sea-worthy amphibious craft?

[jkittel]

Rather then try to design an unsinkable live-aboard yacht, I have begun to wonder if the ability to go on land may be more valuable then the ability to safely submerge. When rough weather approaches the owner would move on land, going for the highest ground possible before 'laying anchor'. Performing maintenance and repairs to the hull single-handedly would be infinitely easier with the ability to simply drive up onto dry land. Furthermore the vehicle would already possess the means to escape to the sea if it's built as a backyard project.

However I have not found any existing amphibious craft that appears sea-worthy, and there are also many modes of traction that would allow the yacht to move across the land.

One method is with low pressure tires which evenly distribute the weight of the vehicle as well as provide buoyancy. This old popular mechanics article describes a cross-county cruise ship. http://blog.modernmechanix.com/2007/08/29/cross-country-cruise-ship/#more-2971

Treads are another method, and are particularly popular for multi-unit vehicles as one unit can help the other overcome difficult terrain. Of the tracked units I've found, the Arktos seems closest to the sea-worthiness desired. http://www.arktoscraft.com/gallery.htm. The downside of treads is that the buoyancy has to come from the vehicle itself rather then its locomotive units.

Between treads vs. wheels, which do you think would make more sense? The Arckos design seems better at handling difficult terrain then any vehicle that uses the Rolligon low pressure tires, however tread vehicles are very high maintenance and I would be worried about the long term exposure of the treads to sea water. Most amphibious vehicles are trucks or tanks that double as poor boats, however I am interested in a boat that can handle rough seas and also do a poor imitation of a land vehicle. What hull design do you think would make the most sense? Let’s aim for a maximum width on land of a triple-wide trailer home, or 16 feet.

[ted655]

"Between treads vs. wheels, which do you think would make more sense?"
With treads you'll have fewer water tight seals. Actually there are several already "swamp" exploration & construction equipped amphos. The technology is out there. Most use tracks. Do some more Googling.
.
Just how far OUT in a ocean will your contraption cruise. If it can't GET to any land in time, then what???
.
Give me a soundly designed & built boat with a sea-anchor! I will hove to & strap myself in my bunk, then tidy up & be on my way.
.
What you will have is a collection of anchors just waiting to sink. Good luck but please don't try to cross an ocean in it.

[kach22i]

Hovercraft, that's my choice - I own one.

Have you seen this?
http://forums.pelicanparts.com/showthread.php?t=125505&page=801

[Guillermo]

George had posted also this, some time ago:
http://www.youtube.com/watch?v=eaGLNcIkSm0

jkittel: do search these forums for "amphibious"

Chears

[rwatson]

For an affordable version of amphibious small craft try

www.sealegs.com

also Derek Kelsall has dome quite a bit of work on an amphibious catamaran. Try
http://www.kelsall.com/t1p.html

I am on your side - I have been tossing around the idea of a self launching small boat for years. The main reason to own a boat is to get to lovely unspoiled places in a bit of comfort - who needs to worry about getting onto that secluded beach on a small dinghy through the surf, and leaving the comforts of home hanging off a bit of string half a mile offshore.

I hope you come up with something I can afford to buy or build soon.
Go for it.

[Hotel Lima]

how about this?

http://www.maritimesales.com/UD10.htm

[safewalrus]

Be nice if it could fly too?


I think your chasing rainbows - like the motor sailer instead of 50-50 tou end up with 40 - 40 or slanted one way or another! Just asking too much! But best of luck in your search!

the Walrus

[la cage]

There was a huge Steel Cat built some years ago in Australia that circumnavigated Aus. Because of his trouble with slipping he built two powered rocker arms inside each hull at the balance point. This enabled him to walk the boat up the beach. In one instance for a longer stay he finished up in a farmers paddock. I like the idea of an ocean going boat that in tidal areas would be beached at high tide, and then raised at one end to level off. After your stay you move out at high tide. Of course it would make more sense if it was built using my method of construction. Cheers from down under. Peter Bourne. www.bourneboats.com.au

[rwatson]

That big cat sounds feasible - I wonder who the designer was.

The Sea Lark at Maritime Sales is a good start, but 7.5 knots in light seas, with a 2 metre draught is a bit of a different animal.

The link provided on You Tube was a great one - can also be found with a bit more info at
http://www.gizmag.com/go/6906/

It almost does fly!!!
A bigger version of this with accomodation and a bit bigger hull for bigger seas would be the go. I'm inspired!!!

Hey La Cage - you are just up the road from me in Drouin!

Keep up the good work everyone :-)

[la cage]

I think the big steel cat was designed by the builder. He wrote a book about his adventures. Wnston Boord the steel merchant in Warragul was his mate, he would put you right about it. Cheers Peter. wwwbourneboats.

[rwatson]

Yes I have read that book while waiting to get some steel cut. With a steel catamaran that size, no wonder his best mate was a steel merchant.
Of all the owner/builder tragedy stories, that was close to the top of the list.
Warrigal must be the home of home builders. Is "la Cage" insured ?

[alexlebrit]

I love the Fast Track, even got in contact with them about it, but never had a reply. I wonder if they're actually going to do anything with it, or whether it'll just die out.

One thing I did wonder though, on land the tracks are pushed downwards to provide suspension travel, on water they're lifted up so that the hull provides flotation at start up. I'd have thought once they'd built up speed though it'd be better to push the tracks down and lift the hull completely out of the water.

Think snowmobile on water and you'll see what I mean.

[kach22i]

I wonder if they're actually going to do anything with it, or whether it'll just die out.
I don't remember if it's the same company, but the US Military has contracted with some west coast ship builders to develop a LCAC (large hovercraft) replacement which looks very similar.

I posted it about a year ago. Its a monster of a tracked vehicle.

[kach22i]

I don't remember if it's the same company, but the US Military has contracted with some west coast ship builders to develop a LCAC (large hovercraft) replacement which looks very similar.

I posted it about a year ago. Its a monster of a tracked vehicle.

Found it, T-Craft thread:
http://www.boatdesign.net/forums/showthread.php?t=16917

[rwatson]

Had a chat with a company that does re-treads on rubber tracks. Tracks of this size would run to $AU10,000 each - and be at the mercy of ultra-violet, and the cables could be subject to rust from the salwater environment.
No wonder they spent so much on development.

