how about a combo PWC & motorcycle?

[Squidly-Diddly]

Optimized for yacht to shore excursions, so you anchor out, and then easily get supplies and explore the land without:

Worrying about leaving your boat or outboard with strangers, and paying, dealing with and finding a place to tie up.

Dealing with renting, then returning a car or scooter, then lugging stuff from rental office to your(hopefully still) waiting boat.

I'm thinking about a modestly powered(500cc or less, probably 250cc) craft built for comfort and easy handling, with fat scooter tires like a Yamaha Zuma or Honda Big Ruckus.

Make the floats/hull out of same stuff used for plastic kayaks, with similar hatches for dry storage or lots of fuel or fresh water.

Big problem is how do you put your feet down to balance at stops. I think that is going to need to be a foot operated two leg kick stand.

Toothed Belt drive at rear wheel. Instead of a dedicated Water Pump or prop, maybe make the rear wheel a turbine with shrouds/fender directing the blast aft?

Steering by front wheel only?

Maybe have the entire front end(steering head, forks, wheel) tip forward up out of the water in PWC mode and lock down for scooter mode, or use that motion as front suspension.

If the floatation in front was split or just had a blunt nose with a straight lip it would be easy to securely mount the craft to the stern of the mother-ship at two points, for both easy boarding and use as emergency or auxiliary motor.

I'd also want to carry it on typical yacht stern staircases, probably on single
rail which could be bolted on or just ride on pads. Existing winches and rigging would haul it up and it would be tied off similar to method used to tie a motorcycle in the back of a pickup(just two point on either side of the bed and using the cycle's own front suspension as compression.

It would be nice if the hull/floats and cycle could completely disconnect easily and if both could then function separately, as unencumbered utility scooter and....some sort of extra big and wide messed up SOT kayak with a big hole in the middle spanned by a plank(row boat due to width?), or "paddle in the center boat"?

I'd like to settle on standardized Hard Points for hull and scooter mating, thus you could have some ability to configure a craft with more or less hull or scooter. 2 or 3 hull sizes and 125, 250, or 500cc scooter.

[claydog]

What ever it ends up being, it won't be very good as either a pwc or a scooter. That said, and knowing a snowmobile can cross and turn in open water with no floatation (you just need a running start ) maybe along the lines of a Can-Am Spyder could be modified into something like what your thinking of.

[Dave Gudeman]

How about just using the scooter engine to power a PWC, but leave the PWC hull at the shore and drive the scooter away? Without an engine, the PWC hull would not be very attractive to steal, especially if it only worked with a particular model of scooter.

The hull could be designed so that you can lock the scooter in it in an upright stance for riding. The front wheel is clamped to the PWC steering mechanism so when you turn the handlebars, it steers the craft. The rear wheel is clamped to a drum so that when the engine turns the rear wheel, it turns the drum and the turning drum powers a propeller or pump to drive the craft.

With this, the scooter doesn't have to carry the hull and other boat apparatus around with it so it could be made lighter and more efficient. You could do the same thing with a bicycle.

[Village_Idiot]

Claydog came closest...

Go with a snowmobile concept. Replace the skis with water-durable wheels with integral rudders on the shafts, or outboard of the wheel axles (you can even retain the skis in a hydrofoil/hydroplane fashion). Replace the belt with water-durable wheels on the rear of the machine, driven by chain (or belt) from above the water line. Integral saddlebags can be designed into the rear body that provide floatation in water, and storage on land. As necessary, extra floatation will need to be designed into the forward bodywork as well. It will be a "four-wheeler" rather than a "two-wheeler", so will be less efficient, but fewer issues with stability at rest. It will do neither job particularly well, but should do them nonetheless...

[fcfc]

Like this ? http://www.youtube.com/watch?v=CyFdGWxfl8g

[Squidly-Diddly]

as well as pretty heavy, I'm sure.

I was going for minimalist light weight low cost, low performance craft.

I'd be happy with 10mph in the water and 35mph on land, but hopefully under 300lbs and under $5,000.00, thus I would be OK for the wheels to be dragging in the water.

Probably a two person capacity tandem recumbent seating style, mostly to lower the center of gravity in the water.

A four wheeler is a possibility, but I'd be using 20" or 16" bicycle wheels and tires on a lighter weight 'quad' like a Rhoads, but tandem.

While detaching hull would be nice, I'd like it to be a true amphib and be able to cruise in and out of water and vise-versa as a unit. I'd want to be able to cruise from land, across some land, and out to sea.

[Village_Idiot]

Think 'inflateable pontoons/sponsons" attached to the bike frame outrigger style, with the beams able to rotate about the bike axis. Rotate up for land travel, rotate down and inflate for water travel. Air carries the most weight for the least hull weight.

[Doug Lord]

Originally Posted by Dave Gudeman

How about just using the scooter engine to power a PWC, but leave the PWC hull at the shore and drive the scooter away? Without an engine, the PWC hull would not be very attractive to steal, especially if it only worked with a particular model of scooter.

The hull could be designed so that you can lock the scooter in it in an upright stance for riding. The front wheel is clamped to the PWC steering mechanism so when you turn the handlebars, it steers the craft. The rear wheel is clamped to a drum so that when the engine turns the rear wheel, it turns the drum and the turning drum powers a propeller or pump to drive the craft.

With this, the scooter doesn't have to carry the hull and other boat apparatus around with it so it could be made lighter and more efficient. You could do the same thing with a bicycle.

------------------
Dave, I think that is an excellent solution!

