Teardrops n Tiny Travel Trailers

Hello

Welcome to my first post on tnttt.

I only, as of about 2 weeks ago, discovered tnttt and the idea of diy trailers, and foamies in general. My head is racing with ideas of building a foamie camper on a 5x8 trailer, but I think I will attempt a slightly different project first, while I continue planning my camper.

I came across some YouTube videos that I’m sure several people here have watched, linked below, called “The Tesla Catamaran”, and its follow up video “Taking the Tesla Boat out on the water!”

The Tesla Catamaran

https://www.youtube.com/watch?v=6BMskpsLiYA

Taking the Tesla Boat out on the water!

https://www.youtube.com/watch?v=8qXxXzXERKU


These videos are packed to the brim with facsinating, entertaining information. It is a bit tough to do them justice here, so I’d suggest at least skimming the first video a bit. They basically build some pontoon runners using plywood, fiberglass and epoxy, and they connect the two runners together using a frame made from metal pipe. Ultimately, they finish with a very modular vessel, that you can easily take apart, and toss on a trailer. The runners are approx 16 ft long, and the entire vessel is about 10 feet wide. The runners are about 21 inches tall.

I want to try to build one, minus any of the Tesla battery parts (I’ll use 12V car battery).

I have a small cottage on a lake in Nova Scotia. I would like to basically copy this design, except for a few details.

- Replace the use of wood, with foam where possible
- Replace the use of metal pipe with an appropriately sized PVC pipe
- Cement the PVC frame together, as it doesn’t need to be modular. It won’t leave my property/lake
- Bolt the Cemented PVC frame into each of the 2 holes on each pontoon (similar to how they do it)
- Use PVC tees at 16” on center, across the deck frame to create ‘joists’ for decking
- Use PVC lumber as the decking, across PVC pipe ‘joists’
- Remove the horizontal metal brace under the decking that is used for a swamp motor
- Use hot wire cutting when possible, as well as a router if needed
- Control motor speed forwards and backwards, on the deck, using an arduino, and 50A motor drivers
- Control motor steering with a linear actuator, using the same arduino, and ln298n motor driver
- Make the electronics modular so that things can be taken apart quickly

I think I have all the gear and know-how required to variable drive my two Minn Kota C2 30 endurance trolling motors, which draw something like 25 amps at max power. I have two “Cytron 30A 5-30V Single Brushed DC Motor Driver”, which allow you to control the speed and direction of a motor using an arduino.

I found some electric actuators that I hope to use to control the steering for each motor. This is done using the arduino, as well as the ln298n motor driver, which allows you to control the extension, retraction, and holding position of an electric linear actuator.

I think I can get some waterproof twist-lock plugs for the motors and actuators, as well as some waterproof connectors for the control system on deck, down to the main power case under the deck.

I started this thread to be a platform for ideas, discussion, and progress. I understand that this is also information overload, and I may’ve missed some details or considerations.

I’ll include a rough sketch to give an idea of what I was thinking for bracing the deck frame into the runners.




I have questions that I am just going to start firing off here, to get some opinions.

1. Do you think I could use 1” XPS foam for the initial runner frame? I will try to get high compressive strength foam

2. What size PVC do you think would be suitable to make the boat frame out of to support 3 adults. I am a bit lost with this, so any discussion or suggestions are welcome.

3. I want to make the runners 16 feet long, and I dont want to butt joints end to end, so I will have to combine 3 8 ft lengths of XPS together. Is it okay to do a stepped joints, instead of a scarfed joints? If so, what would you suggest for the run of the step. If the step can be smaller, perhaps I could use two sheets, and make it a bit shorter then 16 feet.

4. If the PVC pipes that act as the joists on the deck frame make sense, would it be better to have parallel or perpendicular to the runners, for the purpose of strength? The deck boards will be attached to these joists using stainless nuts and bolts.

Alright, I think that is enough for now to start me off. Give me everything you got!

T

Remember that water can exert a lot of force.

I'd plan to glass the foam for the floats inside and out, at least on the bottom. That will give strength and rigidity. Glassing just the outside means you are relying 100% on the fiberglass for strength. The foam will add little in that configuration.

I'd use 2" rather than 1". It will be easier to work with. Make sure you glass both sides of a splice. It will make it easier to handle. Don't worry too much about gluing the foam together. The foam will break just past glue joint on even the best joint. Rely on the epoxy.

You'll want bulkheads inside your floats. It'll make it easier to assemble and keep it from filling with water if you damage a float.

If you've never worked with epoxy, build something small first to get used to it; a canoe or dingy or even just a box. You don't want to be in a situation where you find out you forget something or you have epoxy kicking off because underestimated how fast you can apply it and mixed up too much.

This is the only thing with your plan that jumps at me:

(I’ll use 12V car battery).

At the very least, you'll need to use an RV/marine battery since car batteries are built for a quick starting serge. Maybe you're already there.

I run a Weize 50 amp lithium for my Minkota trolling motor for my drift boat. They're only $190.

Tony

Pmullen503 wrote:Remember that water can exert a lot of force.

You'll want bulkheads inside your floats. It'll make it easier to assemble and keep it from filling with water if you damage a float.

