Very long and skinny pontoon hulls

Ad Hoc
I would really appreciate if you would help understand how would this kind of vehicle behave in reasonable conditions?

About 30' total length

A single 80cm dia aluminium pontoon type with inflatable fairing at the waterline and beam for stability and inflatable nose cone for "suspension, cushion, air-bag"

120hp air prop at the back above deck, power transmitted through prop shaft and raised up to the prop with chain drive. 1000cc motorcycle engine and enough fuel for average 200km range mounted in the pontoon well forward

 

Saqa, I am intrigued by the 'inflatable fairing' at the waterline, and also by your inflatable nose cone - could you give us some details (maybe even a sketch or two, or photos?) as to how these work?

Does this form the outrigger / ama that will be necessary for stability if the main hull is only 0.8 m. wide?

It all sounds very dubious to me......

 

Hi man
No outriggers. Just an inflatable v bottom boat with a socket for pipe fitted to the back third. An inflatable nose fairing resembling the bow of a wave piercing cat hull fitted to the front of the pipe. Total length of about 30'and nose fairing about 8' or so with a socket for the front of the pip

So the last third of the pontoon wearing the inflatable boat and front 1m inserted into the nose fairing
I am doing a drawing but will take some time

 

In order to do that, you need a design. Once you have a design then a means of comparison can be made.
Currently, all you have are "words" that decsribe what you wish for or would like.

I can describe in 'words'...a big red button, I press it and I am magically transported from my current location, to one shown on the dial of the button..say Paris, or New York, in an instant. The red button has a nice tacit feel to it, the platform I stand on..soft gentle, fluffy...it could even be a booth with piped water music and a/c... etc etc Great idea huh??

And that's the problem with words and "ideas". They can all sound wonderful and jolly well done, good idea..etc.
But in reality what is REALLY possible?

The only way to know this, is to Design the concept into something that is based upon sound science and engineering, rather than just 'words'.
That means taking time to understand some of the most basics, like weights, and drawing to scale. Sounds simple enough, yet when you draw to scale what you want then say, select a motor, for example, will it fit?
If it does, how much does it weigh?...and then how much does the whole DESIGN weigh...does the motor even exist in that size or power range?

One cannot escape the basics of design it is very methodological and yet, to many that are not designers/NAs, it is tedious slowing me down and why waste my time with such stuff and stop asking me silly questions etc etc.
And that's where it all goes wrong.

Ignoring the basics...

 

Saqa, the old story about boats is that you can have only two of the following, out of three parameters, speed, comfort, and economy, you seem to want all three ! I don't fancy your chances.

 

Ok thanks anyway. I asked for some help to understand those basics in the first place so I can make a start on a drawing that would make at least half a sense but no dramas on declining. Will try to draw something up

I once asked my local engineering shop if they can make a frame for a cube that is 2m x 2m x 2m with 3mm 100mm x 100mm aluminium extrusion using whatever cuts and joints they knew to be strong with 12 of those 2m long pieces. They asked for a drawing.......

 

Yes, one would think that building something like this would be intuitive - but by asking for a drawing to build to, your local shop is covering themselves against any possible later accusations that it was not built to the required spec.

What you are proposing Saqa is very different, and much more complicated - so much so that I think that none of us have a foggiest idea really as to what you are proposing, hence the requests for further information and sketches if possible.
I am sure that it is crystal clear in your mind, but we cannot mind read.

 

All pretty lighthearted from my end, including that while I cannot actually understand; "so much so that I think that none of us have a foggiest idea really as to what you are proposing", I can accept it

Maybe it's just the fact that I have spent a lifetime taking requirements verbally from prospective clients and turning them into drawings and physical objects to the clients thorough satisfaction

I find language and comprehension skills are disappearing from the human collective. Probably due to instant gratification from today's technological aids

The workshop is the engineering place. I am not an engineer. I do know my requirements. I have the job to offer. They should have the ability to take my requirements, do up a drawing, ask if that is what I had in mind then make it and charge me for the effort

If I raise that as a general question, no one is obligated to help as there is no job offer. Maybe someone might want to discuss the issue as a response to request to understand the basics to help get started on my own drawings, not an unreasonable presumption

I am rushing to finish my homemade chicken curry n rice. Then pick up my daughter from school. Then take her to after school swim lessons. Then pick up my wife from work. Then cook for the gyals. Then I might be able to do a drawing

No reason we can't try a language exercise in taking things literally

Again, since the medium of text suffers when conveying emotion, all very lighthearted

Take a 20' pontoon with 80cm dia and stick it 3' into a 13' long bow shaped inflatable bag

Stick 10' of the other end of the pontoon into a planing inflatable

Power it with 120hp of air prop and rudder

As much of the heavy stuff all well forward of the middle

How would she behave?

 

"stream of consciousness" ideas rarely land on the solution, you need a coherent approach starting with what the objective is, the other day you said you want to go fishing 70km away across a wide open bay, and be back by lunch, for cheap, you are starting well behind scratch with that kind of wish list

 

It depends, but very likely it would behave unpredictably.

 

A good way to

Do you mean she would be found lacking in directional stability or that there isn't enough precedent in existing craft to know what would happen?

 

You said it yourself... "rarely". I note that you did not say "NEVER"

 

Great.
So the basics of what though...?

 

I am trying to imagine this, but not succeeding very well.

So, we have a standard inflatable dinghy, and you basically want to put a long nose on it sticking out front?
If 10' of the pontoon is inside the dinghy (how is it attached?), and 3' is inside a 13' bow shaped inflatable bag (again, how is this attached?), then you will have a 20' long 'appendage' (for want of a better word at the moment) sticking out in front of the dinghy.
Is this correct?
How wide is the 13' bow shaped inflatable bag?

I am trying hard to picture this beast, but my mind is boggled.
A diagram or sketch is worth a thousand words - Saqa, please do post even just a simple sketch of what you have in mind.
It is no doubt crystal clear in your mind, but not in ours.

 

Drawing right now but might take me a while thanks man