[kach22i]

Had a chat with a company that does re-treads on rubber tracks. Tracks of this size would run to $AU10,000 each - and be at the mercy of ultra-violet, and the cables could be subject to rust from the salwater environment.
No wonder they spent so much on development.
The US Navy put 13.6 million into a robotic Jet-Ski (a single prototype)...............but I'm just a stupid taxpayer.

[Jongscx]

My first question was whether it was to be primarily a land vehicle or a boat. But you answered that already.

My suggestion would be a multi-hull, possibly a cat and have wheels fold into the middle. Now, did you want them to retract automatically, or are you fine with having to bolt them on/off each time?

Another idea might be a trimaran with the outriggers folding up. Then the wheels would extend down from there. You could then build a larger boat, because you would have the stability, but still stay at your 16ft width on land.

[jkittel]

Yes, I think Trimarin with folding outriggers is probably the best solution. Even if wheels are used instead of tread, large wheels are not cheap, and keeping them dry and protected during long voyages would be a big priority. I like the idea of folding outriggers because they could still be deployed on land, allowing the boat to generate electricity from a wind turbine both at sea and on land, albiet stationary.

Depending on how the outriggers are attached, they could be used as very slow moving oars to pull/lift/drag the boat at a mild 1mph. Something like the backswimmer beatle when its trapped on land...

[Jongscx]

Could you just use a bunch of small wheels? Although cost-wise, it may be the same...

moving them about would be more manageable, and getting individual units damaged wouldn't be so costly.

I was thinking about the old russian tanks that could have rubber wheels installed in place of the tread/runners... If you had to beach somewhere that had soft ground, you might be able to get some type or rubber tread to temporarily increase your footprint...

Not sure, it's late and I'm tired... but it sounds good while I'm typing it...:P

[rwatson]

Just to throw some ideas in the pot - I favoured a tracked version till I found out how expensive and delicate they were.
The speed thing on land is not important to me, but at sea a decent speed would be usefull.
The idea of solid tyres is along the right line I think - getting a flat tyre on a pneumatic tyre could be tricky, and they get bogged on sand easily.
I envisage one wheel on each side, an aluminium version of the old solid tractor wheels, the ones found on early non rubber tyred tractors. A solid metal rim (maybe with a layer of solid rubber around it), about 2 ft high and 3 ft wide for the boat.
They had ridges across the wheels to help with grip, and were wide enough to spread the weight across a large ground area.
Fitting this to a conventional hull is a design problem, but I have been looking at a Bolger design in boats called a step sharpie.
http://www.ace.net.au/schooner/fms.htm
It has a flat bottom with a step in it. These boats can get 30 mph with 100hp outboards, so that is great. The flat bottoms could allow the solid tyres to act as paddlewheels during the transition from water to land and vice versa. The flat bottom section makes it easy to have the wheels raise and lower as required.
I have attached a rough concept to illustrate the idea.
Could this work I wonder ?

[Jongscx]

Would it be better to have the wheels in the front? as they would be in contact with the ground sooner... then, it would skid on the hull for a while, until the rear wheels contacted the ground. Wear wouldn't be too much of an issue as this would only apply when you're having to climb a sandy beach (or i'm totally wrong on this one...)

I don't see the advantage of having a large metal wheel though, except for simplicity...

[rwatson]

Yes, there are some good points in what you say.
My thinking is as follows.
1) Only 2 main driving wheels, and the small retractable steering wheels at the bow for sheer engineeering simplicity. For a start, no need for suspension as a tricycle always has its feet on the ground ( similar to the other smaller amphibious boats sold by Sealegs in new Zealand)
2) Wheels at the rear, for the same reason tractors do - that going up hill, the weight provides traction to the load bearing wheels. Front wheel drive can lose traction.
3) Big wheels in diameter and width to handle sand, rocks and generally rough surfaces with about 2 tonne of boat.
4) The ability to 'paddle wheel' when coming ashore - when its too shallow and dangerous to leave the outboard leg down any more.
5) Simple agricultural engineering = low cost and maintenance

Lots of smaller wheels need individual suspension, lots of bearings to get salt in, go rusty or oxidise. Tall wheels keep their bearings out of the sand and constant immersion in salt water. There is also the problems of 'putting the wheels away" when motoring or sailing at sea - if they were left in place, they would create lots of drag. In the case of 'lots of wheels', we have the problems of supplying drive to numerous wheels - electrics and hydraulics are very expensive and prone to failure, and even more difficult to raise into the hull for sailing or motoring..

Sounds logical tonight - tommorrow - who knows :-)

[captaintrue]

A topic that I've mulled over here and there. I've even considered metal conveyor under the belly of a boat to make it easier to bring onto shore. A cat with retractable or removable wheel system (even small wheels--not all of them have to have 'drive' to them) would probably be idea on a cat.

Trailerable ~= Amphibious.
Anyways, if you think about it a trailerable multihull is essentially amphibious. Key thing if your catamaran, pontoon boat or trimaran is trailable AND is large enough to carry an ATV or a motorcycle or tractor or other machine capable of pulling it onto shore, you can have the best of both worlds--of course you'd need to get the ATV, motorcycle or tractor on shore via a tender. I'd give extra attention to hulls/skegs/floats toughened up in the forward sections for anything that I'd bring onto land frequently.

Adding A Winch.
Also, putting a winch on a boat could allow it to pull itself onto shore. One could go out from the boat in a tender, find a solid tree/post or the like and winch a boat onto shore. With the right lay of land one could use the same winch to get it the water again.

***
In any case, IMHO worthile would be the effort of making a hull capable of withstanding repeated grounding.

A cat, tri or pontoon boat would probably be a lot easier to add wheels to than a large monohull.

Also a powered wheel system (rather than a passive trailer or winched system) requires a bit more engineering and complexity. A towed or winched trailer or wheeled system ought to go a long, long way. Whereas a powered wheel system--as nice as it might be the complexity seems to be a bit much especially in view of the impact saltwater might have on even readily available components taken from buses or cars.

[rambat]

One of my favorites is the Orbiter, the design had a specific mission. IMHO amphibians need to be designed around their desired operation. Many try to be a great car and a fast boat but must compromise in the end. The Orbiter had to be designed as a liveaboard and a RV. Check it out at:

http://www.dobbertinhydrocar.com/Orbiter%20On%20Location%20(Water).htm

[Jimbo1490]

Having wheels wet all of the time (obviously) ruins any hydrodynamic efficiency such a craft might otherwise have. Thus the piss-poor hull shapes chosen by amphib builders; since it doesn't matter much they just make it pointy on the front, seaworthy and comfy/functional on the inside. But that's hardly a way to design a yacht, IMHO.

