Interesting Outdrive picture

[Loneranger]

I am sure others have seen this configuration before but I came across this picture last night while looking at underwater LED lights. If anyone has experience with this type of outdrive, tell me more about it? It seems like something that would be on a go fast boat. It also seems to be a much more accessable and repairable drive than a traditional sterndrive but I really have no idea. What do you think?

John

 

[fwebster]

Arneson drives.............surface piercing drive. The prop runs about 1/2 submerged and not at all practical for a pleasure boat. They are very expensive and are generally only used in very high hp applications.

 

[Four Suns]

There are a couple of Fountain fishing boats here that have those. I'm not sure the boat is even in the water when they go flying by me.

 

[berth control]

I talked to a guy at the boat show with the "miss gieco" insurance boat. They had some turbine drives paired to two of those. He said the props were about $15,000 each!

 

[Loneranger]

I had a feeling they were used on go fast boats. Thanks for the info.

I had heard that they would run with the prop only half below water, I guess that decreases drag on the prop?

John

 

[Sorrento 25]

Oh yeah. I had an old POS Bayliner with a nice old 150 Merc V-6 that did mid 50's with me alone. I added a jack plate, low water pickup/nose cone, and a cleaver surface-piercing prop and it picked up to the mid 70's with no other changes.

 

[Carver370]

These few videos pretty much sum it up on how they look when running and work.

http://www.youtube.com/watch?v=Zasoso42xdo

http://www.youtube.com/watch?v=YhCtHRLLZmw&feature=related

http://www.youtube.com/watch?v=tJicKKodHZo&feature=channel_page

 

[sbw1]

Sea Ray used these drives on one of their big Dancers a few years ago.A friend took me on a ride. It was very quiet and fast. Also very tough to back out of a slip and steer in reverse

 

[jitts3]

I liked the video where they fired it up with the little fish around!
I

 

[Scott1]

Those are arnesons......surface drives that really need the right hull to work right. Most all of the big Pershings have them...ditto for similar big boats. I know they have put some on some 30+ foot sundancers too. If you run merc #6's you can usually have arnesons as an option too. Bow has to be naturally lifting in most circumsances...otherwise prop work is needed. Lots of cats and staggard v's run them. Very efficient, and fast. The "fountain worldwide" runs them with ilmore V10's. Quite a few cats too.

Here is a side by side 382 formula refitted with ASD's.

http://www.youtube.com/watch?v=bxjsIl3F3x8

And of course a 32 skater with asd's.

http://www.youtube.com/watch?v=oxUy_4gJunY&feature=related

 

[rblatter]

One of the first non go-fast boats to use this drive, Sunseeker boats, above 40ft. Great boats, but not production line boats. I remember seeing this 63 Sunseeker here in Montreal with Arneson drives that belonged to the remaining members of the Beach Boys.... tremendous wake behind this machine..

R.Blatter
310 Sundancer 2001

 

[Four Suns]

tremendous wake behind this machine..

I assume you mean the rooster tail created by these things. They basically get their speed from two areas. One is a decrease in drag by not having a bunch of hardware below in the water but the main reason is they are like a free-air jet drive. Because they are on the surface, they can eject a lot of mass (the water in the rooster tail) easier because it's in the air than a prop can under water which basically screws its way forward.

The problem is when they are not ejecting all the water in a rooster tail, they suck... like around the dock.

 

[rblatter]

Yes i meant rooster tail and not wake, am I mistaken but could not these drives be moved up and down a bit to adjust the angle for the props to be in deeper in the water...

R.Blatter
310 Sundancer 2001

 

[rblatter]

http://www.arneson-industries.com/

Intersting site, Bravo adapter....

R.Blatter
310 Sundancer 2001

 

[Scott1]

A common misconception about ASD's is they are difficult to manuver around the dock. They are no different than any other surface drive....like a #6. Staggered engine v's are the first to claim this title, but its the placement of the drives so close to the center line that makes them difficult. They have much less leverage when pushing or pulling that close to the center. It is true that some of the reverse thrust is lost when it hits the transom, but the props are usually placed so far back, and on extension boxes, that this is just a wash. If you talk with owners they will say it might take some getting used too, but really not any harder.

They have a speed advantage b/c less is in the water and the props can properly ventilate when running half in the water. The rooster tail is a pure after effect of the prop blades tossing water in the air, drive trim buttons, and big power.....and is not a trait desired to make the boat faster. Just looks cool. Any drive...ASD, #6, BPM, weisman, or a bravo can toss a proper roost. Prop just has to have a very high X dimension.

Here is a 36 skater with #6 drives. Big roost.

http://www.youtube.com/watch?v=tGDKxUVn5UI&feature=channel_page


And here is a 30 skater with ASD's. Couldnt find the video.

 

[370Dancer]

The first ones I ever saw were on a Wellcraft 50' Scarab around 1988. I was on the platform tending lines when leaving the St. Pete show. Captain put the drives in reverse, and some papers sitting on the engine cover were sucked under the platform!

 

[Four Suns]

They have a speed advantage b/c less is in the water and the props can properly ventilate when running half in the water. The rooster tail is a pure after effect of the prop blades tossing water in the air, drive trim buttons, and big power.....and is not a trait desired to make the boat faster. Just looks cool.

I'm not sure if we are saying the same thing or not. You are correct that the rooster tail does not cause the boat to go faster but it is the effect of ejecting mass into air instead of underwater. It would be like saying the rocket plume on the space shuttle does not cause the thrust... Although true, you could not get the thrust without the side effect of the plume.

It's like a jet drive in a boat as well. If you have the jet exhaust under water, the thrust is far less than when the jet is exiting in free air because there is less back pressure. A surface piercing drive gets more thrust because it flings water in the air instead of against water like a regular prop. So although the plume doesn't cause the thrust, the thrust from pushing the water into free air causes the plume. Can't have one without the other. I understand it doesn't have to be a big 45 degree rooster tail... that's not what I'm talking about.

Thrust is all about how much mass flow you can produce (like a rocket). Pushing water into free air produces more mass flow than pushing water against water for a given power source.

I think we are saying the same thing though and that's what you are calling ventilation.

 

[Four Suns]

As a side... if you don't believe me on this... A good example that EVERYONE here is probably familiar with is when you have a spray nozzle on the end of a garden hose and are filling up a bucket of water to wash your boat. Ever noticed that if you are holding the nozzle in air you have a force you can really feel pushing back but as soon as you put it underwater in the bucket to fill it up the force goes way down? In fact, if you are like me, the force will go down enough on the sprayer that you'll put that little mettle clip down to keep it spraying underwater and it'll stay under water just fine until someone bumps the hose and then the sprayer will come out of the water a little and go bazerk and be like a wild snake on the boat deck. Same concept... that back pressure in the bucket significantly reduces the amount of mass flow coming out the hose. It's faster to fill the bucket up by keeping the nozzle out of the water as it can eject more mass into free air...

Now you can all nerd out with your friends and impress the chicks when you wash the boat.

 

[Turtlesboat]

I always wondered why when I'm drinking a glass of milk and I start to laugh, the milk shoots out of my nose and throws my head back. But when I laugh into the glass of milk, no head thrust.

 

[Four Suns]

I guess it probably takes longer to pee in the water than standing out of the water and peeing... that would be a good beer drinking experiment.