torpedo

Postby bob smith » Tue Oct 11, 2016 10:08 am

Regarding the tabs, did you experience porposing? Mine in its original state would porpose and I had installed Bennet trim planes to correct it.
The new configuration moved the CG forward about 5", added an inch to the beam and removed about 250 lb from the BBC (aluminum heads, intake, exhaust, water pump). Now there is no hint of porposing and she rides noticeably better than before.
If you haven't played around with weight distribution/CG, I'd try before adding the tabs.
Bob Smith
Chester, SC

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Roberta
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Re: Roberta's Torpedo

Postby Roberta » Tue Oct 11, 2016 10:30 am

It would need more weight in the front to bring the bow down. I really don't want to do that as it already sits low in the bow at no wake speeds. Up to 40 mph it rides fine, but above that It wants to climb out of the water. The tabs will bring her down without get to far forward with the CG. Thanks for the comments, though.

Roberta :D :D :D
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

bob smith
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Re: Roberta's Torpedo

Postby bob smith » Tue Oct 11, 2016 12:33 pm

I forget, did you lengthen the build?
Bob Smith
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Dave Grason
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Re: Roberta's Torpedo

Postby Dave Grason » Tue Oct 11, 2016 1:20 pm

Can you even respace the frames for additional length? I would have figured that the torpedo harpin would give problems if someone wanted to do that.

On the OTHER hand, the original Ventnor boats that put this style on the map were often double cockpits. I'd be willing to be that they pushed the dashboard and front windshield a little forward and simply moved the back of the rear seat just a little aft. Hmmm. They could probably squeeze out just enough that way.

Ok, I'm sorry. You folks were talking about CB and CG. My bad. :roll:
Isn't it amazing!! The person that never has the fortitude to pursue his own dreams, will be the first to try and discourage you from pursuing yours.

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Roberta
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Re: Roberta's Torpedo

Postby Roberta » Tue Oct 11, 2016 2:33 pm

Yeah, Really Dave!!! :lol: :lol: The Harpin makes lengthening difficult, if not impossible without a redesign. At 19' 3", it's long enough for me.

Roberta :D :D :D
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

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kens
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Re: Roberta's Torpedo

Postby kens » Tue Oct 11, 2016 3:33 pm

Why trim tabs??
I noticed you currently have a heavily raked prop, that will raise the bow.
Would it be easier to try a 0 rake prop than to modify the transom with tabs?
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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Roberta
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Re: Roberta's Torpedo

Postby Roberta » Tue Oct 11, 2016 3:47 pm

What prop would you suggest? I'm running a 13X13 four blade OJ (1" bore) full cup now. There aren't many props in this range available.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

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kens
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Re: Roberta's Torpedo

Postby kens » Tue Oct 11, 2016 4:04 pm

Roberta wrote:What prop would you suggest? I'm running a 13X13 four blade OJ (1" bore) full cup now. There aren't many props in this range available.

Roberta

Say what???
1" props in the 13" & 14" sizes are made by all the prop makers, Michigan, OJ, ACME, and so on.
When I look for inboard props on Ebay, I cannot get away from all the different ski boat props………...
Try a 13x13 4bld without any rake.
Borrow one if you have to.
ACME has a good program where they fit you a prop until you are happy, if, you pay their price $$.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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jenko
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Re: Roberta's Torpedo

Postby jenko » Tue Oct 11, 2016 4:28 pm

I agree with kens the prop rake adjustment is the way to go.
It will more than likely be more efficient as well
Decreasing cup has a similar effect to decreasing aft rake ,also diameter changes boat attitude,
I would talk to a good prop shop

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Roberta
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Re: Roberta's Torpedo

Postby Roberta » Tue Oct 11, 2016 4:55 pm

Looking at the MW, OJ, and Acme websites I find no info on rake for OJ and MW props. Acme sizes near what I need are listed at a 7 rake and only a 3 blade.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

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Roberta
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Re: Roberta's Torpedo

Postby Roberta » Tue Oct 11, 2016 5:09 pm

Also I am reading that the higher rake is better for speed. Lower and zero rake is intended more for slower work boats. I still think the trim tabs to poke the bow down at speeds above 40 is the solution.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

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kens
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Re: Roberta's Torpedo

Postby kens » Tue Oct 11, 2016 5:38 pm

Roberta wrote:Looking at the MW, OJ, and Acme websites I find no info on rake for OJ and MW props. Acme sizes near what I need are listed at a 7 rake and only a 3 blade.

Roberta


Call ACME and talk them thru it. They have helped many people get the right prop.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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kens
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Re: Roberta's Torpedo

Postby kens » Tue Oct 11, 2016 5:40 pm

kens wrote:
Roberta wrote:Looking at the MW, OJ, and Acme websites I find no info on rake for OJ and MW props. Acme sizes near what I need are listed at a 7 rake and only a 3 blade.

Roberta


Call ACME and talk them thru it. They have helped many people get the right prop.


And you don't know how much rake you got now, and don't know how much is in the other OJ's props.
OJ had better be able to tell you, if they know what their own stuff is.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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jenko
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Re: Roberta's Torpedo

Postby jenko » Tue Oct 11, 2016 6:30 pm

Roberta wrote:Also I am reading that the higher rake is better for speed. Lower and zero rake is intended more for slower work boats. I still think the trim tabs to poke the bow down at speeds above 40 is the solution.

Roberta

drag boats us cleaver props which have no rake for stern lift
Anyway have a read of this http://continuouswave.com/whaler/reference/prop3.html

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kens
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Re: Roberta's Torpedo

Postby kens » Wed Oct 12, 2016 3:40 am

Rake alone does not give or take away speed. It had more to do with running attitude. In your case, m if you get rid of the bow high attitude then you push the throttle up farther.
Your final top speed is the result of connecting given HP to the water, with whatever prop connects best.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:


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