Why not have retractable wheels, you know, jet aircraft style? These could retract into wells or recesses built into the hull and be covered by a valance door when retracted. Or a sleek bulge could be faired onto the hull containing the retractable wheels. Either way, you get to have a real efficient boat hull shape when you don't need the wheels, which is most of the time.

I've attached a couple of pics of a Mitsubishi MU-2 for examples. The subject aircraft came both ways; with faired bulges that house the retracted gear and with the gear retracting into the hull proper.

Just as with aircraft, the valance doors need not be strong enough to stay attached if the wheels were extended under way; we just don't do that as it outside of the operating envelope :p They are only deployed when the craft is ready to 'land'.

Jimbo

[rwatson]

I have been mentally designing all sorts of methods , major considerations of weight and the interior room that is taken up with all the transmission, axles, controls etc is a real problem.
I have considered aluminium versions of the old all metal tractor wheels, 4wd and agricultural wheel items, rubber tracks etc etc.

At the moment, my mind is set along the idea of 'skis' or powered 'rubbing strips'

Imagine, if you can follow my twisted logic, the bottom of a hull having 4 longitudinal substantial strips of aluminium (or solid 'plastic' or whatever). 2 on the port side, two on the starboard
These 'skis' strips are like rubbing strips, faired to allow minimum disturbance in water flow, but much wider. They could even be set flush with the hull in grooves.

The difference to normal rubbing strips ends when these 'skis' can be extended away from the hull by about 6 inches or so (with what? - perhaps half a dozen hydraulic pistons like outboard raising mechanisms), raising the hull. They can also be pushed longitudinally towards the bow, or towards the stern

So, on beaching, they act as hull protectors, then the crew apply power to every second 'ski', This will lift the boat say 6 inches, and then power is applied to push the strips longitudinally to the stern, causing the boat to move forward.

Then the previously unused set of 'skis' lift the boat again, allowing the first set to be repositioned forward. This second set is then moved to the stern causing the boat to move forward, and the process is repeated.
The ski's on the port and starboard sides can be operated independently to allow steering.
The concept is identical to a skier walking on skis, except the ski-poles would be replaced with a second set of skis. (like someone having no arms but 4 legs, all with skis on them)

To my mind, this overcomes a few of the problems inherent in other concepts.
1) The major cost and complexity of tilting whole hulls.
2) Maximum surface area of contact with sand to prevent bogging.
3) Low down weight with minimum moving (wearing out) parts like bearings, rollers etc
4) made of materials that are not going to fail in marine environment like lots of little roller wheels on tracks
5) Assistance in protecting the hull during grounding
6) minimum intrusion into the hull
7) simple hydraulic drive mechanism with little room taken up in the hull

[Jimbo1490]

Yeah, I get it. It's not unlike the locomotion use by walking dragline excavators.

Jimbo

[rwatson]

Oh wow - it has been done! Thats great because there is half a chance it might work.
I still am wrestling with the method of activating it - something low maintenance, easy to install, robust.
For the lifting mechanism, maybe 5 or 6 hydraulic thingos on a hydraulic line or perhaps some sort of cam operated by a screw arrangement ?
Any ideas appreciated.

[Pericles]

Something like this would do as a superyacht tender.

http://www.gibbstech.co.uk/

Pericles

[kach22i]

The Orbiter
That's an interesting craft.

http://www.dobbertinhydrocar.com/Dobbertin%20Surface%20Orbiter.html
http://www.dobbertinhydrocar.com/DSO/ORBITER_AT_CHARLOTTE.jpg


http://www.dobbertinhydrocar.com/Orbiter%20On%20Location%20(Water).htm
http://www.dobbertinhydrocar.com/DSO/Orb_-_lake.jpg


Started out as this (click hull):
http://www.dobbertinhydrocar.com/Dobbertin%20Surface%20Orbiter.html
http://www.dobbertinhydrocar.com/DSO/Orbiter_Original_Hull.jpg

[captaintrue]

Yeah, I get it. It's not unlike the locomotion use by walking dragline excavators.

Jimbo
Ah yes I suppose its similar in conention. Good call.


http://www.youtube.com/watch?v=3sAH8xL2W30

As for what would make a craft seaworthy tends to touch upon of structural integrity, ballasting, keel (retractable or otherwise). IMHO a sea anchor is a must.

[rambat]

Big wheels with track like segments seen it before and it looks workable, maybe even for water propulsion, see attached

[rwatson]

The heading on the thread is
"Sea Worthy Amphibious Yacht"
Not much sail on some of these examples.
I think I have outlined my priorities elsewhere, but my preferences are for sail (for economy and safety in case of engine failure), and the ability to get up on a beach out of heavy swells.
Nothing quite so silly as leaving the yacht swinging on the end of a bit of rope while you negotiate the waves in a tiny inflatable. Thats why the marina's make such a lot of money - but who wants to explore remote marina's!
A lot of old sea captains negotiated their way around the world, only to be drowned while being transferred to shore in the longboat.

Rambat - I put up a similar concept (Big Wheels) about half a dozen posts ago - (old metal tractor wheels), but the room they take up, weight and transmission design , and hydrodynamics killed the enthusiam.
As a result, some other lightweight , hull protecting, low maintenance methods would win it for me.

[tspeer]

Derek Kelsall has a design for an amphibious catamaran (http://www.kelsall.com/t1.html). Wheels are mounted in the topsides of the hulls:
http://www.kelsall.com/images/designs/t1a2.jpg
http://www.kelsall.com/images/designs/t1a3.jpg

The hulls fold under the bridge deck:
http://www.kelsall.com/images/designs/t1a1.jpg

On the water, the wheels act as built-in fenders. On land, the boat can be trailered on the wheels. I don't see any reason why the wheels couldn't be powered, or why the design couldn't be scaled up. The beams could be hydraulically actuated.

Note how the beams are used to lever the hulls into place, and a cross-member added to lock them in place:
http://www.kelsall.com/images/designs/t1p2.jpg
http://www.kelsall.com/images/designs/t1p4.jpg

Given the seaworthiness of the catamaran hull form, I think this meets your criteria of a seaworthy amphibious vehicle.

