Surface drive vs Sterndrive complex question
 

Curious if a "standard" style sterndrive (like a Bravo XR, Imco SC, SCX, or BMAX etc) is harder on internal componets like gears, or would a surface drive (like a #6, M8, Indy, NXT etc.) be more strenuous on gears etc? Equal HP/Torque/boat.

Surface drives require a much more expensive prop. Normaly its larger in diamiter which explains some of the increase in price. The higher price might lead me to believe they are stronger. Leading me to believe a "surface style" drive is harder on internal componets and propellers or they would not need to be stronger. But these $5400 and up props still throw blades off like its their job!

Standard style sterndrives have a competely submerged prop which might seem like thats putting more pressure on internal componets compared to a surface piercing prop.

Any thoughts or better yet proof!

Surfacing a propeller is harder on it than keeping it fully submerged. Every rotation the blades are getting loaded and unloaded as they enter and leave the water. That is why sufacing bravo style props with big hp often leads to pitching off blade tips (I have thrown 2 of them myself in 3 years). The loading and unloading causes flex that a submerged drive doesnt usually see.

I have no clue if surfacing is harder on gearsets, i just assume that the gears are stronger in these drives because they are designed to be behind big HP.

I agree with you on why the surface drive props are stronger and how the gears are normally stronger for higher horsepower applications.

Still courious which is tougher on gears etc.

its measured by lbs per sq inch of torque on the gear face...the more surface area of gears touching each other spread the load out....so bigger gears with multiple teeth meshing at the same time is alot stronger..so lets say 500hp/trq motors on 1sq/inch of gears per revolution....and 1075 hp/trq motors on 3sq/inch of gears per revolution,,,,equals the #6drives etc are alot stronger bc the gears see alot less load repectivly on the gears

Surfacing style props are harder on everything. Not only are they usually higher hp apps, but the loading and unloading of the surfacing blade causes a vibration as the blade "slaps" back into the water. Many people will complain about low speed vibrations with surfacing style drives.

Agreed w/above on surfacing props and l/u's. Want to start breaking stuff, thats how you do it.

Good point's a friend made to me about this argumnet are that,
#1. If your boat requires much "up trim" and bow lift to run, surface drive won't work since the prop is out of the water.
#2. Around dock they suck. To prove this one to you ride in one of your friends fast O/B's where the motor is jacked to the moon. Watch when you come into dock. The motors have almost no effect.
In reverse they have none.
Surface drives are the same.
$3. If you ever swim off the back of your boat...., yikes.

i have surface drives on my boat and there better around the docks than the bravos that usd to be on it,,,,, an out board is a completely different animal especially if they are set high....a surface drive is set back away from the boat and is trimable up and down... the drive grabs all the water around the docks in the down position and is very responsive.....

Only relating....
 

what my friends have told me about theirs. One of them has his on his shop floor.

Would think the effect of trim (lack of) would be tough to dispute.

Do you swim off the back of an outboard boat?

all the....
 

time.

At rest, wheels are way under water and straight under motors and protected by the cavitation plates. Not on a stick 3' behind the boat.

Have also read what I wrote, many times by many different people.

Even though I am a big fan of the arneson drive its not included in my question.

What I am getting at is..... how is the new SCX Surface drive going to handle 800 to 1000 hp when the standard scx is rated for 800. Seems like most of us agree that a surface style drive and prop are harder on internal parts than a sterndrive. So maybe that's the reason the new scx surface drive is not out yet?

I see your still deliberating on this. My offer still stands. :party-smiley-004:

How large is this "Cav" Plate? And how large is the propeller guard on an Arneson?

The outboard's I run (28' Skaters) are set with the propellers the same height as the Arnesons run so I don't follow the "way under water" comparison.

The amount of people injured on Bravo's and Outboard's propellers seem to disagree with your generalizations. The propeller setback on a Merc I/O is in the same basic place as an Arneson also. Give them all the respect and don't jump on any of them

You wish! Even though I am enjoying the cruiser......

Anyone have any test date or opinions on this? Just so courious maybe I should send it in to Myth Busters!

If the drive on his shop floor is an Arneson ASD7M and it is not damaged, I am interested in buying it and freeing up some of his garage space. Have one sitting in the garage now. Trying to save up for a 2nd. The economy is killing me and I can't afford a new one very soon like I planned. Send a PM if interested.

