TX 18 EXTRA FUEL

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Prarie Dog
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Re: TX 18 EXTRA FUEL

Post by Prarie Dog » Thu Aug 20, 2015 11:07 pm

Hi Will, good to see you're still on the forum.

Tom thanks for the info.

Jaques, I do understand the difference between cruise and full throttle consumption. Thats why in my last paragraph I used 7gph for that calculation. The reasoning is that it's likely this hull will need something like 70hp to cruise at 30mph or so. It would only run 25 or so with the 60 that was initially mounted on the hull. It has a T Top and the hull traps a lot of air.

It's also unreasonable to think we would go the entire way during a day of inshore fishing but it could happen with nice conditions and light winds. If I'm going to add fuel capacity it seems reasonable to add enough to get her done. I just noticed that Newt posted on here about Matagorda Harbor and the fuel there, but I've been through there several times that they've been closed.

Thanks for the insight on your boat Larry but a flat bottom probably runs a lot more free than this big air trap.



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Cracker Larry
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Re: TX 18 EXTRA FUEL

Post by Cracker Larry » Fri Aug 21, 2015 7:47 am

Thanks for the insight on your boat Larry but a flat bottom probably runs a lot more free than this big air trap.
I'm sure you are right about that. The sled has a lot more drag and wetted surface than my flat bottom boats.
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Re: TX 18 EXTRA FUEL

Post by TomW1 » Fri Aug 21, 2015 7:37 pm

[quote="Prarie Dog Thanks for the insight on your boat Larry but a flat bottom probably runs a lot more free than this big air trap.[/quote]

Paul the TX is designed to run on the edges of the two v-hulls and the last portion of the flat making it very efficient and comfortable for long runs in your neck of the woods. The air between the v-hulls helps with raising the whole hull as you get up on plane then is not much of a factor. The air then provides a cushion and provides the smooth ride these boats are known for. Since it is always there it doesn't affect fuel economy much. Correct me if I'm wrong Jacques this is my memories from school

The other thing to think about is the prop and being able to raise and lower it. My studies show that there is a need to be able to raise or lower the prop by a couple of inches as conditions dictate. Usually from hole shot to full speed, you actually need to lower the prop, unlike a tunnel boat where you need to raise the prop. I don't know if you have a jack plate but Jacques in his study plans highly recommends one.

Hope this helps a little.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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Jim_Davisson
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Re: TX 18 EXTRA FUEL

Post by Jim_Davisson » Sat Aug 22, 2015 7:20 pm

Prairie Dog, you might want to look into the Yamaha command link plus for real time fuel consumption prior to adding to much tank. Switching to a 4 bladed prop for just such trips is another idea. For example on my boat with a heavy load my fuel economy increased with a 4 bladed prop at 3600 rpm (smaller diameter/increased pitch worked for me), of course top speed decreased but that is of no concern to me at all. I only have the one smart guage, but its invaluable to me and helps keep cost of ownership down with the same amount of fun. Cheers
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Re: TX 18 EXTRA FUEL

Post by Prarie Dog » Sat Aug 22, 2015 9:24 pm

TomW1 wrote:[quote="Prarie Dog Thanks for the insight on your boat Larry but a flat bottom probably runs a lot more free than this big air trap.
Paul the TX is designed to run on the edges of the two v-hulls and the last portion of the flat making it very efficient and comfortable for long runs in your neck of the woods. The air between the v-hulls helps with raising the whole hull as you get up on plane then is not much of a factor. The air then provides a cushion and provides the smooth ride these boats are known for. Since it is always there it doesn't affect fuel economy much. Correct me if I'm wrong Jacques this is my memories from school

The other thing to think about is the prop and being able to raise and lower it. My studies show that there is a need to be able to raise or lower the prop by a couple of inches as conditions dictate. Usually from hole shot to full speed, you actually need to lower the prop, unlike a tunnel boat where you need to raise the prop. I don't know if you have a jack plate but Jacques in his study plans highly recommends one.

Hope this helps a little.

Tom[/quote]

Thanks Tom
I havent calculated the area of the trap on the font of the TX18 but it's a bunch and it causes a lot of drag. If you doubt what I'm saying stand on the deck of a boat at 30 and hold a 5 gallon bucket with the open end forward, then relate that to the area on the front of the boat. I don't have a problem with trading ride quality for horsepower but it is there. It's much dirtier than a OD18 for example. The boat also has a jack plate, being able to adjust the prop height is how the trim is controlled on this boat, works fine.

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Re: TX 18 EXTRA FUEL

Post by Prarie Dog » Sat Aug 22, 2015 9:26 pm

Jim_Davisson wrote:Prairie Dog, you might want to look into the Yamaha command link plus for real time fuel consumption prior to adding to much tank. Switching to a 4 bladed prop for just such trips is another idea. For example on my boat with a heavy load my fuel economy increased with a 4 bladed prop at 3600 rpm (smaller diameter/increased pitch worked for me), of course top speed decreased but that is of no concern to me at all. I only have the one smart guage, but its invaluable to me and helps keep cost of ownership down with the same amount of fun. Cheers
Jim, I haven't thought about switching the prop but it is a thought, I don't know if the instrumentation on the boat will show fuel flow but it has about everything one can have.

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Re: TX 18 EXTRA FUEL

Post by JohnC » Sun Sep 20, 2015 11:08 am

Hi Paul,
Is the Texas Sled back in Texas? Tell Brother David we said "hi" and we miss him. As to the hull, I remember taping the line for the graphite, sure was a looooong way around at the waterline :D
John

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