[Kay9]

Wow and the tires act as built in fenders....Ingenous.

[rwatson]

yes -that also got a mention about a month ago on this thread. I am in regular email to him on these ideas. The killer for that idea is how to motorize the wheels, and do it with a flexible transmission - driven from a motor in the main hull.
Those mobile ladder platforms used in building contruction have steerable hydraulic motors, but they are not marinised and would probably be a mess in a short time. The size of the deisal engine used to power those ladder/platform machines is way to big for a small yacht.
If someone knows whereto get marine quality hydraulic wheel hubs - I would be over the moon. I have even checked those track add ons you can get for 4wd vehicles, but they arnt recomended for salt water. Getting power to them would have to be with axles as well.

[Kay9]

Why not use diesel electric....Give each wheel a small electric motor as well as the prop?

K9

[rwatson]

Same problem - any suitable marinised electric wheels out there ?

I sent an inquiry re deisal electric to OSSA Powerlite products some months ago, but they 'iced' me and didnt bother replying to my email after I explained the plan, and filled out their 3 page questionaiare. They probably dont work for under quarter of a mill!

[captaintrue]

re: drowning in a tender -- PFDs and safety should be of utmost importance.

Link that might be of interests re: amphibious catamaran--

http://www.youtube.com/watch?v=31Fc1y_vw3w

[rwatson]

Great product that sea-quad! Thats the sort of innovation we need in this boat world. Thanks for the link captain

[BMcF]

Here's an option..has a 45-knot open-sea capapability in catamaran mode and deployable/retractable skirt system for amphib mode. Bit pricey..only for the most descriminating yacht owner with very, very deep pockets. :D We are on the design team for this thing...pic shows it in amphib mode and I'm not sure I can show it with skirt system stowed...without permission from the project office.

http://www.fvn.no/multimedia/archive/00363/TCraft1_363072a.jpg

[kach22i]

Here's an option..has a 45-knot open-sea capapability in catamaran mode and deployable/retractable skirt system
I'm working on a design/model with a retractable skirt for heavy weather, but it's just a hobby.

Have you seen the inflatable attachment to the CB90? I'm assuming it's to extend it's rough seas capabilities with extra buoyancy.

http://www.navytimes.com/news/2007/06/navy_riverineboats_070616/
http://www.navytimes.com/xml/news/2007/06/navy_riverineboats_070616/nt_riverine3_500_070615.JPG

EDIT: Can you post anything on the 57 foot RC SES model yet?

[BMcF]

That pic of the Dockstavarvet design looks like it was taken at the floating causeway at the MACC exhibition at Little Crekk..been there with our own craft.:D

Should have some good pics to post of the 57' SES model soon..hulls are about complete and outfitting begins soon.

[kach22i]

BMcF, your image says T-Craft...........................I thought this was the T-Craft?

http://boatdesign.net/forums/showthread.php?t=16917&highlight=craft
http://the.honoluluadvertiser.com/dailypix/2007/Feb/20/FPI702200319AR_b.jpg

[BMcF]

BMcF, your image says T-Craft...........................I thought this was the T-Craft?

http://boatdesign.net/forums/showthread.php?t=16917&highlight=craft
http://the.honoluluadvertiser.com/dailypix/2007/Feb/20/FPI702200319AR_b.jpg

Yup..it was..one of the losing team's concepts.;)

[kach22i]

Yup..it was..one of the losing team's concepts.;)
I'd like to see all the concepts.

By the time I get my model working I bet somewhere and someone will have already built a better version of it in some Skunk Works.

Back to reality, I need to get an architectural proposal out, cheers.

[rwatson]

Yeah yeah - fling enough money at a concept and you can have bikini clad chicks carrying you everywhere in LearJets and bell helicoptors.
How about concepts that the average boat nut can build/buy that achieve the same thing.
Skirted amphibious catamarans are a good start, but the weight and payload for smallish craft are problematic.

[BMcF]

The one in the virtual pic I posted will carry about 400 tons payload. As for the cost...I'd be shopping for bikini-clad chicks..cheaper by far.:D

[rambat]

I would like to ask BMcF is there a reason to design fingers on the SES/Hovercraft (T-Craft) as you show? It seems the requirement is to only beach itself far enough on shore to unload the vehicles, would a simpler multi-loop skirt not do the job?

[captaintrue]

I dunno. Analysis says: its better to build a bit bigger to include a tender and tow the a wheeled multihill to the beach rather than building an 'all in one amphibious'--even if the ship has motive capability onshore, still seems more resourceful and economical to have it winch itself onto shore.

But yet still, its probably best to quit thinking automobile (landlubber gear) in your style of wheel placement. Also, a removeable chain drive seems to be the simplest and most cost-effective way to drive the wheels.

http://www.loyalhannadockyard.com/DUKW.htm

[rwatson]

The 'self winching' idea is an economical and efficient way to get a boat ashore - but its a bugger of a way to self launch.
To get onto a beach, you need get a line ashore , which means someone has to go over the edge in who knows what type of sea, while the boat gets pounded on the sand, then haul a light line up to somewhere solid, or haul an anchor up the beach, then probably get a heavier line attached, and then get back on the boat to start winching if they are by themselves.
Now we have to get the boat back to sea. Its ok if you remembered to put another anchor out before you took to land, but what if you crossed a sandbar on the way to another water body, or you are just launching the boat?
The DUKW has more or less demonstrated that big wheels will do the job, but at severe loss of efficiency in water. Also, before a DUKW gets wet, you have to close a number of cooling ports to the engine, and change some settings in the drive chain. If you dont, you sink. This is a major problem with semi conventional drive techniques.
Its true that a chain drive is simple and effective for many operations. However, in a marine environment (sand,salt etc) they are short lived due to the many rollers and links that it consists of. A chain that would move say a 2 tonne yacht would be pretty heavy to unfasten and store somewhere, and then you would have to wash and desalt it.
Another potential method that doesnt get a lot of press is an Oscillation thruster. This is a series of weights driven by and engine that work like a skipper of a small sailing dinghy who 'pumps' the boat forward with sudden movements of his body, creating forward momentum. I have read stories of how this technique is used for heavy equipment that has to be moved across say swampy ground where tracks dont provide enough grip or surface area.