I plan to basically copy the bulkhead layout that is used in the Tesla Catamaran video, more or less. They also epoxy in their bulkheads so that none of the bulkheads can flood. I believe they include 1 waterproof hatch on top of a bulkhead on each runner. They also closed off the hole inside the coupler that they place the boat frame into on the runner, so that bulkhead can't flood either. I intend to copy that, but haven't decided on how to do that yet.

Here is a screenshot from 25:48 into the Tesla video where you can see the bulkhead layout on a 1:4 scale model made out of thin plywood, as well as scale completed model in the background.

tony.latham wrote:This is the only thing with your plan that jumps at me:

(I’ll use 12V car battery).

At the very least, you'll need to use an RV/marine battery since car batteries are built for a quick starting serge. Maybe you're already there.

I run a Weize 50 amp lithium for my Minkota trolling motor for my drift boat. They're only $190.

Tony

Good call Tony. I was a little loosy-goosy with my language there. I guess in my mind's eye I didn't have any particular battery style in mind, except for that it would be a big, fat honker of a battery, maybe 100 ah 12v. Suggestions welcome.

...fat honker of a battery, maybe 100 ah 12v. Suggestions welcome.

A 100 ah AGM only has 50 usable amps and will weigh about 70 pounds. This is the battery I bought for my troller:

https://www.amazon.com/gp/product/B08ZMMG2K4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

It, too, has 50 usable amps but weighs 15 pounds. I used it all fall and really like it. Ask me in seven or eight years how it's doing, but it's guaranteed for ten. We shall see.

My Minkota is their 55 model. I almost always run it on the low setting for trolling and think I can squeeze six hours out of it. If I were planning on running on high for extended periods, I'd be looking for a 100 amp lithium. But you can do the math for your needs.

Tony

Now that I look at the screenshot showing the completed scale model in the background, I wanted to clarify about another aspect of my planned build that resembles the model, but is different from their final version. I will copy the style of boat frame the model has, where the vertical supports come straight up out of the runner coupler, as opposed to the final build they did, where the boatframe is rounded 90 degrees into the runner coupler. In my case, the boat deck would end up being a rectangle about 9 feet wide, and maybe about 6 feet long. I would deck the whole thing and perhaps include a ladder on the left or right side of the boat frame, if its tenable. On the other side, I am thinking and planning some sort of floating small ramp or staircase that i can easily deploy so that my dog can climb back up if he jumps into the water when we pause to swim, or whatever. He likes to swim a lot still but his hips aren’t so great, so some sort of small, non-slip set of plastic stairs or something. Still chewing on this.


Completed fullsize build, with rounded frames going into the runner couplers


completed scale model with square frame


A rough version of what I was thinking for the framing, including approx locations of pvc pipe joists on the boat deck.


I was thinking that each of the 4 boat frame pipes that come up straight out of the runner coupler go be cemented into a 3 way PVC fitting, and you could then connect the sides of the frame on end near each runner, and then place 7 more pvc pipe ‘joists distributed down the rectangle with tees on either side of the frame, and pipe cemented in between.

PVC fittting at top of each vertical pvc pipe coming out of each runner coupler.


A simple tee that would connect the 7 pvc pipes joists running across the frame.



Does anyone have a suggested starting point for plastic pipe that might be appropriate for the frame?

T

tony.latham wrote:

...fat honker of a battery, maybe 100 ah 12v. Suggestions welcome.

A 100 ah AGM only has 50 usable amps and will weigh about 70 pounds. This is the battery I bought for my troller:

https://www.amazon.com/gp/product/B08ZMMG2K4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

It, too, has 50 usable amps but weighs 15 pounds. I used it all fall and really like it. Ask me in seven or eight years how it's doing, but it's guaranteed for ten. We shall see.

My Minkota is their 55 model. I almost always run it on the low setting for trolling and think I can squeeze six hours out of it. If I were planning on running on high for extended periods, I'd be looking for a 100 amp lithium. But you can do the math for your needs.

Tony

Thanks Tony, that is really interesting. Admittedly, the world of LiFePO4 batteries is one that I am really not too familiar with, but it seems like I'll have to learn quickly! Something that I would like to do is to rig up some system inside the battery compartment, so that when I am parked on shore, I can charge the battery using shore AC power and a long extension chord. I currently have a charger that can handle AGM, but I presume that LiFePO4 batteries are more intricate when it comes to charging.

but I presume that LiFePO4 batteries are more intricate when it comes to charging.

They do take a different charging regime. I use this one:

https://www.amazon.com/gp/product/B004LWVEKS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Tony

Looks like I could go with a LiFePO4 12v battery system, and I could have a plug socket wired into the battery compartment box, and that plug socket could be wired to a contactor switch whose coil is activated when 12v goes through it, and this 12 volts could be controlled as a part of a 3 position switch on the battery compartment box. Middle position is off, right position sends 12v to the "Main" contactor coil that routes the 12v batteries power through to the "main" power system of the vessel. Turning it to left position could send 12v through the "charging" contactor coil, which would connect the 12V battery system directly to plug socket mounted on the box.

