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Old 09-15-2008, 07:58 PM
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Rik: Interesting reading, do you have a picture of your set up from the side and with the props you mention? The only real experiece I have with Arneson is from my employer's Nor-Tech 4300 Super Cat with 480 Yanmar diesels. The "ride" was DISASTEROUS compared to the other boats I run, which is mostly all kinds of Fountains. The whole boat was vibrating, the axles were not tied up (no tie bar).. When one of the props got a severe damage when we hit a big wooden "tree" the boat could not be driven on one engine even with the wheel turned fully over, the boat just went around in a big circle....... (because of the distance between the sponsons. What do you do then when out in 6 ft. seas?? The angle was not enough to get the boat to steer straight foreward. And in the real seas, it is important to get the bow towards the sea when off plane. The other one was a 48 Fountain Express Cruiser. Same vibration there. Is this because of the surface piercing props or can it be the gearboxes or axles or what? There is no vibration from Merc drives. I agree Arneson shold be fine on most stepped hulls, but on old non-stepped boats, the boat very often goes much slower. One guy here has an old -Fountain 12M where he have put in 480 Yanmars... The boat runs only 60 mph. All my experience with boats, (and it reminds me every time I test out new props) is that everything other than cats, or Vees with extreme power/weight ratio, likes props with round ears and curved blades. I have never seen an Arneson with anything else than cleavers. And they never gives any specia bow lift. The boats go SLOW with cleavers. No trim response.. Is it possible to get bow-lift-props that fit the big arnesons? Non stepped hulls need as much bow lift as possible without trimming the drive up to "shallow/beach position".

Only my impression though... Let me know if I have missed out something.

:-) Erik
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Old 09-17-2008, 12:00 AM
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With regards to the Nortec; if they have a vibration issue either they did not align the engines or whose ever propellers they used were out of balance to cause the vibration. If you are confusing a harmonics noise for vibration then welcome to the world of cats. They resonate any noise anywhere in the boat. Think of them like two large drums. Same for rides, the hull is the hull, not every problem with a boat is related to the drives. Maybe it is just not going fast enough for the cat to air out properly? Cats do ride differently than Vís and the slower speeds you are experiencing are not doing respect to the capabilities of boat itself.

As to what to do when you hit a tree. Try avoiding all trees in the water would be my first thought. If you hit something like a tree and cause damage, then you will have to address the damage once you get back out of the water. I really do not have an answer for running over trees.

Question has to be how many of the Merc drives were in front of a diesel engine? I think you are comparing apples to oranges in the setup and associated side effects. Diesels vibrate a lot more than a gas engine.

Once again are you comparing speeds on the non stepped hulls with a gas engine to a diesel engine setup. We have the majority of our applications non stepped hulls and yes for the most part non stepped bottoms are not as fast as the stepped bottom design boats. All of the Magnumís, Pershings and such are non stepped and run very well though.

As for the older 12 M Fountain, (this is a 36í V bottom with twin Yanmar 480ís) the boat is simply to heavy for the engine weight. Once again not really anyoneís fault but what was the owner expecting for speed when a 36í boat weighs some 5,500 Ė 6,000 kg? With a small bottom and all that weight the boat is actually running well. Take the weight of those 480ís with the marine gears (1.800 lbs each) out of the equation and put a lighter more power gas engine in the boat and then look at the speeds. We have several 12 M fountains with Arnesonís and gas engines that run over 100 mph. Once again someone has over reached the expectations from a 20 yr old boat design with heavy diesel engines.

As for propellers, for a diesel application or a gas application. Mercury and Hering both offer differing degrees of rake in their cleaver propellers and this translates to differing amounts of bow lift from degrees of rake.

What you have to look at is where the CG of the boat lies with the diesel engines in comparison to the gas engines. This changes a lot in the performance of the boat especially when you add an additional 727 kg and them move it forward in the hull by half a meter in comparison to the gas engine setup.

As to your original comments (which is in regards to the Ilmor Fountain package) you would not be using the same drives as what you have seen on the Nortec Cat, not the triple 48í Fountain with Diesels. Rather you would be using a smaller drive unit that has a normal mechanical tie bar assembly and uses standard Mercury or Hering propellers.

The boat will get on plane and run reliably wit the Arnesons that are made for that setup. (http://www.arneson-industries.com/pa...ducts&id=asd7m) Please remember the boat you originally addressed is not a 20 + yr old hull and is not under powered and over weighted. Itís a modern designed efficient hull with a light weight powerful engine.
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Old 09-17-2008, 12:22 AM
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Well put Rik. I love the 30 skater, Dale Rayzors i think?, thats my fav. boat with arns. Fountain Worldwide is a dandy also. I'd love to have a custom fountain with 710s/ASD's.
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Old 09-17-2008, 12:43 PM
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Here's a 38' Fountain wide body with 625 Ilmors.
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Old 09-17-2008, 05:35 PM
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Maybe you are right... :-) Anyway, these were MY own experiences. I am very interested in different ways of propulsion to fast boats. I agree about that diesel-vibration thing. Hi-Perf boats makes most sence for me with gas power whatever whoever says. Started a triple Cummins 320 47 Lightning the other day, and is is a totally different animal with triple gas........