[BMcF]

I would like to ask BMcF is there a reason to design fingers on the SES/Hovercraft (T-Craft) as you show? It seems the requirement is to only beach itself far enough on shore to unload the vehicles, would a simpler multi-loop skirt not do the job?

The requirement/objective was for the beast to traverse mudflats and beaches (within reason on grade and 'flatness') with a certain degree of autonomy and considerable range. Thus, a low-speed hovercraft skirt system was designed along the lines of those already used on 'tundra platforms' and the US Army's 'amphibious' barge conversion kits. It also had to be fully retractable and that drove a segmented skirt also..but for reasons that are much clearer if I could show the craft ins 'SES mode' and I have not found a public domain shot that would suggest I'm at liberty to do that yet.

As an SES in 'long range transit mode' the craft uses only waterjet propulsion with diesel prime movers and, of course, its lift fans. In high-speed SES mode, the air screws are also lit off. In amphib mode, only the air screws provide propulsion and steering control.

Since the craft is both a high-speed SES and a fully amphibious low-speed hovercraft (but not at the same time), it must have the SES bow and stern seals and the ACV peripheral skirt..and use both in amphib mode.

[tspeer]

...The killer for that idea is how to motorize the wheels, and do it with a flexible transmission - driven from a motor in the main hull....

Why would you have to motorize those wheels at all? You could have a single drive wheel on a strut that was lowered from the bridge deck. It wouldn't have as much traction as you'd get from having all the weight of the boat on it, but it would be adequate if the terrain wasn't too steep.

Actually, motorizing the main wheels isn't that difficult, either, if you go diesel-electric. Each wheel can have its own electric motor, with the genset in the hulls or bridgedeck. And with each wheel individually driven, you can steer with differential torque.

[rwatson]

Motorizing the wheels with either hydraulic or electric motors IS a great idea - just where do you get MARINIZED (rustproof/waterproof) drive unites from ?

I would be interested in a rough sketch of "a single drive wheel on a strut" that you have in mind, to see what you mean.

My thoughts against lowering wheels include strong enough suspension, flexible power trains and a whole host of other little problems.

[Jimbo1490]

You really will need to power most, if not all of the wheels for the thing to be practical. One traction wheel is just not going to cut it. It's hard enough to haul a boat and trailer out of a slippery ramp driving TWO wheels.

And I think wheels are the way to go rather than walking 'feet'. The complexity and expense/maintenance of a suspension is out of the question; tundra type tires get by that problem and help with load spreading, which is absolutely essential on a soft beach.

I have an idea that encompasses the above and more but it is hard to describe with words. Pencil sketches show the basic soundness of the concept but I've been too busy to sit for a CAD drawing lately. Maybe this weekend I'll get to it.

[captaintrue]

Motorizing the wheels with either hydraulic or electric motors IS a great idea - just where do you get MARINIZED (rustproof/waterproof) drive unites from ?

* Make them (use brass, aluminum brass...saltwater friendly metals)
* Take existing components and coat them with protective coatings?
* Strategic use of oil/grease

[A chain-drive could be disassembled, coated/treated and then reassembled.]

[kach22i]

Wheels and tracks are fine if you have something solid to grip on to. The idea situation is to go where they don't expect you, like a place really muddy or swampy or covered with thin or unstable ice.

[rwatson]

"Make them (use brass, aluminum brass...saltwater friendly metals)
* Take existing components and coat them with protective coatings?
* Strategic use of oil/grease"

Not feasible to interrupt a 100 a day production line, with the custom cast components that you had to have specially poured, and they wont warrant for performance due to lack of testing.
And you cant just coat components. Zinc adds size to parts, well outside close tolerances, and other coatings just dont cut it for long term performance.

I have just about given up on conventional wheel/track designs due to the potential expense and lack of marine standard components.

[captaintrue]

"Make them (use brass, aluminum brass...saltwater friendly metals)
* Take existing components and coat them with protective coatings?
* Strategic use of oil/grease"

Not feasible to interrupt a 100 a day production line...

...I have just about given up on conventional wheel/track designs due to the potential expense and lack of marine standard components.

Fair enough. And then there are coatings which few seem to pay attention to.

[SamM1234]

This may be a dumb idea; I didn't really think this through. But, what about extendable support poles similar to the ones you see on construction equipment. The support poles would retract completely inside the hull when not used and would not have any moving parts/mechanisms below the water line. This would not allow the boat to move over land, but would allow to come close to the beach and raise it out of the water. So, one could still have it close by and could sleep on it not feeling the wave motion, provided it is parked at high tide. Hull cleaning and maintenance tasks could be done easier while on poles too. I don't know if the wave action would bury the pole foundations in the sand though after a while. I've seen it happen with bridge supports if not protected by big rocks.

[kach22i]

Some duct tape, a snorkel and a oxygen tank and you could walk underwater with this.:D

http://forums.pelicanparts.com/showthread.php?t=125505&page=991
http://forums.pelicanparts.com/uploads12/330937928_bf6f55c436_o1200967755.jpg

[rwatson]

Ah yes - but is it MARINISED - and will it SAIL ??? :-)
The pole idea has potential, and has appeared on other discussions as well.
The transition from sea to land will be solved commercially for affordable prices one day - but will I live to see it ?
There must be some rich inventor out there ....

[SamM1234]

Well, I think a pole is marinized since it's just a piece of metal/other material with no moving parts. Perhaps, they can be hydraulically actuated similar to the ones on the vehicle above. Then, we need to see how much space and weight they take inside the hull to determine the performance/accommodations penalty. Was there a discussion about this in detail, can you send a link?

[rambat]

"Well, I think a pole is marinized since it's just a piece of metal/other material with no moving parts. Perhaps, they can be hydraulically actuated similar to the ones on the vehicle above. Then, we need to see how much space and weight they take inside the hull to determine the performance/accommodations penalty. Was there a discussion about this in detail, can you send a link?"

I think you are describing a Jack-up vessel, we have hundreds of them operating in the wetlands and shallow coastal waters here in the Gulf.