[Wavewacker]

Squidly, I have given thought to similar contraptions as well. The problems I see about going small and light weight is the lack of power to pull its own weight. I have years of messing with go carts, mini bikes and off road contraptions using air cooled engines. The Rukus is a good start with pontoons, perhaps inflatables or using an existing inflatable boat with a frame that can attach to the bike. Falling over at stops is simple to fix with training wheels that can be dropped, but you should be able to balance it a hold it up.

There are motorcycle tires used for mud/sand drags that have a paddle tread or cupped tread. If you could could simply attach a tread over the existing tires, like snow chains, that could give you some propulsion, but you won't be pulling a skier. You could also incorporate a trolling motor.

I believe it will take at least a 500cc, 750 or even a 1000 cc might be better considering the following;

You will have additional weight of the amphi vehicle on the bike or trike plus the weight of two people. Most small bikes wont take the weight limit beyond two people....

Add to that the weight of groceries and supplies you may want to haul back....

You will need enough power to pull up grades, at boat ramps and out of banks along the water, not all grades would be like a beach....

Now, consider the speed of the vehicle, it's not getting to 30 or 45 mph, as much as it is getting it started and holding speed up a grade, I live in the Ozarks, even city streets can be hard to climb for a small hp engine.

If I were you, I'd go with a dual sport motorcycle and afix a simple frame to hold inflatable pontoons that you can drop off when beached. A quick release frame. The pontoons can stay on while you get to the boat and hoist the entire machione up at the stern, having some lockable frame attachment. But when you get there, unhook it and take off, lock the pontoons to a tree or whatever. This will put you on and off road, street legal.

I bought a 650 Honda Transalp for on and off road touring and trying to figure out ways to get it aboard or a boat/pontoon system for it. It weighs 325 pounds.....

Considering the cat you have, you should be able to take on any small contraption, for the money, I'd consider that awsome quad above, that's pretty cool, but it's not street legal.....

[Squidly-Diddly]

but with a squared off stern, and squared off bow(for easy attachment to mothership as mention before) and a Honda Trail 90cc or 110cc 4stroke driving smaller diameter, fatter tires to drop the gearing even more. Maybe 1/2 of a Honda 110's lowrange would be enough to haul the craft up a launch ramp with one person.

Instead of Training WHEELS, I'd use skids/mudpaddles...for hauling up past the squishy wet mud found at the water's edge in many spots. These would be operated by feet, so would be hands free in traffic, and use the legs braced against the backrest for hauling up.

My recumbent touring bike riding friends assure me handling of such a vehicle at 300lbs would be fine for it intended use, even in heavy crowded traffic and pedestrian dense areas found at marina areas and coastal towns.

The front and rear wheels rotate upward(not sure yet about whether forward or rearward) would be equipped with fenders that would roughly conform to the hull.

Now I'm thinking the water propulsion would be a separate unit, but driven by the same toothed belt, and not worry about having both the water pump and rear tire spinning on both land and sea.

So it would be mostly a fat SOT kayak with drop down wheels, instead of a scooter with floats.

A slightly bigger and slower version of this, with drop down recumbent bike fat tires. http://www.jet-kayak.com/jetkayakhawaiigt.html

http://www.jet-kayak.com/images/SurfangoHWb.jpg


I'm not liking the upright-cycle/detach-the-pontoons concept too much. Mostly because it isn't really an amphibian and seems like it wouldn't be an easy to store item on a yacht. I don't want to be stuck returning to the spot where the floats are(hopefully still) waiting. I also see major seaworthiness problems with a conventional upright motor cycle based craft, and seaworthiness seems more critical than land-worthiness.

[michael pierzga]

Im not sure if anyone mentioned this but its very hard to travel internationally with a motorized vehicle. Rules and regulations are dense. Customs will challenge you or The police will get you at the first roundabout. Better study up on what the best vehicle is for easy...below the radar..operation

[Squidly-Diddly]

and blinkers, and their heights, etc.

Things that don't apply to recumbent bikes.

What about internationally traveling yachts that carry PWC and motor dingys?

Are they allowed to operate in foreign ports? Don't all PWC in USA need US Coast Guard or DMV stickers?

[michael pierzga]

Never had a PWC.

Motorized Tenders are declared, then treated just like the yacht..registration, paperwork, many times you must even purchase a separate cruising permit for the tender.

With motorbikes and stuff the rules are not so clear. The most popular motorized vechicle on yachts is the electric bike or electric trik. Seems the police dont know what to do with them.

The italian Trik is a speedy shopper but a bit heavy.

The M55 is a lightweight rig, 40mph and 75 miles range

http://www.m55-bike.com/en/m55-bike-models/terminus

[fcfc]

Street legal and tender certification are country issues. I do not think US is as sensitive as spain on this point. And I do not think Spain can forbid a US guy using his US registered road object and his US tender temporarily on Spanish roads and waters. A Spanish guy would have much more problems.

What would be more of concern is corrosion. I am not sure a standard bike can resist very long with significative marine corrosion. And capsize. A small tender or PWC is likely to capsize one day or other.

[Dave Gudeman]

Originally Posted by Squidly-Diddly

I'm not liking the upright-cycle/detach-the-pontoons concept too much. Mostly because it isn't really an amphibian and seems like it wouldn't be an easy to store item on a yacht. I don't want to be stuck returning to the spot where the floats are(hopefully still) waiting. I also see major seaworthiness problems with a conventional upright motor cycle based craft, and seaworthiness seems more critical than land-worthiness.

I'd love it if you can come up with something truly amphibious, street legal, able to carry two people, simple enough that it isn't constantly breaking down, and light enough to be carried on small-yacht davits.

Unfortunately, I think "simple enough that it isn't constantly breaking down" rules out most of the suggestions on this thread.