Surface Drive

About inboard or outboard motors.

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Andy Garrett
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Surface Drive

Postby Andy Garrett » Fri Nov 06, 2015 1:06 pm

I was just reading about surface drives. Embarrassingly, I was unfamiliar with this drive option.

A number of sources list some real advantages for this system including reduced fuel costs due to better efficiency, increased speeds, better shallow water opperations, lower vibration, etc.

Anyone have experience with surface drives? Is there a place for if in the Glen-L world?
Andy Garrett

Perhaps the slowest Zip build in Glen-L history...

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Andy Garrett
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Re: Surface Drive

Postby Andy Garrett » Fri Nov 06, 2015 1:09 pm

While looking at pictures of these systems, I found this wild contraption--racing paddle wheel?:
Image
Andy Garrett

Perhaps the slowest Zip build in Glen-L history...

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Dave Grason
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Re: Surface Drive

Postby Dave Grason » Fri Nov 06, 2015 1:46 pm

Andy Garrett wrote:While looking at pictures of these systems, I found this wild contraption--racing paddle wheel?:
Image


The photo didn't reproduce for me. I can't see what it is.

I'm not super familiar with the surface drive system either. So, this might be a case of the blind leading the blind. However, as I understand it, the advantage is the lack of cavitation that is suffered by other drive systems. In other words, the surface drive system does not create vacuum pockets (voids) under the water which cause increased drag. By piercing the surface, there is no void created. This increases efficiency in a very dramatic way.

BUT YOU JUST GOTTA KNOW... that there HAS to be a down side... RIGHT? After all, there is no such thing as the perfect system. 8)

As I understand it, reverse is a bit... excuse me... reverse is really difficult. :lol: The boat using a surface must have a transom that is angled at least 45 degrees if reverse is to be used at all.

I have always been enthusiastic about these super go-fast boats that run close to 200 mph - Skater, MTI, Donzi, Formula, Magnum and others.
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.

slug
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Re: Surface Drive

Postby slug » Fri Nov 06, 2015 1:59 pm

http://thebrigade.com/2015/07/09/russia ... and-story/

You aircraft/boat guys might want to take a look at this.

Doug

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vupilot
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Re: Surface Drive

Postby vupilot » Fri Nov 06, 2015 8:40 pm

We use surface drive on a many of our performance r/c boats, I figure the theory is the same and its interesting to study but unless you are about total performance its not the most practical thing for a pleasure boat. On the models there is a ton of tuning in 1/16" increments that goes into these systems and those small adjustments make big changes in performance. In propeller theory a prop with more pitch will propel the boat faster for each revolution but if you cant get the engine rpm high enough to produce maximum performance the prop cant do its job so raising the prop about halfway out of the water allows the engine to not be bogged down by the high pitch props. You might think one prop blade out of the water all the time would be less efficient but the most efficient prop is actually a single bladed prop on its own but the problem with that is a single blade prop cant be balanced efficiently, the most efficient balance is to put a second blade on the opposite side of the hub. Its really fascinating to read up on actually but for the majority of pleasure boats the traditional submerged propeller drive is the way to go for a practical compromise.

Slug,
Ive long been fascinated by the Russian Ekranoplan. It baffles me that the world water speed record is STILL 317 mph from 1978. A speed I surpass in the air daily flying at work. I've studied all of the books on the water speed record and the attempts of people like Donald Campbell, Ken Warby, John Cobb and Lee Taylor. I feel one of the last great world records would be to substantially raise the world water speed record. The problem seems that the small, light, jet and rocket powered boats built to set these records inevitably hit a small wave and become airborne and uncontrollably crash with tragic results. It seems if one were to think more like that Ekranoplan and make a boat that is large enough not to be affected by the smallest of waves and controllable (flyable?) like the Ekranoplan such that if it becomes airborne from a small wave you could make a smooth and controlled return to water (landing) and then attempts to break the record could be made again without it being a death wish. I find it interesting that the current world water speed record boats under construction all follow the same old design thoughts of the 70's with modern materials and don't pull more design elements from aircraft. http://quicksilver-wsr.com/ I think you have to think of a 500mph boat not as a object that sits with its weight on the water and rises on top of it on sponsons but more of a plane that flies above the water but with a hull which never actually departs its surface and if it did, could be pilotable so as not to be a tragic event. Then I could foresee water records closing the gap to that of the land speed record which we all know is already over the speed of sound. Anybody got say.. 25 million bucks burning a hole in a pocket? Wouldn't that make some headlines in the boat community? Group of Glen-L boat builders breaks water speed record!?!!