[creosote]

yes -that also got a mention about a month ago on this thread. I am in regular email to him on these ideas. The killer for that idea is how to motorize the wheels, and do it with a flexible transmission - driven from a motor in the main hull.
Those mobile ladder platforms used in building contruction have steerable hydraulic motors, but they are not marinised and would probably be a mess in a short time. The size of the deisal engine used to power those ladder/platform machines is way to big for a small yacht.
If someone knows whereto get marine quality hydraulic wheel hubs - I would be over the moon. I have even checked those track add ons you can get for 4wd vehicles, but they arnt recomended for salt water. Getting power to them would have to be with axles as well.

I'm posting to this thread because I think I found the boat I was looking for in a new thread.

Why not fix a low profile motorcycle tire to the prop of an electric pod like Azipod? The pod can already "steer" and is a marinized electric motor, it just needs a spring/shock absorber.

If that doesn't work, replace the prop with a pulley and drive the wheels with a belt or plastic chain.

[creosote]

Rwatson as writing about this...


Derek Kelsall has a design for an amphibious catamaran (http://www.kelsall.com/t1.html). Wheels are mounted in the topsides of the hulls:
http://www.kelsall.com/images/designs/t1a2.jpg
http://www.kelsall.com/images/designs/t1a3.jpg

The hulls fold under the bridge deck:
http://www.kelsall.com/images/designs/t1a1.jpg

On the water, the wheels act as built-in fenders. On land, the boat can be trailered on the wheels. I don't see any reason why the wheels couldn't be powered, or why the design couldn't be scaled up. The beams could be hydraulically actuated.

Note how the beams are used to lever the hulls into place, and a cross-member added to lock them in place:
http://www.kelsall.com/images/designs/t1p2.jpg
http://www.kelsall.com/images/designs/t1p4.jpg

Given the seaworthiness of the catamaran hull form, I think this meets your criteria of a seaworthy amphibious vehicle.

[cthippo]

Some duct tape, a snorkel and a oxygen tank and you could walk underwater with this.:D

http://forums.pelicanparts.com/showthread.php?t=125505&page=991
http://forums.pelicanparts.com/uploads12/330937928_bf6f55c436_o1200967755.jpg

What keeps it from sinking into the bottom?

[irv]

Kach221, Yes the navy has built some very experimental stuff. I work at PSNS and some of its still here. Some have been sent to dremo and bought for pennys on the thousand. Just a while ago, a guy bought a experimental boat built by Boeing that was just sitting behine the industrial area for 30 some years or more. Not sure how to access it but the military does have a web site that offers all their back yard clutter thats no longer classified. You might not find what you want, but some of the parts can be had for sure.

[kach22i]

the military does have a web site that offers all their back yard clutter
Would you by chance have a link or a few key words I could Google?

I was looking for the cooling fans on an armored vehicle a while back and could find nothing at the so-called surplus sites.

[creosote]

The road wheels that we are used to have many problems in the sea. How about a different kind of wheel? Rolligon.

http://www.youtube.com/watch?v=cXcuinvxsoY

Tundra and deep snow.

From http://albeerolligon.com/history.htm

On the day the Rolligon idea was born, Bill was returning with a group of Eskimo hunters from highly successful walrus hunt. Cut off from their village and usual landing place by an ice-floe, they were forced to beach their heavily loaded sealskin boat on a steep, rocky beach. The boat, filled with five tons of the Eskimos’ winter meat supply, was in danger of being cut on the sharp beach rock. However primitive ingenuity prevailed. On the spot, the stone-age hunters blew up several tightly-sewn sealskins, converting them into crude pneumatic rollers. On these pillow-like bags they were able to pull the heavy craft over the sharp rocks and steep gravel bank to safety

A low pressure tube...:idea: RIB sponsons.

Make a trimaran with rolligon styled sponsons for the outriggers. Rotate and roll on them up the beach.

[creosote]

If the point is just to get on the beach, keep the rolligon outriggers in position and roll sideways onto the beach, like a crab. If the rolligons were less bouyant, you have a SWATH.

If you're okay with spinning outriggers.

http://gsl.erdc.usace.army.mil/gl-history/images/gl_img_93.jpg

Floating Archimedean Screws that propel the vehicle in water and drag it onto shore.

The toy company Tyco built one:

http://www.youtube.com/watch?v=5yIkxN-2BLM
(It hits the water at 2:15)

Note that the US Army's review and the youtube video show that this concept doesn't work well on hard surfaces.

[rwatson]

Its interesting that this topic has resurrected itself about the time I was inspired by a recent event to rethink the amphibious yacht. I had taken my 'non sailing' partner down to a yacht club, to get some experience with 'off the beach' dinghy sailing. She took it all in good spirits, getting wet and cold during the launch, wet an cold during the mandatory capsize practice, and cold and tired hauling the dinghy on its trailer up the beach to the club house.

Unfortunately, a couple of other attendees were quite put off the idea from this experience. I was reminded of those two person, heavily ballasted dinghys used for handicapped sailors that dont capsize. ( see Access Dinghys
http://www.youtube.com/watch?v=JBA-zFJ3M94 )

If we made the ballast from batteries, could we use the power to have them propel themselves down the beach and into the water, and then back onto the beach after a sail ? maybe along the lines of
http://www.sealegs.com/

Us oldies like the concept of sailing without suffering.

[creosote]

Their biggest Sea Legs can carry itself and 700 kg of a payload onto the beach. How much does a sailboat weigh?:confused:

[rwatson]

Their biggest Sea Legs can carry itself and 700 kg of a payload onto the beach. How much does a sailboat weigh?:confused:

or how long is a piece of string - a sailboat can weigh 300 kilos to 3 tonne - its just a matter of beefing up the landing gear.

The Access dinghies I was talking about are only about 300 kilos inclusing the ballast, so I am not sure why you are confused.

[creosote]

Because I got wrapped up in the idea of big power cats and monohulls with ballast.
As I looked at the sea legs website, I saw a lot of boats parked on the sand. So as the weight goes past 700 kg, it's going to need more wheel area to keep from sinking in the sand. With more wheel "floatation" it would be a shame if it just became ballast when in boat mode.

"Waste not, want not."

[rwatson]

Because I got wrapped up in the idea of big power cats and monohulls with ballast.
As I looked at the sea legs website, I saw a lot of boats parked on the sand. So as the weight goes past 700 kg, it's going to need more wheel area to keep from sinking in the sand. With more wheel "floatation" it would be a shame if it just became ballast when in boat mode.


Maybe you could think of monohulls with lots of water ballast - that way you can dump it on landing.

