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Opinions of surface drives

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Old 10-08-2002, 02:51 PM
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My father did the Kaama and I worked with him on our WSD drive and now the WMD drive.
All three drives were built for specific reasons. Every drive can do atleast one thing right.
The Kaama has a gearset added to it to bring the propshaft closer to parallel to the running surface as well as ratio.
As for surface drives like the Arneson they are not very good around the dock for the reasons they are good at high speeds(if you can keep them straight on a twin)
Having a 6 deg transom will not allow you to trim to level because the prop comes out of the water so you need to add rocker to assist the bow to come up, Buzzi used anti dive planes.
With the advent of stepped hulls it makes trimmability a problem in a Vee bottom.
On cats the natural down angle helps keep the bow stay down at high speeds. But you can do that with a normal drive too. That makes the acceleration a little slower.
I hope this helps a little. There is no "perfect" drive. On the WMD project we did 7 different studies.
As for racing, bring it on. We don't race ourselves and claim to be the best we like competition.
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Old 10-08-2002, 05:50 PM
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I was under the impression that a stepped bottom boat performs better with surface drives than a non-stepped bottom boat? Look at Fountain’s success with the Arneson’s!

As for rocker, don’t the stepped bottom boats remove the need for it? I thought I read that in a Poker Runs America article a while back.

No surface drive can have positive trim, whether it’s a Bravo, SSM, Arneson or even Weismann as when the propeller is at the surface, you cannot trim it any higher correct?

What is a 6-degree transom?
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Old 10-08-2002, 05:59 PM
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[QUOTE]Originally posted by shifter
[B]
As for surface drives like the Arneson they are not very good around the dock for the reasons they are good at high speeds(if you can keep them straight on a twin)



shifter: what other weaknesses do you think Arneson drives have?
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Old 10-08-2002, 06:24 PM
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Transoms always have angle, that is how they get the boat out of the mold. The "standard" transom is 13 degrees. I have seen everything from 0 to 16 deg.
Our drives are not like arnesons, they are more like a stern drive meets a surface drive except the WMD it goes under surface also.
Depending on prop placement from the transom and cg, the leverage is greatly effected on the boat. Propeller bite is proportional to trimability on any boat. If you run 1/3 the blade area in the water the acceleration and control of the boat goes down and the speed comes up, less drag. If you burry the drives and get maximum bite you get good acceleration and control and a bad top speed.
The angle of the bottom acts like a trim tab . If you run negative angle of attack to the running surface the force is lift and drag. Saw tooth bottoms run on points insted of surfaces. less drag less trimability. You can still have rocker with a Step bottom. This is good for another thread.
I am not a naval archetect, I can hardly spell it. I can ask some friends for some more tecnical answers on the hull.
All for now.
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Old 10-08-2002, 06:29 PM
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Quote:
Originally posted by Two K's
Know what would be cool. A twin arneson/single engine setup.How about it Howard?
Hot Boat did that only with Bravo 1's towards the back of the mag on the cover is Feline Frenzy.
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Old 10-08-2002, 06:56 PM
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Hey guys, Some of the reason you don't see many arneson drives compared to Mercury outdrives are the engine drive packaging. When you go for a different drive than Mercury the manufactuer are on there own. Most of these guys don't like to do any more R&D than they are already doing. In other words if it aint broke don't fix it! that does not mean that the Arneson drive is not a great drive.
 
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Old 10-08-2002, 07:50 PM
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What does “keep them straight” mean? Isn't there a mechanical tie bar on the Arneson's like every other drive?

When you mount a drive at the surface, you are not running sub-level, merely at the top so there still is no positive trim to be had. This is why I believe, with the elevated X dimensions of today’s drives, manufacturers have made the boat carry itself by better hull designs more than relying upon the lift coming from the trimming out of the sub-surfaced drives.
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Old 10-08-2002, 08:02 PM
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Bootless
Right Lets say a properly designed Bottom! (As there are a hell of a lot more improperly designed around)Also check out the Cat picture that Too Old Posted that has a Hydraulic tie bar for one,

But the other is look at that particular Steering setup, the Ball socket position in relation to the Rams you see what happens in a turn there! The Geometry is a little funky.

As far as strength and reliability in a Stern drive System the Arneson is the best !
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Old 10-08-2002, 08:17 PM
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HyperBaja, I read that article and thought it was very ineresting.I think this twin single stuff started on drag boats with v drives. I just think that surface drives work better as twins than a single,but singles are still great. Just have to get used to the boat wanting to make unexpected turn when backing off throttle, so I thought that a twin/single setup or even a duo prop version might cure this and maybe have more benefits. Hell, if they were able to build shifting into say the drop center housing and bring the engine back that I think would be a big plus.Getting back to the original question on this thread.I think one of the reasons why you don't see a whole lot of surface drives is that those props sticking out of the water 3' back scares the nornal everyday boater and even the mild performance boater [oh boy what if somebody falls into that thing!!!] I think they are great and if I had the cash to buy them, I'd be bolting them on my cobra. I also think I think toooo much
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Old 10-08-2002, 09:48 PM
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Steve1. My KAAMAs have an hydraulic tie-bar setup, which is basically a set of rams identical to the steering rams, looped to each other. With all the air out, and seals in good shape the work great. (and this took me a while to figure out).




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