Latest Pandemic Daydream Syndrome, Jen Cay, the toy hauler ferry pontoon / beach house

This is 6.8m x 5m overall, 5m x 5m x 3m (+ some more on the top) house box, 0.6m height hull (0.3m trimaran hulls + 0.3m flat bottom). Guesstimate capable ~7000kg at 0.5m waterline. The purpose is for ferrying a large SxS ATV from ship to shore, can beach to sand. And voila! It's a beach house! So the load including ATV, fridge, washer, burner, oven, solar, batteries, A/C, watermaker, generator, black tank, gray tank, white tank, hot water tank, fuel tank, RV fuel station, propane... Guesstimate should be around 2000~3000kg typical load. It's for hoisting from a mothership crane to set on sea near shore, then tow by a RHIB to the beach. 4 electric outboard can help it self-propel a little bit (maybe if it's not windy)..

The white tank can be empty when deploying since there's a watermaker anyway. So the cargo loads should be close to 2000kg during hoisting. Thought is a full aluminum frame should be able to handle this. And guesstimate all the structures, frames, hulls, roof, walls, compartments, probably too around 2000~3000kg; with aluminum for most the load bearing, and FRP on top frames at the upper section for better weight & weather proofing. So guesstimating the crane could be hoisting up to 5000kg. It's hoisted on the top, the 4 red dots are the hoist points.

I have some questions.

The hulls use flat surfaces, supported with tube frames in hull. So it should be simple to build, just need aluminum plates. How thick the plate should be? Is 3/16 overkill?

Sands are loose material, but not exactly soft material. And aluminum is not nearly as abrasion resistant as steel. Would it be useful to add a coating? e.g. Like some of those epoxy based cargo holding paints?

The hoist points are definitely the most critical part of the design. Should these places use steel? Or maybe at least steel lined? I'm guessing it's probably not good match between aluminum and steel hooks? Or perhaps it's ok with all aluminum if strictly only use strap/slings (should be ok at this weight)?

There are 10 points in the frame that are critical and strongly reinforced (4 the hoist points, 4 corners at the base, and 2 at the mid section of the base). Instead of weld, rivet, and side plates, which may still leave some microscopic gaps for wiggles. But since melt point of Al isn't that high, what about this idea; weld, drill, then use special designed side plate both as reinforcing and mold, directly cast molten Al to form the rivet inside, and fill all other small gaps? There are probably numbers of sketchy technical aspects to this I'm sure? Any chance it can be done to rival weld? Had this ever been done before?

 

Can you explain, for the simple-minded like myself, what this is supposed to achieve ? I am confused.

 

The daydream idea is that some super rich dude has a 60m yacht and has a deck or even a support vessel to carry this thing. He regularly go hide in a uninhabited island, maybe his undeveloped private island, somewhere in the world. He can just drop this boat house in water from his yacht near the shore and tow it to the beach, live there a couple weeks, or months; explore the island in his favorite ATV. But of course, someone could just use this as a normal boathouse too. This is from a very simple & bored mind. Please, humor me.

 

The rich dude doesn't want to live on the luxury 60m yacht ? Why did he buy it ?

 

Even by a simple view, it appears to be too high and not a large enough hulls. You'll need to resolve how it does not roll over. The centers, pick one, all appear to be too high. It looks like a boat wake would roll her over.

I don't profess any expertise in stability discussions, but I would not ride in it. For one thing, the hulls don't appear to have enough volume for enough buoyancy foam to offset the hull weights and loads. I'd say if she rolls on her side, the quad and pax go to bottom fast.

Humored?

 

I am also completely baffled by this proposal.
Anybody with a 60 metre yacht is going to much prefer to stay on the yacht, rather than 'roughing it' camping on this wee 'houseboat'.
And from a design point of view re the buoyancy and stability, Fallguy is justified in expressing concern above.

It is all very well having an ATV on board (taking up most of the space it would appear - not much living space left over?) - but how are you going to get it on to the beach? You will need a ramp like a landing craft.
And you will only be able to use this ATV on a private island - if you try to take it ashore anywhere else, authorities will be jumping on you wanting to ensure that it is locally taxed, insured etc.
And most places do not allow ATVs to go roaming on beaches - certainly it is not allowed here.

And finally - anybody who has a 60 metre yacht wants their toys and accessories to look cool / sexy / chic - do they really want to be seen posing in a floating homebuilt garden shed / garage?

 

I actually am hoping someone can explain how safe centers are determined.

 

Humored very well here..

