Random Insanity.

So I've purchased a boat. Her name is actually Random Insanity.

There were some videos of her posted by the original builder on youtube. And I've included a short one here of her on a straight line.



I'm currently in the process of freshening her up. But that is a topic for another thread in another forum.

My reason for posting here is that the original builder has said she is a bit sluggish answering her helm when she's planing.

I am looking to improve her steering performance, and while I'm at it, I was wondering if there was something I could do to improve her wave riding, since the flat hull is just begging to jackhammer all who ride in it in any kind of a chop.

The other thing I was wondering about was whether or not there would be some way to possibly reduce her wetted area to reduce her hull drag, although that is very much a back burner sort of project at the moment.

And on top of all that, I'm not necessarily looking to rebuild the entire hull. I was hoping that this could be a "bolt-on" parts project. (the hull is based on Bolger's Instant Boat concept)

Its a tall order, I'm sure, but I'm also reasonably sure that its not impossible.

Thank you in advance to all who answer for your time, and I look forward to any and all advice I get.

 

Is this one of those high speed paddlewheels or does she have 4 or more outboards? I can't tell from the video.

 

Its a paddle wheel.

 

Welcome to the forum.

I'll assume you're using rudders, which are always going to be a bit sluggish, compaired to other forms of steering. You might be able to increase their size and shape, for better response, but you'll also likely pick up some drag too.

If the hull is flat bottomed, there's not much you can do about its tendency to pound, especially when driven hard. It's the nature of the beast and good for quick acceleration, but absolutely lousy for the ride it provides.

The same can be said about reducing wetted surface. This requires a new underwater portion of the hull. Adding things will just increase wetted surface and drag. Reducing wetted surface is just as it sounds, you literally carve away areas of the immersed sections.

 

Hi Steffen.
An additional possible cause of the sluggish rudder response is the gyroscopic effect of the spinning paddle wheel, apart the insufficient rudder area.
The gyroscopic effect is inherent in the design of this boat and there is not much you can do about it, mainly because of the flat bottom.
Hence you are left with an increase of the rudder size as a makeshift remedy.
If you decide to give it a try, be aware that the structural loads on the rudder post will grow as a power function of the increase of rudder area - hence a major redesign of the rudder post and the surrounding hull structure will likely be required.

 

Not much hull in the water to get a grip on to steer it, by the look of it.

 

True, Mr. E.
Hence a hydroplane-style skid fin might also be tried: http://thunderboats.ning.com/profiles/blogs/skid-fins-the-loads-they-carry

 

Hmm. Ok, so how big would you make these fins, and where would you place them on the hull for maximum effect?

The 'Insanity measures 16 feet at the waterline and has a waterline beam of 7'6" (22 x 8 overall dimensions with a draft of between 4"-9" depending on operating conditions)

 

Normally they are placed slightly behind the midship, like 40% of the static LWL. Depends on the actual wetted length when running at speed. The general rule is - the fin should be as far forward as possible. At the same time it has to be in water at any time, when the boat is at speed and at a running trim. These two conditions determine the fin position.
From what I can see in the video of your boat, you can place it pretty much at the midship.

 

I asked a guy about his sternwheeler as he also had problems steering with windage and just sluggish response. He installed leeboards which helped with steering a straight line and in turning, as it gave a centrally located point that the hull could pivot around instead of slipping sideways in turns.

Since the boat uses a car differential for the paddle wheels, a possible good idea would have been to leave the brakes on so when one was applied, the other side would spin that much faster and help in turns. Maybe you could put them back on.

 

At the speed those wheels are turning I'd be worried about a spin out if either slowed down much.


Steffens ... a question about your rudders: are they in front of the wheels or behind them?

As I understand it, with paddlewheels the main rudders were in front of the wheels because they worked best when water was being pulled over them whereas the "monkey rudders" suspended after were good for backing up.

If your rudders are aft of the wheels they may also be having to deal with all the cavitation from them.

 

There's a lot of issues at play here. What is the speed of this puppy? What is the speed the steering begins to get soft? Can you post pictures of the bottom, the rudders, etc.? There's good reasons this form of propulsion was quickly tossed over the side, in favor of other approaches, but you still have to live with the compromises of the SOR decision compilations. I don't think much benefit will come from midship foils, though tracking will improve, steering likely will not.

 

Yes, an illustration of the rudder set-up would be helpful.

 

Given the environment these rudders are working, I don't think much will be gained, unless they're much deeper and this will detract from top speed potential and add considerably to draft. Without some idea of how this boat is setup, this is all just specualtion. I personally think the design compromises are maxed out, or near so, making modifications a difficult thing to justify.

 

All it needs is a cabin structure with a canopy, and the mist bath for occupants would be a summer treat.