I'll ask him but.....
 

he doesn't normally sell many of his trinkets. He has a cat that when he bought it was twin turbine/surface drive, he then converted to single turbine, then turbo diesel and #3 (I think 3, and yes it died a grizzly death) and now 250 Merc O/B's amongst numerous other floating toys.
I was there picking up a boat several mnths ago and he had a just delivered, new in the box Arneson drive on the shop floor.
Was for his buddies 23' (I think) Eliminator w/a dual whipple monster motor. The guy has been through every hyper/Bravo drive he could find and all failed. Was into I think 130's w/more on the table.
The surface drive looked like a natural.
A really smart guy, did everything right. First time to the water w/the surface drive the boat burned to the water line.
Not sure where that one might be either.

They did a trip to Howards a few yrs back and brought back a wicked on board (Howards turbine Skater) video of them getting a ride proving Howard could spray the Golden Gate Bridge.
He could! His Skater has jet ski power plants to manuver it in/around the dock/ramp area before firing off the turbines!

Talk about thinking outside the box :eek:

Check out my buddies "wife's boat" :)
21' Ron Jones.
Before paint and after paint. Yes, he has some talented friends.

http://i290.photobucket.com/albums/l.../geansboat.jpg

http://i290.photobucket.com/albums/l...thnewpaint.jpg

Regarding the boat with the Arneson Drive that burned down to the waterline, I have his ASD7M drive and transmission. If we are talking about the same person that lives in Shreveport, LA. Drive only had about 3-4 hours on it. He got a new boat. I am still looking for a 2nd. If I can't find one, I will just buy a new one as soon as the stock market improves.......I guess I will be waiting until you know who is out of office.:flag:

That's him....
 

Excellent score! My buddies would be much older than that one.

I got a pretty good deal. Still cost. About the trim issue. I have been doing research and I have talked to several Arneson boat owners, all with twin applications and 38 foot boats and single notched transoms. It seems that the correct props is the key. Most people are trying 5 blade props. After talking to an individual that owns a 38 foot formula, single notch transom with ASD7M drives, he likes the 4 blades props better. He basically said that he had a hard time trimming up with the 5 blades, but had no problem trimming with the 4 blade. It makes since, as 5 blades give more stern lift. Anyway, I plan on trying both through BBlades test program....one day.

Makes sense to me...
 

Never even thought of that. Get the props to bite and half your battle is over.
IMO, 95% of the bad experienced I've seen are from rigs not fully dialed. A bunch of those people were just happy w/the really cool rooster tails on their 65 mph boats :lolhit:
Besides, if you're making more power than a drive can handle, what's your choice?

I think the last one on the boat your surface drive came off of was a B-Max.

Dennis Fisher has an ASD8 In Line drive and it is not sitting on the floor, it is sitting on the transom of his Eagle, another Ron Jones boat, and he is rigging it with a Turbine.

As Dave pointed out Jerry Longoria had the 22' Eliminator with the #7M on it that unfortunately caught fire.

Uhm...
 

I'll get specifics for you when he brings the Warlock here to store in the next few wks.
We were going to run the Eagle in the Parker 300 last 2yrs yr but did not work out.
Classic boat race in next few mnths if all goes well. Dennis's fault if not ;)
If you're friends w/him ask him about me. Maybe ask K.Warby about me as well.

How bought a picture of same boat w/a nitrous ingested 502?

OK OK, this guy has too many toys:drink:

Uhmmmm, kinda looks similar.

http://i290.photobucket.com/albums/l...pixs/eagle.jpg

I guess I should get in this since two of my best friends, who do not know each other, have injected me into the frey.

Gary,
You are off on reversing with the Arneson. The prop is not surfacing when you need reverse, at least I hope not. Jerry's 22 Eliminator backed and handled at the dock just like any other single, twins are so much better.

I met Rik in 1995 when Howard invited us out for a boat ride. Us being me, Gean & Chalaine. Other than stepping all over his tongue following Chalaine around, he was and still is one of the good guys. You remember that the Eagle came from the San Francisco area. Rik was the one who went to inspect it to see if a restoration was possible and he did not even bill me for the gas. I think I have him talked into coming to Louisiana to help me get the T58 fired up. Good guy for sure.

Rik,
I met Gary in 2001 at a boating event he organized in Carrolton, Kentucky. All proceeds went to the Make a Wish foundation. I spent two days riding Make a Wish kids and their families in the Warlock. It was way cool. Gary introduced me to Ken Warby at that event which led to the trip to your shop so two of my boating heros could meet.

Side note: Sitting at the table with two of boatings greatest Icons while they traded stories was one of the high points of my life.

Back on subject, I have attend several events with Gary and he has stayed here at the house several times. He has graciously said I can leave the Warlock at his place in Florida for quite a while so Gean & I can do the Florida boating scene without having to pull 2,000 miles each trip. He is also one of the good guys.

