J or Shine - TX18 - Inverted V through to transom

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Re: J or Shine - TX18 - Inverted V through to transom

Post by jacquesmm » Thu Feb 16, 2012 10:36 am

lung wrote:. . .

That being said, I've wondered if the inversion could be continued to the transom.
Yes, we show that on the "bonus plans".
The TX18 plans include the lines and expanded plates for a higher freeboard version, closer to the original Hickmans lines and that hull has a remnant of inverted vee at the transom.
I have seen Hickmans original plans with or without a small vestigial vee at the transom. Either he hesitated about it or as I concluded, ended with a flat transom for inshore boats and with some vee for offshore ones.


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Re: J or Shine - TX18 - Inverted V through to transom

Post by Tex 2009 » Thu Feb 16, 2012 12:14 pm

The picture of the allum hull is a design of the baby cats that are running in the backwaters now in texas. It is supposed to be a scaled down version of a catermaran.
Where is this allum hull being built? I would like to go by and see it.
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Re: J or Shine - TX18 - Inverted V through to transom

Post by Tex 2009 » Thu Feb 16, 2012 12:15 pm

The Baby Cats are produced by Trans Sport Boats.
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Re: J or Shine - TX18 - Inverted V through to transom

Post by jacquesmm » Thu Feb 16, 2012 12:47 pm

The superstructure of the boat looks like the TX18 but the bottom is completely different.
It is a mix of catamaran shape with some inverted vee.
I don't see a benefit, quite the opposite.
The inverted vee compresses an air cushion and provides lift which means less running draft.
Our hull shape will run better and shallower.
At rest, our TX18 has more waterplane and at equal weight, it has less draft. That is plain simple physics.
At rest our TX18 is better too.

Then there is cavitation: I designed and worked on enough shallow water cats to know those problems. A local cat builder worked for 3 years trying to solve them by modifying molds at a great cost. There is no way around it, that water is going to be turbulent there unless you compress it like the inverted vee does.
With a single engine, the inverted vee is a superior shape.

Did you notice that the manufacturer of that boat does not announce any draft on his specs list?

Why would we want to handicap a good running hull like the TX18 by changing the shape? Where is the benefit?
Convince me that there is a benefit and I may do it.

BTW, our Hickmans sled type design (the bonus plan) has only a few inches of inverted vee at the transom, nothing like this Al boat.
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Re: J or Shine - TX18 - Inverted V through to transom

Post by lung » Thu Feb 16, 2012 10:54 pm

Jacques: The front angle picture looks to me to be identical to the TX18. The rear bottom appears to have the same outside panel, as shown from the transom, the only difference being the extreme "V" of the two inside bottom panels. The 4 bladed cupped prop probably helps deal w/cavitation. Like I said, I hope he at least paid for a set of plans.
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Re: J or Shine - TX18 - Inverted V through to transom

Post by jacquesmm » Fri Feb 17, 2012 9:12 am

I'll look more into it.
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Re: J or Shine - TX18 - Inverted V through to transom

Post by nicademas » Sun Feb 19, 2012 12:43 am

Jacques:

First, thanks for the quick response(s). I've been pulling some information provided from the designer of the Al version of the Hickman with the inverted V running to transom. He does confirm it is a Hickman hull with the modification in question. The guides who have bought and used this hull report, repeatedly, that is will get up and run in the same depth of water as it sits, and reports range from 5"-7" when loaded.

I do understand your contention that the air pocket created by the Inverted V will raise the boat a bit in the water column on plane/at speed, but that would make it run skinnier (inch or two I would guess) than a standard V hull, but I don't see how the physics indicates that it would run skinnier than this modified version. At rest, there is no doubt the TX18 will sit in the water with less draft, as there is simply more displacement. But running, the Inverted V to transom will deliver water to a prop positioned higher than the TX18, as with the TX18, the prop still has to be positioned nearly parallel to the transom bottom itself. This modification, I'm almost certain, would still provide the air pocket and some rise, as this phenomenon is generated from the fore section of the hull back to the point where it touches the water, underway, and that doesn't change much with this modification.

The static draft is not in question here. The hole shot depth and running depth is the concern. My guess is that the TX18 will get up and run in 10"-12" of water. With this modification of running the IV to transom, it appears we can get the TX18 running in 5"-7" less water. That is a very significant difference in flats/back lake fishing. And one I think many would appreciate!! I, for one, have held off on building this boat for five years because of the concern about running depth.

Here are some of the quotes from the designer of the modified Aluminum version that runs the Inverted Vee to transom. The guides who have chimed in on this boat and have run it in application corroborate. I'm hopeful this will provide some indication that offering this modification could provide a very tangible benefit in running depth and hole shot depth requirements.


QUOTES FROM AL HICKMAN VERSION DESIGNER:

This is the inverted vee hull, based upon the original Albert Hickman design, but, redesigned for the Laguna by carrying the vee completely through the hull. In 1914 when Hickman first developed the hull there were no outboards and he made the transom area flat-bottomed to carry the extra weight of the engine and transmission.