The wheels and sand problem was one of the reasons that I favoured the 'walking frame' idea I mentioned back in post 26 ( dragline locomotion )

I was pondering the concept yesterday as I sat on the rocky seashore whacking oysters on the head and devouring them. Rubber tyres and sharp oyster shells would be a problem. They are all over the sandy beaches down here.

The other night I was watching 'batman returns'. He did a 'revolving car' trick by putting down a big hydraulic 'foot', and lifted and rotated the whole car on it. I gotta have one of those as well.

[creosote]

There is one thing that batman never worries about: Where to store all those gizmos.

http://www.outdoorsmagic.com/gear-news/biggest-swiss-army-knife-ever/4173.html

[BATAAN]

DUKW was preferred by southern California coastal survey crews due to its safety in surf. I have seen (and will try to find) a series of photos of one of these ugly floating trucks on a 15 foot breaker, serenely making its way to shore and taking soundings all the way, then drive along the beach, turn and go back out into the surf until outside the breaker line, turn and make soundings a certain distance, turn and surf ashore again, all day long. This was in the 1940s. Nothing else could have done the job and the driver/coxswains were amazed at the ability of the things.

[kach22i]

I think it was around 1973 when I was 13 years old that my family took the DUKW/duck ride on lake Michigan and the sand dunes. We went up a river with high cliffs and a few million dollar homes perched above. It was a blast, wish I had some photos.

[rwatson]

The LARC amphibious truck at

http://www.maritimesales.com/DUS10.htm

seems to be still for sale since 2007. Now $120,000

[BATAAN]

LARC is the the successor to DUKW and many have been used in tourist businesses around the world. What with the down economy everywhere, not so many people paying for rides in funny floating trucks.

[thehildi25]

Hey guys, Im pretty much new here. I just recently finished my prototype amphibious vehicle. The hull is filled full of foam an the canopy roof is hydraulically operated. Right now I am awaiting a final test with an electric outdrive that I ducted (Kort's Nozzle). A goal of mine would to make this vehicle seaworthy (reproductions), but not necessarily the prototype. Check out the website for pictures.

www.HCFabrications.webs.com

[rwatson]

Not exactly seaworthy yet, but a fun start. How did you seal the driveline from water entry ?

[thehildi25]

Hi RWatson, Its a rear engine vehicle based off of the VW chassis. So there isn't a driveline, just a transaxle. Which is encapsulated to the axles of the rear tires. My most current video the one where I drive it into the water gave me an Idea of what I need to take care of and the angle that my craft will sit. I added a lot of displacement since that video and figure to sit even higher. I also made some hydro inserts that could be inserted and attached in the side air intake duct, creating more displacement and directing flow under the vehicle.

Rob

[Kaluvic]

I'll jump in here....Ive also been doing some modeling/messing around with this idea.
Some thoughts....

The boat would beach stern first so that the bow is always to any surf, that means that the rudders (in my case 2) have to fold up out of the way...something like the way a Hobie's do.

Tracks would give a greater surface area for "floating" on the wet sand...two track pods (one port and one starboard) would deploy through the hull like aircraft landing gear....these two pods would be located so to carry around 85% of the weight.

Each pod has a hydraulic drive motor on the pod...this reduces the drive "linkage" to hoses.

When the tracks are retracted into the hull, the doors are closed and the water evacuated....they don't stay submerged.

Forward is a single pod with twin wheels side by side...its not steerable but is allowed to rotate like the tail wheel on a tail dragger.

The boat is a mono...I have two designs...in one, the the tracks deploy from the sides of the bilge keels....

This boat is quit large....like 20 meters LOA...the idea is to be able to crawl out of the sea and back in again...not necessarily to travel any great distances over land.

I recognize that this doesn't really meet the inexpensive/retro fit type application that may be the intent of the thread...but it may have some validity.

[rwatson]

I liked the idea of tracks till I started making inquiries of track makers.

Tracks can be :-
Steel - waaaay to heavy and prone to rust out
Aluminium - dont get made at all, they are not strong enough for day to day use
Plastic/Rubber Compound - will degrade very quickly in a marine environment. Limited use in freshwater exposure.


Overall though, the "crawl out", "crawl in" concept would be useful. In a Cyclone Yasi scenario, you could get well above high water.

Way, way back in the amphbious discussion, there was mention of a large steel catamaran that "walked" up the beach into a field, by having two hydraulic arms mounted each side of the centre of hulls, and simply lifted and pushed its way over the sand. Nice, simple approach - and the hydraulics would be easy to stow.

[Tiny Turnip]

http://www.youtube.com/watch?v=3mr_pCrhTkk

[Kaluvic]

The tracks would be rubber, I'm not sure why the life span would be shorter than that of a tire or the tube on a shaft log?
I've had tracks on a Jeep that I've used all seasons for about 5 years and also on a couple quads...I'm very impressed with their resilience.
The jeep tracks have carbon fiber rods that run from side to side "cast" in to the construction of the track...I believe this is to give stiffness in that direction.
The tracks I propose for the boat, would not be the same shape as what I've got on these vehicles....more like a lower profile version of these http://www.landluvr.com/models.htm with drive capacity....(these are pull behind)
Being able to get out when bad weather is coming would be great...but I'm think-in it would be used way more often for more mundane reasons...like destination planing may look very different if you no longer have to worry about a safe anchorage.

Tiny Turnup...pretty cool video....thanks.

[rwatson]

The tracks would be rubber, I'm not sure why the life span would be shorter than that of a tire or the tube on a shaft log?......

The are *exactly* the gear that I spoke to the local rep about. They were sending a shipment to Antarctica at the time. Not only did he say the rubber couldnt be guaranteed in a marine environment, but the three-wheel attachment would also not be suitable.

Considering that the cost was well of $aus12,000, I wasnt happy to take the risk.

I am guessing that sun,sand and salt water are a far more toxic combination than snow and fresh water environment. I would love to hear differently.

[Kaluvic]

Could be...I haven't exposed them to sea water.
I'm not really figuring on buying off the shelf...its probably all custom.
There seem to be folks out there with the expertise that you can work with.

[creosote]

If tires rot in the sun and saltwater, why not paint them? You have to paint steel to protect it, and steel is cheeper than Monel. There must be a paint that is cheaper to use than reinventing vulcanized rubber tire.