From there, I just have to plug something like the following LiFePO4 charger into my house power. I could snip off the jumper cables, and wire on a 120v plug and then plug an extension cable into that and run it down to battery box power socket. I guess I could snip off the jumper cables and wire in a female plug socket, so that means that I would need a male plug socket mounted on the battery compartment box. Only thing that spooks me about that idea so far is when I am getting ready to charge the battery, and I turn the switch to activate the "charging" line. That would mean that the male plug socket is live at that point. It would have a plastic cover of course, but that borders close to unsafe. Luckily I just had an idea to install additional secret "on" switch that also has to be thrown for charging or "mains" functionality to occur, and only people who should know about it, will know about it.

https://www.amazon.ca/lifepo4-charger-Fully-Automatic-Lead-Acid-Desulfator/dp/B09CGYLD8Z/ref=sr_1_8?crid=1URP15GOET0IT&keywords=lifepo4+battery+charger&qid=1674019208&sprefix=lifepo4+battery+chager%2Caps%2C89&sr=8-8

I will presume that I'll pick up a 100 ah LiFePO4 battery for this system, even though it'll be a bit costly. If I take care of it, it'll hold its value.

Earlier today I had actually ordered a 12v DC Voltage/Amp/power display screen, I'll have to see if this would work with the LiFePO4 battery as well.

https://www.amazon.ca/gp/product/B07T8GN61Z/ref=ppx_yo_dt_b_asin_title_o00_s02?ie=UTF8&psc=1

I was also thinking a bit more about originally wanting to make the frame out of some type of PVC but perhaps that is complicating my life unnecessarily. In the tesla catamaran video, he uses 2.5 inch OD aluminum tube for his frame, and perhaps I should do the same. It would be a bit heavier, but there will be plenty of buoyancy, and I also do not ever have to ever carry the frame more then 25 feet. I can still do my frame in the way previously described, vertical pieces coming out of runner couplers, and forming a rectangle deck, but using aluminum pipe and fittings now instead of pvc. I will have to look into the types of fittings that tube have available. Hopefully there are similar corner and tee pieces.

I guess I will plan to go forward with metal piping now, rather then pvc.

There's always schedule 80 PVC pipe .... a little heavier , gray , and lots stronger...

The secret of PVC outside is to paint it as the sun weakens the plastic over time , becoming brittle .... We've made many Bows now with PVC (Archery) and it works a treat , and you can heat bend it into many shapes , just don't scorch it when heating ...

GPW wrote:There's always schedule 80 PVC pipe .... a little heavier , gray , and lots stronger...

The secret of PVC outside is to paint it as the sun weakens the plastic over time , becoming brittle .... We've made many Bows now with PVC (Archery) and it works a treat , and you can heat bend it into many shapes , just don't scorch it when heating ...

I keep jumping back and forth on plastic vs metal for the frame. Plastic seems like it would be much more convenient to both work with, and obtain locally from big box stores, but I wasn't sure if it would have the strength to maintain the frame I proposed. I'll take a look at sched80 pvc, any suggestions on size? I want to maximize strength but also make it doable to get fittings locally .

In terms of other things related to this. I have ordered up most of the electronics for the motor speed control, and actuators for steering, as well as a few other odds and ends like GPS, temperature, etc. I would like to make a little testbed that has a trolling motor connected to an actuator, and I can control the speed, forward/reverse, and direction of the motor, using an arduino. Hopefully this weekend.

Looks like the LiFePO4 batteries are a bit more expensive up here in Canada, so I'll probably have to pay like 260 cdn for a 50ah battery, as well as pick up a charger. I am going to put that off a bit longer until I am sure I am going to dive into this.

The framework I'm seeing in the video is chain link fence top rail and bolt-together corner castings for building your own, custom sizes of chain link gates. You can get that stuff at any of the bigger home improvement outlets
I had concerns about your using PVC pipe for the frame. I don't think the flexability of that stuff would lend itself well to what you're doing, especially in a floating structure.

I think you'd be setting yourself up for a failure of Youtube magnitude, but I'm just an "eyeball engineer", so it's just my opinion.

Roger

GTS225 wrote:The framework I'm seeing in the video is chain link fence top rail and bolt-together corner castings for building your own, custom sizes of chain link gates. You can get that stuff at any of the bigger home improvement outlets
I had concerns about your using PVC pipe for the frame. I don't think the flexability of that stuff would lend itself well to what you're doing, especially in a floating structure.

I think you'd be setting yourself up for a failure of Youtube magnitude, but I'm just an "eyeball engineer", so it's just my opinion.

Roger

Thanks Roger, my afterthought about plastic framing and questions of its rigidity was causing me to waffle. I'll go back to the idea of using metal now. Thanks for the detail about it resembling fence construction supplies, this had not dawned on me and its incredibly helpful.

I plan to somewhat build it by 'committee' of various sources, so I'm hoping to avoid any major failure. I think the whole thing can be planned out on paper roughly before ever touching a piece of gear, and its also the way I like to do things, and I think everyone here will be really helpful!

Hrm, now do I have any buddies in the 'fence' industry locally here.

T

There's always something simple ...