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The Game Changer

digginfool

digginfool

Well-known member
It may not be my place to talk about this boat as it is not mine but I did get to take it for a ride yesterday and OMG. I've never seen a boat with a more appropriate name. This boat truly is a game changer. It's an 11 foot Benny Webb with a direct drive Waterthunder LS3. The owner of the boat said Waterthunder told him it made 1100 lbs of thrust on the stand. I believe it. I've never been on a boat that pushed you back in the seat as hard as this does. Period. The best part is that the engine sips fuel and you can buy that fuel on any corner. No rides to the airport, not paying $5.00/gallon. The setup costs no more than a well built 540. Can't wait to see how this pans out over the long haul. I'm seriously tempted to dump my 540 for this setup. If you see the boat, make sure you talk to the owner. Heck, he might even let you take it for a spin! If he offers you a ride, don't turn him down because this boat truly lives up to its name.
 
Hi diggin, It's always good to see new innovation. I remember a while back where Waterthunder was working on a thrust bearing for a direct drive. With 1100 lbs. of thrust it sounds like he figured it out. Does that engine have thrust bearing on it?
:rebel: :florida: :old_glory:
 
He has a machined bracket that fits behind the flywheel that I believe has a thrust bearing and acts as a motormount as well.
 
So funny, this is exactly what a proper ecotec boat feels like and peoples reaction to is when they drive one. The ecotec makes a few hundred pounds more thrust though.

Good to hear the LS DD is working well. I like the platform and hope to see more of it around.

Always things that can be improved, our "sport" needs the constant progress or it will fade eventually.

digginfool said:
It may not be my place to talk about this boat as it is not mine but I did get to take it for a ride yesterday and OMG. I've never seen a boat with a more appropriate name. This boat truly is a game changer. It's an 11 foot Benny Webb with a direct drive Waterthunder LS3. The owner of the boat said Waterthunder told him it made 1100 lbs of thrust on the stand. I believe it. I've never been on a boat that pushed you back in the seat as hard as this does. Period. The best part is that the engine sips fuel and you can buy that fuel on any corner. No rides to the airport, not paying $5.00/gallon. The setup costs no more than a well built 540. Can't wait to see how this pans out over the long haul. I'm seriously tempted to dump my 540 for this setup. If you see the boat, make sure you talk to the owner. Heck, he might even let you take it for a spin! If he offers you a ride, don't turn him down because this boat truly lives up to its name.
Click to expand...
 
OneBFC said:
Always things that can be improved, our "sport" needs the constant progress or it will fade eventually
Click to expand...

I agree, but I disagree. No doubt, this platform will have its place. Just like CM gearbox boats, ecotechs, or even rotax powered boats have their place. Improvements in anything are always welcome, but sometimes tried and true is still best OVERALL. I think it’s hard to beat a fresh built AC motor with modern electronic ignition and a properly set-up fuel injection system. But I run light aircraft riveted boats. If I ran a big welded barge, I’m sure I would want a CM gearbox. I’d like to see more of these DD LS boats on the water, but us 540 guys aren’t going to be trading in anytime soon.
 
I'm not sure what RPM he has it pitched to. I just know that by the time you hit 2,500, you don't want to be looking down anymore. :D
 
So is that one of the key elements to making a DD work, making the blades shorter so that you can spin it past 3K RPM? I always thought 3K RPM was the limit.
 
Seven3 said:
So is that one of the key elements to making a DD work, making the blades shorter so that you can spin it past 3K RPM? I always thought 3K RPM was the limit.
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http://www.epi-eng.com/propeller_technology/selecting_a_propeller.htm

It's fairly simple yet complicated at the same time. Like all things airboat really.

Disc loading is the task master that ultimately impacts efficient use of available power. The larger the disc the more thrust is produced from the same amount of power.

So, a short blade at higher RPM isn't as efficient as a long blade at low rpm.

That doesn't mean a shorter blade won't work. It just means you give up some potential thrust. However, if you gain 100 hp at 3500 rpm vs 3000 rpm, and you need a shorter prop to keep 3500 rpm tip speed in check, It may work out in your favor some.