On the Eagle. Yes - those pics are of the same boat. I did the restoration of the 1969 Ron Jones ET in 2002 using the original #2 Merc Speed master lower unit powered by a 502 Chevy . Rik put me on to a G.E. T58 turbine in 2006 and the idea was born to convert the boat and use an Arneson #8. I sent dimensions of the boat to Howard and he sent me all the changes he wanted made to the hull. I had to change the transom angle, shorten the setback, add outer tunnel lifting strikes, etc. I got off on other projects and it has been 3 years with little progress. Now it has been moved to the front of the line should run in two weeks or so. Here is what it looks like this morning.

http://i305.photobucket.com/albums/n...h96/ET-330.jpg

The turbines that were in the Warlock when I got it were Lycombing T53s. I have never run a G.E. T58 which is why I am working on Rik to come and help me get it going. I would hate to screw it up. He is very up on them as two of them powered Howard's 40 Skater.

Gary - If I get Rik here maybe I can get you here as well so ya'll can put on the gloves.

LT

Dennis, sorry I missed your post. We just go back from a week in the Keys to bust the Sonic's cherry.
Ramp, dock, store, gas, tiki bar, pool all on site and a 1/2 hr day trip to Key West.
It sucked and most likely you would have hated it ;)

http://i290.photobucket.com/albums/l...utsideroom.jpg

Now that the SCX4 is finally made public by IMCO I am even more curious about my original question.

I have seen the original SCX last aprox 400-500 hours before needing gears, behind 850hp on a 36 apache.

Will the new SCX4 last as long since its a surfacing drive?

Maybe easier on uppers, harder on lowers and shafts,,if you lift it up higher?

Well the easiest way to find out...

You buy 2 for your fountain. Kristy and I will ride with you at Boyne Thunder and see if we like them. If they run good enough to keep up with your saber (with me behind the wheel of the saber) then maybe I will get a pair for the Baja!

Come on Kevo, you go first! You know they will work great on the Outlaw!

Anyone do some lab testing to answer my question yet? LOL!

Since Imco does not wrnty the scx4 it makes me wonder even more about my original question.

Also thinking about how fountains have such a high X Dim they break bravo shafts and props like its their job. So will that be the case with the scx4 also?

Only time will tell. Just would love to know now so we all could decide if we want to buy them or go another route.

I still think they are great drives that will work amazing on some applications.

My personal application I want a drive that Gains speed, last 500hrs between overhauls, strong behind 900-1000hp, and installs on a bravo style boat.

The SCX does this minus the gaining speed
The Arneson does this for me but not everyone
The X power does but price is to high

SCX4??? Only time will tell UNLESS we answer my original question!!!

If you dont want to worry about that, go with the
big shafts and SSM props on the scx4.

I agree that's the only way to go but still does not answer if a surface drive application puts more or less stress on internal drive parts.
If it's harder on parts then the SCX 4 will not be for me. If it's equal or less then it will be a smash hit!

I'd say:
700HP on the internals with 14% prop slip is 700HP on the internals with 14% prop slip regardless of height except for the propshaft and lower bearings. A surfacing drive would deflect the propshaft up more so than a submerged drive. That's probaby harder use.
As far as load unload due to number of blades. 5400 RPM divided by 1.5:1 ratio divided by 60 seconds in a minute equals 60 revolutions per second divided by 5 blades equals 1/300th of a second between pulses that the slip is absorbing/cusioning so likely no measurable difference in loading of the gears. With 5 blades a blade is always in the water pushing anyways. Now with a 2 blade, pulses would be 1/30th of a second apart and you could possibly have no blades in the water pushing at times. Maybe that would be harder but you'll still have the slip cusioning the pulses.
And I got my degree online!

Now thats some math !

That's priceless!! :drink:

Is all this factored on flat water or 3-4 footers? LOL

LOL! So after all this math and stress and chit we still do not know the answer!! Good thing the lexus dealer I just dropped my load of cars at had "stess relieving hand soap"! Hope it starts working soon......

Im guessing that there is a reason why Imco is offering the scx4 with the #6 propshaft, the bigger it is the stronger it is. Im going to run my scx4 drives as hard as i possibly can and i highly doubt I will have any problems if these drives are anywhere near as strong as my previous scx uppers. Imco didn't offer a warranty on my scx uppers that i purchased 2 years ago and i had zero failures with the scx uppers but i did have propshaft failures with my old sc lowers. My new scx4 drives will solve that problem and if anybody can break these new drives i can :lolhit: