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Sea-Dog
14-10-2010, 07:29 AM
Sometimes the brain tends to wander a bit.

Mine went down an odd path yesterday when it started wondering how a boat would ride if the outboard was mounted at the bow instead of the stern.


Would the outboard jump out of the water when going over waves?
Would the ride be flatter?
Would the boat have to be reversed onto trailer?
How would a foil act?Man, I think I need to go fishin'

stinky-stabi
14-10-2010, 07:54 AM
WTF???? you need to stay away from those orchy bottles

LoungeLizard
14-10-2010, 08:05 AM
This is proof that too little fishing can drive a man crazy

Homer_Jay
14-10-2010, 08:13 AM
The netters mount their outboards in the centre of the boat..... so I guess it is just one more step!

But seeing as though the outboard in the centre hasnt taken off in the mainstream market... then I guess it has no benifit other than to keep the props away from the net!

Now did someone say orchy bottle????

Marlin_Mike
14-10-2010, 10:23 AM
WTF? You been drinking those pink girly drinks? Or sniffing the Green Ginger Wine? :):):)

Camhawk88
14-10-2010, 01:47 PM
Same as if you relocated you arse to the top of your head-
very bloody ordinary I would imagine

ric
14-10-2010, 02:52 PM
Mine went down an odd path yesterday when it started wondering how a boat would ride if the outboard was mounted at the bow instead of the stern.


Depending on number of engines there are a couple of things that can happen

1. install 1 etec motor to front - boat goes no where
2. install 2 etec motors to front - boat goes no where + sits slightly bow down.
3. install 3 etec motors to front - very frowned upon..... most of us normally only carry 2 anchors

:)

finga
14-10-2010, 03:17 PM
Sometimes the brain tends to wander a bit.

Mine went down an odd path yesterday when it started wondering how a boat would ride if the outboard was mounted at the bow instead of the stern.
Would the boat have to be reversed onto trailer?Man, I think I need to go fishin'
Well funny you should mention that.
Here's an old picture I found with the original 'Idle Hours' in it.
It was on it's way to getting a cabin put on it.
I don't know why they always put it on the trailer backwards but there must have been a reason.
It had a Holden grey motor with a 3 speed Holden gearbox going straight to the prop shaft.

Chimo
14-10-2010, 03:36 PM
Twas probably easier than moving the trailer wheels, looks like with the bum to the car there was a lot of weight on the tow bar, if the boat was 'right" way round the poor old holden could have had its back wheels in the air..........

C
C

murf
14-10-2010, 07:28 PM
Sometimes the brain tends to wander a bit.

Mine went down an odd path yesterday when it started wondering how a boat would ride if the outboard was mounted at the bow instead of the stern.


Would the outboard jump out of the water when going over waves?
Would the ride be flatter?
Would the boat have to be reversed onto trailer?
How would a foil act?Man, I think I need to go fishin'

hahahaha def go fishing Mate :)

cheers Murf

Gon Fishun
14-10-2010, 07:41 PM
Manouverability would be good.Probaly need traction control for cornering.;D

Sea-Dog
14-10-2010, 08:04 PM
Well funny you should mention that.
Here's an old picture I found with the original 'Idle Hours' in it.
It was on it's way to getting a cabin put on it.
I don't know why they always put it on the trailer backwards but there must have been a reason.
It had a Holden grey motor with a 3 speed Holden gearbox going straight to the prop shaft.

Certainly make it easier for beach launching.

White Pointer
14-10-2010, 10:35 PM
Certainly make it easier for beach launching.

G'day,

In power boats a front drive boat is comparable to a front drive car ... except that the sea doesn't want to play the game. So we keep propulsion at the rear. But we have learned to use auxilliary propulsion with thrusters and auxiliary engines for manouvering so I think we are doing pretty well.

Are you OK now?

Regards,

White Pointer

Sea-Dog
14-10-2010, 10:37 PM
...

Would the outboard jump out of the water when going over waves?
Would the ride be flatter?
Would the boat have to be reversed onto trailer?
How would a foil act?Man, I think I need to go fishin'

[It feels a bit weird quoting myself]

There are crazier ideas though:

Mount a boat on skis (hydrofoil),
Use a water pump to propel boat (jetboat),
Make a barge with vertical take-off/landing (hovercraft),
Mount a mini-bike hooked up to an industrial pump into a bathtub (jetski),
Mount a conveyor belt underneath a mini-bike in a bathtub mounted with skis at the front (snowmobile)All that aside -

I'm not thinking of building one, just thought it might promote some discussion a bit beyond just taking the piss. (Some of which was very funny ;D )

Actually addressing the physics involved might prove to be interesting, or at least mildly entertaining.