So why does so many fast boats have outdrives and not Arnesons?? Just asking here Especially in the 600-800hp range where the Bravo outdrive is not strong enough and people can't afford No6s. Why is the No6 an option for 38, 42, 42PR and 47-Fountains with 525 hp and above, and not Arneson? I guess the boat needs to be adapted quite a bit to fit the different configuration? Both will need a gearbox too. This is interesting. I follow Craig's P1 racing and know it works well, no problem there. I just said that non stepped boats needs lift. A lot of positive trim is not good for the ride, but often neccesary to get the bow up and get the boat out of the water when running on flat water. Then cleavers does not do that job. This is my experience though, but after reading about the different characteristics of all the mercury props on their site, it seems like I am right too. So why has almost all arneson drives cleavers if the boat needs a chopper/round eared prop with cupped blades? If you have another prop that will create better bow-lift for the 12M guy, he might buy a set of new props. He is trimming up to get the bow up, but what happensis that the props are trimmed out of the water so very little area is submerged. What would you suggesrt to get more speed on this boat? I agree about the added weight. The guys should maybe build a pad to carry all that diesel weight (side by side engine set up).

I did that myself on a boat that had the point of gravity a little too far back to get the hull higher in the water. In addition I made the pad a bit shorter than the rest of the hull (like a notched transom) to get the bow to raise more easily and to reduce the risk of the bow to drop with the new pad. That made this the fastest boat by far of it's kind, and better seaworthyness too. And is still after 4 years. I run the same 4-blade Mach over the hub chopper as before, and a gearcase with the axel paralell to the water line.

About that rake-thing.. Is more rake = more bow lift? just asking!!



ANYWAY, Fountain should definately make a 42 Poker Run/LGT in a "P1-edition" which was the theme in this thread.

:-)
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Old 09-17-2008, 05:48 PM
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Is it made a test with regular outdrives, arnesons and the Black Hawk drive some time (on the same boat/engine)? Would be interesting to see. How the thrust is applied to the hull and what difference it makes.
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Old 09-17-2008, 08:51 PM
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Why out drives instead of Arneson's. Simple. Most people know one thing and they follow that one thing.

Manufacturers use Merc b/c Merc provides an engine/outdrive package all in one stop shopping rather than sourcing each item separately. Also Merc (was) offering the OEM's some creative financing in order to keep and persuade them not to use anyone else.

In other words it just business tactics.

In regards to Rake: More rake = more bow lift. Less Rake = Less Bow lift.

Cleavers are/were designed for the surfacing applications. They work well at being efficient in the surfacing mode but they also have some trade offs. Changing the cup, camber and rake will greatly affect the performance of the boat. What works well on a gas power does not work as well on a diesel powered boat. Different propeller rpm and different torque levels require a different designed propeller to function at their best.

As to transmission concerns, I am the one that invented the idea of putting the transmission inside the standoff box to keep the engine in the same standard Bravo location and not affect the CG of the boat.

I might be doing a new 42' Poker Run Edition soon.

FYI, here's a photo of how the Cat could have been setup
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Old 09-17-2008, 09:34 PM
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Quote:
Originally Posted by Rik View Post
............I might be doing a new 42' Poker Run Edition soon.

FYI, here's a photo of how the Cat could have been setup
Hey Rik, You thinking maybe some 710s or what?
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Old 09-18-2008, 04:20 AM
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Ok, a 42 Pokr Run in light blue with some P1 graphics would be a really nice looking boat!

Camber, what is that really? I have a 34P Bravo prop in my truck which is from WCM- It is written "Raised Camber" on it. Never really understood what was meant with that....

It is a little strange that a new 47 Lightning will run 75 mph with twin 480 Yanmars and arneson (which is very good), but that 12M only run 60 mph with the same power and also Arneson on this boat. Yes, not a step-bottomboat, but the 12M is MUCH lighter and smaller!!!

The Nor-Tech looks wonderful.

One final question, there is a guy here with a Hydrolit C31 with a big gas engine. He has put on a Arneson drive like the one which is mounted on the cat you attached a picture of. The steering consist of one ram on one side attached to the black box. Is it normal to have only one ram in a single engine application? The steering is not working right, and no-one manage to fix the problem. He has around 850 hp.

Thanx
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Old 09-18-2008, 08:20 AM
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Hey Rik,
I am told that i can not install Arnesons on my 38 Comp due to the staggared engine set up. Is this true? Is it because there is not enough room to mount the two drives so close together?

Sorry to Hi-Jack the thread.
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