I can't really guess what rich like to do. Maybe sometimes they like rougher experiences?

Some the question did had a little thought on it. The pontoon can be pulled on beach with pulleys, ropes, and maybe winch tied to tree or rocks on shore. It's meant to slide up on sand. Stability issue is true for concern. Was trying to limit the footprint much as possible. Deck space is premium even on big yachts. In case the design is wrong... maybe then have to tie big inflatable pontoon to the sides to keep it from tipping over?

 

Fun idea! But if you just want to go a short distance from yacht to shore a barge style hull would be much more sensible and has a lower center of gravity. I see no advantage to a pontoon or multihull for this idea. Also less square would be better.

But an amphibian vehicle like a tender with retractable wheels or a "velomoboat" or even larger expedition vehicle or RV could be the better solution. You still live on your yacht at anchor but you can explore an island with a more suitable vehicle.

Another example would be the amphibian buses. But you could build something similar with a lightweight flat bottom displacement hull, then add wheels and a roof. With enough solar and driving slow enough they could be powered by solar and could have luxury accommodations.

With wheel hub motors it wouldn't be too hard to design and build an offroad capable boat with retractable wheels. People that are not super rich have build some crazy vehicles. As long as it doesn't have to be road legal and doesn't drive too fast for serious safety concerns on land to matter (say <30kmh).

Inspired by this thread I had an idea for a 10m (32') amphibian 1800kg trailer / landing craft that can carry a small car. Basically build a boat around a road legal trailer and have the front 2m being able to fold up and over for driving and unloading. If you can stay below 1800kg trailer weight the car wouldn't have to be too beefy. Maybe there will be a more compact electric vehicle soon that can pull this much and can power both the car, the boat and the hotel loads.

Fundamental flaw I suspect is that you shouldn't and are not allowed to just drive around on random islands. Some are private, some are nature preserves that require special permits, others have governments that regulate what kind of vehicles are legal. Of course for the super-rich fines are just pocket change.

 

The amphibian vehicle does make a great deal more sense

 

The old WWII Willy's Jeep was made in an amphibious version, sure to be something in that vein available.

 

@Dejay , Thanks for the thoughtful response. Maybe the achilles heel of this idea is indeed there is not really any unowned or unruled piece of land (or ocean); anywhere that's left anymore. Not nowadays... It's not the kind of days like some pirates can just stash rums on some beach somewhere, and nobody know or cares. There is probably indeed nowhere you can freely bring a motor onshore anymore.

But political practicality aside, I still think a quad would be lot more fuel efficient than an amphibian bus to explore the shores. It's about 800kg sitting in the center, so that should be quite significant center weight. The white tanks are also toward center and low. They can be filled up (after hoisted down to water) and act as ballast. (There are ramp doors that can keep the sea splashing in if it's sitting very low in water.)

Trimarans and cats mostly have rather square deck space because they can. So the trimaran hulls make this less square in water; and will take less length up on the carrier. Probably less beam than flatbottom too, beam space is even more at premium on ships.

Politics aside, I'd prefer this if compared to amphibian bus. A lot less mechanicals and fuel burn.

 

How about starting with one of these, sticking a quad in rather than a wheelchair, and then working out a simple camper within the remaining displacement?

Boats for disabled people — Wheelyboat Trust https://www.wheelyboats.org/wheelyboat-models

Or the super rich dude carries his linen marquee, solar fridge and firebowl in the wheelyboat too, and has a couple of flunkys to set it all up while he sips his cocktail?

 

hmm.. This is interesting. It's trading length for beam. If they have a V30 I'm sure it can work right out the box, the ramp should be wide enough for the quad!

 

@dreamingbarrierreef have a chat with @DogCavalry - he is building a 26' Sea Sled and one of his prime objectives with this boat is to be able to transport an ATV (along with other equipment and personnel) to different construction sites that he is working on.
Sea Sled madness. It’s in my brain. https://www.boatdesign.net/threads/sea-sled-madness-it%E2%80%99s-in-my-brain.63079/

@Tiny Turnip I do like the design of those larger Wheelyboats with the bow ramps - DBR. TT makes a very valid point re sticking with a simple and basic concept (like this) rather than the proposal in your original post.
You just need to add a bit of a limousine touch to it, and you will be well away!
Limo tenders for super yachts appear to be all the rage now.
Throw in some style like this Venetian Limo tender, and you could be on to a winner.
10.5m Venetian Superyacht Limousine Tender http://hodgdonyachts.com/10-5m-venetian-superyacht-limousine-tender/