Why are outboards (almost) always mounted at the stern?

What pros and cons are there for bow mounted main propulsion - dragging the boat along instead of pushing it where you want it to go.


I imagine a front mounted outboard would have clean, undisturbed water - got to be more efficient, although somewhat more vulnerable to damage.

If the bow profile was right - she'd cut through waves, whereas a stern-mounted outboard pushes the bow skyward when the bow meets the waves - Forces in two directions.

No more bow rising to climb onto the plane - the whole boat would just lift a bit.

I think on tight turns at speed the bum might be a bit skittery if you didn't have external keel/deep V bottom.

If a foil was fitted (like an SE sport or Permatrim) the effect of trim up/down would be greatly enhanced. Might be a bit too sensitive to downward trim??

Any thoughts?

Sea-Dog
14-10-2010, 10:45 PM
G'day,

In power boats a front drive boat is comparable to a front drive car ... except that the sea doesn't want to play the game. So we keep propulsion at the rear. But we have learned to use auxilliary propulsion with thrusters and auxiliary engines for manouvering so I think we are doing pretty well.

Are you OK now?

Regards,

White Pointer

G'day WP,

I was responding to Finga's post about his boat with the bow at the rear of the trailer.

Make it easier with the bow pointing into the waves, that's all.

Not doing OK yet - still have unresolved questions as per prev post which I posted before viewing yours.

What do you mean the sea doesn't want to play the game?

Just an exercise in thinking - that's all.

Cheers, Sea Dog

MyEscape
15-10-2010, 05:01 AM
Way, way too much time on you hands

eugah
15-10-2010, 05:40 AM
Were you visiting Nimbin at the time you were thinking of this? It would explain things


Adrian

finga
15-10-2010, 06:15 AM
Oi. My mum was born in Nimbin....:(

Jarrah Jack
15-10-2010, 09:02 AM
Oi. My mum was born in Nimbin....:(

Now I get it..:)

Defore
15-10-2010, 09:05 AM
Every time you take a wave over the bow the motor would drown.

And it would be really scary trimming the motor up, to see the propeller coming up through the bottom of the boat ;D

Ian

dreemon
15-10-2010, 10:53 AM
But you wouldn't have to worry about triming it up if it's mounted to a realllllllly long bow sprit with a jack plate so that you can raise the motor out of the way of a big wave,

Wait,.. . . forget it, won't work cause you'll have no place for your anchor :-?

Sea-Dog
15-10-2010, 08:51 PM
Every time you take a wave over the bow the motor would drown.

And it would be really scary trimming the motor up, to see the propeller coming up through the bottom of the boat ;D

Ian

How often do you take a wave over the bow?


Trimming direction of course, would have to be reverse of normal.

Trim down - moves toward the hull (obviously limited to just a few degrees. Who wants to bury the bow?)

Trim/tilt up - moves away from the hull.

Good to see you're thinking though - a better attempt than some of the intellectual midgets here.

Or does nobody have a grasp of basic physics? I remember something in a book about pearls and swine :-X

Lets put this in a different light so the simpler ones can understand the concept of motive force from the front of a vessel.

Does a boat handle slop any differently when it is being towed, compared with when under its own power? Does the bow rise as much?

I don't recall seeing any boats taking water over the bow whilst being towed, unless they were already full of water.

Its the old lever and fulcrum coming into play. The longer the lever - the easier to lift the load.

In a normal boat the lifting end of the lever is the bow, the moving fulcrum is the wave.

Bow hits wave, and bow (hopefully) lifts easily with the height of the water surface.

Front of boat now has upward momentum and outboard still travels along at same height as previously, attempting to drive the hull forward at the outboard's level.

The wave continues to travel towards the stern acting as the fulcrum, so the bow accelerates its lifting movement.

As the wave travels toward the stern the balance point of the boat is reached and the gravitational forces pushing down on the bow exceed the lifting forces so the bow slows its rise, then begins to drop.

Stern then climbs over the wave, still trying to push in a straight line which is now pointing toward the sky.

Reach the top of the wave with the stern, no water under the hull and down she comes with a splash/slap depending on hull construction.

Then the fun starts all over again..

You can simulate the effect by holding the end of a pen about a centimetre below the edge of a table/bench etc (to simulate a wave.) and trying to keep the end you're holding at that same height (like the outboard) push the pen towards the table and as you get about 4cm from the edge of the table with the the end you're holding - the front end shoots towards the sky.

Now... simulate the effect of the propulsion coming from the front end of the pen. Hold the tip of the pen about 1Cm above the level of the table and pull the pen onto the table.

Notice the difference? - Smooth motion isn't it?

Nice if that could be tranlated to a tinnie.

That's why my questions.

Cheers, and have fun with your pens.

Surething
15-10-2010, 09:09 PM
I tink that the rain needs to stop, the sun needs to come out, some minds need to stop wondering, and some serious fishing needs to be done!!!

rando
15-10-2010, 09:38 PM
I think Ive seen this concept on Quantum,They were however doing tests on ships rather than small vessels.
The results were interesting, better steering response & better fuel efficiency.
The japs have done the tank testing and are up to sea trials on a prototype , i cant remember the details but it was a pretty big ship.

warti
15-10-2010, 11:27 PM
Common theme there. All big vessels that are heavy and their nose doesnt really get airborn. Motors on the front of a fishing boat would be air born half the time and fuel efficiency would be out the window. Plus youd look like a ######.

Rodpal
15-10-2010, 11:59 PM
ha ha ha unreal man, i love the bit would the boat have to be backed onto the trailer haha its as crazy as roasting your nuts which of cause i like to do haha

oldboot
16-10-2010, 11:31 PM
all these ideas look silly if you are making the asumption that it is a plaining hull, and fast.

If it was a displacement hull with a high bow and the motor was infact inside a false bow...it could work quite well........don't all the rick fishos have bow mount motors.

even better would be to have a boat with not front or back and a motor each end.......not only could the boat go in any direction but slow manoverabilty would be excelent.....you could approach or depart a warf sideways.


Hmm.... that sounds like the James Holt Ferry.( now the island)... that thing used to dock sideways.

Of course you would have to arrange for the motors to rise verticaly for trailering or shallow water.


As for the boat backward on the trailer.....if it is a prop and fixed skeg.....there is no ouboard in the way..so you can trailer it backwards.

You fellas that drive on think you are smart..........that thing you could drive it off..and if someone else was dealing with the car.......a very quick getaway.


Some of the rescue lifeboats in the UK go on the slip trolly backwards and they launch straight out of the lifeboat shed fully loaded props running.. ...down the slip rails.

cheers

Sea-Dog
17-10-2010, 08:28 AM
One other possible effect of front propulsion & steering would be less likelihood of broaching in a following sea.

All you'd need is a skeg at the rear, like a surfboard or inboard ski-boat and the front could be pulled around in the direction you want the boat to be pointing.

I am surprised and pleased to hear that the concept has been explored on quantum, and the japanese are up to prototyping.

Perhaps Nimbin has been a popular international tourist destination for the egg-heads......


As someone suggested - motor at each end, like four wheel drive for boats. The pushme-pullyou boat. I can't really see many applications for this, but that's only my set of blinkers. Hmmm

I just had a look at Volvo-Penta's website because I remembered playing with a simulator based on their IPS system. http://www.volvopenta.com/volvopenta/australia/en-au/marine_leisure_engines/volvo_penta_ips_old/Pages/ips_900.aspx

Its the undisturbed water concept again. However these units are still rear-mounted. Interesting though.

shrunken pojie
17-10-2010, 10:47 AM
As someone suggested - motor at each end, like four wheel drive for boats. The pushme-pullyou boat. I can't really see many applications for this, but that's only my set of blinkers. Hmmm

Landing barges like the Manta Ray and the Sydney Ferries both do this. Not sure how and the quick google I just did didn't help.

Captain Seaweed
17-10-2010, 12:09 PM
Sea dog, are you available for a trip Monday or Tuesday off Mooloolahaba, we need to get you fixed up quick smart. It hurts to see a man go down like this! Just kidding mate I need your brains on my boat mate!!

Marty

dreemon
17-10-2010, 03:02 PM
Sea-Dog, what type of boat do you have in mind for the use of front engine ? rec, commercial, fishing, etc, and what sort of length ? sounds like offshore use . . so how do you think it would react on bar crossings?