[Kaluvic]

If tires rot in the sun and saltwater, why not paint them? You have to paint steel to protect it, and steel is cheeper than Monel. There must be a paint that is cheaper to use than reinventing vulcanized rubber tire.

Interesting point.

[rwatson]

Painting flexible things doesnt seem to work very well. If its soft enough to flex, it rubs off easily. If its tough enough to not flex, it cracks.

I suspect that its the constant immersion of rubber in saltwater that is a problem. It rusts the steel belt, as well as cracking the rubber. The supporting metal (wheels, axles etc) of the rubber has to be a problem as well, but since it doesnt flex, paint would be a big help. No different than a trailer. Sealing the bearings and drive shaft is the bigger problem. Saltwater is compressed into the rubber seals, and eventually rusts the steel.

However, there is an oyster farmer here in Tassie who built stainless steel axles and differentials for semi amphibious trucks. It reduced the maintenance, but it still made for a lot of work.

[creosote]

"Saltwater is compressed into the rubber seals, and eventually rusts the steel."

If you have a source of freshwater on board then you could create a system to apply a counterpressure of fresh water from the inside of the seal area.

There are many makers of automatic lubricators that supply oil and grease to maachines, adapt that to supply freshwater to a seal at a pressure slightly higher than the pressure of the sea water. This would probably require two sets of seals, but if salt water is that bad, it could be worth it.

[Kaluvic]

I'm thinking the tracks can be rinsed after stowing and the fresh water evacuated from the chambers.
I really think the salt water can be dealt with.

[creosote]

Off-road tire makers claim to have kevlar belted tires, if this is steel free then they would make a great choice for moving across the sand.

I was thinking about the DUKW and its central tire inflation system. Air is much more available on the sea than fresh water, so use that instead of water to provide back pressure against the seals. If the air leaks into the boat, no problem. A central air system could also power an air ride suspension, and air rotors to move the wheels.

[BATAAN]

This may make some craft suitable for assaulting a beach under fire or crawling above the hurricane surge but it'll all take away from what makes a good, responsive boat. I'd sure love to see a scale model, even in non-functioning mockup or computer generated form, to refine the idea.

[Kaluvic]

Creosote....that's exactly the idea.
I have long believed in the benefits of stored energy in the form of compressed air on my "Dream Boat"...not the only stored energy of course.

Bataan ...I'm no where near clever enough on the computer to come up with a computer generated form...but I'm a big fan of scale modeling. I've been working with a meter long rough model for some time now. The design has now evolved sufficiently to necessitate building an updated model....I plan on starting the lofting Sunday.
We're talking "work" model ...not pretty, but dimensionally accurate.

I did contact a well known boat designer thinking that for a few grand I could get some preliminary lines and calcs done....that was naive of me.

[hoytedow]

http://www.spiegel.de/fotostrecke/fotostrecke-76402.html

from http://www.boote-forum.de/showthread.php?t=143441

[rwatson]

http://www.spiegel.de/fotostrecke/fotostrecke-76402.html

from http://www.boote-forum.de/showthread.php?t=143441

oh yes - I want one ..... Santa !

[hoytedow]

I, too, think its cool.

[hoytedow]

http://www.spiegel.de/fotostrecke/fotostrecke-76402.html

from http://www.boote-forum.de/showthread.php?t=143441

Check the video: http://www.youtube.com/watch?v=Ceh9pJeD6QA

[kach22i]

Amphibious vehicle Iguana 29: Out of the water
http://www.spiegel.de/fotostrecke/fotostrecke-76402-10.html
http://cdn3.spiegel.de/images/image-295072-galleryV9-ngot.jpg

I like it, some nice photos too.

[rwatson]

I wonder if the plans are for sale ?

[Squidly-Diddly]

1)SeaWorthy AND RoadWorthy AND Soft Sand/Swamp Worthy

2)SeaWorthy AND RoadWorthy(needs a ramp or gravel, but then does OK on roads)

3)SeaWorthy AND Soft Sand/Swamp Worthy(has tracks or limited drive like SeaLegs, not able to be used in traffic).

4)SeaWorthy AND RoadWorthy....with good provision for dragging itself past sand or mud with a winch and/or "sand ladders".


I don't know of any #1, because I wouldn't consider any military landing amphibs to be "seaworthy", even if some guy crosses the Atlantic in one. Some guy did that in a Klepper, but I wouldn't rate those as "off shore".

I'm not sure if there is anything but #3.


I'd like to see an aluminum hull boat with with recesses for truck size tires that would fold down, with either electric or belt drive with 4x4.

Basically a 30-40' cabin cruiser or trawler with 8' beam which would drive a bit more cumbersome than an RV. Like an underpowered, overloaded jacked up 4X4 RV. Able to drive in traffic and on HWY, just have to take the hills and curves nice and easy, but definitely boat based, not RV based like that converted bus.

[Tiny Turnip]

Is self launching a useful phrase ? You surely aint going to want to commute far on road in an iguana, but I guess if you can afford one, you probably won't need to commute...

Not sure what counts as seaworthy. Here's a couple of very different films, each very capable and very entertaining in its own way...

http://youtu.be/3mr_pCrhTkk

http://youtu.be/UO4cw565V98

[spidennis]

I wish these links still worked, I'd like to see this!

Derek Kelsall has a design for an amphibious catamaran (http://www.kelsall.com/t1.html). Wheels are mounted in the topsides of the hulls:
http://www.kelsall.com/images/designs/t1a2.jpg
http://www.kelsall.com/images/designs/t1a3.jpg

The hulls fold under the bridge deck:
http://www.kelsall.com/images/designs/t1a1.jpg

On the water, the wheels act as built-in fenders. On land, the boat can be trailered on the wheels. I don't see any reason why the wheels couldn't be powered, or why the design couldn't be scaled up. The beams could be hydraulically actuated.

Note how the beams are used to lever the hulls into place, and a cross-member added to lock them in place:
http://www.kelsall.com/images/designs/t1p2.jpg
http://www.kelsall.com/images/designs/t1p4.jpg

Given the seaworthiness of the catamaran hull form, I think this meets your criteria of a seaworthy amphibious vehicle.

[rwatson]

I wish these links still worked, I'd like to see this!


http://www.kelsall.com/Designs/KSSAK18.htm


and other photos

[spidennis]

http://www.kelsall.com/Designs/KSSAK18.htm


and other photos

thanks!