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Andy Garrett
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Re: Surface Drive

Postby Andy Garrett » Sat Nov 07, 2015 9:12 am

Great response Chris.

Your explaination about a single propeller blade is spot on as well.
I remember reading recently on the Everal propeller made for planes. Looks crazy!

It just seems that with the conversations around here which detail how to get that little extra speed out of a power and drive set-up, surface drives would have a place at the table, even for pleasure boats. Better effeciency (read: lower fuel costs), lower vibration, tighter turns, etc. It just seems logical.
Perhaps a lack of off-the-shelf units ready for Glen-L designs is the obstacle.
Andy Garrett

Perhaps the slowest Zip build in Glen-L history...

JasonG
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Re: Surface Drive

Postby JasonG » Sat Nov 07, 2015 4:43 pm

We use surface drive on a many of our performance r/c boats, I figure the theory is the same and its interesting to study but unless you are about total performance its not the most practical thing for a pleasure boat. On the models there is a ton of tuning in 1/16" increments that goes into these systems and those small adjustments make big changes in performance. In propeller theory a prop with more pitch will propel the boat faster for each revolution but if you cant get the engine rpm high enough to produce maximum performance the prop cant do its job so raising the prop about halfway out of the water allows the engine to not be bogged down by the high pitch props. You might think one prop blade out of the water all the time would be less efficient but the most efficient prop is actually a single bladed prop on its own but the problem with that is a single blade prop cant be balanced efficiently, the most efficient balance is to put a second blade on the opposite side of the hub. Its really fascinating to read up on actually but for the majority of pleasure boats the traditional submerged propeller drive is the way to go for a practical compromise.


It's amazing how technology from real racing boats applies to the model boats. There is also a plethora of prop modifications that affect performance at this level! Good response! :D

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gap998
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Re: Surface Drive

Postby gap998 » Sun Nov 08, 2015 11:00 am

Surface drives are really interesting - This company has a number of " Off the shelf" designs including Bravo I/O conversions. From what I've read, reversing shouldn't be a problem as at low speeds, the drive is trimmed below the surface like a conventional drive.

http://www.arneson-industries.com/page. ... &id=drives
Gary

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chugalug
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Re: Surface Drive

Postby chugalug » Sun Nov 08, 2015 11:16 am

:D Suppose you could mount a Go-Devil surface drive on your zips.might have to beef up the bottom to withstand all the sticks and mud tho.might have awesome mud roostertail tho :lol:
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JasonG
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Re: Surface Drive

Postby JasonG » Sun Nov 08, 2015 11:36 am


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jamundsen
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Re: Surface Drive

Postby jamundsen » Tue Nov 10, 2015 5:10 am

Check out the Sea Fury drives. They are out of Austrsilia I think. They back up pretty good according to their literature. I have been looking at them in case I build the Cruise Missile.
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kens
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Re: Surface Drive

Postby kens » Tue Nov 10, 2015 9:50 am

The whole idea of surface drives is to reduce underwater drag of driveline parts.
As speed goes up, drag goes up exponentially, so getting rid of underwater drag is important for racing speeds.
With surface drive there no strut nor rudder in the water. Only the prop is in the water, and it is a surface drive cleaver at that.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:


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