==========

Since I own the Laguna Tiger and built it I thought I might help you out with some facts. The boat is 18' X 8' beam, weighs 520 #, runs 40 mph with 2 people on it. 90 hp Yamaha power. It's all welded aluminum as this is the first one and it would have been much less expensive to build it out of aluminum instead of having to make a plug and then a mold to build in glass. The only other option would be plywood and that would still really be just a plug as far as I am concerned. I took the boat to Corpus two weeks ago for initial testing, it was really great, much better than expected actually. With a 20 mph SE wind, we, three people, took it into CC Bay, i ran the boat at all possible angles to the waves, even to the point of turning it around at 3500 rpm in a small circle.

Resulting in NO pounding and NO spray in the boat. Albert Hickman's #1 claim was always that his "Sea Sleds" never, ever pounded in rough seas. Neither does my version, it is spooky smooth and dry. I took several area Charter Captains riding on it and to a man they said it was the best ride they had ever experienced, bar none.

While the boat that i saw pictured on this site, the TX18, that is a kit boat that has similar vee design, but, it is a flat-bottom-transom design very close to Hickman's original drawings. It will work, but, does not run well in shallow water as the engine will overheat if you try to run shallow. It has no way to feed water up to a raised engine like mine does. I had several options when thinking about my design, I could either build it flat as Hickman did, put in a tunnel as most S TX flats have, or, get creative and run the inverted vee design completely though the hull and use that as a tunnel. i decided on number three as it made the boat more unique and I liked to idea of extending the inverted vee through to try and capture even more of the air-cushion ride. It worked...If you would like more info jsut email me with a regular email address and I will forward all of the details to you.

===========

NO sneezing. we put a sneeze-bar under the bow to prevent that just in case. Don't know if it worked, or, if it just hasen't done it, but, it never has sneezed.

Here's a few spec's that I know to be facts from the week's testing that I have already done if it.

Length = 18'
Beam = 8'
weight = 520 lbs. bare hull weight
draft / loaded = 7"
draft w/1 person on front deck = 5.5" hull levels out with one person on the front
draft w/2 perons in front of console = 6"
draft w/3 persons scattered front to rear = 7"
hole shot = very good, instant, will get up with jack plate all the way up.
runs = very shallow, whatever it takes to feed enough water to the prop to push the boat, i would guess 4"??? The prop is up in the vee, about the bottom of the boat when running with the [jack plate] up.
Turns = like a sports car, no slippage at all, very positive, very solid feel.
ride = soft, NO pounding just as hickman advertised in 1914
dry = spooky, NO spray in the boat to-date, even trying to hit waves at crazy angles to make it spray. Spooky how dry it is.
stable = 2" of list with 600 lbs on either gunnel

END QUOTES

Thanks for taking the time to look into this modification further!

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Re: J or Shine - TX18 - Inverted V through to transom

Post by gstanfield » Sun Feb 19, 2012 11:35 am

So your guy is claiming that his hull will get up with less than half of the prop in the water? A 4 blade F90 prop off the yamaha ebsite has a diameter of 13-1/4" so to get up in 5" of water would make the prop barely even touching the water considering that the propr isn't even the lowest point on the outboard. The water pickup would be well out of the water too which I wouldn't think to be a good idea myself :!: I'm no boat designer, but it sounds like a sales pitch to me and I'm not buying it.

I've been wrong before, but I've never seen an outboard get much thrust with half the prop out of the water. :doh:

My points are aimed at the "getting up in 5-7" portion. I can't say what I think it would do while running as I don't know the physics of it. I do understand the physics of sitting still though :wink:

Sorry to be disagreeable, I'm just having a hard time buying the sales pitch 8)

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Re: J or Shine - TX18 - Inverted V through to transom

Post by nicademas » Sun Feb 19, 2012 1:52 pm

I have two points George.

First, the designer of this aluminum boat is not "my" guy. I have never met him or spoken with him. I am also not by any means pimping his boat, methods, ad infinitum. Just showing what detail he has provided on tx fishing forums. There is a long time guide in Buras, LA named Taylor that used this boat and also reported similar performance numbers.

Second, my point in questioning the design modification is to see if I can have the TX18 running shallower than what looks possible with the flat transom. If not, then I will not be wasting my time and money with this boat, as it will take a moderate chop well and float shallow (two primary requirements of mine), but by no chance get me to where I want to fish.

If you look at the transom in the first picture, does it not look as though the inverted vee extending to the transom would feed water to a prop positioned higher?

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Re: J or Shine - TX18 - Inverted V through to transom

Post by sds » Sun Feb 19, 2012 4:57 pm

I can see the prop getting water running, kind of like the tunnel gets water to the prop on an XF20. As for the hole shot, maybe reduced stern volume, combined with a weight shift to the back gets the prop deep enough to bite, kind of performing the function of a jack plate?

OTOH, it also seems like reduced plane area would make it take longer to jump up.

Just musing here. Uncharted territory. It seems like the "through V" option is provided for in the TX18 plans, so if you're convinced Nic, why not?

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