1100lbs of thrust from 3 skinny, short blades is quite a bit. I would like to see the boat strapped to a test rig.
 
Hi all.....been a while sense ive been on this board.

I also had Dave build me a DD LS.
The motor is a LS3 block
EFI holley system
430 CI, Chevrolet cnc heads.

Dave (Waterthunder) has a thrust tester, it will measure thrust output.....it makes 1100 pounds + At 3600 with the Alpha 66
Most straight valve 0-540 make 940 =/-, angle valve 1000 +if its 10-to 1
I was at the last Thruman outting......Black full deck,,,,,,,,Midnight Rider..

The prop is a 3 blade Sensenich Alpha,,,,,,it makes thrust up to 3600......at 66 inches
Right now Im running it at 68 Inches and turning it 3200.
It will run with most 0-540 boats......
Ill post up a couple pictures and race videos...
 
If those numbers are of a test run on a fully rigged boat vs engine on a stand with a prop on it, then that's good numbers for sure.

Would be nice to have someone post a video of that test since a 66 inch blade prop is darn short to produce that with.

Can tell you are all smiles about how it performs and really that's what it's all about.

Good stuff
 
It is what it is...it aint a full racer, but it is a fun boat to ride, performs amazing well, snaps hard.
Remember its about 20% displacement disadvantage to a 0 540
Those thrust numbers were on tester, not a boat.....No cage etc in the way.
The 3 blade Alpha is the only prop we tested that work in the higher rpm band, the Saber stopped converting about 3100,,,,,

https://southernairboat.com/gallery/#
I posted a couple pictures on main gallery

IMG_6373-800x600.jpg

IMG_6377-800x600.jpg
 
Davie GSO480 said:
It is what it is...it aint a full racer, but it is a fun boat to ride, performs amazing well, snaps hard.
Remember its about 20% displacement disadvantage to a 0 540
Those thrust numbers were on tester, not a boat.....No cage etc in the way.
The 3 blade Alpha is the only prop we tested that work in the higher rpm band, the Saber stopped converting about 3100,,,,,

https://southernairboat.com/gallery/#
I posted a couple pictures on main gallery
Click to expand...

You need to change your user name. So tell us a little bit about the headers. Who made them and what is different about them?

DD-LS-600x800.jpg
 
I think whats nice about this set up is you have an affordable set up and its a new motor not a 50 year old non Airworthy rebuilt motor
also you can go to any auto parts house and get parts for it even on the week ends at a reasonable price, Aircraft parts you can't just go buy anywhere and there is nothing cheap about them I know I have worked in the Aircraft industry for 42 yrs and like what was pointed out you can run it on pump gas, Dave has been a game changer and innovator for as long as I have known him, lycoming and Continental have done very little to improve there engine design in 50 plus years other than up grade there ignition system and add up graded fuel injection and to buy a new Airworthy engine from them cost more than a new high class airboat, are the motors reliable yes but they are also expensive to own and operate thats why I think what WaterThunder is doing is fantastic and affordable
 
Please help me understand my ignorant thinking what's so game changing about a V8 car motor DD spinning a prop built for a 4cyl AC Motor? Not bashing just trying to understand . beautiful boat BTW.
 
I agree Sniper, this is a good thing. More options are always better, especially when you’re talking about cheaper options in a very expensive hobby. One thing that is causing me doubt is that prop. That’s not a lot of prop. I have a buddy who runs a 5 blade Alpha on his 540, I believe it’s a 70”, but not sure. Dave himself is always saying, the proof is in the prop. My angle valve IO-540 with Airflow Performance fuel injection and Pacemaker Ignition spins a 2 blade 72” Q pitched at the 3 mark at 2900 RPM. I’m curious what that DD would spin my prop set at the 3 mark, and conversely I’m curious what my 540 would spin that 3 blade Alpha at. I realize we can’t just swap props and see, because I can’t spin my engine that many RPM. But I think that would tell us a lot. But I’m not an engine builder, just merely curious because one day I’m going to need to power a brand new hull I have sitting in my garage...and if this DD LS stuff is a worthy competitor to my 540, I’d like to find out.
 
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